mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-11-26 05:10:05 +00:00
f46f2d3e5d
The code patterns generated by DXC around function calls can cause many store to be storing the same value that was just loaded from the same location: ``` %10 = OpLoad %type %var OpStore %var %10 ``` We want to clean these up very early on because they can cause other transformations to do a lot of work. For the cases I see, they can be removed during local-single-block-elim. For one set of shaders the compile time goes from 248s to 182s. A 26% improvement. Part of https://github.com/KhronosGroup/SPIRV-Tools/issues/1494.
255 lines
8.9 KiB
C++
255 lines
8.9 KiB
C++
// Copyright (c) 2017 The Khronos Group Inc.
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// Copyright (c) 2017 Valve Corporation
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// Copyright (c) 2017 LunarG Inc.
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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 "local_single_block_elim_pass.h"
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#include "iterator.h"
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namespace spvtools {
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namespace opt {
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namespace {
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const uint32_t kStoreValIdInIdx = 1;
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} // anonymous namespace
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bool LocalSingleBlockLoadStoreElimPass::HasOnlySupportedRefs(uint32_t ptrId) {
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if (supported_ref_ptrs_.find(ptrId) != supported_ref_ptrs_.end()) return true;
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if (get_def_use_mgr()->WhileEachUser(ptrId, [this](ir::Instruction* user) {
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SpvOp op = user->opcode();
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if (IsNonPtrAccessChain(op) || op == SpvOpCopyObject) {
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if (!HasOnlySupportedRefs(user->result_id())) {
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return false;
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}
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} else if (op != SpvOpStore && op != SpvOpLoad && op != SpvOpName &&
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!IsNonTypeDecorate(op)) {
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return false;
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}
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return true;
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})) {
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supported_ref_ptrs_.insert(ptrId);
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return true;
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}
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return false;
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}
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bool LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElim(
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ir::Function* func) {
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// Perform local store/load, load/load and store/store elimination
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// on each block
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bool modified = false;
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std::vector<ir::Instruction*> instructions_to_kill;
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std::unordered_set<ir::Instruction*> instructions_to_save;
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for (auto bi = func->begin(); bi != func->end(); ++bi) {
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var2store_.clear();
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var2load_.clear();
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auto next = bi->begin();
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for (auto ii = next; ii != bi->end(); ii = next) {
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++next;
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switch (ii->opcode()) {
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case SpvOpStore: {
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// Verify store variable is target type
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uint32_t varId;
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ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
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if (!IsTargetVar(varId)) continue;
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if (!HasOnlySupportedRefs(varId)) continue;
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// If a store to the whole variable, remember it for succeeding
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// loads and stores. Otherwise forget any previous store to that
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// variable.
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if (ptrInst->opcode() == SpvOpVariable) {
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// If a previous store to same variable, mark the store
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// for deletion if not still used.
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auto prev_store = var2store_.find(varId);
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if (prev_store != var2store_.end() &&
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instructions_to_save.count(prev_store->second) == 0) {
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instructions_to_kill.push_back(prev_store->second);
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}
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bool kill_store = false;
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auto li = var2load_.find(varId);
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if (li != var2load_.end()) {
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if (ii->GetSingleWordInOperand(kStoreValIdInIdx) ==
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li->second->result_id()) {
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// We are storing the same value that already exists in the
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// memory location. The store does nothing.
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kill_store = true;
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}
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}
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if (!kill_store) {
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var2store_[varId] = &*ii;
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var2load_.erase(varId);
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} else {
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instructions_to_kill.push_back(&*ii);
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modified = true;
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}
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} else {
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assert(IsNonPtrAccessChain(ptrInst->opcode()));
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var2store_.erase(varId);
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var2load_.erase(varId);
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}
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} break;
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case SpvOpLoad: {
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// Verify store variable is target type
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uint32_t varId;
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ir::Instruction* ptrInst = GetPtr(&*ii, &varId);
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if (!IsTargetVar(varId)) continue;
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if (!HasOnlySupportedRefs(varId)) continue;
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uint32_t replId = 0;
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if (ptrInst->opcode() == SpvOpVariable) {
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// If a load from a variable, look for a previous store or
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// load from that variable and use its value.
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auto si = var2store_.find(varId);
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if (si != var2store_.end()) {
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replId = si->second->GetSingleWordInOperand(kStoreValIdInIdx);
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} else {
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auto li = var2load_.find(varId);
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if (li != var2load_.end()) {
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replId = li->second->result_id();
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}
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}
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} else {
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// If a partial load of a previously seen store, remember
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// not to delete the store.
