SPIRV-Cross/spirv_hlsl.cpp

/*
 * Copyright 2016-2017 Robert Konrad
 *
 * 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.
 */

#include "spirv_hlsl.hpp"
#include "GLSL.std.450.h"
#include <algorithm>

using namespace spv;
using namespace spirv_cross;
using namespace std;

string CompilerHLSL::type_to_glsl(const SPIRType &type)
{
	// Ignore the pointer type since GLSL doesn't have pointers.

	switch (type.basetype)
	{
	case SPIRType::Struct:
		// Need OpName lookup here to get a "sensible" name for a struct.
		if (backend.explicit_struct_type)
			return join("struct ", to_name(type.self));
		else
			return to_name(type.self);

	case SPIRType::Image:
	case SPIRType::SampledImage:
		return image_type_glsl(type);

	case SPIRType::Sampler:
		// Not really used.
		return "sampler";

	case SPIRType::Void:
		return "void";

	default:
		break;
	}

	if (type.vecsize == 1 && type.columns == 1) // Scalar builtin
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return "bool";
		case SPIRType::Int:
			return backend.basic_int_type;
		case SPIRType::UInt:
			return backend.basic_uint_type;
		case SPIRType::AtomicCounter:
			return "atomic_uint";
		case SPIRType::Float:
			return "float";
		case SPIRType::Double:
			return "double";
		case SPIRType::Int64:
			return "int64_t";
		case SPIRType::UInt64:
			return "uint64_t";
		default:
			return "???";
		}
	}
	else if (type.vecsize > 1 && type.columns == 1) // Vector builtin
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return join("bool", type.vecsize);
		case SPIRType::Int:
			return join("int", type.vecsize);
		case SPIRType::UInt:
			return join("uint", type.vecsize);
		case SPIRType::Float:
			return join("float", type.vecsize);
		case SPIRType::Double:
			return join("double", type.vecsize);
		case SPIRType::Int64:
			return join("i64vec", type.vecsize);
		case SPIRType::UInt64:
			return join("u64vec", type.vecsize);
		default:
			return "???";
		}
	}
	else
	{
		switch (type.basetype)
		{
		case SPIRType::Boolean:
			return join("bool", type.columns, "x", type.vecsize);
		case SPIRType::Int:
			return join("int", type.columns, "x", type.vecsize);
		case SPIRType::UInt:
			return join("uint", type.columns, "x", type.vecsize);
		case SPIRType::Float:
			return join("float", type.columns, "x", type.vecsize);
		case SPIRType::Double:
			return join("double", type.columns, "x", type.vecsize);
		// Matrix types not supported for int64/uint64.
		default:
			return "???";
		}
	}
}

void CompilerHLSL::emit_header()
{
	for (auto &header : header_lines)
		statement(header);

	if (header_lines.size() > 0)
	{
		statement("");
	}
}

void CompilerHLSL::emit_interface_block_globally(const SPIRVariable &var)
{
	add_resource_name(var.self);
	statement("static ", variable_decl(var), ";");
}

const char *CompilerHLSL::to_storage_qualifiers_glsl(const SPIRVariable &var)
{
	// Input and output variables are handled specially in HLSL backend.
	// The variables are declared as global, private variables, and do not need any qualifiers.
	if (var.storage == StorageClassUniformConstant || var.storage == StorageClassUniform ||
	    var.storage == StorageClassPushConstant)
	{
		return "uniform ";
	}

	return "";
}

void CompilerHLSL::emit_builtin_outputs_in_struct()
{
	bool legacy = options.shader_model <= 30;
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!(active_output_builtins & (1ull << i)))
			continue;

		const char *type = nullptr;
		const char *semantic = nullptr;
		auto builtin = static_cast<BuiltIn>(i);
		switch (builtin)
		{
		case BuiltInPosition:
			type = "float4";
			semantic = legacy ? "POSITION" : "SV_Position";
			break;

		default:
			SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");
			break;
		}

		if (type && semantic)
			statement(type, " ", builtin_to_glsl(builtin), " : ", semantic, ";");
	}
}

void CompilerHLSL::emit_builtin_inputs_in_struct()
{
	bool legacy = options.shader_model <= 30;
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!(active_input_builtins & (1ull << i)))
			continue;

