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https://github.com/KhronosGroup/SPIRV-Tools
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048dcd38ce
WebGPU requires certain variables to be initialized, whereas there are known issues with using initializers in Vulkan. This PR is the first of three implementing a pass to decompose initialized variables into a variable declaration followed by a store. This has been broken up into multiple PRs, because there 3 distinct cases that need to be handled, which require separate implementations. This first PR implements the basic infrastructure that is needed, and handling of Function storage class variables. Private and Output will be handled in future PRs. This is part of resolving #2388
113 lines
3.6 KiB
C++
113 lines
3.6 KiB
C++
// Copyright (c) 2019 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 "source/opt/generate_webgpu_initializers_pass.h"
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#include "source/opt/ir_context.h"
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namespace spvtools {
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namespace opt {
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using inst_iterator = InstructionList::iterator;
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namespace {
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bool NeedsWebGPUInitializer(Instruction* inst) {
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if (inst->opcode() != SpvOpVariable) return false;
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auto storage_class = inst->GetSingleWordOperand(2);
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if (storage_class != SpvStorageClassOutput &&
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storage_class != SpvStorageClassPrivate &&
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storage_class != SpvStorageClassFunction) {
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return false;
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}
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if (inst->NumOperands() > 3) return false;
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return true;
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}
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} // namespace
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Pass::Status GenerateWebGPUInitializersPass::Process() {
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auto* module = context()->module();
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bool changed = false;
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// Handle global/module scoped variables
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for (auto iter = module->types_values_begin();
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iter != module->types_values_end(); ++iter) {
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Instruction* inst = &(*iter);
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if (inst->opcode() == SpvOpConstantNull) {
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null_constant_type_map_[inst->type_id()] = inst;
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seen_null_constants_.insert(inst);
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continue;
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}
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if (!NeedsWebGPUInitializer(inst)) continue;
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changed = true;
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auto* constant_inst = GetNullConstantForVariable(inst);
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if (seen_null_constants_.find(constant_inst) ==
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seen_null_constants_.end()) {
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constant_inst->InsertBefore(inst);
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null_constant_type_map_[inst->type_id()] = inst;
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seen_null_constants_.insert(inst);
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}
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AddNullInitializerToVariable(constant_inst, inst);
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}
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// Handle local/function scoped variables
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for (auto func = module->begin(); func != module->end(); ++func) {
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auto block = func->entry().get();
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for (auto iter = block->begin();
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iter != block->end() && iter->opcode() == SpvOpVariable; ++iter) {
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Instruction* inst = &(*iter);
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if (!NeedsWebGPUInitializer(inst)) continue;
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changed = true;
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auto* constant_inst = GetNullConstantForVariable(inst);
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AddNullInitializerToVariable(constant_inst, inst);
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}
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}
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return changed ? Status::SuccessWithChange : Status::SuccessWithoutChange;
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}
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Instruction* GenerateWebGPUInitializersPass::GetNullConstantForVariable(
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Instruction* variable_inst) {
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auto constant_mgr = context()->get_constant_mgr();
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auto* def_use_mgr = get_def_use_mgr();
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auto* ptr_inst = def_use_mgr->GetDef(variable_inst->type_id());
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auto type_id = ptr_inst->GetInOperand(1).words[0];
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if (null_constant_type_map_.find(type_id) == null_constant_type_map_.end()) {
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auto* constant_type = context()->get_type_mgr()->GetType(type_id);
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auto* constant = constant_mgr->GetConstant(constant_type, {});
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return constant_mgr->GetDefiningInstruction(constant, type_id);
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} else {
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return null_constant_type_map_[type_id];
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}
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}
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void GenerateWebGPUInitializersPass::AddNullInitializerToVariable(
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Instruction* constant_inst, Instruction* variable_inst) {
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auto constant_id = constant_inst->result_id();
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variable_inst->AddOperand(Operand(SPV_OPERAND_TYPE_ID, {constant_id}));
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get_def_use_mgr()->AnalyzeInstUse(variable_inst);
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}
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} // namespace opt
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} // namespace spvtools
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