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auto si = var2store_.find(varId);
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if (si != var2store_.end()) instructions_to_save.insert(si->second);
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}
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if (replId != 0) {
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// replace load's result id and delete load
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context()->KillNamesAndDecorates(&*ii);
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context()->ReplaceAllUsesWith(ii->result_id(), replId);
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instructions_to_kill.push_back(&*ii);
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modified = true;
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} else {
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if (ptrInst->opcode() == SpvOpVariable)
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var2load_[varId] = &*ii; // register load
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}
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} break;
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case SpvOpFunctionCall: {
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// Conservatively assume all locals are redefined for now.
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// TODO(): Handle more optimally
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var2store_.clear();
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var2load_.clear();
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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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for (ir::Instruction* inst : instructions_to_kill) {
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context()->KillInst(inst);
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}
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return modified;
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}
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void LocalSingleBlockLoadStoreElimPass::Initialize(ir::IRContext* c) {
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InitializeProcessing(c);
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// Initialize Target Type Caches
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seen_target_vars_.clear();
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seen_non_target_vars_.clear();
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// Clear collections
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supported_ref_ptrs_.clear();
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// Initialize extensions whitelist
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InitExtensions();
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}
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bool LocalSingleBlockLoadStoreElimPass::AllExtensionsSupported() const {
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// If any extension not in whitelist, return false
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for (auto& ei : get_module()->extensions()) {
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const char* extName =
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reinterpret_cast<const char*>(&ei.GetInOperand(0).words[0]);
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if (extensions_whitelist_.find(extName) == extensions_whitelist_.end())
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return false;
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}
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return true;
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}
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Pass::Status LocalSingleBlockLoadStoreElimPass::ProcessImpl() {
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// Assumes relaxed logical addressing only (see instruction.h).
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if (context()->get_feature_mgr()->HasCapability(SpvCapabilityAddresses))
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return Status::SuccessWithoutChange;
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// Do not process if module contains OpGroupDecorate. Additional
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// support required in KillNamesAndDecorates().
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// TODO(greg-lunarg): Add support for OpGroupDecorate
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for (auto& ai : get_module()->annotations())
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if (ai.opcode() == SpvOpGroupDecorate) return Status::SuccessWithoutChange;
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// If any extensions in the module are not explicitly supported,
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// return unmodified.
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if (!AllExtensionsSupported()) return Status::SuccessWithoutChange;
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// Process all entry point functions
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ProcessFunction pfn = [this](ir::Function* fp) {
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return LocalSingleBlockLoadStoreElim(fp);
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};
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bool modified = ProcessEntryPointCallTree(pfn, get_module());
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return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;
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}
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LocalSingleBlockLoadStoreElimPass::LocalSingleBlockLoadStoreElimPass() {}
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Pass::Status LocalSingleBlockLoadStoreElimPass::Process(ir::IRContext* c) {
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Initialize(c);
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return ProcessImpl();
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}
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void LocalSingleBlockLoadStoreElimPass::InitExtensions() {
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extensions_whitelist_.clear();
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extensions_whitelist_.insert({
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"SPV_AMD_shader_explicit_vertex_parameter",
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"SPV_AMD_shader_trinary_minmax",
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"SPV_AMD_gcn_shader",
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"SPV_KHR_shader_ballot",
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"SPV_AMD_shader_ballot",
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"SPV_AMD_gpu_shader_half_float",
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"SPV_KHR_shader_draw_parameters",
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"SPV_KHR_subgroup_vote",
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"SPV_KHR_16bit_storage",
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"SPV_KHR_device_group",
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"SPV_KHR_multiview",
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"SPV_NVX_multiview_per_view_attributes",
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"SPV_NV_viewport_array2",
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"SPV_NV_stereo_view_rendering",
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"SPV_NV_sample_mask_override_coverage",
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"SPV_NV_geometry_shader_passthrough",
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"SPV_AMD_texture_gather_bias_lod",
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"SPV_KHR_storage_buffer_storage_class",
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// SPV_KHR_variable_pointers
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// Currently do not support extended pointer expressions
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"SPV_AMD_gpu_shader_int16",
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"SPV_KHR_post_depth_coverage",
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"SPV_KHR_shader_atomic_counter_ops",
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"SPV_EXT_shader_stencil_export",
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"SPV_EXT_shader_viewport_index_layer",
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"SPV_AMD_shader_image_load_store_lod",
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"SPV_AMD_shader_fragment_mask",
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"SPV_EXT_fragment_fully_covered",
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"SPV_AMD_gpu_shader_half_float_fetch",
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"SPV_GOOGLE_decorate_string",
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"SPV_GOOGLE_hlsl_functionality1",
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"SPV_NV_shader_subgroup_partitioned",
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"SPV_EXT_descriptor_indexing",
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});
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}
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} // namespace opt
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} // namespace spvtools
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