		const char *type = nullptr;
		const char *semantic = nullptr;
		auto builtin = static_cast<BuiltIn>(i);
		switch (builtin)
		{
		case BuiltInFragCoord:
			type = "float4";
			semantic = legacy ? "POSITION" : "SV_Position";
			break;

		default:
			SPIRV_CROSS_THROW("Unsupported builtin in HLSL.");
			break;
		}

		if (type && semantic)
			statement(type, " ", builtin_to_glsl(builtin), " : ", semantic, ";");
	}
}

uint32_t CompilerHLSL::type_to_consumed_locations(const SPIRType &type) const
{
	// TODO: Need to verify correctness.
	uint32_t elements = 0;

	if (type.basetype == SPIRType::Struct)
	{
		for (uint32_t i = 0; i < uint32_t(type.member_types.size()); i++)
			elements += type_to_consumed_locations(get<SPIRType>(type.member_types[i]));
	}
	else
	{
		uint32_t array_multiplier = 1;
		for (uint32_t i = 0; i < uint32_t(type.array.size()); i++)
		{
			if (type.array_size_literal[i])
				array_multiplier *= type.array[i];
			else
				array_multiplier *= get<SPIRConstant>(type.array[i]).scalar();
		}
		elements += array_multiplier * type.columns;
	}
	return elements;
}

void CompilerHLSL::emit_interface_block_in_struct(const SPIRVariable &var, unordered_set<uint32_t> &active_locations)
{
	auto &execution = get_entry_point();
	auto &type = get<SPIRType>(var.basetype);

	string binding;
	bool use_binding_number = true;
	bool legacy = options.shader_model <= 30;
	if (execution.model == ExecutionModelFragment && var.storage == StorageClassOutput)
	{
		binding = join(legacy ? "COLOR" : "SV_Target", get_decoration(var.self, DecorationLocation));
		use_binding_number = false;
	}

	const auto get_vacant_location = [&]() -> uint32_t {
		for (uint32_t i = 0; i < 64; i++)
			if (!active_locations.count(i))
				return i;
		SPIRV_CROSS_THROW("All locations from 0 to 63 are exhausted.");
	};

	auto &m = meta[var.self].decoration;
	auto name = to_name(var.self);
	if (use_binding_number)
	{
		uint32_t binding_number;

		// If an explicit location exists, use it with TEXCOORD[N] semantic.
		// Otherwise, pick a vacant location.
		if (m.decoration_flags & (1ull << DecorationLocation))
			binding_number = m.location;
		else
			binding_number = get_vacant_location();

		if (type.columns > 1)
		{
			if (!type.array.empty())
				SPIRV_CROSS_THROW("Arrays of matrices used as input/output. This is not supported.");

			// Unroll matrices.
			for (uint32_t i = 0; i < type.columns; i++)
			{
				SPIRType newtype = type;
				newtype.columns = 1;
				statement(variable_decl(newtype, join(name, "_", i)), " : TEXCOORD", binding_number, ";");
				active_locations.insert(binding_number++);
			}
		}
		else
		{
			statement(variable_decl(type, name), " : TEXCOORD", binding_number, ";");

			// Structs and arrays should consume more locations.
			uint32_t consumed_locations = type_to_consumed_locations(type);
			for (uint32_t i = 0; i < consumed_locations; i++)
				active_locations.insert(binding_number + i);
		}
	}
	else
		statement(variable_decl(type, name), " : ", binding, ";");
}

void CompilerHLSL::emit_builtin_variables()
{
	// Emit global variables for the interface variables which are statically used by the shader.
	for (uint32_t i = 0; i < 64; i++)
	{
		if (!((active_input_builtins | active_output_builtins) & (1ull << i)))
			continue;

		const char *type = nullptr;
		auto builtin = static_cast<BuiltIn>(i);

		switch (builtin)
		{
		case BuiltInFragCoord:
		case BuiltInPosition:
			type = "float4";
			break;

		default:
			SPIRV_CROSS_THROW(join("Unsupported builtin in HLSL: ", unsigned(builtin)));
			break;
		}

		if (type)
			statement("static ", type, " ", builtin_to_glsl(builtin), ";");
	}
}

void CompilerHLSL::emit_resources()
{
	auto &execution = get_entry_point();

