SPIRV-Cross/spirv_cross.cpp

/*
 * Copyright 2015-2021 Arm Limited
 * SPDX-License-Identifier: Apache-2.0 OR MIT
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * At your option, you may choose to accept this material under either:
 *  1. The Apache License, Version 2.0, found at <http://www.apache.org/licenses/LICENSE-2.0>, or
 *  2. The MIT License, found at <http://opensource.org/licenses/MIT>.
 */

#include "spirv_cross.hpp"
#include "GLSL.std.450.h"
#include "spirv_cfg.hpp"
#include "spirv_common.hpp"
#include "spirv_parser.hpp"
#include "spirv_cross_util.hpp"
#include <algorithm>
#include <cstring>
#include <utility>

using namespace std;
using namespace spv;
using namespace SPIRV_CROSS_NAMESPACE;

Compiler::Compiler(vector<uint32_t> ir_)
{
    Parser parser(std::move(ir_));
    parser.parse();
    set_ir(std::move(parser.get_parsed_ir()));
}

Compiler::Compiler(const uint32_t *ir_, size_t word_count)
{
    Parser parser(ir_, word_count);
    parser.parse();
    set_ir(std::move(parser.get_parsed_ir()));
}

Compiler::Compiler(const ParsedIR &ir_)
{
    set_ir(ir_);
}

Compiler::Compiler(ParsedIR &&ir_)
{
    set_ir(std::move(ir_));
}

void Compiler::set_ir(ParsedIR &&ir_)
{
    ir = std::move(ir_);
    parse_fixup();
}

void Compiler::set_ir(const ParsedIR &ir_)
{
    ir = ir_;
    parse_fixup();
}

string Compiler::compile()
{
    return "";
}

bool Compiler::variable_storage_is_aliased(const SPIRVariable &v)
{
    auto &type = get<SPIRType>(v.basetype);
    bool ssbo = v.storage == StorageClassStorageBuffer ||
                ir.meta[type.self].decoration.decoration_flags.get(DecorationBufferBlock);
    bool image = type.basetype == SPIRType::Image;
    bool counter = type.basetype == SPIRType::AtomicCounter;
    bool buffer_reference = type.storage == StorageClassPhysicalStorageBufferEXT;

    bool is_restrict;
    if (ssbo)
        is_restrict = ir.get_buffer_block_flags(v).get(DecorationRestrict);
    else
        is_restrict = has_decoration(v.self, DecorationRestrict);

    return !is_restrict && (ssbo || image || counter || buffer_reference);
}

bool Compiler::block_is_control_dependent(const SPIRBlock &block)
{
    for (auto &i : block.ops)
    {
        auto ops = stream(i);
        auto op = static_cast<Op>(i.op);

        switch (op)
        {
        case OpFunctionCall:
        {
            uint32_t func = ops[2];
            if (function_is_control_dependent(get<SPIRFunction>(func)))
                return true;
            break;
        }

        // Derivatives
        case OpDPdx:
        case OpDPdxCoarse:
        case OpDPdxFine:
        case OpDPdy:
        case OpDPdyCoarse:
        case OpDPdyFine:
        case OpFwidth:
        case OpFwidthCoarse:
        case OpFwidthFine:

        // Anything implicit LOD
        case OpImageSampleImplicitLod:
        case OpImageSampleDrefImplicitLod:
        case OpImageSampleProjImplicitLod:
        case OpImageSampleProjDrefImplicitLod:
        case OpImageSparseSampleImplicitLod:
        case OpImageSparseSampleDrefImplicitLod:
        case OpImageSparseSampleProjImplicitLod:
        case OpImageSparseSampleProjDrefImplicitLod:
        case OpImageQueryLod:
        case OpImageDrefGather:
        case OpImageGather:
        case OpImageSparseDrefGather:
        case OpImageSparseGather:

        // Anything subgroups
        case OpGroupNonUniformElect:
        case OpGroupNonUniformAll:
        case OpGroupNonUniformAny:
        case OpGroupNonUniformAllEqual:
        case OpGroupNonUniformBroadcast:
        case OpGroupNonUniformBroadcastFirst:
        case OpGroupNonUniformBallot:
        case OpGroupNonUniformInverseBallot:
        case OpGroupNonUniformBallotBitExtract:
        case OpGroupNonUniformBallotBitCount:
        case OpGroupNonUniformBallotFindLSB:
        case OpGroupNonUniformBallotFindMSB:
        case OpGroupNonUniformShuffle:
        case OpGroupNonUniformShuffleXor:
        case OpGroupNonUniformShuffleUp:
        case OpGroupNonUniformShuffleDown:
        case OpGroupNonUniformIAdd:
        case OpGroupNonUniformFAdd:
        case OpGroupNonUniformIMul:
        case OpGroupNonUniformFMul:
        case OpGroupNonUniformSMin:
        case OpGroupNonUniformUMin:
        case OpGroupNonUniformFMin:
        case OpGroupNonUniformSMax:
        case OpGroupNonUniformUMax:
        case OpGroupNonUniformFMax:
        case OpGroupNonUniformBitwiseAnd:
        case OpGroupNonUniformBitwiseOr:
        case OpGroupNonUniformBitwiseXor:
        case OpGroupNonUniformLogicalAnd:
        case OpGroupNonUniformLogicalOr:
        case OpGroupNonUniformLogicalXor:
        case OpGroupNonUniformQuadBroadcast:
        case OpGroupNonUniformQuadSwap:

        // Control barriers
        case OpControlBarrier:
            return true;

        default:
            break;
        }
    }

    return false;
}

bool Compiler::block_is_pure(const SPIRBlock &block)
{
    // This is a global side effect of the function.
    if (block.terminator == SPIRBlock::Kill ||
        block.terminator == SPIRBlock::TerminateRay ||
        block.terminator == SPIRBlock::IgnoreIntersection ||
        block.terminator == SPIRBlock::EmitMeshTasks)
        return false;

    for (auto &i : block.ops)
    {
        auto ops = stream(i);
        auto op = static_cast<Op>(i.op);

        switch (op)
        {
        case OpFunctionCall:
        {
            uint32_t func = ops[2];
            if (!function_is_pure(get<SPIRFunction>(func)))
                return false;
            break;
        }

        case OpCopyMemory:
        case OpStore:
        {
            auto &type = expression_type(ops[0]);
            if (type.storage != StorageClassFunction)
                return false;
            break;
        }

        case OpImageWrite:
            return false;

        // Atomics are impure.
        case OpAtomicLoad:
        case OpAtomicStore:
        case OpAtomicExchange:
        case OpAtomicCompareExchange:
        case OpAtomicCompareExchangeWeak:
        case OpAtomicIIncrement:
        case OpAtomicIDecrement:
        case OpAtomicIAdd:
        case OpAtomicISub:
        case OpAtomicSMin:
        case OpAtomicUMin:
        case OpAtomicSMax:
        case OpAtomicUMax:
        case OpAtomicAnd:
        case OpAtomicOr:
        case OpAtomicXor:
            return false;

        // Geometry shader builtins modify global state.
        case OpEndPrimitive:
        case OpEmitStreamVertex:
        case OpEndStreamPrimitive:
        case OpEmitVertex:
            return false;

        // Mesh shader functions modify global state.
        // (EmitMeshTasks is a terminator).
        case OpSetMeshOutputsEXT:
            return false;

        // Barriers disallow any reordering, so we should treat blocks with barrier as writing.
        case OpControlBarrier:
        case OpMemoryBarrier:
            return false;

        // Ray tracing builtins are impure.
        case OpReportIntersectionKHR:
        case OpIgnoreIntersectionNV:
        case OpTerminateRayNV:
        case OpTraceNV:
        case OpTraceRayKHR:
        case OpExecuteCallableNV:
        case OpExecuteCallableKHR:
        case OpRayQueryInitializeKHR:
        case OpRayQueryTerminateKHR:
        case OpRayQueryGenerateIntersectionKHR:
        case OpRayQueryConfirmIntersectionKHR:
        case OpRayQueryProceedKHR:
            // There are various getters in ray query, but they are considered pure.
            return false;

            // OpExtInst is potentially impure depending on extension, but GLSL builtins are at least pure.

        case OpDemoteToHelperInvocationEXT:
            // This is a global side effect of the function.
            return false;

        case OpExtInst:
        {
            uint32_t extension_set = ops[2];
            if (get<SPIRExtension>(extension_set).ext == SPIRExtension::GLSL)
            {
                auto op_450 = static_cast<GLSLstd450>(ops[3]);
                switch (op_450)
                {
                case GLSLstd450Modf:
                case GLSLstd450Frexp:
                {
                    auto &type = expression_type(ops[5]);
                    if (type.storage != StorageClassFunction)
                        return false;
                    break;
                }

                default:
                    break;
                }
            }
            break;
        }

        default:
            break;
        }
    }

    return true;
}

string Compiler::to_name(uint32_t id, bool allow_alias) const
{
    if (allow_alias && ir.ids[id].get_type() == TypeType)
    {
        // If this type is a simple alias, emit the
        // name of the original type instead.
        // We don't want to override the meta alias
        // as that can be overridden by the reflection APIs after parse.
        auto &type = get<SPIRType>(id);
        if (type.type_alias)
        {
            // If the alias master has been specially packed, we will have emitted a clean variant as well,
            // so skip the name aliasing here.
            if (!has_extended_decoration(type.type_alias, SPIRVCrossDecorationBufferBlockRepacked))
                return to_name(type.type_alias);
        }
    }

    auto &alias = ir.get_name(id);
    if (alias.empty())
        return join("_", id);
    else
        return alias;
}

bool Compiler::function_is_pure(const SPIRFunction &func)
{
    for (auto block : func.blocks)
        if (!block_is_pure(get<SPIRBlock>(block)))
            return false;

    return true;
}

bool Compiler::function_is_control_dependent(const SPIRFunction &func)
{
    for (auto block : func.blocks)
        if (block_is_control_dependent(get<SPIRBlock>(block)))
            return true;

    return false;
}

void Compiler::register_global_read_dependencies(const SPIRBlock &block, uint32_t id)
{
    for (auto &i : block.ops)
    {
        auto ops = stream(i);
        auto op = static_cast<Op>(i.op);

        switch (op)
        {
        case OpFunctionCall:
        {
            uint32_t func = ops[2];
            register_global_read_dependencies(get<SPIRFunction>(func), id);
            break;
        }

        case OpLoad:
        case OpImageRead:
        {
            // If we're in a storage class which does not get invalidated, adding dependencies here is no big deal.
            auto *var = maybe_get_backing_variable(ops[2]);
            if (var && var->storage != StorageClassFunction)
            {
                auto &type = get<SPIRType>(var->basetype);

                // InputTargets are immutable.
                if (type.basetype != SPIRType::Image && type.image.dim != DimSubpassData)
                    var->dependees.push_back(id);
            }
            break;
        }

        default:
            break;
        }
    }
}

void Compiler::register_global_read_dependencies(const SPIRFunction &func, uint32_t id)
{
    for (auto block : func.blocks)
        register_global_read_dependencies(get<SPIRBlock>(block), id);
}

SPIRVariable *Compiler::maybe_get_backing_variable(uint32_t chain)
{
    auto *var = maybe_get<SPIRVariable>(chain);
    if (!var)
    {
        auto *cexpr = maybe_get<SPIRExpression>(chain);
        if (cexpr)
            var = maybe_get<SPIRVariable>(cexpr->loaded_from);

        auto *access_chain = maybe_get<SPIRAccessChain>(chain);
        if (access_chain)
            var = maybe_get<SPIRVariable>(access_chain->loaded_from);
    }

    return var;
}

void Compiler::register_read(uint32_t expr, uint32_t chain, bool forwarded)
{
    auto &e = get<SPIRExpression>(expr);
    auto *var = maybe_get_backing_variable(chain);

    if (var)
    {
        e.loaded_from = var->self;

        // If the backing variable is immutable, we do not need to depend on the variable.
        if (forwarded && !is_immutable(var->self))
            var->dependees.push_back(e.self);

        // If we load from a parameter, make sure we create "inout" if we also write to the parameter.
        // The default is "in" however, so we never invalidate our compilation by reading.
        if (var && var->parameter)
            var->parameter->read_count++;
    }
}

void Compiler::register_write(uint32_t chain)
{
    auto *var = maybe_get<SPIRVariable>(chain);
    if (!var)
    {
        // If we're storing through an access chain, invalidate the backing variable instead.
        auto *expr = maybe_get<SPIRExpression>(chain);
        if (expr && expr->loaded_from)
            var = maybe_get<SPIRVariable>(expr->loaded_from);

        auto *access_chain = maybe_get<SPIRAccessChain>(chain);
        if (access_chain && access_chain->loaded_from)
            var = maybe_get<SPIRVariable>(access_chain->loaded_from);
    }

    auto &chain_type = expression_type(chain);

    if (var)
    {
        bool check_argument_storage_qualifier = true;
        auto &type = expression_type(chain);

        // If our variable is in a storage class which can alias with other buffers,
        // invalidate all variables which depend on aliased variables. And if this is a
        // variable pointer, then invalidate all variables regardless.
        if (get_variable_data_type(*var).pointer)
        {
            flush_all_active_variables();

            if (type.pointer_depth == 1)
            {
                // We have a backing variable which is a pointer-to-pointer type.
                // We are storing some data through a pointer acquired through that variable,
                // but we are not writing to the value of the variable itself,
                // i.e., we are not modifying the pointer directly.
                // If we are storing a non-pointer type (pointer_depth == 1),
                // we know that we are storing some unrelated data.
                // A case here would be
                // void foo(Foo * const *arg) {
                //   Foo *bar = *arg;
                //   bar->unrelated = 42;
                // }
                // arg, the argument is constant.
                check_argument_storage_qualifier = false;
            }
        }

        if (type.storage == StorageClassPhysicalStorageBufferEXT || variable_storage_is_aliased(*var))
            flush_all_aliased_variables();
        else if (var)
            flush_dependees(*var);

        // We tried to write to a parameter which is not marked with out qualifier, force a recompile.
        if (check_argument_storage_qualifier && var->parameter && var->parameter->write_count == 0)
        {
            var->parameter->write_count++;
            force_recompile();
        }
    }
    else if (chain_type.pointer)
    {
        // If we stored through a variable pointer, then we don't know which
        // variable we stored to. So *all* expressions after this point need to
        // be invalidated.
        // FIXME: If we can prove that the variable pointer will point to
        // only certain variables, we can invalidate only those.
        flush_all_active_variables();
    }

    // If chain_type.pointer is false, we're not writing to memory backed variables, but temporaries instead.
    // This can happen in copy_logical_type where we unroll complex reads and writes to temporaries.
}

void Compiler::flush_dependees(SPIRVariable &var)
{
    for (auto expr : var.dependees)
        invalid_expressions.insert(expr);
    var.dependees.clear();
}

void Compiler::flush_all_aliased_variables()
{
    for (auto aliased : aliased_variables)
        flush_dependees(get<SPIRVariable>(aliased));
}

void Compiler::flush_all_atomic_capable_variables()
{
    for (auto global : global_variables)
        flush_dependees(get<SPIRVariable>(global));
    flush_all_aliased_variables();
}

void Compiler::flush_control_dependent_expressions(uint32_t block_id)
{
    auto &block = get<SPIRBlock>(block_id);
    for (auto &expr : block.invalidate_expressions)
        invalid_expressions.insert(expr);
    block.invalidate_expressions.clear();
}

void Compiler::flush_all_active_variables()
{
    // Invalidate all temporaries we read from variables in this block since they were forwarded.
    // Invalidate all temporaries we read from globals.
    for (auto &v : current_function->local_variables)
        flush_dependees(get<SPIRVariable>(v));
    for (auto &arg : current_function->arguments)
        flush_dependees(get<SPIRVariable>(arg.id));
    for (auto global : global_variables)
        flush_dependees(get<SPIRVariable>(global));

    flush_all_aliased_variables();
}

uint32_t Compiler::expression_type_id(uint32_t id) const
{
    switch (ir.ids[id].get_type())
    {
    case TypeVariable:
        return get<SPIRVariable>(id).basetype;

    case TypeExpression:
        return get<SPIRExpression>(id).expression_type;

    case TypeConstant:
        return get<SPIRConstant>(id).constant_type;

    case TypeConstantOp:
        return get<SPIRConstantOp>(id).basetype;

    case TypeUndef:
        return get<SPIRUndef>(id).basetype;

    case TypeCombinedImageSampler:
        return get<SPIRCombinedImageSampler>(id).combined_type;

    case TypeAccessChain:
        return get<SPIRAccessChain>(id).basetype;

    default:
        SPIRV_CROSS_THROW("Cannot resolve expression type.");
    }
}

const SPIRType &Compiler::expression_type(uint32_t id) const
{
    return get<SPIRType>(expression_type_id(id));
}

bool Compiler::expression_is_lvalue(uint32_t id) const
{
    auto &type = expression_type(id);
    switch (type.basetype)
    {
    case SPIRType::SampledImage:
    case SPIRType::Image:
    case SPIRType::Sampler:
        return false;

    default:
        return true;
    }
}

bool Compiler::is_immutable(uint32_t id) const
{
    if (ir.ids[id].get_type() == TypeVariable)
    {
        auto &var = get<SPIRVariable>(id);

        // Anything we load from the UniformConstant address space is guaranteed to be immutable.
        bool pointer_to_const = var.storage == StorageClassUniformConstant;
        return pointer_to_const || var.phi_variable || !expression_is_lvalue(id);
    }
    else if (ir.ids[id].get_type() == TypeAccessChain)
        return get<SPIRAccessChain>(id).immutable;
    else if (ir.ids[id].get_type() == TypeExpression)
        return get<SPIRExpression>(id).immutable;
    else if (ir.ids[id].get_type() == TypeConstant || ir.ids[id].get_type() == TypeConstantOp ||
             ir.ids[id].get_type() == TypeUndef)
        return true;
    else
        return false;
}

static inline bool storage_class_is_interface(spv::StorageClass storage)
{
    switch (storage)
    {
    case StorageClassInput:
    case StorageClassOutput:
    case StorageClassUniform:
    case StorageClassUniformConstant:
    case StorageClassAtomicCounter:
    case StorageClassPushConstant:
    case StorageClassStorageBuffer:
        return true;

    default:
        return false;
    }
}

bool Compiler::is_hidden_variable(const SPIRVariable &var, bool include_builtins) const
{
    if ((is_builtin_variable(var) && !include_builtins) || var.remapped_variable)
        return true;

    // Combined image samplers are always considered active as they are "magic" variables.
    if (find_if(begin(combined_image_samplers), end(combined_image_samplers), [&var](const CombinedImageSampler &samp) {
            return samp.combined_id == var.self;
        }) != end(combined_image_samplers))
    {
        return false;
    }

    // In SPIR-V 1.4 and up we must also use the active variable interface to disable global variables
    // which are not part of the entry point.
    if (ir.get_spirv_version() >= 0x10400 && var.storage != spv::StorageClassGeneric &&
        var.storage != spv::StorageClassFunction && !interface_variable_exists_in_entry_point(var.self))
    {
        return true;
    }

    return check_active_interface_variables && storage_class_is_interface(var.storage) &&
           active_interface_variables.find(var.self) == end(active_interface_variables);
}

bool Compiler::is_builtin_type(const SPIRType &type) const
{
    auto *type_meta = ir.find_meta(type.self);

    // We can have builtin structs as well. If one member of a struct is builtin, the struct must also be builtin.
    if (type_meta)
        for (auto &m : type_meta->members)
            if (m.builtin)
                return true;

    return false;
}

bool Compiler::is_builtin_variable(const SPIRVariable &var) const
{
    auto *m = ir.find_meta(var.self);

    if (var.compat_builtin || (m && m->decoration.builtin))
        return true;
    else
        return is_builtin_type(get<SPIRType>(var.basetype));
}

bool Compiler::is_member_builtin(const SPIRType &type, uint32_t index, BuiltIn *builtin) const
{
    auto *type_meta = ir.find_meta(type.self);

    if (type_meta)
    {
        auto &memb = type_meta->members;
        if (index < memb.size() && memb[index].builtin)
        {
            if (builtin)
                *builtin = memb[index].builtin_type;
            return true;
        }
    }

    return false;
}

bool Compiler::is_scalar(const SPIRType &type) const
{
    return type.basetype != SPIRType::Struct && type.vecsize == 1 && type.columns == 1;
}

bool Compiler::is_vector(const SPIRType &type) const
{
    return type.vecsize > 1 && type.columns == 1;
}

bool Compiler::is_matrix(const SPIRType &type) const
{
    return type.vecsize > 1 && type.columns > 1;
}

bool Compiler::is_array(const SPIRType &type) const
{
    return type.op == OpTypeArray || type.op == OpTypeRuntimeArray;
}

bool Compiler::is_pointer(const SPIRType &type) const
{
    return type.op == OpTypePointer && type.basetype != SPIRType::Unknown; // Ignore function pointers.
}

bool Compiler::is_physical_pointer(const SPIRType &type) const
{
    return type.op == OpTypePointer && type.storage == StorageClassPhysicalStorageBuffer;
}

bool Compiler::is_physical_pointer_to_buffer_block(const SPIRType &type) const
{
    return is_physical_pointer(type) && get_pointee_type(type).self == type.parent_type &&
           (has_decoration(type.self, DecorationBlock) ||
            has_decoration(type.self, DecorationBufferBlock));
}

bool Compiler::is_runtime_size_array(const SPIRType &type)
{
    return type.op == OpTypeRuntimeArray;
}

