mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-12-03 07:51:04 +00:00
755e5c9420
* Combines OpAccessChain, OpInBoundsAccessChain, OpPtrAccessChain and OpInBoundsPtrAccessChain * New folding rule to fold add with 0 for integers * Converts to a bitcast if the result type does not match the operand type V
289 lines
11 KiB
C++
289 lines
11 KiB
C++
// Copyright (c) 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "combine_access_chains.h"
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#include "constants.h"
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#include "ir_builder.h"
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#include "ir_context.h"
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namespace spvtools {
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namespace opt {
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Pass::Status CombineAccessChains::Process() {
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bool modified = false;
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for (auto& function : *get_module()) {
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modified |= ProcessFunction(function);
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}
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return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
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}
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bool CombineAccessChains::ProcessFunction(Function& function) {
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bool modified = false;
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cfg()->ForEachBlockInReversePostOrder(
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function.entry().get(), [&modified, this](BasicBlock* block) {
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block->ForEachInst([&modified, this](Instruction* inst) {
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switch (inst->opcode()) {
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case SpvOpAccessChain:
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case SpvOpInBoundsAccessChain:
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case SpvOpPtrAccessChain:
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case SpvOpInBoundsPtrAccessChain:
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modified |= CombineAccessChain(inst);
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break;
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default:
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break;
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}
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});
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});
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return modified;
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}
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uint32_t CombineAccessChains::GetConstantValue(
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const analysis::Constant* constant_inst) {
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if (constant_inst->type()->AsInteger()->width() <= 32) {
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if (constant_inst->type()->AsInteger()->IsSigned()) {
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return static_cast<uint32_t>(constant_inst->GetS32());
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} else {
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return constant_inst->GetU32();
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}
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} else {
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assert(false);
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return 0u;
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}
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}
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uint32_t CombineAccessChains::GetArrayStride(const Instruction* inst) {
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uint32_t array_stride = 0;
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context()->get_decoration_mgr()->WhileEachDecoration(
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inst->type_id(), SpvDecorationArrayStride,
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[&array_stride](const Instruction& decoration) {
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assert(decoration.opcode() != SpvOpDecorateId);
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if (decoration.opcode() == SpvOpDecorate) {
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array_stride = decoration.GetSingleWordInOperand(1);
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} else {
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array_stride = decoration.GetSingleWordInOperand(2);
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}
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return false;
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});
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return array_stride;
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}
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const analysis::Type* CombineAccessChains::GetIndexedType(Instruction* inst) {
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analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
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analysis::TypeManager* type_mgr = context()->get_type_mgr();
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Instruction* base_ptr = def_use_mgr->GetDef(inst->GetSingleWordInOperand(0));
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const analysis::Type* type = type_mgr->GetType(base_ptr->type_id());
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assert(type->AsPointer());
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type = type->AsPointer()->pointee_type();
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std::vector<uint32_t> element_indices;
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uint32_t starting_index = 1;
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if (IsPtrAccessChain(inst->opcode())) {
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// Skip the first index of OpPtrAccessChain as it does not affect type
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// resolution.
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starting_index = 2;
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}
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for (uint32_t i = starting_index; i < inst->NumInOperands(); ++i) {
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Instruction* index_inst =
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def_use_mgr->GetDef(inst->GetSingleWordInOperand(i));
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const analysis::Constant* index_constant =
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context()->get_constant_mgr()->GetConstantFromInst(index_inst);
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if (index_constant) {
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uint32_t index_value = GetConstantValue(index_constant);
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element_indices.push_back(index_value);
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} else {
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// This index must not matter to resolve the type in valid SPIR-V.
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element_indices.push_back(0);
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}
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}
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type = type_mgr->GetMemberType(type, element_indices);
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return type;
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}
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bool CombineAccessChains::CombineIndices(Instruction* ptr_input,
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Instruction* inst,
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std::vector<Operand>* new_operands) {
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analysis::DefUseManager* def_use_mgr = context()->get_def_use_mgr();
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analysis::ConstantManager* constant_mgr = context()->get_constant_mgr();
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Instruction* last_index_inst = def_use_mgr->GetDef(
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ptr_input->GetSingleWordInOperand(ptr_input->NumInOperands() - 1));
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const analysis::Constant* last_index_constant =
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constant_mgr->GetConstantFromInst(last_index_inst);
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Instruction* element_inst =
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def_use_mgr->GetDef(inst->GetSingleWordInOperand(1));
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const analysis::Constant* element_constant =
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constant_mgr->GetConstantFromInst(element_inst);
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// Combine the last index of the AccessChain (|ptr_inst|) with the element
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// operand of the PtrAccessChain (|inst|).
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const bool combining_element_operands =
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IsPtrAccessChain(inst->opcode()) &&
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IsPtrAccessChain(ptr_input->opcode()) && ptr_input->NumInOperands() == 2;
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uint32_t new_value_id = 0;
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const analysis::Type* type = GetIndexedType(ptr_input);
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if (last_index_constant && element_constant) {
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// Combine the constants.
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uint32_t new_value = GetConstantValue(last_index_constant) +
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GetConstantValue(element_constant);
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const analysis::Constant* new_value_constant =
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constant_mgr->GetConstant(last_index_constant->type(), {new_value});
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Instruction* new_value_inst =
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constant_mgr->GetDefiningInstruction(new_value_constant);
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new_value_id = new_value_inst->result_id();
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} else if (!type->AsStruct() || combining_element_operands) {
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// Generate an addition of the two indices.