	// Output all basic struct types which are not Block or BufferBlock as these are declared inplace
	// when such variables are instantiated.
	for (auto &id : ids)
	{
		if (id.get_type() == TypeType)
		{
			auto &type = id.get<SPIRType>();
			if (type.basetype == SPIRType::Struct && type.array.empty() && !type.pointer &&
			    (meta[type.self].decoration.decoration_flags &
			     ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))) == 0)
			{
				emit_struct(type);
			}
		}
	}

	bool emitted = false;

	// Output UBOs and SSBOs
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			if (var.storage != StorageClassFunction && type.pointer && type.storage == StorageClassUniform &&
			    !is_hidden_variable(var) && (meta[type.self].decoration.decoration_flags &
			                                 ((1ull << DecorationBlock) | (1ull << DecorationBufferBlock))))
			{
				emit_buffer_block(var);
				emitted = true;
			}
		}
	}

	// Output push constant blocks
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);
			if (var.storage != StorageClassFunction && type.pointer && type.storage == StorageClassPushConstant &&
			    !is_hidden_variable(var))
			{
				emit_push_constant_block(var);
				emitted = true;
			}
		}
	}

	if (execution.model == ExecutionModelVertex && options.shader_model <= 30)
	{
		statement("uniform float4 gl_HalfPixel;");
		emitted = true;
	}

	// Output Uniform Constants (values, samplers, images, etc).
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			if (var.storage != StorageClassFunction && !is_builtin_variable(var) && !var.remapped_variable &&
			    type.pointer &&
			    (type.storage == StorageClassUniformConstant || type.storage == StorageClassAtomicCounter))
			{
				emit_uniform(var);
				emitted = true;
			}
		}
	}

	if (emitted)
		statement("");
	emitted = false;

	// Emit builtin input and output variables here.
	emit_builtin_variables();

	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			if (var.storage != StorageClassFunction && !var.remapped_variable && type.pointer &&
			    (var.storage == StorageClassInput || var.storage == StorageClassOutput) && !is_builtin_variable(var) &&
			    interface_variable_exists_in_entry_point(var.self))
			{
				// Only emit non-builtins here. Builtin variables are handled separately.
				emit_interface_block_globally(var);
				emitted = true;
			}
		}
	}

	if (emitted)
		statement("");
	emitted = false;

	unordered_set<uint32_t> active_inputs;
	unordered_set<uint32_t> active_outputs;
	vector<SPIRVariable *> input_variables;
	vector<SPIRVariable *> output_variables;
	for (auto &id : ids)
	{
		if (id.get_type() == TypeVariable)
		{
			auto &var = id.get<SPIRVariable>();
			auto &type = get<SPIRType>(var.basetype);

			if (!var.remapped_variable && type.pointer &&
			    (var.storage == StorageClassInput || var.storage == StorageClassOutput) && !is_builtin_variable(var) &&
			    interface_variable_exists_in_entry_point(var.self))
			{
				if (var.storage == StorageClassInput)
					input_variables.push_back(&var);
				else
					output_variables.push_back(&var);
			}
		}
	}

	const auto variable_compare = [&](const SPIRVariable *a, const SPIRVariable *b) -> bool {
		// Sort input and output variables based on, from more robust to less robust:
		// - Location
		// - Variable has a location
		// - Name comparison
		// - Variable has a name
		// - Fallback: ID
		bool has_location_a = (get_decoration_mask(a->self) & (1ull << DecorationLocation)) != 0;
		bool has_location_b = (get_decoration_mask(b->self) & (1ull << DecorationLocation)) != 0;

		if (has_location_a && has_location_b)
		{
			return get_decoration(a->self, DecorationLocation) <
			       get_decoration(b->self, DecorationLocation);
		}
		else if (has_location_a && !has_location_b)
			return true;
		else if (!has_location_a && has_location_b)
			return false;

		const auto &name1 = to_name(a->self);
		const auto &name2 = to_name(b->self);

		if (name1.empty() && name2.empty())
			return a->self < b->self;
		else if (name1.empty())
			return true;
		else if (name2.empty())
			return false;

		return name1.compare(name2) < 0;
	};

	if (!input_variables.empty() || active_input_builtins)
	{
		require_input = true;
		statement("struct SPIRV_Cross_Input");

		begin_scope();
		sort(input_variables.begin(), input_variables.end(), variable_compare);
		emit_builtin_inputs_in_struct();
		for (auto var : input_variables)
			emit_interface_block_in_struct(*var, active_inputs);
		end_scope_decl();
		statement("");
	}
	else
		require_input = false;

	if (!output_variables.empty() || active_output_builtins)
	{
		require_output = true;
		statement("struct SPIRV_Cross_Output");

		begin_scope();
		// FIXME: Use locations properly if they exist.
		sort(output_variables.begin(), output_variables.end(), variable_compare);
		emit_builtin_outputs_in_struct();
		for (auto var : output_variables)
			emit_interface_block_in_struct(*var, active_outputs);
		end_scope_decl();
		statement("");
	}
	else
		require_output = false;