ShaderResources Compiler::get_shader_resources() const
{
    return get_shader_resources(nullptr);
}

ShaderResources Compiler::get_shader_resources(const unordered_set<VariableID> &active_variables) const
{
    return get_shader_resources(&active_variables);
}

bool Compiler::InterfaceVariableAccessHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    uint32_t variable = 0;
    switch (opcode)
    {
    // Need this first, otherwise, GCC complains about unhandled switch statements.
    default:
        break;

    case OpFunctionCall:
    {
        // Invalid SPIR-V.
        if (length < 3)
            return false;

        uint32_t count = length - 3;
        args += 3;
        for (uint32_t i = 0; i < count; i++)
        {
            auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
            if (var && storage_class_is_interface(var->storage))
                variables.insert(args[i]);
        }
        break;
    }

    case OpSelect:
    {
        // Invalid SPIR-V.
        if (length < 5)
            return false;

        uint32_t count = length - 3;
        args += 3;
        for (uint32_t i = 0; i < count; i++)
        {
            auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
            if (var && storage_class_is_interface(var->storage))
                variables.insert(args[i]);
        }
        break;
    }

    case OpPhi:
    {
        // Invalid SPIR-V.
        if (length < 2)
            return false;

        uint32_t count = length - 2;
        args += 2;
        for (uint32_t i = 0; i < count; i += 2)
        {
            auto *var = compiler.maybe_get<SPIRVariable>(args[i]);
            if (var && storage_class_is_interface(var->storage))
                variables.insert(args[i]);
        }
        break;
    }

    case OpAtomicStore:
    case OpStore:
        // Invalid SPIR-V.
        if (length < 1)
            return false;
        variable = args[0];
        break;

    case OpCopyMemory:
    {
        if (length < 2)
            return false;

        auto *var = compiler.maybe_get<SPIRVariable>(args[0]);
        if (var && storage_class_is_interface(var->storage))
            variables.insert(args[0]);

        var = compiler.maybe_get<SPIRVariable>(args[1]);
        if (var && storage_class_is_interface(var->storage))
            variables.insert(args[1]);
        break;
    }

    case OpExtInst:
    {
        if (length < 3)
            return false;
        auto &extension_set = compiler.get<SPIRExtension>(args[2]);
        switch (extension_set.ext)
        {
        case SPIRExtension::GLSL:
        {
            auto op = static_cast<GLSLstd450>(args[3]);

            switch (op)
            {
            case GLSLstd450InterpolateAtCentroid:
            case GLSLstd450InterpolateAtSample:
            case GLSLstd450InterpolateAtOffset:
            {
                auto *var = compiler.maybe_get<SPIRVariable>(args[4]);
                if (var && storage_class_is_interface(var->storage))
                    variables.insert(args[4]);
                break;
            }

            case GLSLstd450Modf:
            case GLSLstd450Fract:
            {
                auto *var = compiler.maybe_get<SPIRVariable>(args[5]);
                if (var && storage_class_is_interface(var->storage))
                    variables.insert(args[5]);
                break;
            }

            default:
                break;
            }
            break;
        }
        case SPIRExtension::SPV_AMD_shader_explicit_vertex_parameter:
        {
            enum AMDShaderExplicitVertexParameter
            {
                InterpolateAtVertexAMD = 1
            };

            auto op = static_cast<AMDShaderExplicitVertexParameter>(args[3]);

            switch (op)
            {
            case InterpolateAtVertexAMD:
            {
                auto *var = compiler.maybe_get<SPIRVariable>(args[4]);
                if (var && storage_class_is_interface(var->storage))
                    variables.insert(args[4]);
                break;
            }

            default:
                break;
            }
            break;
        }
        default:
            break;
        }
        break;
    }

    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
    case OpLoad:
    case OpCopyObject:
    case OpImageTexelPointer:
    case OpAtomicLoad:
    case OpAtomicExchange:
    case OpAtomicCompareExchange:
    case OpAtomicCompareExchangeWeak:
    case OpAtomicIIncrement:
    case OpAtomicIDecrement:
    case OpAtomicIAdd:
    case OpAtomicISub:
    case OpAtomicSMin:
    case OpAtomicUMin:
    case OpAtomicSMax:
    case OpAtomicUMax:
    case OpAtomicAnd:
    case OpAtomicOr:
    case OpAtomicXor:
    case OpArrayLength:
        // Invalid SPIR-V.
        if (length < 3)
            return false;
        variable = args[2];
        break;
    }

    if (variable)
    {
        auto *var = compiler.maybe_get<SPIRVariable>(variable);
        if (var && storage_class_is_interface(var->storage))
            variables.insert(variable);
    }
    return true;
}

unordered_set<VariableID> Compiler::get_active_interface_variables() const
{
    // Traverse the call graph and find all interface variables which are in use.
    unordered_set<VariableID> variables;
    InterfaceVariableAccessHandler handler(*this, variables);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

    ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
        if (var.storage != StorageClassOutput)
            return;
        if (!interface_variable_exists_in_entry_point(var.self))
            return;

        // An output variable which is just declared (but uninitialized) might be read by subsequent stages
        // so we should force-enable these outputs,
        // since compilation will fail if a subsequent stage attempts to read from the variable in question.
        // Also, make sure we preserve output variables which are only initialized, but never accessed by any code.
        if (var.initializer != ID(0) || get_execution_model() != ExecutionModelFragment)
            variables.insert(var.self);
    });

    // If we needed to create one, we'll need it.
    if (dummy_sampler_id)
        variables.insert(dummy_sampler_id);

    return variables;
}

void Compiler::set_enabled_interface_variables(std::unordered_set<VariableID> active_variables)
{
    active_interface_variables = std::move(active_variables);
    check_active_interface_variables = true;
}

ShaderResources Compiler::get_shader_resources(const unordered_set<VariableID> *active_variables) const
{
    ShaderResources res;

    bool ssbo_instance_name = reflection_ssbo_instance_name_is_significant();

    ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
        auto &type = this->get<SPIRType>(var.basetype);

        // It is possible for uniform storage classes to be passed as function parameters, so detect
        // that. To detect function parameters, check of StorageClass of variable is function scope.
        if (var.storage == StorageClassFunction || !type.pointer)
            return;

        if (active_variables && active_variables->find(var.self) == end(*active_variables))
            return;

        // In SPIR-V 1.4 and up, every global must be present in the entry point interface list,
        // not just IO variables.
        bool active_in_entry_point = true;
        if (ir.get_spirv_version() < 0x10400)
        {
            if (var.storage == StorageClassInput || var.storage == StorageClassOutput)
                active_in_entry_point = interface_variable_exists_in_entry_point(var.self);
        }
        else
            active_in_entry_point = interface_variable_exists_in_entry_point(var.self);

        if (!active_in_entry_point)
            return;

        bool is_builtin = is_builtin_variable(var);

        if (is_builtin)
        {
            if (var.storage != StorageClassInput && var.storage != StorageClassOutput)
                return;

            auto &list = var.storage == StorageClassInput ? res.builtin_inputs : res.builtin_outputs;
            BuiltInResource resource;

            if (has_decoration(type.self, DecorationBlock))
            {
                resource.resource = { var.self, var.basetype, type.self,
                                      get_remapped_declared_block_name(var.self, false) };

                for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
                {
                    resource.value_type_id = type.member_types[i];
                    resource.builtin = BuiltIn(get_member_decoration(type.self, i, DecorationBuiltIn));
                    list.push_back(resource);
                }
            }
            else
            {
                bool strip_array =
                        !has_decoration(var.self, DecorationPatch) && (
                                get_execution_model() == ExecutionModelTessellationControl ||
                                (get_execution_model() == ExecutionModelTessellationEvaluation &&
                                 var.storage == StorageClassInput));

                resource.resource = { var.self, var.basetype, type.self, get_name(var.self) };

                if (strip_array && !type.array.empty())
                    resource.value_type_id = get_variable_data_type(var).parent_type;
                else
                    resource.value_type_id = get_variable_data_type_id(var);

                assert(resource.value_type_id);

                resource.builtin = BuiltIn(get_decoration(var.self, DecorationBuiltIn));
                list.push_back(std::move(resource));
            }
            return;
        }

        // Input
        if (var.storage == StorageClassInput)
        {
            if (has_decoration(type.self, DecorationBlock))
            {
                res.stage_inputs.push_back(
                        { var.self, var.basetype, type.self,
                          get_remapped_declared_block_name(var.self, false) });
            }
            else
                res.stage_inputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
        }
        // Subpass inputs
        else if (var.storage == StorageClassUniformConstant && type.image.dim == DimSubpassData)
        {
            res.subpass_inputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
        }
        // Outputs
        else if (var.storage == StorageClassOutput)
        {
            if (has_decoration(type.self, DecorationBlock))
            {
                res.stage_outputs.push_back(
                        { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, false) });
            }
            else
                res.stage_outputs.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
        }
        // UBOs
        else if (type.storage == StorageClassUniform && has_decoration(type.self, DecorationBlock))
        {
            res.uniform_buffers.push_back(
                { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, false) });
        }
        // Old way to declare SSBOs.
        else if (type.storage == StorageClassUniform && has_decoration(type.self, DecorationBufferBlock))
        {
            res.storage_buffers.push_back(
                { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
        }
        // Modern way to declare SSBOs.
        else if (type.storage == StorageClassStorageBuffer)
        {
            res.storage_buffers.push_back(
                { var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
        }
        // Push constant blocks
        else if (type.storage == StorageClassPushConstant)
        {
            // There can only be one push constant block, but keep the vector in case this restriction is lifted
            // in the future.
            res.push_constant_buffers.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
        }
        else if (type.storage == StorageClassShaderRecordBufferKHR)
        {
            res.shader_record_buffers.push_back({ var.self, var.basetype, type.self, get_remapped_declared_block_name(var.self, ssbo_instance_name) });
        }
        // Atomic counters
        else if (type.storage == StorageClassAtomicCounter)
        {
            res.atomic_counters.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
        }
        else if (type.storage == StorageClassUniformConstant)
        {
            if (type.basetype == SPIRType::Image)
            {
                // Images
                if (type.image.sampled == 2)
                {
                    res.storage_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
                }
                // Separate images
                else if (type.image.sampled == 1)
                {
                    res.separate_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
                }
            }
            // Separate samplers
            else if (type.basetype == SPIRType::Sampler)
            {
                res.separate_samplers.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
            }
            // Textures
            else if (type.basetype == SPIRType::SampledImage)
            {
                res.sampled_images.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
            }
            // Acceleration structures
            else if (type.basetype == SPIRType::AccelerationStructure)
            {
                res.acceleration_structures.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
            }
            else
            {
                res.gl_plain_uniforms.push_back({ var.self, var.basetype, type.self, get_name(var.self) });
            }
        }
    });

    return res;
}

bool Compiler::type_is_top_level_block(const SPIRType &type) const
{
    if (type.basetype != SPIRType::Struct)
        return false;
    return has_decoration(type.self, DecorationBlock) || has_decoration(type.self, DecorationBufferBlock);
}

bool Compiler::type_is_block_like(const SPIRType &type) const
{
    if (type_is_top_level_block(type))
        return true;

    if (type.basetype == SPIRType::Struct)
    {
        // Block-like types may have Offset decorations.
        for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
            if (has_member_decoration(type.self, i, DecorationOffset))
                return true;
    }

    return false;
}

void Compiler::parse_fixup()
{
    // Figure out specialization constants for work group sizes.
    for (auto id_ : ir.ids_for_constant_or_variable)
    {
        auto &id = ir.ids[id_];

        if (id.get_type() == TypeConstant)
        {
            auto &c = id.get<SPIRConstant>();
            if (has_decoration(c.self, DecorationBuiltIn) &&
                BuiltIn(get_decoration(c.self, DecorationBuiltIn)) == BuiltInWorkgroupSize)
            {
                // In current SPIR-V, there can be just one constant like this.
                // All entry points will receive the constant value.
                // WorkgroupSize take precedence over LocalSizeId.
                for (auto &entry : ir.entry_points)
                {
                    entry.second.workgroup_size.constant = c.self;
                    entry.second.workgroup_size.x = c.scalar(0, 0);
                    entry.second.workgroup_size.y = c.scalar(0, 1);
                    entry.second.workgroup_size.z = c.scalar(0, 2);
                }
            }
        }
        else if (id.get_type() == TypeVariable)
        {
            auto &var = id.get<SPIRVariable>();
            if (var.storage == StorageClassPrivate || var.storage == StorageClassWorkgroup ||
                var.storage == StorageClassTaskPayloadWorkgroupEXT ||
                var.storage == StorageClassOutput)
            {
                global_variables.push_back(var.self);
            }
            if (variable_storage_is_aliased(var))
                aliased_variables.push_back(var.self);
        }
    }
}

void Compiler::update_name_cache(unordered_set<string> &cache_primary, const unordered_set<string> &cache_secondary,
                                 string &name)
{
    if (name.empty())
        return;

    const auto find_name = [&](const string &n) -> bool {
        if (cache_primary.find(n) != end(cache_primary))
            return true;

        if (&cache_primary != &cache_secondary)
            if (cache_secondary.find(n) != end(cache_secondary))
                return true;

        return false;
    };

    const auto insert_name = [&](const string &n) { cache_primary.insert(n); };

    if (!find_name(name))
    {
        insert_name(name);
        return;
    }

    uint32_t counter = 0;
    auto tmpname = name;

    bool use_linked_underscore = true;

    if (tmpname == "_")
    {
        // We cannot just append numbers, as we will end up creating internally reserved names.
        // Make it like _0_<counter> instead.
        tmpname += "0";
    }
    else if (tmpname.back() == '_')
    {
        // The last_character is an underscore, so we don't need to link in underscore.
        // This would violate double underscore rules.
        use_linked_underscore = false;
    }

    // If there is a collision (very rare),
    // keep tacking on extra identifier until it's unique.
    do
    {
        counter++;
        name = tmpname + (use_linked_underscore ? "_" : "") + convert_to_string(counter);
    } while (find_name(name));
    insert_name(name);
}

void Compiler::update_name_cache(unordered_set<string> &cache, string &name)
{
    update_name_cache(cache, cache, name);
}

void Compiler::set_name(ID id, const std::string &name)
{
    ir.set_name(id, name);
}

const SPIRType &Compiler::get_type(TypeID id) const
{
    return get<SPIRType>(id);
}

const SPIRType &Compiler::get_type_from_variable(VariableID id) const
{
    return get<SPIRType>(get<SPIRVariable>(id).basetype);
}

uint32_t Compiler::get_pointee_type_id(uint32_t type_id) const
{
    auto *p_type = &get<SPIRType>(type_id);
    if (p_type->pointer)
    {
        assert(p_type->parent_type);
        type_id = p_type->parent_type;
    }
    return type_id;
}

const SPIRType &Compiler::get_pointee_type(const SPIRType &type) const
{
    auto *p_type = &type;
    if (p_type->pointer)
    {
        assert(p_type->parent_type);
        p_type = &get<SPIRType>(p_type->parent_type);
    }
    return *p_type;
}

const SPIRType &Compiler::get_pointee_type(uint32_t type_id) const
{
    return get_pointee_type(get<SPIRType>(type_id));
}

uint32_t Compiler::get_variable_data_type_id(const SPIRVariable &var) const
{
    if (var.phi_variable || var.storage == spv::StorageClass::StorageClassAtomicCounter)
        return var.basetype;
    return get_pointee_type_id(var.basetype);
}

SPIRType &Compiler::get_variable_data_type(const SPIRVariable &var)
{
    return get<SPIRType>(get_variable_data_type_id(var));
}

const SPIRType &Compiler::get_variable_data_type(const SPIRVariable &var) const
{
    return get<SPIRType>(get_variable_data_type_id(var));
}

SPIRType &Compiler::get_variable_element_type(const SPIRVariable &var)
{
    SPIRType *type = &get_variable_data_type(var);
    if (is_array(*type))
        type = &get<SPIRType>(type->parent_type);
    return *type;
}

const SPIRType &Compiler::get_variable_element_type(const SPIRVariable &var) const
{
    const SPIRType *type = &get_variable_data_type(var);
    if (is_array(*type))
        type = &get<SPIRType>(type->parent_type);
    return *type;
}

bool Compiler::is_sampled_image_type(const SPIRType &type)
{
    return (type.basetype == SPIRType::Image || type.basetype == SPIRType::SampledImage) && type.image.sampled == 1 &&
           type.image.dim != DimBuffer;
}

void Compiler::set_member_decoration_string(TypeID id, uint32_t index, spv::Decoration decoration,
                                            const std::string &argument)
{
    ir.set_member_decoration_string(id, index, decoration, argument);
}

void Compiler::set_member_decoration(TypeID id, uint32_t index, Decoration decoration, uint32_t argument)
{
    ir.set_member_decoration(id, index, decoration, argument);
}

void Compiler::set_member_name(TypeID id, uint32_t index, const std::string &name)
{
    ir.set_member_name(id, index, name);
}

const std::string &Compiler::get_member_name(TypeID id, uint32_t index) const
{
    return ir.get_member_name(id, index);
}

void Compiler::set_qualified_name(uint32_t id, const string &name)
{
    ir.meta[id].decoration.qualified_alias = name;
}

void Compiler::set_member_qualified_name(uint32_t type_id, uint32_t index, const std::string &name)
{
    ir.meta[type_id].members.resize(max(ir.meta[type_id].members.size(), size_t(index) + 1));
    ir.meta[type_id].members[index].qualified_alias = name;
}

const string &Compiler::get_member_qualified_name(TypeID type_id, uint32_t index) const
{
    auto *m = ir.find_meta(type_id);
    if (m && index < m->members.size())
        return m->members[index].qualified_alias;
    else
        return ir.get_empty_string();
}

uint32_t Compiler::get_member_decoration(TypeID id, uint32_t index, Decoration decoration) const
{
    return ir.get_member_decoration(id, index, decoration);
}

const Bitset &Compiler::get_member_decoration_bitset(TypeID id, uint32_t index) const
{
    return ir.get_member_decoration_bitset(id, index);
}

bool Compiler::has_member_decoration(TypeID id, uint32_t index, Decoration decoration) const
{
    return ir.has_member_decoration(id, index, decoration);
}

void Compiler::unset_member_decoration(TypeID id, uint32_t index, Decoration decoration)
{
    ir.unset_member_decoration(id, index, decoration);
}

void Compiler::set_decoration_string(ID id, spv::Decoration decoration, const std::string &argument)
{
    ir.set_decoration_string(id, decoration, argument);
}

void Compiler::set_decoration(ID id, Decoration decoration, uint32_t argument)
{
    ir.set_decoration(id, decoration, argument);
}

void Compiler::set_extended_decoration(uint32_t id, ExtendedDecorations decoration, uint32_t value)
{
    auto &dec = ir.meta[id].decoration;
    dec.extended.flags.set(decoration);
    dec.extended.values[decoration] = value;
}

void Compiler::set_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration,
                                              uint32_t value)
{
    ir.meta[type].members.resize(max(ir.meta[type].members.size(), size_t(index) + 1));
    auto &dec = ir.meta[type].members[index];
    dec.extended.flags.set(decoration);
    dec.extended.values[decoration] = value;
}

static uint32_t get_default_extended_decoration(ExtendedDecorations decoration)
{
    switch (decoration)
    {
    case SPIRVCrossDecorationResourceIndexPrimary:
    case SPIRVCrossDecorationResourceIndexSecondary:
    case SPIRVCrossDecorationResourceIndexTertiary:
    case SPIRVCrossDecorationResourceIndexQuaternary:
    case SPIRVCrossDecorationInterfaceMemberIndex:
        return ~(0u);

    default:
        return 0;
    }
}

uint32_t Compiler::get_extended_decoration(uint32_t id, ExtendedDecorations decoration) const
{
    auto *m = ir.find_meta(id);
    if (!m)
        return 0;

    auto &dec = m->decoration;

    if (!dec.extended.flags.get(decoration))
        return get_default_extended_decoration(decoration);

    return dec.extended.values[decoration];
}

uint32_t Compiler::get_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration) const
{
    auto *m = ir.find_meta(type);
    if (!m)
        return 0;

    if (index >= m->members.size())
        return 0;

    auto &dec = m->members[index];
    if (!dec.extended.flags.get(decoration))
        return get_default_extended_decoration(decoration);
    return dec.extended.values[decoration];
}

bool Compiler::has_extended_decoration(uint32_t id, ExtendedDecorations decoration) const
{
    auto *m = ir.find_meta(id);
    if (!m)
        return false;

    auto &dec = m->decoration;
    return dec.extended.flags.get(decoration);
}

bool Compiler::has_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration) const
{
    auto *m = ir.find_meta(type);
    if (!m)
        return false;

    if (index >= m->members.size())
        return false;

    auto &dec = m->members[index];
    return dec.extended.flags.get(decoration);
}

void Compiler::unset_extended_decoration(uint32_t id, ExtendedDecorations decoration)
{
    auto &dec = ir.meta[id].decoration;
    dec.extended.flags.clear(decoration);
    dec.extended.values[decoration] = 0;
}

void Compiler::unset_extended_member_decoration(uint32_t type, uint32_t index, ExtendedDecorations decoration)
{
    ir.meta[type].members.resize(max(ir.meta[type].members.size(), size_t(index) + 1));
    auto &dec = ir.meta[type].members[index];
    dec.extended.flags.clear(decoration);
    dec.extended.values[decoration] = 0;
}