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InstructionBuilder builder(
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context(), inst,
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IRContext::kAnalysisDefUse | IRContext::kAnalysisInstrToBlockMapping);
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Instruction* addition = builder.AddIAdd(last_index_inst->type_id(),
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last_index_inst->result_id(),
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element_inst->result_id());
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new_value_id = addition->result_id();
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} else {
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// Indexing into structs must be constant, so bail out here.
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return false;
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}
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new_operands->push_back({SPV_OPERAND_TYPE_ID, {new_value_id}});
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return true;
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}
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bool CombineAccessChains::CreateNewInputOperands(
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Instruction* ptr_input, Instruction* inst,
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std::vector<Operand>* new_operands) {
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// Start by copying all the input operands of the feeder access chain.
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for (uint32_t i = 0; i != ptr_input->NumInOperands() - 1; ++i) {
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new_operands->push_back(ptr_input->GetInOperand(i));
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}
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// Deal with the last index of the feeder access chain.
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if (IsPtrAccessChain(inst->opcode())) {
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// The last index of the feeder should be combined with the element operand
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// of |inst|.
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if (!CombineIndices(ptr_input, inst, new_operands)) return false;
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} else {
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// The indices aren't being combined so now add the last index operand of
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// |ptr_input|.
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new_operands->push_back(
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ptr_input->GetInOperand(ptr_input->NumInOperands() - 1));
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}
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// Copy the remaining index operands.
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uint32_t starting_index = IsPtrAccessChain(inst->opcode()) ? 2 : 1;
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for (uint32_t i = starting_index; i < inst->NumInOperands(); ++i) {
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new_operands->push_back(inst->GetInOperand(i));
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}
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return true;
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}
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bool CombineAccessChains::CombineAccessChain(Instruction* inst) {
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assert((inst->opcode() == SpvOpPtrAccessChain ||
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inst->opcode() == SpvOpAccessChain ||
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inst->opcode() == SpvOpInBoundsAccessChain ||
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inst->opcode() == SpvOpInBoundsPtrAccessChain) &&
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"Wrong opcode. Expected an access chain.");
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Instruction* ptr_input =
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context()->get_def_use_mgr()->GetDef(inst->GetSingleWordInOperand(0));
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if (ptr_input->opcode() != SpvOpAccessChain &&
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ptr_input->opcode() != SpvOpInBoundsAccessChain &&
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ptr_input->opcode() != SpvOpPtrAccessChain &&
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ptr_input->opcode() != SpvOpInBoundsPtrAccessChain) {
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return false;
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}
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if (Has64BitIndices(inst) || Has64BitIndices(ptr_input)) return false;
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// Handles the following cases:
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// 1. |ptr_input| is an index-less access chain. Replace the pointer
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// in |inst| with |ptr_input|'s pointer.
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// 2. |inst| is a index-less access chain. Change |inst| to an
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// OpCopyObject.
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// 3. |inst| is not a pointer access chain.
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// |inst|'s indices are appended to |ptr_input|'s indices.
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// 4. |ptr_input| is not pointer access chain.
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// |inst| is a pointer access chain.
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// |inst|'s element operand is combined with the last index in
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// |ptr_input| to form a new operand.
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// 5. |ptr_input| is a pointer access chain.
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// Like the above scenario, |inst|'s element operand is combined
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// with |ptr_input|'s last index. This results is either a
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// combined element operand or combined regular index.
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// TODO(alan-baker): Support this properly. Requires analyzing the
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// size/alignment of the type and converting the stride into an element
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// index.
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uint32_t array_stride = GetArrayStride(ptr_input);
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if (array_stride != 0) return false;
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if (ptr_input->NumInOperands() == 1) {
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// The input is effectively a no-op.
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inst->SetInOperand(0, {ptr_input->GetSingleWordInOperand(0)});
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context()->AnalyzeUses(inst);
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} else if (inst->NumInOperands() == 1) {
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// |inst| is a no-op, change it to a copy. Instruction simplification will
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// clean it up.
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inst->SetOpcode(SpvOpCopyObject);
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} else {
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std::vector<Operand> new_operands;
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if (!CreateNewInputOperands(ptr_input, inst, &new_operands)) return false;
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// Update the instruction.
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inst->SetOpcode(UpdateOpcode(inst->opcode(), ptr_input->opcode()));
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inst->SetInOperands(std::move(new_operands));
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context()->AnalyzeUses(inst);
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}
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return true;
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}
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SpvOp CombineAccessChains::UpdateOpcode(SpvOp base_opcode, SpvOp input_opcode) {
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auto IsInBounds = [](SpvOp opcode) {
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return opcode == SpvOpInBoundsPtrAccessChain ||
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opcode == SpvOpInBoundsAccessChain;
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};
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if (input_opcode == SpvOpInBoundsPtrAccessChain) {
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if (!IsInBounds(base_opcode)) return SpvOpPtrAccessChain;
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} else if (input_opcode == SpvOpInBoundsAccessChain) {
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if (!IsInBounds(base_opcode)) return SpvOpAccessChain;
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}
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return input_opcode;
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}
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bool CombineAccessChains::IsPtrAccessChain(SpvOp opcode) {
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return opcode == SpvOpPtrAccessChain || opcode == SpvOpInBoundsPtrAccessChain;
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}
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bool CombineAccessChains::Has64BitIndices(Instruction* inst) {
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for (uint32_t i = 1; i < inst->NumInOperands(); ++i) {
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Instruction* index_inst =
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context()->get_def_use_mgr()->GetDef(inst->GetSingleWordInOperand(i));
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const analysis::Type* index_type =
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context()->get_type_mgr()->GetType(index_inst->type_id());
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if (!index_type->AsInteger() || index_type->AsInteger()->width() != 32)
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return true;
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}
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return false;
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}
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} // namespace opt
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} // namespace spvtools
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