mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-11-30 23:10:05 +00:00
2e4563d94f
Added documentation to the ir context to indicates that TakeNextId() returns 0 when the max id is reached. TODOs were added to each call sight so that we know where we have to start to handle this case. Handle id overflow in |SplitLoopHeader|. Handle id overflow in |GetOrCreatePreHeaderBlock|. Handle failure to create preheader in LICM. Part of https://github.com/KhronosGroup/SPIRV-Tools/issues/1841.
134 lines
4.1 KiB
C++
134 lines
4.1 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 "source/opt/licm_pass.h"
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#include <queue>
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#include <utility>
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#include "source/opt/module.h"
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#include "source/opt/pass.h"
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namespace spvtools {
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namespace opt {
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Pass::Status LICMPass::Process() { return ProcessIRContext(); }
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Pass::Status LICMPass::ProcessIRContext() {
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Status status = Status::SuccessWithoutChange;
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Module* module = get_module();
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// Process each function in the module
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for (auto func = module->begin();
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func != module->end() && status != Status::Failure; ++func) {
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status = CombineStatus(status, ProcessFunction(&*func));
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}
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return status;
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}
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Pass::Status LICMPass::ProcessFunction(Function* f) {
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Status status = Status::SuccessWithoutChange;
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LoopDescriptor* loop_descriptor = context()->GetLoopDescriptor(f);
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// Process each loop in the function
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for (auto it = loop_descriptor->begin();
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it != loop_descriptor->end() && status != Status::Failure; ++it) {
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Loop& loop = *it;
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// Ignore nested loops, as we will process them in order in ProcessLoop
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if (loop.IsNested()) {
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continue;
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}
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status = CombineStatus(status, ProcessLoop(&loop, f));
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}
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return status;
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}
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Pass::Status LICMPass::ProcessLoop(Loop* loop, Function* f) {
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Status status = Status::SuccessWithoutChange;
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// Process all nested loops first
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for (auto nl = loop->begin(); nl != loop->end() && status != Status::Failure;
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++nl) {
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Loop* nested_loop = *nl;
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status = CombineStatus(status, ProcessLoop(nested_loop, f));
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}
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std::vector<BasicBlock*> loop_bbs{};
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status = CombineStatus(
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status,
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AnalyseAndHoistFromBB(loop, f, loop->GetHeaderBlock(), &loop_bbs));
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for (size_t i = 0; i < loop_bbs.size() && status != Status::Failure; ++i) {
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BasicBlock* bb = loop_bbs[i];
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// do not delete the element
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status =
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CombineStatus(status, AnalyseAndHoistFromBB(loop, f, bb, &loop_bbs));
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}
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return status;
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}
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Pass::Status LICMPass::AnalyseAndHoistFromBB(
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Loop* loop, Function* f, BasicBlock* bb,
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std::vector<BasicBlock*>* loop_bbs) {
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bool modified = false;
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std::function<bool(Instruction*)> hoist_inst =
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[this, &loop, &modified](Instruction* inst) {
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if (loop->ShouldHoistInstruction(this->context(), inst)) {
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if (!HoistInstruction(loop, inst)) {
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return false;
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}
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modified = true;
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}
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return true;
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};
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if (IsImmediatelyContainedInLoop(loop, f, bb)) {
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if (!bb->WhileEachInst(hoist_inst, false)) {
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return Status::Failure;
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}
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}
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DominatorAnalysis* dom_analysis = context()->GetDominatorAnalysis(f);
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DominatorTree& dom_tree = dom_analysis->GetDomTree();
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for (DominatorTreeNode* child_dom_tree_node : *dom_tree.GetTreeNode(bb)) {
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if (loop->IsInsideLoop(child_dom_tree_node->bb_)) {
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loop_bbs->push_back(child_dom_tree_node->bb_);
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}
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}
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return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
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}
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bool LICMPass::IsImmediatelyContainedInLoop(Loop* loop, Function* f,
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BasicBlock* bb) {
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LoopDescriptor* loop_descriptor = context()->GetLoopDescriptor(f);
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return loop == (*loop_descriptor)[bb->id()];
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}
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bool LICMPass::HoistInstruction(Loop* loop, Instruction* inst) {
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// TODO(1841): Handle failure to create pre-header.
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BasicBlock* pre_header_bb = loop->GetOrCreatePreHeaderBlock();
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if (!pre_header_bb) {
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return false;
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}
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inst->InsertBefore(std::move(&(*pre_header_bb->tail())));
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context()->set_instr_block(inst, pre_header_bb);
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return true;
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}
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} // namespace opt
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} // namespace spvtools
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