StorageClass Compiler::get_storage_class(VariableID id) const
{
    return get<SPIRVariable>(id).storage;
}

const std::string &Compiler::get_name(ID id) const
{
    return ir.get_name(id);
}

const std::string Compiler::get_fallback_name(ID id) const
{
    return join("_", id);
}

const std::string Compiler::get_block_fallback_name(VariableID id) const
{
    auto &var = get<SPIRVariable>(id);
    if (get_name(id).empty())
        return join("_", get<SPIRType>(var.basetype).self, "_", id);
    else
        return get_name(id);
}

const Bitset &Compiler::get_decoration_bitset(ID id) const
{
    return ir.get_decoration_bitset(id);
}

bool Compiler::has_decoration(ID id, Decoration decoration) const
{
    return ir.has_decoration(id, decoration);
}

const string &Compiler::get_decoration_string(ID id, Decoration decoration) const
{
    return ir.get_decoration_string(id, decoration);
}

const string &Compiler::get_member_decoration_string(TypeID id, uint32_t index, Decoration decoration) const
{
    return ir.get_member_decoration_string(id, index, decoration);
}

uint32_t Compiler::get_decoration(ID id, Decoration decoration) const
{
    return ir.get_decoration(id, decoration);
}

void Compiler::unset_decoration(ID id, Decoration decoration)
{
    ir.unset_decoration(id, decoration);
}

bool Compiler::get_binary_offset_for_decoration(VariableID id, spv::Decoration decoration, uint32_t &word_offset) const
{
    auto *m = ir.find_meta(id);
    if (!m)
        return false;

    auto &word_offsets = m->decoration_word_offset;
    auto itr = word_offsets.find(decoration);
    if (itr == end(word_offsets))
        return false;

    word_offset = itr->second;
    return true;
}

bool Compiler::block_is_noop(const SPIRBlock &block) const
{
    if (block.terminator != SPIRBlock::Direct)
        return false;

    auto &child = get<SPIRBlock>(block.next_block);

    // If this block participates in PHI, the block isn't really noop.
    for (auto &phi : block.phi_variables)
        if (phi.parent == block.self || phi.parent == child.self)
            return false;

    for (auto &phi : child.phi_variables)
        if (phi.parent == block.self)
            return false;

    // Verify all instructions have no semantic impact.
    for (auto &i : block.ops)
    {
        auto op = static_cast<Op>(i.op);

        switch (op)
        {
        // Non-Semantic instructions.
        case OpLine:
        case OpNoLine:
            break;

        case OpExtInst:
        {
            auto *ops = stream(i);
            auto ext = get<SPIRExtension>(ops[2]).ext;

            bool ext_is_nonsemantic_only =
                ext == SPIRExtension::NonSemanticShaderDebugInfo ||
                ext == SPIRExtension::SPV_debug_info ||
                ext == SPIRExtension::NonSemanticGeneric;

            if (!ext_is_nonsemantic_only)
                return false;

            break;
        }

        default:
            return false;
        }
    }

    return true;
}

bool Compiler::block_is_loop_candidate(const SPIRBlock &block, SPIRBlock::Method method) const
{
    // Tried and failed.
    if (block.disable_block_optimization || block.complex_continue)
        return false;

    if (method == SPIRBlock::MergeToSelectForLoop || method == SPIRBlock::MergeToSelectContinueForLoop)
    {
        // Try to detect common for loop pattern
        // which the code backend can use to create cleaner code.
        // for(;;) { if (cond) { some_body; } else { break; } }
        // is the pattern we're looking for.
        const auto *false_block = maybe_get<SPIRBlock>(block.false_block);
        const auto *true_block = maybe_get<SPIRBlock>(block.true_block);
        const auto *merge_block = maybe_get<SPIRBlock>(block.merge_block);

        bool false_block_is_merge = block.false_block == block.merge_block ||
                                    (false_block && merge_block && execution_is_noop(*false_block, *merge_block));

        bool true_block_is_merge = block.true_block == block.merge_block ||
                                   (true_block && merge_block && execution_is_noop(*true_block, *merge_block));

        bool positive_candidate =
            block.true_block != block.merge_block && block.true_block != block.self && false_block_is_merge;

        bool negative_candidate =
            block.false_block != block.merge_block && block.false_block != block.self && true_block_is_merge;

        bool ret = block.terminator == SPIRBlock::Select && block.merge == SPIRBlock::MergeLoop &&
                   (positive_candidate || negative_candidate);

        if (ret && positive_candidate && method == SPIRBlock::MergeToSelectContinueForLoop)
            ret = block.true_block == block.continue_block;
        else if (ret && negative_candidate && method == SPIRBlock::MergeToSelectContinueForLoop)
            ret = block.false_block == block.continue_block;

        // If we have OpPhi which depends on branches which came from our own block,
        // we need to flush phi variables in else block instead of a trivial break,
        // so we cannot assume this is a for loop candidate.
        if (ret)
        {
            for (auto &phi : block.phi_variables)
                if (phi.parent == block.self)
                    return false;

            auto *merge = maybe_get<SPIRBlock>(block.merge_block);
            if (merge)
                for (auto &phi : merge->phi_variables)
                    if (phi.parent == block.self)
                        return false;
        }
        return ret;
    }
    else if (method == SPIRBlock::MergeToDirectForLoop)
    {
        // Empty loop header that just sets up merge target
        // and branches to loop body.
        bool ret = block.terminator == SPIRBlock::Direct && block.merge == SPIRBlock::MergeLoop && block_is_noop(block);

        if (!ret)
            return false;

        auto &child = get<SPIRBlock>(block.next_block);

        const auto *false_block = maybe_get<SPIRBlock>(child.false_block);
        const auto *true_block = maybe_get<SPIRBlock>(child.true_block);
        const auto *merge_block = maybe_get<SPIRBlock>(block.merge_block);

        bool false_block_is_merge = child.false_block == block.merge_block ||
                                    (false_block && merge_block && execution_is_noop(*false_block, *merge_block));

        bool true_block_is_merge = child.true_block == block.merge_block ||
                                   (true_block && merge_block && execution_is_noop(*true_block, *merge_block));

        bool positive_candidate =
            child.true_block != block.merge_block && child.true_block != block.self && false_block_is_merge;

        bool negative_candidate =
            child.false_block != block.merge_block && child.false_block != block.self && true_block_is_merge;

        ret = child.terminator == SPIRBlock::Select && child.merge == SPIRBlock::MergeNone &&
              (positive_candidate || negative_candidate);

        if (ret)
        {
            auto *merge = maybe_get<SPIRBlock>(block.merge_block);
            if (merge)
                for (auto &phi : merge->phi_variables)
                    if (phi.parent == block.self || phi.parent == child.false_block)
                        return false;
        }

        return ret;
    }
    else
        return false;
}

bool Compiler::execution_is_noop(const SPIRBlock &from, const SPIRBlock &to) const
{
    if (!execution_is_branchless(from, to))
        return false;

    auto *start = &from;
    for (;;)
    {
        if (start->self == to.self)
            return true;

        if (!block_is_noop(*start))
            return false;

        auto &next = get<SPIRBlock>(start->next_block);
        start = &next;
    }
}

bool Compiler::execution_is_branchless(const SPIRBlock &from, const SPIRBlock &to) const
{
    auto *start = &from;
    for (;;)
    {
        if (start->self == to.self)
            return true;

        if (start->terminator == SPIRBlock::Direct && start->merge == SPIRBlock::MergeNone)
            start = &get<SPIRBlock>(start->next_block);
        else
            return false;
    }
}

bool Compiler::execution_is_direct_branch(const SPIRBlock &from, const SPIRBlock &to) const
{
    return from.terminator == SPIRBlock::Direct && from.merge == SPIRBlock::MergeNone && from.next_block == to.self;
}

SPIRBlock::ContinueBlockType Compiler::continue_block_type(const SPIRBlock &block) const
{
    // The block was deemed too complex during code emit, pick conservative fallback paths.
    if (block.complex_continue)
        return SPIRBlock::ComplexLoop;

    // In older glslang output continue block can be equal to the loop header.
    // In this case, execution is clearly branchless, so just assume a while loop header here.
    if (block.merge == SPIRBlock::MergeLoop)
        return SPIRBlock::WhileLoop;

    if (block.loop_dominator == BlockID(SPIRBlock::NoDominator))
    {
        // Continue block is never reached from CFG.
        return SPIRBlock::ComplexLoop;
    }

    auto &dominator = get<SPIRBlock>(block.loop_dominator);

    if (execution_is_noop(block, dominator))
        return SPIRBlock::WhileLoop;
    else if (execution_is_branchless(block, dominator))
        return SPIRBlock::ForLoop;
    else
    {
        const auto *false_block = maybe_get<SPIRBlock>(block.false_block);
        const auto *true_block = maybe_get<SPIRBlock>(block.true_block);
        const auto *merge_block = maybe_get<SPIRBlock>(dominator.merge_block);

        // If we need to flush Phi in this block, we cannot have a DoWhile loop.
        bool flush_phi_to_false = false_block && flush_phi_required(block.self, block.false_block);
        bool flush_phi_to_true = true_block && flush_phi_required(block.self, block.true_block);
        if (flush_phi_to_false || flush_phi_to_true)
            return SPIRBlock::ComplexLoop;

        bool positive_do_while = block.true_block == dominator.self &&
                                 (block.false_block == dominator.merge_block ||
                                  (false_block && merge_block && execution_is_noop(*false_block, *merge_block)));

        bool negative_do_while = block.false_block == dominator.self &&
                                 (block.true_block == dominator.merge_block ||
                                  (true_block && merge_block && execution_is_noop(*true_block, *merge_block)));

        if (block.merge == SPIRBlock::MergeNone && block.terminator == SPIRBlock::Select &&
            (positive_do_while || negative_do_while))
        {
            return SPIRBlock::DoWhileLoop;
        }
        else
            return SPIRBlock::ComplexLoop;
    }
}

const SmallVector<SPIRBlock::Case> &Compiler::get_case_list(const SPIRBlock &block) const
{
    uint32_t width = 0;

    // First we check if we can get the type directly from the block.condition
    // since it can be a SPIRConstant or a SPIRVariable.
    if (const auto *constant = maybe_get<SPIRConstant>(block.condition))
    {
        const auto &type = get<SPIRType>(constant->constant_type);
        width = type.width;
    }
    else if (const auto *var = maybe_get<SPIRVariable>(block.condition))
    {
        const auto &type = get<SPIRType>(var->basetype);
        width = type.width;
    }
    else if (const auto *undef = maybe_get<SPIRUndef>(block.condition))
    {
        const auto &type = get<SPIRType>(undef->basetype);
        width = type.width;
    }
    else
    {
        auto search = ir.load_type_width.find(block.condition);
        if (search == ir.load_type_width.end())
        {
            SPIRV_CROSS_THROW("Use of undeclared variable on a switch statement.");
        }

        width = search->second;
    }

    if (width > 32)
        return block.cases_64bit;

    return block.cases_32bit;
}

bool Compiler::traverse_all_reachable_opcodes(const SPIRBlock &block, OpcodeHandler &handler) const
{
    handler.set_current_block(block);
    handler.rearm_current_block(block);

    // Ideally, perhaps traverse the CFG instead of all blocks in order to eliminate dead blocks,
    // but this shouldn't be a problem in practice unless the SPIR-V is doing insane things like recursing
    // inside dead blocks ...
    for (auto &i : block.ops)
    {
        auto ops = stream(i);
        auto op = static_cast<Op>(i.op);

        if (!handler.handle(op, ops, i.length))
            return false;

        if (op == OpFunctionCall)
        {
            auto &func = get<SPIRFunction>(ops[2]);
            if (handler.follow_function_call(func))
            {
                if (!handler.begin_function_scope(ops, i.length))
                    return false;
                if (!traverse_all_reachable_opcodes(get<SPIRFunction>(ops[2]), handler))
                    return false;
                if (!handler.end_function_scope(ops, i.length))
                    return false;

                handler.rearm_current_block(block);
            }
        }
    }

    if (!handler.handle_terminator(block))
        return false;

    return true;
}

bool Compiler::traverse_all_reachable_opcodes(const SPIRFunction &func, OpcodeHandler &handler) const
{
    for (auto block : func.blocks)
        if (!traverse_all_reachable_opcodes(get<SPIRBlock>(block), handler))
            return false;

    return true;
}

uint32_t Compiler::type_struct_member_offset(const SPIRType &type, uint32_t index) const
{
    auto *type_meta = ir.find_meta(type.self);
    if (type_meta)
    {
        // Decoration must be set in valid SPIR-V, otherwise throw.
        auto &dec = type_meta->members[index];
        if (dec.decoration_flags.get(DecorationOffset))
            return dec.offset;
        else
            SPIRV_CROSS_THROW("Struct member does not have Offset set.");
    }
    else
        SPIRV_CROSS_THROW("Struct member does not have Offset set.");
}

uint32_t Compiler::type_struct_member_array_stride(const SPIRType &type, uint32_t index) const
{
    auto *type_meta = ir.find_meta(type.member_types[index]);
    if (type_meta)
    {
        // Decoration must be set in valid SPIR-V, otherwise throw.
        // ArrayStride is part of the array type not OpMemberDecorate.
        auto &dec = type_meta->decoration;
        if (dec.decoration_flags.get(DecorationArrayStride))
            return dec.array_stride;
        else
            SPIRV_CROSS_THROW("Struct member does not have ArrayStride set.");
    }
    else
        SPIRV_CROSS_THROW("Struct member does not have ArrayStride set.");
}

uint32_t Compiler::type_struct_member_matrix_stride(const SPIRType &type, uint32_t index) const
{
    auto *type_meta = ir.find_meta(type.self);
    if (type_meta)
    {
        // Decoration must be set in valid SPIR-V, otherwise throw.
        // MatrixStride is part of OpMemberDecorate.
        auto &dec = type_meta->members[index];
        if (dec.decoration_flags.get(DecorationMatrixStride))
            return dec.matrix_stride;
        else
            SPIRV_CROSS_THROW("Struct member does not have MatrixStride set.");
    }
    else
        SPIRV_CROSS_THROW("Struct member does not have MatrixStride set.");
}

size_t Compiler::get_declared_struct_size(const SPIRType &type) const
{
    if (type.member_types.empty())
        SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

    // Offsets can be declared out of order, so we need to deduce the actual size
    // based on last member instead.
    uint32_t member_index = 0;
    size_t highest_offset = 0;
    for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
    {
        size_t offset = type_struct_member_offset(type, i);
        if (offset > highest_offset)
        {
            highest_offset = offset;
            member_index = i;
        }
    }

    size_t size = get_declared_struct_member_size(type, member_index);
    return highest_offset + size;
}

size_t Compiler::get_declared_struct_size_runtime_array(const SPIRType &type, size_t array_size) const
{
    if (type.member_types.empty())
        SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

    size_t size = get_declared_struct_size(type);
    auto &last_type = get<SPIRType>(type.member_types.back());
    if (!last_type.array.empty() && last_type.array_size_literal[0] && last_type.array[0] == 0) // Runtime array
        size += array_size * type_struct_member_array_stride(type, uint32_t(type.member_types.size() - 1));

    return size;
}

uint32_t Compiler::evaluate_spec_constant_u32(const SPIRConstantOp &spec) const
{
    auto &result_type = get<SPIRType>(spec.basetype);
    if (result_type.basetype != SPIRType::UInt && result_type.basetype != SPIRType::Int &&
        result_type.basetype != SPIRType::Boolean)
    {
        SPIRV_CROSS_THROW(
            "Only 32-bit integers and booleans are currently supported when evaluating specialization constants.\n");
    }

    if (!is_scalar(result_type))
        SPIRV_CROSS_THROW("Spec constant evaluation must be a scalar.\n");

    uint32_t value = 0;

    const auto eval_u32 = [&](uint32_t id) -> uint32_t {
        auto &type = expression_type(id);
        if (type.basetype != SPIRType::UInt && type.basetype != SPIRType::Int && type.basetype != SPIRType::Boolean)
        {
            SPIRV_CROSS_THROW("Only 32-bit integers and booleans are currently supported when evaluating "
                              "specialization constants.\n");
        }

        if (!is_scalar(type))
            SPIRV_CROSS_THROW("Spec constant evaluation must be a scalar.\n");
        if (const auto *c = this->maybe_get<SPIRConstant>(id))
            return c->scalar();
        else
            return evaluate_spec_constant_u32(this->get<SPIRConstantOp>(id));
    };

#define binary_spec_op(op, binary_op)                                              \
    case Op##op:                                                                   \
        value = eval_u32(spec.arguments[0]) binary_op eval_u32(spec.arguments[1]); \
        break
#define binary_spec_op_cast(op, binary_op, type)                                                         \
    case Op##op:                                                                                         \
        value = uint32_t(type(eval_u32(spec.arguments[0])) binary_op type(eval_u32(spec.arguments[1]))); \
        break

    // Support the basic opcodes which are typically used when computing array sizes.
    switch (spec.opcode)
    {
        binary_spec_op(IAdd, +);
        binary_spec_op(ISub, -);
        binary_spec_op(IMul, *);
        binary_spec_op(BitwiseAnd, &);
        binary_spec_op(BitwiseOr, |);
        binary_spec_op(BitwiseXor, ^);
        binary_spec_op(LogicalAnd, &);
        binary_spec_op(LogicalOr, |);
        binary_spec_op(ShiftLeftLogical, <<);
        binary_spec_op(ShiftRightLogical, >>);
        binary_spec_op_cast(ShiftRightArithmetic, >>, int32_t);
        binary_spec_op(LogicalEqual, ==);
        binary_spec_op(LogicalNotEqual, !=);
        binary_spec_op(IEqual, ==);
        binary_spec_op(INotEqual, !=);
        binary_spec_op(ULessThan, <);
        binary_spec_op(ULessThanEqual, <=);
        binary_spec_op(UGreaterThan, >);
        binary_spec_op(UGreaterThanEqual, >=);
        binary_spec_op_cast(SLessThan, <, int32_t);
        binary_spec_op_cast(SLessThanEqual, <=, int32_t);
        binary_spec_op_cast(SGreaterThan, >, int32_t);
        binary_spec_op_cast(SGreaterThanEqual, >=, int32_t);
#undef binary_spec_op
#undef binary_spec_op_cast

    case OpLogicalNot:
        value = uint32_t(!eval_u32(spec.arguments[0]));
        break;

    case OpNot:
        value = ~eval_u32(spec.arguments[0]);
        break;

    case OpSNegate:
        value = uint32_t(-int32_t(eval_u32(spec.arguments[0])));
        break;

    case OpSelect:
        value = eval_u32(spec.arguments[0]) ? eval_u32(spec.arguments[1]) : eval_u32(spec.arguments[2]);
        break;

    case OpUMod:
    {
        uint32_t a = eval_u32(spec.arguments[0]);
        uint32_t b = eval_u32(spec.arguments[1]);
        if (b == 0)
            SPIRV_CROSS_THROW("Undefined behavior in UMod, b == 0.\n");
        value = a % b;
        break;
    }

    case OpSRem:
    {
        auto a = int32_t(eval_u32(spec.arguments[0]));
        auto b = int32_t(eval_u32(spec.arguments[1]));
        if (b == 0)
            SPIRV_CROSS_THROW("Undefined behavior in SRem, b == 0.\n");
        value = a % b;
        break;
    }

    case OpSMod:
    {
        auto a = int32_t(eval_u32(spec.arguments[0]));
        auto b = int32_t(eval_u32(spec.arguments[1]));
        if (b == 0)
            SPIRV_CROSS_THROW("Undefined behavior in SMod, b == 0.\n");
        auto v = a % b;

        // Makes sure we match the sign of b, not a.
        if ((b < 0 && v > 0) || (b > 0 && v < 0))
            v += b;
        value = v;
        break;
    }

    case OpUDiv:
    {
        uint32_t a = eval_u32(spec.arguments[0]);
        uint32_t b = eval_u32(spec.arguments[1]);
        if (b == 0)
            SPIRV_CROSS_THROW("Undefined behavior in UDiv, b == 0.\n");
        value = a / b;
        break;
    }

    case OpSDiv:
    {
        auto a = int32_t(eval_u32(spec.arguments[0]));
        auto b = int32_t(eval_u32(spec.arguments[1]));
        if (b == 0)
            SPIRV_CROSS_THROW("Undefined behavior in SDiv, b == 0.\n");
        value = a / b;
        break;
    }

    default:
        SPIRV_CROSS_THROW("Unsupported spec constant opcode for evaluation.\n");
    }

    return value;
}

uint32_t Compiler::evaluate_constant_u32(uint32_t id) const
{
    if (const auto *c = maybe_get<SPIRConstant>(id))
        return c->scalar();
    else
        return evaluate_spec_constant_u32(get<SPIRConstantOp>(id));
}

size_t Compiler::get_declared_struct_member_size(const SPIRType &struct_type, uint32_t index) const
{
    if (struct_type.member_types.empty())
        SPIRV_CROSS_THROW("Declared struct in block cannot be empty.");

    auto &flags = get_member_decoration_bitset(struct_type.self, index);
    auto &type = get<SPIRType>(struct_type.member_types[index]);

    switch (type.basetype)
    {
    case SPIRType::Unknown:
    case SPIRType::Void:
    case SPIRType::Boolean: // Bools are purely logical, and cannot be used for externally visible types.
    case SPIRType::AtomicCounter:
    case SPIRType::Image:
    case SPIRType::SampledImage:
    case SPIRType::Sampler:
        SPIRV_CROSS_THROW("Querying size for object with opaque size.");

    default:
        break;
    }

    if (type.pointer && type.storage == StorageClassPhysicalStorageBuffer)
    {
        // Check if this is a top-level pointer type, and not an array of pointers.
        if (type.pointer_depth > get<SPIRType>(type.parent_type).pointer_depth)
            return 8;
    }

    if (!type.array.empty())
    {
        // For arrays, we can use ArrayStride to get an easy check.
        bool array_size_literal = type.array_size_literal.back();
        uint32_t array_size = array_size_literal ? type.array.back() : evaluate_constant_u32(type.array.back());
        return type_struct_member_array_stride(struct_type, index) * array_size;
    }
    else if (type.basetype == SPIRType::Struct)
    {
        return get_declared_struct_size(type);
    }
    else
    {
        unsigned vecsize = type.vecsize;
        unsigned columns = type.columns;