	// Global variables.
	for (auto global : global_variables)
	{
		auto &var = get<SPIRVariable>(global);
		if (var.storage != StorageClassOutput)
		{
			add_resource_name(var.self);
			statement("static ", variable_decl(var), ";");
			emitted = true;
		}
	}

	if (emitted)
		statement("");

	if (requires_op_fmod)
	{
		statement("float mod(float x, float y)");
		begin_scope();
		statement("return x - y * floor(x / y);");
		end_scope();
		statement("");
	}
}

void CompilerHLSL::emit_buffer_block(const SPIRVariable &var)
{
	auto &type = get<SPIRType>(var.basetype);

	add_resource_name(type.self);

	statement("struct _", to_name(type.self));
	begin_scope();

	type.member_name_cache.clear();

	uint32_t i = 0;
	for (auto &member : type.member_types)
	{
		add_member_name(type, i);
		emit_struct_member(type, member, i);
		i++;
	}
	end_scope_decl();
	statement("");

	statement("cbuffer ", to_name(type.self));
	begin_scope();
	statement("_", to_name(type.self), " ", to_name(var.self), ";");
	end_scope_decl();
}

void CompilerHLSL::emit_push_constant_block(const SPIRVariable &)
{
	statement("constant block");
}

void CompilerHLSL::emit_function_prototype(SPIRFunction &func, uint64_t return_flags)
{
	auto &execution = get_entry_point();
	// Avoid shadow declarations.
	local_variable_names = resource_names;

	string decl;

	auto &type = get<SPIRType>(func.return_type);
	decl += flags_to_precision_qualifiers_glsl(type, return_flags);
	decl += type_to_glsl(type);
	decl += " ";

	if (func.self == entry_point)
	{
		if (execution.model == ExecutionModelVertex)
		{
			decl += "vert_main";
		}
		else
		{
			decl += "frag_main";
		}
		processing_entry_point = true;
	}
	else
		decl += to_name(func.self);

	decl += "(";
	for (auto &arg : func.arguments)
	{
		// Might change the variable name if it already exists in this function.
		// SPIRV OpName doesn't have any semantic effect, so it's valid for an implementation
		// to use same name for variables.
		// Since we want to make the GLSL debuggable and somewhat sane, use fallback names for variables which are duplicates.
		add_local_variable_name(arg.id);

		decl += argument_decl(arg);
		if (&arg != &func.arguments.back())
			decl += ", ";

		// Hold a pointer to the parameter so we can invalidate the readonly field if needed.
		auto *var = maybe_get<SPIRVariable>(arg.id);
		if (var)
			var->parameter = &arg;
	}

	decl += ")";
	statement(decl);
}

void CompilerHLSL::emit_hlsl_entry_point()
{
	auto &execution = get_entry_point();
	statement(require_output ? "SPIRV_Cross_Output " : "void ", "main(",
	          require_input ? "SPIRV_Cross_Input stage_input)" : ")");
	begin_scope();

	if (require_input)
	{
		for (auto &id : ids)
		{
			// Copy builtins from entry point arguments to globals.
			for (uint32_t i = 0; i < 64; i++)
			{
				if (!(active_input_builtins & (1ull << i)))
					continue;

				auto builtin = builtin_to_glsl(static_cast<BuiltIn>(i));
				statement(builtin, " = stage_input.", builtin, ";");
			}

			if (id.get_type() == TypeVariable)
			{
				auto &var = id.get<SPIRVariable>();
				auto &type = get<SPIRType>(var.basetype);