        // Vectors.
        if (columns == 1)
        {
            size_t component_size = type.width / 8;
            return vecsize * component_size;
        }
        else
        {
            uint32_t matrix_stride = type_struct_member_matrix_stride(struct_type, index);

            // Per SPIR-V spec, matrices must be tightly packed and aligned up for vec3 accesses.
            if (flags.get(DecorationRowMajor))
                return matrix_stride * vecsize;
            else if (flags.get(DecorationColMajor))
                return matrix_stride * columns;
            else
                SPIRV_CROSS_THROW("Either row-major or column-major must be declared for matrices.");
        }
    }
}

bool Compiler::BufferAccessHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    if (opcode != OpAccessChain && opcode != OpInBoundsAccessChain && opcode != OpPtrAccessChain)
        return true;

    bool ptr_chain = (opcode == OpPtrAccessChain);

    // Invalid SPIR-V.
    if (length < (ptr_chain ? 5u : 4u))
        return false;

    if (args[2] != id)
        return true;

    // Don't bother traversing the entire access chain tree yet.
    // If we access a struct member, assume we access the entire member.
    uint32_t index = compiler.get<SPIRConstant>(args[ptr_chain ? 4 : 3]).scalar();

    // Seen this index already.
    if (seen.find(index) != end(seen))
        return true;
    seen.insert(index);

    auto &type = compiler.expression_type(id);
    uint32_t offset = compiler.type_struct_member_offset(type, index);

    size_t range;
    // If we have another member in the struct, deduce the range by looking at the next member.
    // This is okay since structs in SPIR-V can have padding, but Offset decoration must be
    // monotonically increasing.
    // Of course, this doesn't take into account if the SPIR-V for some reason decided to add
    // very large amounts of padding, but that's not really a big deal.
    if (index + 1 < type.member_types.size())
    {
        range = compiler.type_struct_member_offset(type, index + 1) - offset;
    }
    else
    {
        // No padding, so just deduce it from the size of the member directly.
        range = compiler.get_declared_struct_member_size(type, index);
    }

    ranges.push_back({ index, offset, range });
    return true;
}

SmallVector<BufferRange> Compiler::get_active_buffer_ranges(VariableID id) const
{
    SmallVector<BufferRange> ranges;
    BufferAccessHandler handler(*this, ranges, id);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);
    return ranges;
}

bool Compiler::types_are_logically_equivalent(const SPIRType &a, const SPIRType &b) const
{
    if (a.basetype != b.basetype)
        return false;
    if (a.width != b.width)
        return false;
    if (a.vecsize != b.vecsize)
        return false;
    if (a.columns != b.columns)
        return false;
    if (a.array.size() != b.array.size())
        return false;

    size_t array_count = a.array.size();
    if (array_count && memcmp(a.array.data(), b.array.data(), array_count * sizeof(uint32_t)) != 0)
        return false;

    if (a.basetype == SPIRType::Image || a.basetype == SPIRType::SampledImage)
    {
        if (memcmp(&a.image, &b.image, sizeof(SPIRType::Image)) != 0)
            return false;
    }

    if (a.member_types.size() != b.member_types.size())
        return false;

    size_t member_types = a.member_types.size();
    for (size_t i = 0; i < member_types; i++)
    {
        if (!types_are_logically_equivalent(get<SPIRType>(a.member_types[i]), get<SPIRType>(b.member_types[i])))
            return false;
    }

    return true;
}

const Bitset &Compiler::get_execution_mode_bitset() const
{
    return get_entry_point().flags;
}

void Compiler::set_execution_mode(ExecutionMode mode, uint32_t arg0, uint32_t arg1, uint32_t arg2)
{
    auto &execution = get_entry_point();

    execution.flags.set(mode);
    switch (mode)
    {
    case ExecutionModeLocalSize:
        execution.workgroup_size.x = arg0;
        execution.workgroup_size.y = arg1;
        execution.workgroup_size.z = arg2;
        break;

    case ExecutionModeLocalSizeId:
        execution.workgroup_size.id_x = arg0;
        execution.workgroup_size.id_y = arg1;
        execution.workgroup_size.id_z = arg2;
        break;

    case ExecutionModeInvocations:
        execution.invocations = arg0;
        break;

    case ExecutionModeOutputVertices:
        execution.output_vertices = arg0;
        break;

    case ExecutionModeOutputPrimitivesEXT:
        execution.output_primitives = arg0;
        break;

    default:
        break;
    }
}

void Compiler::unset_execution_mode(ExecutionMode mode)
{
    auto &execution = get_entry_point();
    execution.flags.clear(mode);
}

uint32_t Compiler::get_work_group_size_specialization_constants(SpecializationConstant &x, SpecializationConstant &y,
                                                                SpecializationConstant &z) const
{
    auto &execution = get_entry_point();
    x = { 0, 0 };
    y = { 0, 0 };
    z = { 0, 0 };

    // WorkgroupSize builtin takes precedence over LocalSize / LocalSizeId.
    if (execution.workgroup_size.constant != 0)
    {
        auto &c = get<SPIRConstant>(execution.workgroup_size.constant);

        if (c.m.c[0].id[0] != ID(0))
        {
            x.id = c.m.c[0].id[0];
            x.constant_id = get_decoration(c.m.c[0].id[0], DecorationSpecId);
        }

        if (c.m.c[0].id[1] != ID(0))
        {
            y.id = c.m.c[0].id[1];
            y.constant_id = get_decoration(c.m.c[0].id[1], DecorationSpecId);
        }

        if (c.m.c[0].id[2] != ID(0))
        {
            z.id = c.m.c[0].id[2];
            z.constant_id = get_decoration(c.m.c[0].id[2], DecorationSpecId);
        }
    }
    else if (execution.flags.get(ExecutionModeLocalSizeId))
    {
        auto &cx = get<SPIRConstant>(execution.workgroup_size.id_x);
        if (cx.specialization)
        {
            x.id = execution.workgroup_size.id_x;
            x.constant_id = get_decoration(execution.workgroup_size.id_x, DecorationSpecId);
        }

        auto &cy = get<SPIRConstant>(execution.workgroup_size.id_y);
        if (cy.specialization)
        {
            y.id = execution.workgroup_size.id_y;
            y.constant_id = get_decoration(execution.workgroup_size.id_y, DecorationSpecId);
        }

        auto &cz = get<SPIRConstant>(execution.workgroup_size.id_z);
        if (cz.specialization)
        {
            z.id = execution.workgroup_size.id_z;
            z.constant_id = get_decoration(execution.workgroup_size.id_z, DecorationSpecId);
        }
    }

    return execution.workgroup_size.constant;
}

uint32_t Compiler::get_execution_mode_argument(spv::ExecutionMode mode, uint32_t index) const
{
    auto &execution = get_entry_point();
    switch (mode)
    {
    case ExecutionModeLocalSizeId:
        if (execution.flags.get(ExecutionModeLocalSizeId))
        {
            switch (index)
            {
            case 0:
                return execution.workgroup_size.id_x;
            case 1:
                return execution.workgroup_size.id_y;
            case 2:
                return execution.workgroup_size.id_z;
            default:
                return 0;
            }
        }
        else
            return 0;

    case ExecutionModeLocalSize:
        switch (index)
        {
        case 0:
            if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_x != 0)
                return get<SPIRConstant>(execution.workgroup_size.id_x).scalar();
            else
                return execution.workgroup_size.x;
        case 1:
            if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_y != 0)
                return get<SPIRConstant>(execution.workgroup_size.id_y).scalar();
            else
                return execution.workgroup_size.y;
        case 2:
            if (execution.flags.get(ExecutionModeLocalSizeId) && execution.workgroup_size.id_z != 0)
                return get<SPIRConstant>(execution.workgroup_size.id_z).scalar();
            else
                return execution.workgroup_size.z;
        default:
            return 0;
        }

    case ExecutionModeInvocations:
        return execution.invocations;

    case ExecutionModeOutputVertices:
        return execution.output_vertices;

    case ExecutionModeOutputPrimitivesEXT:
        return execution.output_primitives;

    default:
        return 0;
    }
}

ExecutionModel Compiler::get_execution_model() const
{
    auto &execution = get_entry_point();
    return execution.model;
}

bool Compiler::is_tessellation_shader(ExecutionModel model)
{
    return model == ExecutionModelTessellationControl || model == ExecutionModelTessellationEvaluation;
}

bool Compiler::is_vertex_like_shader() const
{
    auto model = get_execution_model();
    return model == ExecutionModelVertex || model == ExecutionModelGeometry ||
           model == ExecutionModelTessellationControl || model == ExecutionModelTessellationEvaluation;
}

bool Compiler::is_tessellation_shader() const
{
    return is_tessellation_shader(get_execution_model());
}

bool Compiler::is_tessellating_triangles() const
{
    return get_execution_mode_bitset().get(ExecutionModeTriangles);
}

void Compiler::set_remapped_variable_state(VariableID id, bool remap_enable)
{
    get<SPIRVariable>(id).remapped_variable = remap_enable;
}

bool Compiler::get_remapped_variable_state(VariableID id) const
{
    return get<SPIRVariable>(id).remapped_variable;
}

void Compiler::set_subpass_input_remapped_components(VariableID id, uint32_t components)
{
    get<SPIRVariable>(id).remapped_components = components;
}

uint32_t Compiler::get_subpass_input_remapped_components(VariableID id) const
{
    return get<SPIRVariable>(id).remapped_components;
}

void Compiler::add_implied_read_expression(SPIRExpression &e, uint32_t source)
{
    auto itr = find(begin(e.implied_read_expressions), end(e.implied_read_expressions), ID(source));
    if (itr == end(e.implied_read_expressions))
        e.implied_read_expressions.push_back(source);
}

void Compiler::add_implied_read_expression(SPIRAccessChain &e, uint32_t source)
{
    auto itr = find(begin(e.implied_read_expressions), end(e.implied_read_expressions), ID(source));
    if (itr == end(e.implied_read_expressions))
        e.implied_read_expressions.push_back(source);
}

void Compiler::add_active_interface_variable(uint32_t var_id)
{
    active_interface_variables.insert(var_id);

    // In SPIR-V 1.4 and up we must also track the interface variable in the entry point.
    if (ir.get_spirv_version() >= 0x10400)
    {
        auto &vars = get_entry_point().interface_variables;
        if (find(begin(vars), end(vars), VariableID(var_id)) == end(vars))
            vars.push_back(var_id);
    }
}

void Compiler::inherit_expression_dependencies(uint32_t dst, uint32_t source_expression)
{
    // Don't inherit any expression dependencies if the expression in dst
    // is not a forwarded temporary.
    if (forwarded_temporaries.find(dst) == end(forwarded_temporaries) ||
        forced_temporaries.find(dst) != end(forced_temporaries))
    {
        return;
    }

    auto &e = get<SPIRExpression>(dst);
    auto *phi = maybe_get<SPIRVariable>(source_expression);
    if (phi && phi->phi_variable)
    {
        // We have used a phi variable, which can change at the end of the block,
        // so make sure we take a dependency on this phi variable.
        phi->dependees.push_back(dst);
    }

    auto *s = maybe_get<SPIRExpression>(source_expression);
    if (!s)
        return;

    auto &e_deps = e.expression_dependencies;
    auto &s_deps = s->expression_dependencies;

    // If we depend on a expression, we also depend on all sub-dependencies from source.
    e_deps.push_back(source_expression);
    e_deps.insert(end(e_deps), begin(s_deps), end(s_deps));

    // Eliminate duplicated dependencies.
    sort(begin(e_deps), end(e_deps));
    e_deps.erase(unique(begin(e_deps), end(e_deps)), end(e_deps));
}

SmallVector<EntryPoint> Compiler::get_entry_points_and_stages() const
{
    SmallVector<EntryPoint> entries;
    for (auto &entry : ir.entry_points)
        entries.push_back({ entry.second.orig_name, entry.second.model });
    return entries;
}

void Compiler::rename_entry_point(const std::string &old_name, const std::string &new_name, spv::ExecutionModel model)
{
    auto &entry = get_entry_point(old_name, model);
    entry.orig_name = new_name;
    entry.name = new_name;
}

void Compiler::set_entry_point(const std::string &name, spv::ExecutionModel model)
{
    auto &entry = get_entry_point(name, model);
    ir.default_entry_point = entry.self;
}

SPIREntryPoint &Compiler::get_first_entry_point(const std::string &name)
{
    auto itr = find_if(
        begin(ir.entry_points), end(ir.entry_points),
        [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool { return entry.second.orig_name == name; });

    if (itr == end(ir.entry_points))
        SPIRV_CROSS_THROW("Entry point does not exist.");

    return itr->second;
}

const SPIREntryPoint &Compiler::get_first_entry_point(const std::string &name) const
{
    auto itr = find_if(
        begin(ir.entry_points), end(ir.entry_points),
        [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool { return entry.second.orig_name == name; });

    if (itr == end(ir.entry_points))
        SPIRV_CROSS_THROW("Entry point does not exist.");

    return itr->second;
}

SPIREntryPoint &Compiler::get_entry_point(const std::string &name, ExecutionModel model)
{
    auto itr = find_if(begin(ir.entry_points), end(ir.entry_points),
                       [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool {
                           return entry.second.orig_name == name && entry.second.model == model;
                       });

    if (itr == end(ir.entry_points))
        SPIRV_CROSS_THROW("Entry point does not exist.");

    return itr->second;
}

const SPIREntryPoint &Compiler::get_entry_point(const std::string &name, ExecutionModel model) const
{
    auto itr = find_if(begin(ir.entry_points), end(ir.entry_points),
                       [&](const std::pair<uint32_t, SPIREntryPoint> &entry) -> bool {
                           return entry.second.orig_name == name && entry.second.model == model;
                       });

    if (itr == end(ir.entry_points))
        SPIRV_CROSS_THROW("Entry point does not exist.");

    return itr->second;
}

const string &Compiler::get_cleansed_entry_point_name(const std::string &name, ExecutionModel model) const
{
    return get_entry_point(name, model).name;
}

const SPIREntryPoint &Compiler::get_entry_point() const
{
    return ir.entry_points.find(ir.default_entry_point)->second;
}

SPIREntryPoint &Compiler::get_entry_point()
{
    return ir.entry_points.find(ir.default_entry_point)->second;
}

bool Compiler::interface_variable_exists_in_entry_point(uint32_t id) const
{
    auto &var = get<SPIRVariable>(id);

    if (ir.get_spirv_version() < 0x10400)
    {
        if (var.storage != StorageClassInput && var.storage != StorageClassOutput &&
            var.storage != StorageClassUniformConstant)
            SPIRV_CROSS_THROW("Only Input, Output variables and Uniform constants are part of a shader linking interface.");

        // This is to avoid potential problems with very old glslang versions which did
        // not emit input/output interfaces properly.
        // We can assume they only had a single entry point, and single entry point
        // shaders could easily be assumed to use every interface variable anyways.
        if (ir.entry_points.size() <= 1)
            return true;
    }

    // In SPIR-V 1.4 and later, all global resource variables must be present.

    auto &execution = get_entry_point();
    return find(begin(execution.interface_variables), end(execution.interface_variables), VariableID(id)) !=
           end(execution.interface_variables);
}

void Compiler::CombinedImageSamplerHandler::push_remap_parameters(const SPIRFunction &func, const uint32_t *args,
                                                                  uint32_t length)
{
    // If possible, pipe through a remapping table so that parameters know
    // which variables they actually bind to in this scope.
    unordered_map<uint32_t, uint32_t> remapping;
    for (uint32_t i = 0; i < length; i++)
        remapping[func.arguments[i].id] = remap_parameter(args[i]);
    parameter_remapping.push(std::move(remapping));
}

void Compiler::CombinedImageSamplerHandler::pop_remap_parameters()
{
    parameter_remapping.pop();
}

uint32_t Compiler::CombinedImageSamplerHandler::remap_parameter(uint32_t id)
{
    auto *var = compiler.maybe_get_backing_variable(id);
    if (var)
        id = var->self;

    if (parameter_remapping.empty())
        return id;

    auto &remapping = parameter_remapping.top();
    auto itr = remapping.find(id);
    if (itr != end(remapping))
        return itr->second;
    else
        return id;
}

bool Compiler::CombinedImageSamplerHandler::begin_function_scope(const uint32_t *args, uint32_t length)
{
    if (length < 3)
        return false;

    auto &callee = compiler.get<SPIRFunction>(args[2]);
    args += 3;
    length -= 3;
    push_remap_parameters(callee, args, length);
    functions.push(&callee);
    return true;
}

bool Compiler::CombinedImageSamplerHandler::end_function_scope(const uint32_t *args, uint32_t length)
{
    if (length < 3)
        return false;

    auto &callee = compiler.get<SPIRFunction>(args[2]);
    args += 3;

    // There are two types of cases we have to handle,
    // a callee might call sampler2D(texture2D, sampler) directly where
    // one or more parameters originate from parameters.
    // Alternatively, we need to provide combined image samplers to our callees,
    // and in this case we need to add those as well.

    pop_remap_parameters();

    // Our callee has now been processed at least once.
    // No point in doing it again.
    callee.do_combined_parameters = false;

    auto &params = functions.top()->combined_parameters;
    functions.pop();
    if (functions.empty())
        return true;

    auto &caller = *functions.top();
    if (caller.do_combined_parameters)
    {
        for (auto &param : params)
        {
            VariableID image_id = param.global_image ? param.image_id : VariableID(args[param.image_id]);
            VariableID sampler_id = param.global_sampler ? param.sampler_id : VariableID(args[param.sampler_id]);

            auto *i = compiler.maybe_get_backing_variable(image_id);
            auto *s = compiler.maybe_get_backing_variable(sampler_id);
            if (i)
                image_id = i->self;
            if (s)
                sampler_id = s->self;

            register_combined_image_sampler(caller, 0, image_id, sampler_id, param.depth);
        }
    }

    return true;
}

void Compiler::CombinedImageSamplerHandler::register_combined_image_sampler(SPIRFunction &caller,
                                                                            VariableID combined_module_id,
                                                                            VariableID image_id, VariableID sampler_id,
                                                                            bool depth)
{
    // We now have a texture ID and a sampler ID which will either be found as a global
    // or a parameter in our own function. If both are global, they will not need a parameter,
    // otherwise, add it to our list.
    SPIRFunction::CombinedImageSamplerParameter param = {
        0u, image_id, sampler_id, true, true, depth,
    };

    auto texture_itr = find_if(begin(caller.arguments), end(caller.arguments),
                               [image_id](const SPIRFunction::Parameter &p) { return p.id == image_id; });
    auto sampler_itr = find_if(begin(caller.arguments), end(caller.arguments),
                               [sampler_id](const SPIRFunction::Parameter &p) { return p.id == sampler_id; });

    if (texture_itr != end(caller.arguments))
    {
        param.global_image = false;
        param.image_id = uint32_t(texture_itr - begin(caller.arguments));
    }

    if (sampler_itr != end(caller.arguments))
    {
        param.global_sampler = false;
        param.sampler_id = uint32_t(sampler_itr - begin(caller.arguments));
    }

    if (param.global_image && param.global_sampler)
        return;

    auto itr = find_if(begin(caller.combined_parameters), end(caller.combined_parameters),
                       [&param](const SPIRFunction::CombinedImageSamplerParameter &p) {
                           return param.image_id == p.image_id && param.sampler_id == p.sampler_id &&
                                  param.global_image == p.global_image && param.global_sampler == p.global_sampler;
                       });

    if (itr == end(caller.combined_parameters))
    {
        uint32_t id = compiler.ir.increase_bound_by(3);
        auto type_id = id + 0;
        auto ptr_type_id = id + 1;
        auto combined_id = id + 2;
        auto &base = compiler.expression_type(image_id);
        auto &type = compiler.set<SPIRType>(type_id, OpTypeSampledImage);
        auto &ptr_type = compiler.set<SPIRType>(ptr_type_id, OpTypePointer);

        type = base;
        type.self = type_id;
        type.basetype = SPIRType::SampledImage;
        type.pointer = false;
        type.storage = StorageClassGeneric;
        type.image.depth = depth;

        ptr_type = type;
        ptr_type.pointer = true;
        ptr_type.storage = StorageClassUniformConstant;
        ptr_type.parent_type = type_id;

        // Build new variable.
        compiler.set<SPIRVariable>(combined_id, ptr_type_id, StorageClassFunction, 0);

        // Inherit RelaxedPrecision.
        // If any of OpSampledImage, underlying image or sampler are marked, inherit the decoration.
        bool relaxed_precision =
            compiler.has_decoration(sampler_id, DecorationRelaxedPrecision) ||
            compiler.has_decoration(image_id, DecorationRelaxedPrecision) ||
            (combined_module_id && compiler.has_decoration(combined_module_id, DecorationRelaxedPrecision));

        if (relaxed_precision)
            compiler.set_decoration(combined_id, DecorationRelaxedPrecision);

        param.id = combined_id;

        compiler.set_name(combined_id,
                          join("SPIRV_Cross_Combined", compiler.to_name(image_id), compiler.to_name(sampler_id)));

        caller.combined_parameters.push_back(param);
        caller.shadow_arguments.push_back({ ptr_type_id, combined_id, 0u, 0u, true });
    }
}

bool Compiler::DummySamplerForCombinedImageHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    if (need_dummy_sampler)
    {
        // No need to traverse further, we know the result.
        return false;
    }

    switch (opcode)
    {
    case OpLoad:
    {
        if (length < 3)
            return false;

        uint32_t result_type = args[0];

        auto &type = compiler.get<SPIRType>(result_type);
        bool separate_image =
            type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer;

        // If not separate image, don't bother.
        if (!separate_image)
            return true;

        uint32_t id = args[1];
        uint32_t ptr = args[2];
        compiler.set<SPIRExpression>(id, "", result_type, true);
        compiler.register_read(id, ptr, true);
        break;
    }

    case OpImageFetch:
    case OpImageQuerySizeLod:
    case OpImageQuerySize:
    case OpImageQueryLevels:
    case OpImageQuerySamples:
    {
        // If we are fetching or querying LOD from a plain OpTypeImage, we must pre-combine with our dummy sampler.
        auto *var = compiler.maybe_get_backing_variable(args[2]);
        if (var)
        {
            auto &type = compiler.get<SPIRType>(var->basetype);
            if (type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer)
                need_dummy_sampler = true;
        }

        break;
    }

    case OpInBoundsAccessChain:
    case OpAccessChain:
    case OpPtrAccessChain:
    {
        if (length < 3)
            return false;

        uint32_t result_type = args[0];
        auto &type = compiler.get<SPIRType>(result_type);
        bool separate_image =
            type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer;
        if (!separate_image)
            return true;

        uint32_t id = args[1];
        uint32_t ptr = args[2];
        compiler.set<SPIRExpression>(id, "", result_type, true);
        compiler.register_read(id, ptr, true);

        // Other backends might use SPIRAccessChain for this later.
        compiler.ir.ids[id].set_allow_type_rewrite();
        break;
    }

    default:
        break;
    }

    return true;
}

bool Compiler::CombinedImageSamplerHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    // We need to figure out where samplers and images are loaded from, so do only the bare bones compilation we need.
    bool is_fetch = false;

    switch (opcode)
    {
    case OpLoad:
    {
        if (length < 3)
            return false;

        uint32_t result_type = args[0];

        auto &type = compiler.get<SPIRType>(result_type);
        bool separate_image = type.basetype == SPIRType::Image && type.image.sampled == 1;
        bool separate_sampler = type.basetype == SPIRType::Sampler;

        // If not separate image or sampler, don't bother.
        if (!separate_image && !separate_sampler)
            return true;

        uint32_t id = args[1];
        uint32_t ptr = args[2];
        compiler.set<SPIRExpression>(id, "", result_type, true);
        compiler.register_read(id, ptr, true);
        return true;
    }

    case OpInBoundsAccessChain:
    case OpAccessChain:
    case OpPtrAccessChain:
    {
        if (length < 3)
            return false;

        // Technically, it is possible to have arrays of textures and arrays of samplers and combine them, but this becomes essentially
        // impossible to implement, since we don't know which concrete sampler we are accessing.
        // One potential way is to create a combinatorial explosion where N textures and M samplers are combined into N * M sampler2Ds,
        // but this seems ridiculously complicated for a problem which is easy to work around.
        // Checking access chains like this assumes we don't have samplers or textures inside uniform structs, but this makes no sense.

        uint32_t result_type = args[0];

        auto &type = compiler.get<SPIRType>(result_type);
        bool separate_image = type.basetype == SPIRType::Image && type.image.sampled == 1;
        bool separate_sampler = type.basetype == SPIRType::Sampler;
        if (separate_sampler)
            SPIRV_CROSS_THROW(
                "Attempting to use arrays or structs of separate samplers. This is not possible to statically "
                "remap to plain GLSL.");

        if (separate_image)
        {
            uint32_t id = args[1];
            uint32_t ptr = args[2];
            compiler.set<SPIRExpression>(id, "", result_type, true);
            compiler.register_read(id, ptr, true);
        }
        return true;
    }

    case OpImageFetch:
    case OpImageQuerySizeLod:
    case OpImageQuerySize:
    case OpImageQueryLevels:
    case OpImageQuerySamples:
    {
        // If we are fetching from a plain OpTypeImage or querying LOD, we must pre-combine with our dummy sampler.
        auto *var = compiler.maybe_get_backing_variable(args[2]);
        if (!var)
            return true;

        auto &type = compiler.get<SPIRType>(var->basetype);
        if (type.basetype == SPIRType::Image && type.image.sampled == 1 && type.image.dim != DimBuffer)
        {
            if (compiler.dummy_sampler_id == 0)
                SPIRV_CROSS_THROW("texelFetch without sampler was found, but no dummy sampler has been created with "
                                  "build_dummy_sampler_for_combined_images().");

            // Do it outside.
            is_fetch = true;
            break;
        }

        return true;
    }

    case OpSampledImage:
        // Do it outside.
        break;

    default:
        return true;
    }

    // Registers sampler2D calls used in case they are parameters so
    // that their callees know which combined image samplers to propagate down the call stack.
    if (!functions.empty())
    {
        auto &callee = *functions.top();
        if (callee.do_combined_parameters)
        {
            uint32_t image_id = args[2];

            auto *image = compiler.maybe_get_backing_variable(image_id);
            if (image)
                image_id = image->self;

            uint32_t sampler_id = is_fetch ? compiler.dummy_sampler_id : args[3];
            auto *sampler = compiler.maybe_get_backing_variable(sampler_id);
            if (sampler)
                sampler_id = sampler->self;

            uint32_t combined_id = args[1];

            auto &combined_type = compiler.get<SPIRType>(args[0]);
            register_combined_image_sampler(callee, combined_id, image_id, sampler_id, combined_type.image.depth);
        }
    }

    // For function calls, we need to remap IDs which are function parameters into global variables.
    // This information is statically known from the current place in the call stack.
    // Function parameters are not necessarily pointers, so if we don't have a backing variable, remapping will know
    // which backing variable the image/sample came from.
    VariableID image_id = remap_parameter(args[2]);
    VariableID sampler_id = is_fetch ? compiler.dummy_sampler_id : remap_parameter(args[3]);

    auto itr = find_if(begin(compiler.combined_image_samplers), end(compiler.combined_image_samplers),
                       [image_id, sampler_id](const CombinedImageSampler &combined) {
                           return combined.image_id == image_id && combined.sampler_id == sampler_id;
                       });

    if (itr == end(compiler.combined_image_samplers))
    {
        uint32_t sampled_type;
        uint32_t combined_module_id;
        if (is_fetch)
        {
            // Have to invent the sampled image type.
            sampled_type = compiler.ir.increase_bound_by(1);
            auto &type = compiler.set<SPIRType>(sampled_type, OpTypeSampledImage);
            type = compiler.expression_type(args[2]);
            type.self = sampled_type;
            type.basetype = SPIRType::SampledImage;
            type.image.depth = false;
            combined_module_id = 0;
        }
        else
        {
            sampled_type = args[0];
            combined_module_id = args[1];
        }

        auto id = compiler.ir.increase_bound_by(2);
        auto type_id = id + 0;
        auto combined_id = id + 1;

        // Make a new type, pointer to OpTypeSampledImage, so we can make a variable of this type.
        // We will probably have this type lying around, but it doesn't hurt to make duplicates for internal purposes.
        auto &type = compiler.set<SPIRType>(type_id, OpTypePointer);
        auto &base = compiler.get<SPIRType>(sampled_type);
        type = base;
        type.pointer = true;
        type.storage = StorageClassUniformConstant;
        type.parent_type = type_id;

        // Build new variable.
        compiler.set<SPIRVariable>(combined_id, type_id, StorageClassUniformConstant, 0);

        // Inherit RelaxedPrecision (and potentially other useful flags if deemed relevant).
        // If any of OpSampledImage, underlying image or sampler are marked, inherit the decoration.
        bool relaxed_precision =
            (sampler_id && compiler.has_decoration(sampler_id, DecorationRelaxedPrecision)) ||
            (image_id && compiler.has_decoration(image_id, DecorationRelaxedPrecision)) ||
            (combined_module_id && compiler.has_decoration(combined_module_id, DecorationRelaxedPrecision));

        if (relaxed_precision)
            compiler.set_decoration(combined_id, DecorationRelaxedPrecision);

        // Propagate the array type for the original image as well.
        auto *var = compiler.maybe_get_backing_variable(image_id);
        if (var)
        {
            auto &parent_type = compiler.get<SPIRType>(var->basetype);
            type.array = parent_type.array;
            type.array_size_literal = parent_type.array_size_literal;
        }

        compiler.combined_image_samplers.push_back({ combined_id, image_id, sampler_id });
    }

    return true;
}

VariableID Compiler::build_dummy_sampler_for_combined_images()
{
    DummySamplerForCombinedImageHandler handler(*this);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);
    if (handler.need_dummy_sampler)
    {
        uint32_t offset = ir.increase_bound_by(3);
        auto type_id = offset + 0;
        auto ptr_type_id = offset + 1;
        auto var_id = offset + 2;

        auto &sampler = set<SPIRType>(type_id, OpTypeSampler);
        sampler.basetype = SPIRType::Sampler;

        auto &ptr_sampler = set<SPIRType>(ptr_type_id, OpTypePointer);
        ptr_sampler = sampler;
        ptr_sampler.self = type_id;
        ptr_sampler.storage = StorageClassUniformConstant;
        ptr_sampler.pointer = true;
        ptr_sampler.parent_type = type_id;

        set<SPIRVariable>(var_id, ptr_type_id, StorageClassUniformConstant, 0);
        set_name(var_id, "SPIRV_Cross_DummySampler");
        dummy_sampler_id = var_id;
        return var_id;
    }
    else
        return 0;
}

void Compiler::build_combined_image_samplers(bool bReserve)
{
    ir.for_each_typed_id<SPIRFunction>([&](uint32_t, SPIRFunction &func) {
        func.combined_parameters.clear();
        func.shadow_arguments.clear();
        func.do_combined_parameters = true;
    });

    combined_image_samplers.clear();
    CombinedImageSamplerHandler handler(*this);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);
    if (bReserve)
    {
        spirv_cross_util::inherit_combined_sampler_bindings(*this);
    }
}

SmallVector<SpecializationConstant> Compiler::get_specialization_constants() const
{
    SmallVector<SpecializationConstant> spec_consts;
    ir.for_each_typed_id<SPIRConstant>([&](uint32_t, const SPIRConstant &c) {
        if (c.specialization && has_decoration(c.self, DecorationSpecId))
            spec_consts.push_back({ c.self, get_decoration(c.self, DecorationSpecId) });
    });
    return spec_consts;
}

SPIRConstant &Compiler::get_constant(ConstantID id)
{
    return get<SPIRConstant>(id);
}

const SPIRConstant &Compiler::get_constant(ConstantID id) const
{
    return get<SPIRConstant>(id);
}

static bool exists_unaccessed_path_to_return(const CFG &cfg, uint32_t block, const unordered_set<uint32_t> &blocks,
                                             unordered_set<uint32_t> &visit_cache)
{
    // This block accesses the variable.
    if (blocks.find(block) != end(blocks))
        return false;

    // We are at the end of the CFG.
    if (cfg.get_succeeding_edges(block).empty())
        return true;

    // If any of our successors have a path to the end, there exists a path from block.
    for (auto &succ : cfg.get_succeeding_edges(block))
    {
        if (visit_cache.count(succ) == 0)
        {
            if (exists_unaccessed_path_to_return(cfg, succ, blocks, visit_cache))
                return true;
            visit_cache.insert(succ);
        }
    }

    return false;
}

void Compiler::analyze_parameter_preservation(
    SPIRFunction &entry, const CFG &cfg, const unordered_map<uint32_t, unordered_set<uint32_t>> &variable_to_blocks,
    const unordered_map<uint32_t, unordered_set<uint32_t>> &complete_write_blocks)
{
    for (auto &arg : entry.arguments)
    {
        // Non-pointers are always inputs.
        auto &type = get<SPIRType>(arg.type);
        if (!type.pointer)
            continue;

        // Opaque argument types are always in
        bool potential_preserve;
        switch (type.basetype)
        {
        case SPIRType::Sampler:
        case SPIRType::Image:
        case SPIRType::SampledImage:
        case SPIRType::AtomicCounter:
            potential_preserve = false;
            break;

        default:
            potential_preserve = true;
            break;
        }

        if (!potential_preserve)
            continue;

        auto itr = variable_to_blocks.find(arg.id);
        if (itr == end(variable_to_blocks))
        {
            // Variable is never accessed.
            continue;
        }

        // We have accessed a variable, but there was no complete writes to that variable.
        // We deduce that we must preserve the argument.
        itr = complete_write_blocks.find(arg.id);
        if (itr == end(complete_write_blocks))
        {
            arg.read_count++;
            continue;
        }

        // If there is a path through the CFG where no block completely writes to the variable, the variable will be in an undefined state
        // when the function returns. We therefore need to implicitly preserve the variable in case there are writers in the function.
        // Major case here is if a function is
        // void foo(int &var) { if (cond) var = 10; }
        // Using read/write counts, we will think it's just an out variable, but it really needs to be inout,
        // because if we don't write anything whatever we put into the function must return back to the caller.
        unordered_set<uint32_t> visit_cache;
        if (exists_unaccessed_path_to_return(cfg, entry.entry_block, itr->second, visit_cache))
            arg.read_count++;
    }
}

Compiler::AnalyzeVariableScopeAccessHandler::AnalyzeVariableScopeAccessHandler(Compiler &compiler_,
                                                                               SPIRFunction &entry_)
    : compiler(compiler_)
    , entry(entry_)
{
}

bool Compiler::AnalyzeVariableScopeAccessHandler::follow_function_call(const SPIRFunction &)
{
    // Only analyze within this function.
    return false;
}

void Compiler::AnalyzeVariableScopeAccessHandler::set_current_block(const SPIRBlock &block)
{
    current_block = &block;

    // If we're branching to a block which uses OpPhi, in GLSL
    // this will be a variable write when we branch,
    // so we need to track access to these variables as well to
    // have a complete picture.
    const auto test_phi = [this, &block](uint32_t to) {
        auto &next = compiler.get<SPIRBlock>(to);
        for (auto &phi : next.phi_variables)
        {
            if (phi.parent == block.self)
            {
                accessed_variables_to_block[phi.function_variable].insert(block.self);
                // Phi variables are also accessed in our target branch block.
                accessed_variables_to_block[phi.function_variable].insert(next.self);

                notify_variable_access(phi.local_variable, block.self);
            }
        }
    };

    switch (block.terminator)
    {
    case SPIRBlock::Direct:
        notify_variable_access(block.condition, block.self);
        test_phi(block.next_block);
        break;

    case SPIRBlock::Select:
        notify_variable_access(block.condition, block.self);
        test_phi(block.true_block);
        test_phi(block.false_block);
        break;

    case SPIRBlock::MultiSelect:
    {
        notify_variable_access(block.condition, block.self);
        auto &cases = compiler.get_case_list(block);
        for (auto &target : cases)
            test_phi(target.block);
        if (block.default_block)
            test_phi(block.default_block);
        break;
    }

    default:
        break;
    }
}

void Compiler::AnalyzeVariableScopeAccessHandler::notify_variable_access(uint32_t id, uint32_t block)
{
    if (id == 0)
        return;

    // Access chains used in multiple blocks mean hoisting all the variables used to construct the access chain as not all backends can use pointers.
    auto itr = rvalue_forward_children.find(id);
    if (itr != end(rvalue_forward_children))
        for (auto child_id : itr->second)
            notify_variable_access(child_id, block);

    if (id_is_phi_variable(id))
        accessed_variables_to_block[id].insert(block);
    else if (id_is_potential_temporary(id))
        accessed_temporaries_to_block[id].insert(block);
}

bool Compiler::AnalyzeVariableScopeAccessHandler::id_is_phi_variable(uint32_t id) const
{
    if (id >= compiler.get_current_id_bound())
        return false;
    auto *var = compiler.maybe_get<SPIRVariable>(id);
    return var && var->phi_variable;
}

bool Compiler::AnalyzeVariableScopeAccessHandler::id_is_potential_temporary(uint32_t id) const
{
    if (id >= compiler.get_current_id_bound())
        return false;

    // Temporaries are not created before we start emitting code.
    return compiler.ir.ids[id].empty() || (compiler.ir.ids[id].get_type() == TypeExpression);
}

bool Compiler::AnalyzeVariableScopeAccessHandler::handle_terminator(const SPIRBlock &block)
{
    switch (block.terminator)
    {
    case SPIRBlock::Return:
        if (block.return_value)
            notify_variable_access(block.return_value, block.self);
        break;

    case SPIRBlock::Select:
    case SPIRBlock::MultiSelect:
        notify_variable_access(block.condition, block.self);
        break;

    default:
        break;
    }

    return true;
}

bool Compiler::AnalyzeVariableScopeAccessHandler::handle(spv::Op op, const uint32_t *args, uint32_t length)
{
    // Keep track of the types of temporaries, so we can hoist them out as necessary.
    uint32_t result_type = 0, result_id = 0;
    if (compiler.instruction_to_result_type(result_type, result_id, op, args, length))
    {
        // For some opcodes, we will need to override the result id.
        // If we need to hoist the temporary, the temporary type is the input, not the result.
        if (op == OpConvertUToAccelerationStructureKHR)
        {
            auto itr = result_id_to_type.find(args[2]);
            if (itr != result_id_to_type.end())
                result_type = itr->second;
        }

        result_id_to_type[result_id] = result_type;
    }

    switch (op)
    {
    case OpStore:
    {
        if (length < 2)
            return false;

        ID ptr = args[0];
        auto *var = compiler.maybe_get_backing_variable(ptr);

        // If we store through an access chain, we have a partial write.
        if (var)
        {
            accessed_variables_to_block[var->self].insert(current_block->self);
            if (var->self == ptr)
                complete_write_variables_to_block[var->self].insert(current_block->self);
            else
                partial_write_variables_to_block[var->self].insert(current_block->self);
        }

        // args[0] might be an access chain we have to track use of.
        notify_variable_access(args[0], current_block->self);
        // Might try to store a Phi variable here.
        notify_variable_access(args[1], current_block->self);
        break;
    }

    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
    {
        if (length < 3)
            return false;

        // Access chains used in multiple blocks mean hoisting all the variables used to construct the access chain as not all backends can use pointers.
        uint32_t ptr = args[2];
        auto *var = compiler.maybe_get<SPIRVariable>(ptr);
        if (var)
        {
            accessed_variables_to_block[var->self].insert(current_block->self);
            rvalue_forward_children[args[1]].insert(var->self);
        }

        // args[2] might be another access chain we have to track use of.
        for (uint32_t i = 2; i < length; i++)
        {
            notify_variable_access(args[i], current_block->self);
            rvalue_forward_children[args[1]].insert(args[i]);
        }

        // Also keep track of the access chain pointer itself.
        // In exceptionally rare cases, we can end up with a case where
        // the access chain is generated in the loop body, but is consumed in continue block.
        // This means we need complex loop workarounds, and we must detect this via CFG analysis.
        notify_variable_access(args[1], current_block->self);

        // The result of an access chain is a fixed expression and is not really considered a temporary.
        auto &e = compiler.set<SPIRExpression>(args[1], "", args[0], true);
        auto *backing_variable = compiler.maybe_get_backing_variable(ptr);
        e.loaded_from = backing_variable ? VariableID(backing_variable->self) : VariableID(0);

        // Other backends might use SPIRAccessChain for this later.
        compiler.ir.ids[args[1]].set_allow_type_rewrite();
        access_chain_expressions.insert(args[1]);
        break;
    }

    case OpCopyMemory:
    {
        if (length < 2)
            return false;

        ID lhs = args[0];
        ID rhs = args[1];
        auto *var = compiler.maybe_get_backing_variable(lhs);

        // If we store through an access chain, we have a partial write.
        if (var)
        {
            accessed_variables_to_block[var->self].insert(current_block->self);
            if (var->self == lhs)
                complete_write_variables_to_block[var->self].insert(current_block->self);
            else
                partial_write_variables_to_block[var->self].insert(current_block->self);
        }

        // args[0:1] might be access chains we have to track use of.
        for (uint32_t i = 0; i < 2; i++)
            notify_variable_access(args[i], current_block->self);

        var = compiler.maybe_get_backing_variable(rhs);
        if (var)
            accessed_variables_to_block[var->self].insert(current_block->self);
        break;
    }

    case OpCopyObject:
    {
        // OpCopyObject copies the underlying non-pointer type, 
        // so any temp variable should be declared using the underlying type.
        // If the type is a pointer, get its base type and overwrite the result type mapping.
        auto &type = compiler.get<SPIRType>(result_type);
        if (type.pointer)
            result_id_to_type[result_id] = type.parent_type;

        if (length < 3)
            return false;

        auto *var = compiler.maybe_get_backing_variable(args[2]);
        if (var)
            accessed_variables_to_block[var->self].insert(current_block->self);

        // Might be an access chain which we have to keep track of.
        notify_variable_access(args[1], current_block->self);
        if (access_chain_expressions.count(args[2]))
            access_chain_expressions.insert(args[1]);

        // Might try to copy a Phi variable here.
        notify_variable_access(args[2], current_block->self);
        break;
    }

    case OpLoad:
    {
        if (length < 3)
            return false;
        uint32_t ptr = args[2];
        auto *var = compiler.maybe_get_backing_variable(ptr);
        if (var)
            accessed_variables_to_block[var->self].insert(current_block->self);

        // Loaded value is a temporary.
        notify_variable_access(args[1], current_block->self);

        // Might be an access chain we have to track use of.
        notify_variable_access(args[2], current_block->self);

        // If we're loading an opaque type we cannot lower it to a temporary,
        // we must defer access of args[2] until it's used.
        auto &type = compiler.get<SPIRType>(args[0]);
        if (compiler.type_is_opaque_value(type))
            rvalue_forward_children[args[1]].insert(args[2]);
        break;
    }

    case OpFunctionCall:
    {
        if (length < 3)
            return false;

        // Return value may be a temporary.
        if (compiler.get_type(args[0]).basetype != SPIRType::Void)
            notify_variable_access(args[1], current_block->self);

        length -= 3;
        args += 3;

        for (uint32_t i = 0; i < length; i++)
        {
            auto *var = compiler.maybe_get_backing_variable(args[i]);
            if (var)
            {
                accessed_variables_to_block[var->self].insert(current_block->self);
                // Assume we can get partial writes to this variable.
                partial_write_variables_to_block[var->self].insert(current_block->self);
            }

            // Cannot easily prove if argument we pass to a function is completely written.
            // Usually, functions write to a dummy variable,
            // which is then copied to in full to the real argument.