				if (var.storage != StorageClassFunction && !var.remapped_variable && type.pointer &&
				    var.storage == StorageClassInput && !is_builtin_variable(var) &&
				    interface_variable_exists_in_entry_point(var.self))
				{
					auto name = to_name(var.self);
					auto &mtype = get<SPIRType>(var.basetype);
					if (mtype.vecsize == 4 && mtype.columns == 4)
					{
						statement(name, "[0] = stage_input.", name, "_0;");
						statement(name, "[1] = stage_input.", name, "_1;");
						statement(name, "[2] = stage_input.", name, "_2;");
						statement(name, "[3] = stage_input.", name, "_3;");
					}
					else
					{
						statement(name, " = stage_input.", name, ";");
					}
				}
			}
		}
	}

	if (execution.model == ExecutionModelVertex)
		statement("vert_main();");
	else if (execution.model == ExecutionModelFragment)
		statement("frag_main();");
	else
		SPIRV_CROSS_THROW("Unsupported shader stage.");

	if (require_output)
	{
		statement("SPIRV_Cross_Output stage_output;");

		// Copy builtins from globals to return struct.
		for (uint32_t i = 0; i < 64; i++)
		{
			if (!(active_output_builtins & (1ull << i)))
				continue;

			auto builtin = builtin_to_glsl(static_cast<BuiltIn>(i));
			statement("stage_output.", builtin, " = ", builtin, ";");
		}

		for (auto &id : ids)
		{
			if (id.get_type() == TypeVariable)
			{
				auto &var = id.get<SPIRVariable>();
				auto &type = get<SPIRType>(var.basetype);

				if (var.storage != StorageClassFunction && !var.remapped_variable && type.pointer &&
				    var.storage == StorageClassOutput && !is_builtin_variable(var) &&
				    interface_variable_exists_in_entry_point(var.self))
				{
					auto name = to_name(var.self);
					statement("stage_output.", name, " = ", name, ";");
				}
			}
		}

		if (execution.model == ExecutionModelVertex)
		{
			if (options.shader_model <= 30)
			{
				statement("stage_output.gl_Position.x = stage_output.gl_Position.x - gl_HalfPixel.x * "
				          "stage_output.gl_Position.w;");
				statement("stage_output.gl_Position.y = stage_output.gl_Position.y + gl_HalfPixel.y * "
				          "stage_output.gl_Position.w;");
			}
			if (options.flip_vert_y)
			{
				statement("stage_output.gl_Position.y = -stage_output.gl_Position.y;");
			}
			if (options.fixup_clipspace)
			{
				statement(
				    "stage_output.gl_Position.z = (stage_output.gl_Position.z + stage_output.gl_Position.w) * 0.5;");
			}
		}

		statement("return stage_output;");
	}

	end_scope();
}

void CompilerHLSL::emit_texture_op(const Instruction &i)
{
	auto ops = stream(i);
	auto op = static_cast<Op>(i.op);
	uint32_t length = i.length;

	if (i.offset + length > spirv.size())
		SPIRV_CROSS_THROW("Compiler::parse() opcode out of range.");

	uint32_t result_type = ops[0];
	uint32_t id = ops[1];
	uint32_t img = ops[2];
	uint32_t coord = ops[3];
	uint32_t dref = 0;
	uint32_t comp = 0;
	bool gather = false;
	bool proj = false;
	const uint32_t *opt = nullptr;

	switch (op)
	{
	case OpImageSampleDrefImplicitLod:
	case OpImageSampleDrefExplicitLod:
		dref = ops[4];
		opt = &ops[5];
		length -= 5;
		break;

	case OpImageSampleProjDrefImplicitLod:
	case OpImageSampleProjDrefExplicitLod:
		dref = ops[4];
		proj = true;
		opt = &ops[5];
		length -= 5;
		break;

	case OpImageDrefGather:
		dref = ops[4];
		opt = &ops[5];
		gather = true;
		length -= 5;
		break;

	case OpImageGather:
		comp = ops[4];
		opt = &ops[5];
		gather = true;
		length -= 5;
		break;

	case OpImageSampleProjImplicitLod:
	case OpImageSampleProjExplicitLod:
		opt = &ops[4];
		length -= 4;
		proj = true;
		break;