            // Might try to copy a Phi variable here.
            notify_variable_access(args[i], current_block->self);
        }
        break;
    }

    case OpSelect:
    {
        // In case of variable pointers, we might access a variable here.
        // We cannot prove anything about these accesses however.
        for (uint32_t i = 1; i < length; i++)
        {
            if (i >= 3)
            {
                auto *var = compiler.maybe_get_backing_variable(args[i]);
                if (var)
                {
                    accessed_variables_to_block[var->self].insert(current_block->self);
                    // Assume we can get partial writes to this variable.
                    partial_write_variables_to_block[var->self].insert(current_block->self);
                }
            }

            // Might try to copy a Phi variable here.
            notify_variable_access(args[i], current_block->self);
        }
        break;
    }

    case OpExtInst:
    {
        for (uint32_t i = 4; i < length; i++)
            notify_variable_access(args[i], current_block->self);
        notify_variable_access(args[1], current_block->self);

        uint32_t extension_set = args[2];
        if (compiler.get<SPIRExtension>(extension_set).ext == SPIRExtension::GLSL)
        {
            auto op_450 = static_cast<GLSLstd450>(args[3]);
            switch (op_450)
            {
            case GLSLstd450Modf:
            case GLSLstd450Frexp:
            {
                uint32_t ptr = args[5];
                auto *var = compiler.maybe_get_backing_variable(ptr);
                if (var)
                {
                    accessed_variables_to_block[var->self].insert(current_block->self);
                    if (var->self == ptr)
                        complete_write_variables_to_block[var->self].insert(current_block->self);
                    else
                        partial_write_variables_to_block[var->self].insert(current_block->self);
                }
                break;
            }

            default:
                break;
            }
        }
        break;
    }

    case OpArrayLength:
        // Only result is a temporary.
        notify_variable_access(args[1], current_block->self);
        break;

    case OpLine:
    case OpNoLine:
        // Uses literals, but cannot be a phi variable or temporary, so ignore.
        break;

        // Atomics shouldn't be able to access function-local variables.
        // Some GLSL builtins access a pointer.

    case OpCompositeInsert:
    case OpVectorShuffle:
        // Specialize for opcode which contains literals.
        for (uint32_t i = 1; i < 4; i++)
            notify_variable_access(args[i], current_block->self);
        break;

    case OpCompositeExtract:
        // Specialize for opcode which contains literals.
        for (uint32_t i = 1; i < 3; i++)
            notify_variable_access(args[i], current_block->self);
        break;

    case OpImageWrite:
        for (uint32_t i = 0; i < length; i++)
        {
            // Argument 3 is a literal.
            if (i != 3)
                notify_variable_access(args[i], current_block->self);
        }
        break;

    case OpImageSampleImplicitLod:
    case OpImageSampleExplicitLod:
    case OpImageSparseSampleImplicitLod:
    case OpImageSparseSampleExplicitLod:
    case OpImageSampleProjImplicitLod:
    case OpImageSampleProjExplicitLod:
    case OpImageSparseSampleProjImplicitLod:
    case OpImageSparseSampleProjExplicitLod:
    case OpImageFetch:
    case OpImageSparseFetch:
    case OpImageRead:
    case OpImageSparseRead:
        for (uint32_t i = 1; i < length; i++)
        {
            // Argument 4 is a literal.
            if (i != 4)
                notify_variable_access(args[i], current_block->self);
        }
        break;

    case OpImageSampleDrefImplicitLod:
    case OpImageSampleDrefExplicitLod:
    case OpImageSparseSampleDrefImplicitLod:
    case OpImageSparseSampleDrefExplicitLod:
    case OpImageSampleProjDrefImplicitLod:
    case OpImageSampleProjDrefExplicitLod:
    case OpImageSparseSampleProjDrefImplicitLod:
    case OpImageSparseSampleProjDrefExplicitLod:
    case OpImageGather:
    case OpImageSparseGather:
    case OpImageDrefGather:
    case OpImageSparseDrefGather:
        for (uint32_t i = 1; i < length; i++)
        {
            // Argument 5 is a literal.
            if (i != 5)
                notify_variable_access(args[i], current_block->self);
        }
        break;

    default:
    {
        // Rather dirty way of figuring out where Phi variables are used.
        // As long as only IDs are used, we can scan through instructions and try to find any evidence that
        // the ID of a variable has been used.
        // There are potential false positives here where a literal is used in-place of an ID,
        // but worst case, it does not affect the correctness of the compile.
        // Exhaustive analysis would be better here, but it's not worth it for now.
        for (uint32_t i = 0; i < length; i++)
            notify_variable_access(args[i], current_block->self);
        break;
    }
    }
    return true;
}

Compiler::StaticExpressionAccessHandler::StaticExpressionAccessHandler(Compiler &compiler_, uint32_t variable_id_)
    : compiler(compiler_)
    , variable_id(variable_id_)
{
}

bool Compiler::StaticExpressionAccessHandler::follow_function_call(const SPIRFunction &)
{
    return false;
}

bool Compiler::StaticExpressionAccessHandler::handle(spv::Op op, const uint32_t *args, uint32_t length)
{
    switch (op)
    {
    case OpStore:
        if (length < 2)
            return false;
        if (args[0] == variable_id)
        {
            static_expression = args[1];
            write_count++;
        }
        break;

    case OpLoad:
        if (length < 3)
            return false;
        if (args[2] == variable_id && static_expression == 0) // Tried to read from variable before it was initialized.
            return false;
        break;

    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
        if (length < 3)
            return false;
        if (args[2] == variable_id) // If we try to access chain our candidate variable before we store to it, bail.
            return false;
        break;

    default:
        break;
    }

    return true;
}

void Compiler::find_function_local_luts(SPIRFunction &entry, const AnalyzeVariableScopeAccessHandler &handler,
                                        bool single_function)
{
    auto &cfg = *function_cfgs.find(entry.self)->second;

    // For each variable which is statically accessed.
    for (auto &accessed_var : handler.accessed_variables_to_block)
    {
        auto &blocks = accessed_var.second;
        auto &var = get<SPIRVariable>(accessed_var.first);
        auto &type = expression_type(accessed_var.first);

        // First check if there are writes to the variable. Later, if there are none, we'll
        // reconsider it as globally accessed LUT.
        if (!var.is_written_to)
        {
            var.is_written_to = handler.complete_write_variables_to_block.count(var.self) != 0 ||
                                handler.partial_write_variables_to_block.count(var.self) != 0;
        }

        // Only consider function local variables here.
        // If we only have a single function in our CFG, private storage is also fine,
        // since it behaves like a function local variable.
        bool allow_lut = var.storage == StorageClassFunction || (single_function && var.storage == StorageClassPrivate);
        if (!allow_lut)
            continue;

        // We cannot be a phi variable.
        if (var.phi_variable)
            continue;

        // Only consider arrays here.
        if (type.array.empty())
            continue;

        // If the variable has an initializer, make sure it is a constant expression.
        uint32_t static_constant_expression = 0;
        if (var.initializer)
        {
            if (ir.ids[var.initializer].get_type() != TypeConstant)
                continue;
            static_constant_expression = var.initializer;

            // There can be no stores to this variable, we have now proved we have a LUT.
            if (var.is_written_to)
                continue;
        }
        else
        {
            // We can have one, and only one write to the variable, and that write needs to be a constant.

            // No partial writes allowed.
            if (handler.partial_write_variables_to_block.count(var.self) != 0)
                continue;

            auto itr = handler.complete_write_variables_to_block.find(var.self);

            // No writes?
            if (itr == end(handler.complete_write_variables_to_block))
                continue;

            // We write to the variable in more than one block.
            auto &write_blocks = itr->second;
            if (write_blocks.size() != 1)
                continue;

            // The write needs to happen in the dominating block.
            DominatorBuilder builder(cfg);
            for (auto &block : blocks)
                builder.add_block(block);
            uint32_t dominator = builder.get_dominator();

            // The complete write happened in a branch or similar, cannot deduce static expression.
            if (write_blocks.count(dominator) == 0)
                continue;

            // Find the static expression for this variable.
            StaticExpressionAccessHandler static_expression_handler(*this, var.self);
            traverse_all_reachable_opcodes(get<SPIRBlock>(dominator), static_expression_handler);

            // We want one, and exactly one write
            if (static_expression_handler.write_count != 1 || static_expression_handler.static_expression == 0)
                continue;

            // Is it a constant expression?
            if (ir.ids[static_expression_handler.static_expression].get_type() != TypeConstant)
                continue;

            // We found a LUT!
            static_constant_expression = static_expression_handler.static_expression;
        }

        get<SPIRConstant>(static_constant_expression).is_used_as_lut = true;
        var.static_expression = static_constant_expression;
        var.statically_assigned = true;
        var.remapped_variable = true;
    }
}

void Compiler::analyze_variable_scope(SPIRFunction &entry, AnalyzeVariableScopeAccessHandler &handler)
{
    // First, we map out all variable access within a function.
    // Essentially a map of block -> { variables accessed in the basic block }
    traverse_all_reachable_opcodes(entry, handler);

    auto &cfg = *function_cfgs.find(entry.self)->second;

    // Analyze if there are parameters which need to be implicitly preserved with an "in" qualifier.
    analyze_parameter_preservation(entry, cfg, handler.accessed_variables_to_block,
                                   handler.complete_write_variables_to_block);

    unordered_map<uint32_t, uint32_t> potential_loop_variables;

    // Find the loop dominator block for each block.
    for (auto &block_id : entry.blocks)
    {
        auto &block = get<SPIRBlock>(block_id);

        auto itr = ir.continue_block_to_loop_header.find(block_id);
        if (itr != end(ir.continue_block_to_loop_header) && itr->second != block_id)
        {
            // Continue block might be unreachable in the CFG, but we still like to know the loop dominator.
            // Edge case is when continue block is also the loop header, don't set the dominator in this case.
            block.loop_dominator = itr->second;
        }
        else
        {
            uint32_t loop_dominator = cfg.find_loop_dominator(block_id);
            if (loop_dominator != block_id)
                block.loop_dominator = loop_dominator;
            else
                block.loop_dominator = SPIRBlock::NoDominator;
        }
    }

    // For each variable which is statically accessed.
    for (auto &var : handler.accessed_variables_to_block)
    {
        // Only deal with variables which are considered local variables in this function.
        if (find(begin(entry.local_variables), end(entry.local_variables), VariableID(var.first)) ==
            end(entry.local_variables))
            continue;

        DominatorBuilder builder(cfg);
        auto &blocks = var.second;
        auto &type = expression_type(var.first);
        BlockID potential_continue_block = 0;

        // Figure out which block is dominating all accesses of those variables.
        for (auto &block : blocks)
        {
            // If we're accessing a variable inside a continue block, this variable might be a loop variable.
            // We can only use loop variables with scalars, as we cannot track static expressions for vectors.
            if (is_continue(block))
            {
                // Potentially awkward case to check for.
                // We might have a variable inside a loop, which is touched by the continue block,
                // but is not actually a loop variable.
                // The continue block is dominated by the inner part of the loop, which does not make sense in high-level
                // language output because it will be declared before the body,
                // so we will have to lift the dominator up to the relevant loop header instead.
                builder.add_block(ir.continue_block_to_loop_header[block]);

                // Arrays or structs cannot be loop variables.
                if (type.vecsize == 1 && type.columns == 1 && type.basetype != SPIRType::Struct && type.array.empty())
                {
                    // The variable is used in multiple continue blocks, this is not a loop
                    // candidate, signal that by setting block to -1u.
                    if (potential_continue_block == 0)
                        potential_continue_block = block;
                    else
                        potential_continue_block = ~(0u);
                }
            }

            builder.add_block(block);
        }

        builder.lift_continue_block_dominator();

        // Add it to a per-block list of variables.
        BlockID dominating_block = builder.get_dominator();

        if (dominating_block && potential_continue_block != 0 && potential_continue_block != ~0u)
        {
            auto &inner_block = get<SPIRBlock>(dominating_block);

            BlockID merge_candidate = 0;

            // Analyze the dominator. If it lives in a different loop scope than the candidate continue
            // block, reject the loop variable candidate.
            if (inner_block.merge == SPIRBlock::MergeLoop)
                merge_candidate = inner_block.merge_block;
            else if (inner_block.loop_dominator != SPIRBlock::NoDominator)
                merge_candidate = get<SPIRBlock>(inner_block.loop_dominator).merge_block;

            if (merge_candidate != 0 && cfg.is_reachable(merge_candidate))
            {
                // If the merge block has a higher post-visit order, we know that continue candidate
                // cannot reach the merge block, and we have two separate scopes.
                if (!cfg.is_reachable(potential_continue_block) ||
                    cfg.get_visit_order(merge_candidate) > cfg.get_visit_order(potential_continue_block))
                {
                    potential_continue_block = 0;
                }
            }
        }

        if (potential_continue_block != 0 && potential_continue_block != ~0u)
            potential_loop_variables[var.first] = potential_continue_block;

        // For variables whose dominating block is inside a loop, there is a risk that these variables
        // actually need to be preserved across loop iterations. We can express this by adding
        // a "read" access to the loop header.
        // In the dominating block, we must see an OpStore or equivalent as the first access of an OpVariable.
        // Should that fail, we look for the outermost loop header and tack on an access there.
        // Phi nodes cannot have this problem.
        if (dominating_block)
        {
            auto &variable = get<SPIRVariable>(var.first);
            if (!variable.phi_variable)
            {
                auto *block = &get<SPIRBlock>(dominating_block);
                bool preserve = may_read_undefined_variable_in_block(*block, var.first);
                if (preserve)
                {
                    // Find the outermost loop scope.
                    while (block->loop_dominator != BlockID(SPIRBlock::NoDominator))
                        block = &get<SPIRBlock>(block->loop_dominator);

                    if (block->self != dominating_block)
                    {
                        builder.add_block(block->self);
                        dominating_block = builder.get_dominator();
                    }
                }
            }
        }

        // If all blocks here are dead code, this will be 0, so the variable in question
        // will be completely eliminated.
        if (dominating_block)
        {
            auto &block = get<SPIRBlock>(dominating_block);
            block.dominated_variables.push_back(var.first);
            get<SPIRVariable>(var.first).dominator = dominating_block;
        }
    }

    for (auto &var : handler.accessed_temporaries_to_block)
    {
        auto itr = handler.result_id_to_type.find(var.first);

        if (itr == end(handler.result_id_to_type))
        {
            // We found a false positive ID being used, ignore.
            // This should probably be an assert.
            continue;
        }

        // There is no point in doing domination analysis for opaque types.
        auto &type = get<SPIRType>(itr->second);
        if (type_is_opaque_value(type))
            continue;

        DominatorBuilder builder(cfg);
        bool force_temporary = false;
        bool used_in_header_hoisted_continue_block = false;

        // Figure out which block is dominating all accesses of those temporaries.
        auto &blocks = var.second;
        for (auto &block : blocks)
        {
            builder.add_block(block);

            if (blocks.size() != 1 && is_continue(block))
            {
                // The risk here is that inner loop can dominate the continue block.
                // Any temporary we access in the continue block must be declared before the loop.
                // This is moot for complex loops however.
                auto &loop_header_block = get<SPIRBlock>(ir.continue_block_to_loop_header[block]);
                assert(loop_header_block.merge == SPIRBlock::MergeLoop);
                builder.add_block(loop_header_block.self);
                used_in_header_hoisted_continue_block = true;
            }
        }

        uint32_t dominating_block = builder.get_dominator();

        if (blocks.size() != 1 && is_single_block_loop(dominating_block))
        {
            // Awkward case, because the loop header is also the continue block,
            // so hoisting to loop header does not help.
            force_temporary = true;
        }

        if (dominating_block)
        {
            // If we touch a variable in the dominating block, this is the expected setup.
            // SPIR-V normally mandates this, but we have extra cases for temporary use inside loops.
            bool first_use_is_dominator = blocks.count(dominating_block) != 0;

            if (!first_use_is_dominator || force_temporary)
            {
                if (handler.access_chain_expressions.count(var.first))
                {
                    // Exceptionally rare case.
                    // We cannot declare temporaries of access chains (except on MSL perhaps with pointers).
                    // Rather than do that, we force the indexing expressions to be declared in the right scope by
                    // tracking their usage to that end. There is no temporary to hoist.
                    // However, we still need to observe declaration order of the access chain.

                    if (used_in_header_hoisted_continue_block)
                    {
                        // For this scenario, we used an access chain inside a continue block where we also registered an access to header block.
                        // This is a problem as we need to declare an access chain properly first with full definition.
                        // We cannot use temporaries for these expressions,
                        // so we must make sure the access chain is declared ahead of time.
                        // Force a complex for loop to deal with this.
                        // TODO: Out-of-order declaring for loops where continue blocks are emitted last might be another option.
                        auto &loop_header_block = get<SPIRBlock>(dominating_block);
                        assert(loop_header_block.merge == SPIRBlock::MergeLoop);
                        loop_header_block.complex_continue = true;
                    }
                }
                else
                {
                    // This should be very rare, but if we try to declare a temporary inside a loop,
                    // and that temporary is used outside the loop as well (spirv-opt inliner likes this)
                    // we should actually emit the temporary outside the loop.
                    hoisted_temporaries.insert(var.first);
                    forced_temporaries.insert(var.first);

                    auto &block_temporaries = get<SPIRBlock>(dominating_block).declare_temporary;
                    block_temporaries.emplace_back(handler.result_id_to_type[var.first], var.first);
                }
            }
            else if (blocks.size() > 1)
            {
                // Keep track of the temporary as we might have to declare this temporary.
                // This can happen if the loop header dominates a temporary, but we have a complex fallback loop.
                // In this case, the header is actually inside the for (;;) {} block, and we have problems.
                // What we need to do is hoist the temporaries outside the for (;;) {} block in case the header block
                // declares the temporary.
                auto &block_temporaries = get<SPIRBlock>(dominating_block).potential_declare_temporary;
                block_temporaries.emplace_back(handler.result_id_to_type[var.first], var.first);
            }
        }
    }

    unordered_set<uint32_t> seen_blocks;

    // Now, try to analyze whether or not these variables are actually loop variables.
    for (auto &loop_variable : potential_loop_variables)
    {
        auto &var = get<SPIRVariable>(loop_variable.first);
        auto dominator = var.dominator;
        BlockID block = loop_variable.second;

        // The variable was accessed in multiple continue blocks, ignore.
        if (block == BlockID(~(0u)) || block == BlockID(0))
            continue;

        // Dead code.
        if (dominator == ID(0))
            continue;

        BlockID header = 0;

        // Find the loop header for this block if we are a continue block.
        {
            auto itr = ir.continue_block_to_loop_header.find(block);
            if (itr != end(ir.continue_block_to_loop_header))
            {
                header = itr->second;
            }
            else if (get<SPIRBlock>(block).continue_block == block)
            {
                // Also check for self-referential continue block.
                header = block;
            }
        }

        assert(header);
        auto &header_block = get<SPIRBlock>(header);
        auto &blocks = handler.accessed_variables_to_block[loop_variable.first];

        // If a loop variable is not used before the loop, it's probably not a loop variable.
        bool has_accessed_variable = blocks.count(header) != 0;

        // Now, there are two conditions we need to meet for the variable to be a loop variable.
        // 1. The dominating block must have a branch-free path to the loop header,
        // this way we statically know which expression should be part of the loop variable initializer.

        // Walk from the dominator, if there is one straight edge connecting
        // dominator and loop header, we statically know the loop initializer.
        bool static_loop_init = true;
        while (dominator != header)
        {
            if (blocks.count(dominator) != 0)
                has_accessed_variable = true;

            auto &succ = cfg.get_succeeding_edges(dominator);
            if (succ.size() != 1)
            {
                static_loop_init = false;
                break;
            }

            auto &pred = cfg.get_preceding_edges(succ.front());
            if (pred.size() != 1 || pred.front() != dominator)
            {
                static_loop_init = false;
                break;
            }

            dominator = succ.front();
        }

        if (!static_loop_init || !has_accessed_variable)
            continue;

        // The second condition we need to meet is that no access after the loop
        // merge can occur. Walk the CFG to see if we find anything.

        seen_blocks.clear();
        cfg.walk_from(seen_blocks, header_block.merge_block, [&](uint32_t walk_block) -> bool {
            // We found a block which accesses the variable outside the loop.
            if (blocks.find(walk_block) != end(blocks))
                static_loop_init = false;
            return true;
        });

        if (!static_loop_init)
            continue;

        // We have a loop variable.
        header_block.loop_variables.push_back(loop_variable.first);
        // Need to sort here as variables come from an unordered container, and pushing stuff in wrong order
        // will break reproducability in regression runs.
        sort(begin(header_block.loop_variables), end(header_block.loop_variables));
        get<SPIRVariable>(loop_variable.first).loop_variable = true;
    }
}

bool Compiler::may_read_undefined_variable_in_block(const SPIRBlock &block, uint32_t var)
{
    for (auto &op : block.ops)
    {
        auto *ops = stream(op);
        switch (op.op)
        {
        case OpStore:
        case OpCopyMemory:
            if (ops[0] == var)
                return false;
            break;

        case OpAccessChain:
        case OpInBoundsAccessChain:
        case OpPtrAccessChain:
            // Access chains are generally used to partially read and write. It's too hard to analyze
            // if all constituents are written fully before continuing, so just assume it's preserved.
            // This is the same as the parameter preservation analysis.
            if (ops[2] == var)
                return true;
            break;

        case OpSelect:
            // Variable pointers.
            // We might read before writing.
            if (ops[3] == var || ops[4] == var)
                return true;
            break;

        case OpPhi:
        {
            // Variable pointers.
            // We might read before writing.
            if (op.length < 2)
                break;

            uint32_t count = op.length - 2;
            for (uint32_t i = 0; i < count; i += 2)
                if (ops[i + 2] == var)
                    return true;
            break;
        }

        case OpCopyObject:
        case OpLoad:
            if (ops[2] == var)
                return true;
            break;

        case OpFunctionCall:
        {
            if (op.length < 3)
                break;

            // May read before writing.
            uint32_t count = op.length - 3;
            for (uint32_t i = 0; i < count; i++)
                if (ops[i + 3] == var)
                    return true;
            break;
        }

        default:
            break;
        }
    }

    // Not accessed somehow, at least not in a usual fashion.
    // It's likely accessed in a branch, so assume we must preserve.
    return true;
}

Bitset Compiler::get_buffer_block_flags(VariableID id) const
{
    return ir.get_buffer_block_flags(get<SPIRVariable>(id));
}

bool Compiler::get_common_basic_type(const SPIRType &type, SPIRType::BaseType &base_type)
{
    if (type.basetype == SPIRType::Struct)
    {
        base_type = SPIRType::Unknown;
        for (auto &member_type : type.member_types)
        {
            SPIRType::BaseType member_base;
            if (!get_common_basic_type(get<SPIRType>(member_type), member_base))
                return false;

            if (base_type == SPIRType::Unknown)
                base_type = member_base;
            else if (base_type != member_base)
                return false;
        }
        return true;
    }
    else
    {
        base_type = type.basetype;
        return true;
    }
}

void Compiler::ActiveBuiltinHandler::handle_builtin(const SPIRType &type, BuiltIn builtin,
                                                    const Bitset &decoration_flags)
{
    // If used, we will need to explicitly declare a new array size for these builtins.

    if (builtin == BuiltInClipDistance)
    {
        if (!type.array_size_literal[0])
            SPIRV_CROSS_THROW("Array size for ClipDistance must be a literal.");
        uint32_t array_size = type.array[0];
        if (array_size == 0)
            SPIRV_CROSS_THROW("Array size for ClipDistance must not be unsized.");
        compiler.clip_distance_count = array_size;
    }
    else if (builtin == BuiltInCullDistance)
    {
        if (!type.array_size_literal[0])
            SPIRV_CROSS_THROW("Array size for CullDistance must be a literal.");
        uint32_t array_size = type.array[0];
        if (array_size == 0)
            SPIRV_CROSS_THROW("Array size for CullDistance must not be unsized.");
        compiler.cull_distance_count = array_size;
    }
    else if (builtin == BuiltInPosition)
    {
        if (decoration_flags.get(DecorationInvariant))
            compiler.position_invariant = true;
    }
}

void Compiler::ActiveBuiltinHandler::add_if_builtin(uint32_t id, bool allow_blocks)
{
    // Only handle plain variables here.
    // Builtins which are part of a block are handled in AccessChain.
    // If allow_blocks is used however, this is to handle initializers of blocks,
    // which implies that all members are written to.

    auto *var = compiler.maybe_get<SPIRVariable>(id);
    auto *m = compiler.ir.find_meta(id);
    if (var && m)
    {
        auto &type = compiler.get<SPIRType>(var->basetype);
        auto &decorations = m->decoration;
        auto &flags = type.storage == StorageClassInput ?
                      compiler.active_input_builtins : compiler.active_output_builtins;
        if (decorations.builtin)
        {
            flags.set(decorations.builtin_type);
            handle_builtin(type, decorations.builtin_type, decorations.decoration_flags);
        }
        else if (allow_blocks && compiler.has_decoration(type.self, DecorationBlock))
        {
            uint32_t member_count = uint32_t(type.member_types.size());
            for (uint32_t i = 0; i < member_count; i++)
            {
                if (compiler.has_member_decoration(type.self, i, DecorationBuiltIn))
                {
                    auto &member_type = compiler.get<SPIRType>(type.member_types[i]);
                    BuiltIn builtin = BuiltIn(compiler.get_member_decoration(type.self, i, DecorationBuiltIn));
                    flags.set(builtin);
                    handle_builtin(member_type, builtin, compiler.get_member_decoration_bitset(type.self, i));
                }
            }
        }
    }
}

void Compiler::ActiveBuiltinHandler::add_if_builtin(uint32_t id)
{
    add_if_builtin(id, false);
}

void Compiler::ActiveBuiltinHandler::add_if_builtin_or_block(uint32_t id)
{
    add_if_builtin(id, true);
}

bool Compiler::ActiveBuiltinHandler::handle(spv::Op opcode, const uint32_t *args, uint32_t length)
{
    switch (opcode)
    {
    case OpStore:
        if (length < 1)
            return false;

        add_if_builtin(args[0]);
        break;

    case OpCopyMemory:
        if (length < 2)
            return false;

        add_if_builtin(args[0]);
        add_if_builtin(args[1]);
        break;

    case OpCopyObject:
    case OpLoad:
        if (length < 3)
            return false;

        add_if_builtin(args[2]);
        break;

    case OpSelect:
        if (length < 5)
            return false;

        add_if_builtin(args[3]);
        add_if_builtin(args[4]);
        break;

    case OpPhi:
    {
        if (length < 2)
            return false;

        uint32_t count = length - 2;
        args += 2;
        for (uint32_t i = 0; i < count; i += 2)
            add_if_builtin(args[i]);
        break;
    }

    case OpFunctionCall:
    {
        if (length < 3)
            return false;

        uint32_t count = length - 3;
        args += 3;
        for (uint32_t i = 0; i < count; i++)
            add_if_builtin(args[i]);
        break;
    }

    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
    {
        if (length < 4)
            return false;

        // Only consider global variables, cannot consider variables in functions yet, or other
        // access chains as they have not been created yet.
        auto *var = compiler.maybe_get<SPIRVariable>(args[2]);
        if (!var)
            break;

        // Required if we access chain into builtins like gl_GlobalInvocationID.
        add_if_builtin(args[2]);

        // Start traversing type hierarchy at the proper non-pointer types.
        auto *type = &compiler.get_variable_data_type(*var);

        auto &flags =
            var->storage == StorageClassInput ? compiler.active_input_builtins : compiler.active_output_builtins;

        uint32_t count = length - 3;
        args += 3;
        for (uint32_t i = 0; i < count; i++)
        {
            // Pointers
            // PtrAccessChain functions more like a pointer offset. Type remains the same.
            if (opcode == OpPtrAccessChain && i == 0)
                continue;

            // Arrays
            if (!type->array.empty())
            {
                type = &compiler.get<SPIRType>(type->parent_type);
            }
            // Structs
            else if (type->basetype == SPIRType::Struct)
            {
                uint32_t index = compiler.get<SPIRConstant>(args[i]).scalar();

                if (index < uint32_t(compiler.ir.meta[type->self].members.size()))
                {
                    auto &decorations = compiler.ir.meta[type->self].members[index];
                    if (decorations.builtin)
                    {
                        flags.set(decorations.builtin_type);
                        handle_builtin(compiler.get<SPIRType>(type->member_types[index]), decorations.builtin_type,
                                       decorations.decoration_flags);
                    }
                }

                type = &compiler.get<SPIRType>(type->member_types[index]);
            }
            else
            {
                // No point in traversing further. We won't find any extra builtins.
                break;
            }
        }
        break;
    }

    default:
        break;
    }

    return true;
}

void Compiler::update_active_builtins()
{
    active_input_builtins.reset();
    active_output_builtins.reset();
    cull_distance_count = 0;
    clip_distance_count = 0;
    ActiveBuiltinHandler handler(*this);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

    ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
        if (var.storage != StorageClassOutput)
            return;
        if (!interface_variable_exists_in_entry_point(var.self))
            return;

        // Also, make sure we preserve output variables which are only initialized, but never accessed by any code.
        if (var.initializer != ID(0))
            handler.add_if_builtin_or_block(var.self);
    });
}

// Returns whether this shader uses a builtin of the storage class
bool Compiler::has_active_builtin(BuiltIn builtin, StorageClass storage) const
{
    const Bitset *flags;
    switch (storage)
    {
    case StorageClassInput:
        flags = &active_input_builtins;
        break;
    case StorageClassOutput:
        flags = &active_output_builtins;
        break;

    default:
        return false;
    }
    return flags->get(builtin);
}

void Compiler::analyze_image_and_sampler_usage()
{
    CombinedImageSamplerDrefHandler dref_handler(*this);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), dref_handler);

    CombinedImageSamplerUsageHandler handler(*this, dref_handler.dref_combined_samplers);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

    // Need to run this traversal twice. First time, we propagate any comparison sampler usage from leaf functions
    // down to main().
    // In the second pass, we can propagate up forced depth state coming from main() up into leaf functions.
    handler.dependency_hierarchy.clear();
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

    comparison_ids = std::move(handler.comparison_ids);
    need_subpass_input = handler.need_subpass_input;
    need_subpass_input_ms = handler.need_subpass_input_ms;

    // Forward information from separate images and samplers into combined image samplers.
    for (auto &combined : combined_image_samplers)
        if (comparison_ids.count(combined.sampler_id))
            comparison_ids.insert(combined.combined_id);
}

bool Compiler::CombinedImageSamplerDrefHandler::handle(spv::Op opcode, const uint32_t *args, uint32_t)
{
    // Mark all sampled images which are used with Dref.
    switch (opcode)
    {
    case OpImageSampleDrefExplicitLod:
    case OpImageSampleDrefImplicitLod:
    case OpImageSampleProjDrefExplicitLod:
    case OpImageSampleProjDrefImplicitLod:
    case OpImageSparseSampleProjDrefImplicitLod:
    case OpImageSparseSampleDrefImplicitLod:
    case OpImageSparseSampleProjDrefExplicitLod:
    case OpImageSparseSampleDrefExplicitLod:
    case OpImageDrefGather:
    case OpImageSparseDrefGather:
        dref_combined_samplers.insert(args[2]);
        return true;

    default:
        break;
    }

    return true;
}

const CFG &Compiler::get_cfg_for_current_function() const
{
    assert(current_function);
    return get_cfg_for_function(current_function->self);
}

const CFG &Compiler::get_cfg_for_function(uint32_t id) const
{
    auto cfg_itr = function_cfgs.find(id);
    assert(cfg_itr != end(function_cfgs));
    assert(cfg_itr->second);
    return *cfg_itr->second;
}

void Compiler::build_function_control_flow_graphs_and_analyze()
{
    CFGBuilder handler(*this);
    handler.function_cfgs[ir.default_entry_point].reset(new CFG(*this, get<SPIRFunction>(ir.default_entry_point)));
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);
    function_cfgs = std::move(handler.function_cfgs);
    bool single_function = function_cfgs.size() <= 1;

    for (auto &f : function_cfgs)
    {
        auto &func = get<SPIRFunction>(f.first);
        AnalyzeVariableScopeAccessHandler scope_handler(*this, func);
        analyze_variable_scope(func, scope_handler);
        find_function_local_luts(func, scope_handler, single_function);

        // Check if we can actually use the loop variables we found in analyze_variable_scope.
        // To use multiple initializers, we need the same type and qualifiers.
        for (auto block : func.blocks)
        {
            auto &b = get<SPIRBlock>(block);
            if (b.loop_variables.size() < 2)
                continue;

            auto &flags = get_decoration_bitset(b.loop_variables.front());
            uint32_t type = get<SPIRVariable>(b.loop_variables.front()).basetype;
            bool invalid_initializers = false;
            for (auto loop_variable : b.loop_variables)
            {
                if (flags != get_decoration_bitset(loop_variable) ||
                    type != get<SPIRVariable>(b.loop_variables.front()).basetype)
                {
                    invalid_initializers = true;
                    break;
                }
            }

            if (invalid_initializers)
            {
                for (auto loop_variable : b.loop_variables)
                    get<SPIRVariable>(loop_variable).loop_variable = false;
                b.loop_variables.clear();
            }
        }
    }

    // Find LUTs which are not function local. Only consider this case if the CFG is multi-function,
    // otherwise we treat Private as Function trivially.
    // Needs to be analyzed from the outside since we have to block the LUT optimization if at least
    // one function writes to it.
    if (!single_function)
    {
        for (auto &id : global_variables)
        {
            auto &var = get<SPIRVariable>(id);
            auto &type = get_variable_data_type(var);

            if (is_array(type) && var.storage == StorageClassPrivate &&
                var.initializer && !var.is_written_to &&
                ir.ids[var.initializer].get_type() == TypeConstant)
            {
                get<SPIRConstant>(var.initializer).is_used_as_lut = true;
                var.static_expression = var.initializer;
                var.statically_assigned = true;
                var.remapped_variable = true;
            }
        }
    }
}

Compiler::CFGBuilder::CFGBuilder(Compiler &compiler_)
    : compiler(compiler_)
{
}

bool Compiler::CFGBuilder::handle(spv::Op, const uint32_t *, uint32_t)
{
    return true;
}

bool Compiler::CFGBuilder::follow_function_call(const SPIRFunction &func)
{
    if (function_cfgs.find(func.self) == end(function_cfgs))
    {
        function_cfgs[func.self].reset(new CFG(compiler, func));
        return true;
    }
    else
        return false;
}

void Compiler::CombinedImageSamplerUsageHandler::add_dependency(uint32_t dst, uint32_t src)
{
    dependency_hierarchy[dst].insert(src);
    // Propagate up any comparison state if we're loading from one such variable.
    if (comparison_ids.count(src))
        comparison_ids.insert(dst);
}

bool Compiler::CombinedImageSamplerUsageHandler::begin_function_scope(const uint32_t *args, uint32_t length)
{
    if (length < 3)
        return false;

    auto &func = compiler.get<SPIRFunction>(args[2]);
    const auto *arg = &args[3];
    length -= 3;

    for (uint32_t i = 0; i < length; i++)
    {
        auto &argument = func.arguments[i];
        add_dependency(argument.id, arg[i]);
    }

    return true;
}

void Compiler::CombinedImageSamplerUsageHandler::add_hierarchy_to_comparison_ids(uint32_t id)
{
    // Traverse the variable dependency hierarchy and tag everything in its path with comparison ids.
    comparison_ids.insert(id);

    for (auto &dep_id : dependency_hierarchy[id])
        add_hierarchy_to_comparison_ids(dep_id);
}

bool Compiler::CombinedImageSamplerUsageHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    switch (opcode)
    {
    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
    case OpLoad:
    {
        if (length < 3)
            return false;

        add_dependency(args[1], args[2]);

        // Ideally defer this to OpImageRead, but then we'd need to track loaded IDs.
        // If we load an image, we're going to use it and there is little harm in declaring an unused gl_FragCoord.
        auto &type = compiler.get<SPIRType>(args[0]);
        if (type.image.dim == DimSubpassData)
        {
            need_subpass_input = true;
            if (type.image.ms)
                need_subpass_input_ms = true;
        }

        // If we load a SampledImage and it will be used with Dref, propagate the state up.
        if (dref_combined_samplers.count(args[1]) != 0)
            add_hierarchy_to_comparison_ids(args[1]);
        break;
    }

    case OpSampledImage:
    {
        if (length < 4)
            return false;

        // If the underlying resource has been used for comparison then duplicate loads of that resource must be too.
        // This image must be a depth image.
        uint32_t result_id = args[1];
        uint32_t image = args[2];
        uint32_t sampler = args[3];

        if (dref_combined_samplers.count(result_id) != 0)
        {
            add_hierarchy_to_comparison_ids(image);

            // This sampler must be a SamplerComparisonState, and not a regular SamplerState.
            add_hierarchy_to_comparison_ids(sampler);

            // Mark the OpSampledImage itself as being comparison state.
            comparison_ids.insert(result_id);
        }
        return true;
    }

    default:
        break;
    }

    return true;
}

bool Compiler::buffer_is_hlsl_counter_buffer(VariableID id) const
{
    auto *m = ir.find_meta(id);
    return m && m->hlsl_is_magic_counter_buffer;
}

bool Compiler::buffer_get_hlsl_counter_buffer(VariableID id, uint32_t &counter_id) const
{
    auto *m = ir.find_meta(id);

    // First, check for the proper decoration.
    if (m && m->hlsl_magic_counter_buffer != 0)
    {
        counter_id = m->hlsl_magic_counter_buffer;
        return true;
    }
    else
        return false;
}

void Compiler::make_constant_null(uint32_t id, uint32_t type)
{
    auto &constant_type = get<SPIRType>(type);

    if (constant_type.pointer)
    {
        auto &constant = set<SPIRConstant>(id, type);
        constant.make_null(constant_type);
    }
    else if (!constant_type.array.empty())
    {
        assert(constant_type.parent_type);
        uint32_t parent_id = ir.increase_bound_by(1);
        make_constant_null(parent_id, constant_type.parent_type);

        if (!constant_type.array_size_literal.back())
            SPIRV_CROSS_THROW("Array size of OpConstantNull must be a literal.");

        SmallVector<uint32_t> elements(constant_type.array.back());
        for (uint32_t i = 0; i < constant_type.array.back(); i++)
            elements[i] = parent_id;
        set<SPIRConstant>(id, type, elements.data(), uint32_t(elements.size()), false);
    }
    else if (!constant_type.member_types.empty())
    {
        uint32_t member_ids = ir.increase_bound_by(uint32_t(constant_type.member_types.size()));
        SmallVector<uint32_t> elements(constant_type.member_types.size());
        for (uint32_t i = 0; i < constant_type.member_types.size(); i++)
        {
            make_constant_null(member_ids + i, constant_type.member_types[i]);
            elements[i] = member_ids + i;
        }
        set<SPIRConstant>(id, type, elements.data(), uint32_t(elements.size()), false);
    }
    else
    {
        auto &constant = set<SPIRConstant>(id, type);
        constant.make_null(constant_type);
    }
}

const SmallVector<spv::Capability> &Compiler::get_declared_capabilities() const
{
    return ir.declared_capabilities;
}

const SmallVector<std::string> &Compiler::get_declared_extensions() const
{
    return ir.declared_extensions;
}

std::string Compiler::get_remapped_declared_block_name(VariableID id) const
{
    return get_remapped_declared_block_name(id, false);
}

std::string Compiler::get_remapped_declared_block_name(uint32_t id, bool fallback_prefer_instance_name) const
{
    auto itr = declared_block_names.find(id);
    if (itr != end(declared_block_names))
    {
        return itr->second;
    }
    else
    {
        auto &var = get<SPIRVariable>(id);

        if (fallback_prefer_instance_name)
        {
            return to_name(var.self);
        }
        else
        {
            auto &type = get<SPIRType>(var.basetype);
            auto *type_meta = ir.find_meta(type.self);
            auto *block_name = type_meta ? &type_meta->decoration.alias : nullptr;
            return (!block_name || block_name->empty()) ? get_block_fallback_name(id) : *block_name;
        }
    }
}

bool Compiler::reflection_ssbo_instance_name_is_significant() const
{
    if (ir.source.known)
    {
        // UAVs from HLSL source tend to be declared in a way where the type is reused
        // but the instance name is significant, and that's the name we should report.
        // For GLSL, SSBOs each have their own block type as that's how GLSL is written.
        return ir.source.hlsl;
    }

    unordered_set<uint32_t> ssbo_type_ids;
    bool aliased_ssbo_types = false;