	default:
		opt = &ops[4];
		length -= 4;
		break;
	}

	auto &imgtype = expression_type(img);
	uint32_t coord_components = 0;
	switch (imgtype.image.dim)
	{
	case spv::Dim1D:
		coord_components = 1;
		break;
	case spv::Dim2D:
		coord_components = 2;
		break;
	case spv::Dim3D:
		coord_components = 3;
		break;
	case spv::DimCube:
		coord_components = 3;
		break;
	case spv::DimBuffer:
		coord_components = 1;
		break;
	default:
		coord_components = 2;
		break;
	}

	if (proj)
		coord_components++;
	if (imgtype.image.arrayed)
		coord_components++;

	uint32_t bias = 0;
	uint32_t lod = 0;
	uint32_t grad_x = 0;
	uint32_t grad_y = 0;
	uint32_t coffset = 0;
	uint32_t offset = 0;
	uint32_t coffsets = 0;
	uint32_t sample = 0;
	uint32_t flags = 0;

	if (length)
	{
		flags = opt[0];
		opt++;
		length--;
	}

	auto test = [&](uint32_t &v, uint32_t flag) {
		if (length && (flags & flag))
		{
			v = *opt++;
			length--;
		}
	};

	test(bias, ImageOperandsBiasMask);
	test(lod, ImageOperandsLodMask);
	test(grad_x, ImageOperandsGradMask);
	test(grad_y, ImageOperandsGradMask);
	test(coffset, ImageOperandsConstOffsetMask);
	test(offset, ImageOperandsOffsetMask);
	test(coffsets, ImageOperandsConstOffsetsMask);
	test(sample, ImageOperandsSampleMask);

	string expr;
	string texop;

	if (op == OpImageFetch)
		texop += "texelFetch";
	else
	{
		texop += "tex2D";

		if (gather)
			texop += "Gather";
		if (coffsets)
			texop += "Offsets";
		if (proj)
			texop += "Proj";
		if (grad_x || grad_y)
			texop += "Grad";
		if (lod)
			texop += "Lod";
	}

	if (coffset || offset)
		texop += "Offset";

	if (is_legacy())
		texop = legacy_tex_op(texop, imgtype);

	expr += texop;
	expr += "(";
	expr += to_expression(img);

	bool swizz_func = backend.swizzle_is_function;
	auto swizzle = [swizz_func](uint32_t comps, uint32_t in_comps) -> const char * {
		if (comps == in_comps)
			return "";

		switch (comps)
		{
		case 1:
			return ".x";
		case 2:
			return swizz_func ? ".xy()" : ".xy";
		case 3:
			return swizz_func ? ".xyz()" : ".xyz";
		default:
			return "";
		}
	};

	bool forward = should_forward(coord);

	// The IR can give us more components than we need, so chop them off as needed.
	auto coord_expr = to_expression(coord) + swizzle(coord_components, expression_type(coord).vecsize);

	// TODO: implement rest ... A bit intensive.

	if (dref)
	{
		forward = forward && should_forward(dref);

		// SPIR-V splits dref and coordinate.
		if (coord_components == 4) // GLSL also splits the arguments in two.
		{
			expr += ", ";
			expr += to_expression(coord);
			expr += ", ";
			expr += to_expression(dref);
		}
		else
		{
			// Create a composite which merges coord/dref into a single vector.
			auto type = expression_type(coord);
			type.vecsize = coord_components + 1;
			expr += ", ";
			expr += type_to_glsl_constructor(type);
			expr += "(";
			expr += coord_expr;
			expr += ", ";
			expr += to_expression(dref);
			expr += ")";
		}
	}
	else
	{
		expr += ", ";
		expr += coord_expr;
	}

	if (grad_x || grad_y)
	{
		forward = forward && should_forward(grad_x);
		forward = forward && should_forward(grad_y);
		expr += ", ";
		expr += to_expression(grad_x);
		expr += ", ";
		expr += to_expression(grad_y);
	}

	if (lod)
	{
		forward = forward && should_forward(lod);
		expr += ", ";
		expr += to_expression(lod);
	}

	if (coffset)
	{
		forward = forward && should_forward(coffset);
		expr += ", ";
		expr += to_expression(coffset);
	}
	else if (offset)
	{
		forward = forward && should_forward(offset);
		expr += ", ";
		expr += to_expression(offset);
	}

	if (bias)
	{
		forward = forward && should_forward(bias);
		expr += ", ";
		expr += to_expression(bias);
	}

	if (comp)
	{
		forward = forward && should_forward(comp);
		expr += ", ";
		expr += to_expression(comp);
	}