    // If we don't have any OpSource information, we need to perform some shaky heuristics.
    ir.for_each_typed_id<SPIRVariable>([&](uint32_t, const SPIRVariable &var) {
        auto &type = this->get<SPIRType>(var.basetype);
        if (!type.pointer || var.storage == StorageClassFunction)
            return;

        bool ssbo = var.storage == StorageClassStorageBuffer ||
                    (var.storage == StorageClassUniform && has_decoration(type.self, DecorationBufferBlock));

        if (ssbo)
        {
            if (ssbo_type_ids.count(type.self))
                aliased_ssbo_types = true;
            else
                ssbo_type_ids.insert(type.self);
        }
    });

    // If the block name is aliased, assume we have HLSL-style UAV declarations.
    return aliased_ssbo_types;
}

bool Compiler::instruction_to_result_type(uint32_t &result_type, uint32_t &result_id, spv::Op op,
                                          const uint32_t *args, uint32_t length)
{
    if (length < 2)
        return false;

    bool has_result_id = false, has_result_type = false;
    HasResultAndType(op, &has_result_id, &has_result_type);
    if (has_result_id && has_result_type)
    {
        result_type = args[0];
        result_id = args[1];
        return true;
    }
    else
        return false;
}

Bitset Compiler::combined_decoration_for_member(const SPIRType &type, uint32_t index) const
{
    Bitset flags;
    auto *type_meta = ir.find_meta(type.self);

    if (type_meta)
    {
        auto &members = type_meta->members;
        if (index >= members.size())
            return flags;
        auto &dec = members[index];

        flags.merge_or(dec.decoration_flags);

        auto &member_type = get<SPIRType>(type.member_types[index]);

        // If our member type is a struct, traverse all the child members as well recursively.
        auto &member_childs = member_type.member_types;
        for (uint32_t i = 0; i < member_childs.size(); i++)
        {
            auto &child_member_type = get<SPIRType>(member_childs[i]);
            if (!child_member_type.pointer)
                flags.merge_or(combined_decoration_for_member(member_type, i));
        }
    }

    return flags;
}

bool Compiler::is_desktop_only_format(spv::ImageFormat format)
{
    switch (format)
    {
    // Desktop-only formats
    case ImageFormatR11fG11fB10f:
    case ImageFormatR16f:
    case ImageFormatRgb10A2:
    case ImageFormatR8:
    case ImageFormatRg8:
    case ImageFormatR16:
    case ImageFormatRg16:
    case ImageFormatRgba16:
    case ImageFormatR16Snorm:
    case ImageFormatRg16Snorm:
    case ImageFormatRgba16Snorm:
    case ImageFormatR8Snorm:
    case ImageFormatRg8Snorm:
    case ImageFormatR8ui:
    case ImageFormatRg8ui:
    case ImageFormatR16ui:
    case ImageFormatRgb10a2ui:
    case ImageFormatR8i:
    case ImageFormatRg8i:
    case ImageFormatR16i:
        return true;
    default:
        break;
    }

    return false;
}

// An image is determined to be a depth image if it is marked as a depth image and is not also
// explicitly marked with a color format, or if there are any sample/gather compare operations on it.
bool Compiler::is_depth_image(const SPIRType &type, uint32_t id) const
{
    return (type.image.depth && type.image.format == ImageFormatUnknown) || comparison_ids.count(id);
}

bool Compiler::type_is_opaque_value(const SPIRType &type) const
{
    return !type.pointer && (type.basetype == SPIRType::SampledImage || type.basetype == SPIRType::Image ||
                             type.basetype == SPIRType::Sampler);
}

// Make these member functions so we can easily break on any force_recompile events.
void Compiler::force_recompile()
{
    is_force_recompile = true;
}

void Compiler::force_recompile_guarantee_forward_progress()
{
    force_recompile();
    is_force_recompile_forward_progress = true;
}

bool Compiler::is_forcing_recompilation() const
{
    return is_force_recompile;
}

void Compiler::clear_force_recompile()
{
    is_force_recompile = false;
    is_force_recompile_forward_progress = false;
}

Compiler::PhysicalStorageBufferPointerHandler::PhysicalStorageBufferPointerHandler(Compiler &compiler_)
    : compiler(compiler_)
{
}

Compiler::PhysicalBlockMeta *Compiler::PhysicalStorageBufferPointerHandler::find_block_meta(uint32_t id) const
{
    auto chain_itr = access_chain_to_physical_block.find(id);
    if (chain_itr != access_chain_to_physical_block.end())
        return chain_itr->second;
    else
        return nullptr;
}

void Compiler::PhysicalStorageBufferPointerHandler::mark_aligned_access(uint32_t id, const uint32_t *args, uint32_t length)
{
    uint32_t mask = *args;
    args++;
    length--;
    if (length && (mask & MemoryAccessVolatileMask) != 0)
    {
        args++;
        length--;
    }

    if (length && (mask & MemoryAccessAlignedMask) != 0)
    {
        uint32_t alignment = *args;
        auto *meta = find_block_meta(id);

        // This makes the assumption that the application does not rely on insane edge cases like:
        // Bind buffer with ADDR = 8, use block offset of 8 bytes, load/store with 16 byte alignment.
        // If we emit the buffer with alignment = 16 here, the first element at offset = 0 should
        // actually have alignment of 8 bytes, but this is too theoretical and awkward to support.
        // We could potentially keep track of any offset in the access chain, but it's
        // practically impossible for high level compilers to emit code like that,
        // so deducing overall alignment requirement based on maximum observed Alignment value is probably fine.
        if (meta && alignment > meta->alignment)
            meta->alignment = alignment;
    }
}

bool Compiler::PhysicalStorageBufferPointerHandler::type_is_bda_block_entry(uint32_t type_id) const
{
    auto &type = compiler.get<SPIRType>(type_id);
    return compiler.is_physical_pointer(type);
}

uint32_t Compiler::PhysicalStorageBufferPointerHandler::get_minimum_scalar_alignment(const SPIRType &type) const
{
    if (type.storage == spv::StorageClassPhysicalStorageBufferEXT)
        return 8;
    else if (type.basetype == SPIRType::Struct)
    {
        uint32_t alignment = 0;
        for (auto &member_type : type.member_types)
        {
            uint32_t member_align = get_minimum_scalar_alignment(compiler.get<SPIRType>(member_type));
            if (member_align > alignment)
                alignment = member_align;
        }
        return alignment;
    }
    else
        return type.width / 8;
}

void Compiler::PhysicalStorageBufferPointerHandler::setup_meta_chain(uint32_t type_id, uint32_t var_id)
{
    if (type_is_bda_block_entry(type_id))
    {
        auto &meta = physical_block_type_meta[type_id];
        access_chain_to_physical_block[var_id] = &meta;

        auto &type = compiler.get<SPIRType>(type_id);

        if (!compiler.is_physical_pointer_to_buffer_block(type))
            non_block_types.insert(type_id);

        if (meta.alignment == 0)
            meta.alignment = get_minimum_scalar_alignment(compiler.get_pointee_type(type));
    }
}

bool Compiler::PhysicalStorageBufferPointerHandler::handle(Op op, const uint32_t *args, uint32_t length)
{
    // When a BDA pointer comes to life, we need to keep a mapping of SSA ID -> type ID for the pointer type.
    // For every load and store, we'll need to be able to look up the type ID being accessed and mark any alignment
    // requirements.
    switch (op)
    {
    case OpConvertUToPtr:
    case OpBitcast:
    case OpCompositeExtract:
        // Extract can begin a new chain if we had a struct or array of pointers as input.
        // We don't begin chains before we have a pure scalar pointer.
        setup_meta_chain(args[0], args[1]);
        break;

    case OpAccessChain:
    case OpInBoundsAccessChain:
    case OpPtrAccessChain:
    case OpCopyObject:
    {
        auto itr = access_chain_to_physical_block.find(args[2]);
        if (itr != access_chain_to_physical_block.end())
            access_chain_to_physical_block[args[1]] = itr->second;
        break;
    }

    case OpLoad:
    {
        setup_meta_chain(args[0], args[1]);
        if (length >= 4)
            mark_aligned_access(args[2], args + 3, length - 3);
        break;
    }

    case OpStore:
    {
        if (length >= 3)
            mark_aligned_access(args[0], args + 2, length - 2);
        break;
    }

    default:
        break;
    }

    return true;
}

uint32_t Compiler::PhysicalStorageBufferPointerHandler::get_base_non_block_type_id(uint32_t type_id) const
{
    auto *type = &compiler.get<SPIRType>(type_id);
    while (compiler.is_physical_pointer(*type) && !type_is_bda_block_entry(type_id))
    {
        type_id = type->parent_type;
        type = &compiler.get<SPIRType>(type_id);
    }

    assert(type_is_bda_block_entry(type_id));
    return type_id;
}

void Compiler::PhysicalStorageBufferPointerHandler::analyze_non_block_types_from_block(const SPIRType &type)
{
    for (auto &member : type.member_types)
    {
        auto &subtype = compiler.get<SPIRType>(member);

        if (compiler.is_physical_pointer(subtype) && !compiler.is_physical_pointer_to_buffer_block(subtype))
            non_block_types.insert(get_base_non_block_type_id(member));
        else if (subtype.basetype == SPIRType::Struct && !compiler.is_pointer(subtype))
            analyze_non_block_types_from_block(subtype);
    }
}

void Compiler::analyze_non_block_pointer_types()
{
    PhysicalStorageBufferPointerHandler handler(*this);
    traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

    // Analyze any block declaration we have to make. It might contain
    // physical pointers to POD types which we never used, and thus never added to the list.
    // We'll need to add those pointer types to the set of types we declare.
    ir.for_each_typed_id<SPIRType>([&](uint32_t id, SPIRType &type) {
        // Only analyze the raw block struct, not any pointer-to-struct, since that's just redundant.
        if (type.self == id &&
            (has_decoration(type.self, DecorationBlock) ||
             has_decoration(type.self, DecorationBufferBlock)))
        {
            handler.analyze_non_block_types_from_block(type);
        }
    });

    physical_storage_non_block_pointer_types.reserve(handler.non_block_types.size());
    for (auto type : handler.non_block_types)
        physical_storage_non_block_pointer_types.push_back(type);
    sort(begin(physical_storage_non_block_pointer_types), end(physical_storage_non_block_pointer_types));
    physical_storage_type_to_alignment = std::move(handler.physical_block_type_meta);
}

bool Compiler::InterlockedResourceAccessPrepassHandler::handle(Op op, const uint32_t *, uint32_t)
{
    if (op == OpBeginInvocationInterlockEXT || op == OpEndInvocationInterlockEXT)
    {
        if (interlock_function_id != 0 && interlock_function_id != call_stack.back())
        {
            // Most complex case, we have no sensible way of dealing with this
            // other than taking the 100% conservative approach, exit early.
            split_function_case = true;
            return false;
        }
        else
        {
            interlock_function_id = call_stack.back();
            // If this call is performed inside control flow we have a problem.
            auto &cfg = compiler.get_cfg_for_function(interlock_function_id);

            uint32_t from_block_id = compiler.get<SPIRFunction>(interlock_function_id).entry_block;
            bool outside_control_flow = cfg.node_terminates_control_flow_in_sub_graph(from_block_id, current_block_id);
            if (!outside_control_flow)
                control_flow_interlock = true;
        }
    }
    return true;
}

void Compiler::InterlockedResourceAccessPrepassHandler::rearm_current_block(const SPIRBlock &block)
{
    current_block_id = block.self;
}

bool Compiler::InterlockedResourceAccessPrepassHandler::begin_function_scope(const uint32_t *args, uint32_t length)
{
    if (length < 3)
        return false;
    call_stack.push_back(args[2]);
    return true;
}

bool Compiler::InterlockedResourceAccessPrepassHandler::end_function_scope(const uint32_t *, uint32_t)
{
    call_stack.pop_back();
    return true;
}

bool Compiler::InterlockedResourceAccessHandler::begin_function_scope(const uint32_t *args, uint32_t length)
{
    if (length < 3)
        return false;

    if (args[2] == interlock_function_id)
        call_stack_is_interlocked = true;

    call_stack.push_back(args[2]);
    return true;
}

bool Compiler::InterlockedResourceAccessHandler::end_function_scope(const uint32_t *, uint32_t)
{
    if (call_stack.back() == interlock_function_id)
        call_stack_is_interlocked = false;

    call_stack.pop_back();
    return true;
}

void Compiler::InterlockedResourceAccessHandler::access_potential_resource(uint32_t id)
{
    if ((use_critical_section && in_crit_sec) || (control_flow_interlock && call_stack_is_interlocked) ||
        split_function_case)
    {
        compiler.interlocked_resources.insert(id);
    }
}

bool Compiler::InterlockedResourceAccessHandler::handle(Op opcode, const uint32_t *args, uint32_t length)
{
    // Only care about critical section analysis if we have simple case.
    if (use_critical_section)
    {
        if (opcode == OpBeginInvocationInterlockEXT)
        {
            in_crit_sec = true;
            return true;
        }

        if (opcode == OpEndInvocationInterlockEXT)
        {
            // End critical section--nothing more to do.
            return false;
        }
    }

    // We need to figure out where images and buffers are loaded from, so do only the bare bones compilation we need.
    switch (opcode)
    {
    case OpLoad:
    {
        if (length < 3)
            return false;

        uint32_t ptr = args[2];
        auto *var = compiler.maybe_get_backing_variable(ptr);

        // We're only concerned with buffer and image memory here.
        if (!var)
            break;

        switch (var->storage)
        {
        default:
            break;

        case StorageClassUniformConstant:
        {
            uint32_t result_type = args[0];
            uint32_t id = args[1];
            compiler.set<SPIRExpression>(id, "", result_type, true);
            compiler.register_read(id, ptr, true);
            break;
        }

        case StorageClassUniform:
            // Must have BufferBlock; we only care about SSBOs.
            if (!compiler.has_decoration(compiler.get<SPIRType>(var->basetype).self, DecorationBufferBlock))
                break;
            // fallthrough
        case StorageClassStorageBuffer:
            access_potential_resource(var->self);
            break;
        }
        break;
    }

    case OpInBoundsAccessChain:
    case OpAccessChain:
    case OpPtrAccessChain:
    {
        if (length < 3)
            return false;

        uint32_t result_type = args[0];

        auto &type = compiler.get<SPIRType>(result_type);
        if (type.storage == StorageClassUniform || type.storage == StorageClassUniformConstant ||
            type.storage == StorageClassStorageBuffer)
        {
            uint32_t id = args[1];
            uint32_t ptr = args[2];
            compiler.set<SPIRExpression>(id, "", result_type, true);
            compiler.register_read(id, ptr, true);
            compiler.ir.ids[id].set_allow_type_rewrite();
        }
        break;
    }

    case OpImageTexelPointer:
    {
        if (length < 3)
            return false;

        uint32_t result_type = args[0];
        uint32_t id = args[1];
        uint32_t ptr = args[2];
        auto &e = compiler.set<SPIRExpression>(id, "", result_type, true);
        auto *var = compiler.maybe_get_backing_variable(ptr);
        if (var)
            e.loaded_from = var->self;
        break;
    }

    case OpStore:
    case OpImageWrite:
    case OpAtomicStore:
    {
        if (length < 1)
            return false;

        uint32_t ptr = args[0];
        auto *var = compiler.maybe_get_backing_variable(ptr);
        if (var && (var->storage == StorageClassUniform || var->storage == StorageClassUniformConstant ||
                    var->storage == StorageClassStorageBuffer))
        {
            access_potential_resource(var->self);
        }

        break;
    }

    case OpCopyMemory:
    {
        if (length < 2)
            return false;

        uint32_t dst = args[0];
        uint32_t src = args[1];
        auto *dst_var = compiler.maybe_get_backing_variable(dst);
        auto *src_var = compiler.maybe_get_backing_variable(src);

        if (dst_var && (dst_var->storage == StorageClassUniform || dst_var->storage == StorageClassStorageBuffer))
            access_potential_resource(dst_var->self);

        if (src_var)
        {
            if (src_var->storage != StorageClassUniform && src_var->storage != StorageClassStorageBuffer)
                break;

            if (src_var->storage == StorageClassUniform &&
                !compiler.has_decoration(compiler.get<SPIRType>(src_var->basetype).self, DecorationBufferBlock))
            {
                break;
            }

            access_potential_resource(src_var->self);
        }

        break;
    }

    case OpImageRead:
    case OpAtomicLoad:
    {
        if (length < 3)
            return false;

        uint32_t ptr = args[2];
        auto *var = compiler.maybe_get_backing_variable(ptr);

        // We're only concerned with buffer and image memory here.
        if (!var)
            break;

        switch (var->storage)
        {
        default:
            break;

        case StorageClassUniform:
            // Must have BufferBlock; we only care about SSBOs.
            if (!compiler.has_decoration(compiler.get<SPIRType>(var->basetype).self, DecorationBufferBlock))
                break;
            // fallthrough
        case StorageClassUniformConstant:
        case StorageClassStorageBuffer:
            access_potential_resource(var->self);
            break;
        }
        break;
    }

    case OpAtomicExchange:
    case OpAtomicCompareExchange:
    case OpAtomicIIncrement:
    case OpAtomicIDecrement:
    case OpAtomicIAdd:
    case OpAtomicISub:
    case OpAtomicSMin:
    case OpAtomicUMin:
    case OpAtomicSMax:
    case OpAtomicUMax:
    case OpAtomicAnd:
    case OpAtomicOr:
    case OpAtomicXor:
    {
        if (length < 3)
            return false;

        uint32_t ptr = args[2];
        auto *var = compiler.maybe_get_backing_variable(ptr);
        if (var && (var->storage == StorageClassUniform || var->storage == StorageClassUniformConstant ||
                    var->storage == StorageClassStorageBuffer))
        {
            access_potential_resource(var->self);
        }

        break;
    }

    default:
        break;
    }

    return true;
}

void Compiler::analyze_interlocked_resource_usage()
{
    if (get_execution_model() == ExecutionModelFragment &&
        (get_entry_point().flags.get(ExecutionModePixelInterlockOrderedEXT) ||
         get_entry_point().flags.get(ExecutionModePixelInterlockUnorderedEXT) ||
         get_entry_point().flags.get(ExecutionModeSampleInterlockOrderedEXT) ||
         get_entry_point().flags.get(ExecutionModeSampleInterlockUnorderedEXT)))
    {
        InterlockedResourceAccessPrepassHandler prepass_handler(*this, ir.default_entry_point);
        traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), prepass_handler);

        InterlockedResourceAccessHandler handler(*this, ir.default_entry_point);
        handler.interlock_function_id = prepass_handler.interlock_function_id;
        handler.split_function_case = prepass_handler.split_function_case;
        handler.control_flow_interlock = prepass_handler.control_flow_interlock;
        handler.use_critical_section = !handler.split_function_case && !handler.control_flow_interlock;

        traverse_all_reachable_opcodes(get<SPIRFunction>(ir.default_entry_point), handler);

        // For GLSL. If we hit any of these cases, we have to fall back to conservative approach.
        interlocked_is_complex =
            !handler.use_critical_section || handler.interlock_function_id != ir.default_entry_point;
    }
}

// Helper function
bool Compiler::check_internal_recursion(const SPIRType &type, std::unordered_set<uint32_t> &checked_ids)
{
    if (type.basetype != SPIRType::Struct)
        return false;

    if (checked_ids.count(type.self))
        return true;

    // Recurse into struct members
    bool is_recursive = false;
    checked_ids.insert(type.self);
    uint32_t mbr_cnt = uint32_t(type.member_types.size());
    for (uint32_t mbr_idx = 0; !is_recursive && mbr_idx < mbr_cnt; mbr_idx++)
    {
        uint32_t mbr_type_id = type.member_types[mbr_idx];
        auto &mbr_type = get<SPIRType>(mbr_type_id);
        is_recursive |= check_internal_recursion(mbr_type, checked_ids);
    }
    checked_ids.erase(type.self);
    return is_recursive;
}

// Return whether the struct type contains a structural recursion nested somewhere within its content.
bool Compiler::type_contains_recursion(const SPIRType &type)
{
    std::unordered_set<uint32_t> checked_ids;
    return check_internal_recursion(type, checked_ids);
}

bool Compiler::type_is_array_of_pointers(const SPIRType &type) const
{
    if (!is_array(type))
        return false;

    // BDA types must have parent type hierarchy.
    if (!type.parent_type)
        return false;

    // Punch through all array layers.
    auto *parent = &get<SPIRType>(type.parent_type);
    while (is_array(*parent))
        parent = &get<SPIRType>(parent->parent_type);

    return is_pointer(*parent);
}

bool Compiler::flush_phi_required(BlockID from, BlockID to) const
{
    auto &child = get<SPIRBlock>(to);
    for (auto &phi : child.phi_variables)
        if (phi.parent == from)
            return true;
    return false;
}

void Compiler::add_loop_level()
{
    current_loop_level++;
}