	if (sample)
	{
		expr += ", ";
		expr += to_expression(sample);
	}

	expr += ")";

	emit_op(result_type, id, expr, forward, false);
}

void CompilerHLSL::emit_uniform(const SPIRVariable &var)
{
	add_resource_name(var.self);
	statement(variable_decl(var), ";");
}

void CompilerHLSL::emit_glsl_op(uint32_t result_type, uint32_t id, uint32_t eop, const uint32_t *args, uint32_t count)
{
	GLSLstd450 op = static_cast<GLSLstd450>(eop);

	switch (op)
	{
	case GLSLstd450InverseSqrt:
	{
		emit_unary_func_op(result_type, id, args[0], "rsqrt");
		break;
	}
	case GLSLstd450Fract:
	{
		emit_unary_func_op(result_type, id, args[0], "frac");
		break;
	}
	case GLSLstd450FMix:
	case GLSLstd450IMix:
	{
		emit_trinary_func_op(result_type, id, args[0], args[1], args[2], "lerp");
		break;
	}
	case GLSLstd450Atan2:
	{
		emit_binary_func_op(result_type, id, args[1], args[0], "atan2");
		break;
	}
	default:
		CompilerGLSL::emit_glsl_op(result_type, id, eop, args, count);
		break;
	}
}

void CompilerHLSL::emit_instruction(const Instruction &instruction)
{
	auto ops = stream(instruction);
	auto opcode = static_cast<Op>(instruction.op);

#define BOP(op) emit_binary_op(ops[0], ops[1], ops[2], ops[3], #op)
#define BOP_CAST(op, type, skip_cast) emit_binary_op_cast(ops[0], ops[1], ops[2], ops[3], #op, type, skip_cast)
#define UOP(op) emit_unary_op(ops[0], ops[1], ops[2], #op)
#define QFOP(op) emit_quaternary_func_op(ops[0], ops[1], ops[2], ops[3], ops[4], ops[5], #op)
#define TFOP(op) emit_trinary_func_op(ops[0], ops[1], ops[2], ops[3], ops[4], #op)
#define BFOP(op) emit_binary_func_op(ops[0], ops[1], ops[2], ops[3], #op)
#define BFOP_CAST(op, type, skip_cast) emit_binary_func_op_cast(ops[0], ops[1], ops[2], ops[3], #op, type, skip_cast)
#define BFOP(op) emit_binary_func_op(ops[0], ops[1], ops[2], ops[3], #op)
#define UFOP(op) emit_unary_func_op(ops[0], ops[1], ops[2], #op)

	switch (opcode)
	{
	case OpMatrixTimesVector:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}
	case OpVectorTimesMatrix:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}
	case OpMatrixTimesMatrix:
	{
		emit_binary_func_op(ops[0], ops[1], ops[3], ops[2], "mul");
		break;
	}
	case OpFMod:
	{
		requires_op_fmod = true;
		CompilerGLSL::emit_instruction(instruction);
		break;
	}
	default:
		CompilerGLSL::emit_instruction(instruction);
		break;
	}
}

string CompilerHLSL::compile()
{
	// Do not deal with ES-isms like precision, older extensions and such.
	CompilerGLSL::options.es = false;
	CompilerGLSL::options.version = 450;
	backend.float_literal_suffix = true;
	backend.double_literal_suffix = false;
	backend.long_long_literal_suffix = true;
	backend.uint32_t_literal_suffix = true;
	backend.basic_int_type = "int";
	backend.basic_uint_type = "uint";
	backend.swizzle_is_function = false;
	backend.shared_is_implied = true;
	backend.flexible_member_array_supported = false;
	backend.explicit_struct_type = false;
	backend.use_initializer_list = true;
	backend.use_constructor_splatting = false;

	update_active_builtins();

	uint32_t pass_count = 0;
	do
	{
		if (pass_count >= 3)
			SPIRV_CROSS_THROW("Over 3 compilation loops detected. Must be a bug!");

		reset();

		// Move constructor for this type is broken on GCC 4.9 ...
		buffer = unique_ptr<ostringstream>(new ostringstream());

		emit_header();
		emit_resources();

		emit_function(get<SPIRFunction>(entry_point), 0);
		emit_hlsl_entry_point();

		pass_count++;
	} while (force_recompile);

	return buffer->str();
}