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6436fd4f1a
Factor out CodeExtractor's analysis of allocas (for shrinkwrapping purposes), and allow the analysis to be reused. This resolves a quadratic compile-time bug observed when compiling AMDGPUDisassembler.cpp.o. Pre-patch (Release + LTO clang): ``` ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name --- 176.5278 ( 57.8%) 0.4915 ( 18.5%) 177.0192 ( 57.4%) 177.4112 ( 57.3%) Hot Cold Splitting ``` Post-patch (ReleaseAsserts clang): ``` ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name --- 1.4051 ( 3.3%) 0.0079 ( 0.3%) 1.4129 ( 3.2%) 1.4129 ( 3.2%) Hot Cold Splitting ``` Testing: check-llvm, and comparing the AMDGPUDisassembler.cpp.o binary pre- vs. post-patch. An alternate approach is to hide CodeExtractorAnalysisCache from clients of CodeExtractor, and to recompute the analysis from scratch inside of CodeExtractor::extractCodeRegion(). This eliminates some redundant work in the shrinkwrapping legality check. However, some clients continue to exhibit O(n^2) compile time behavior as computing the analysis is O(n). rdar://55912966 Differential Revision: https://reviews.llvm.org/D68616 llvm-svn: 374089
70 lines
2.5 KiB
C++
70 lines
2.5 KiB
C++
//===- HotColdSplitting.h ---- Outline Cold Regions -------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//===----------------------------------------------------------------------===//
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//
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// This pass outlines cold regions to a separate function.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
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#define LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
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#include "llvm/IR/PassManager.h"
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namespace llvm {
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class Module;
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class ProfileSummaryInfo;
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class BlockFrequencyInfo;
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class TargetTransformInfo;
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class OptimizationRemarkEmitter;
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class AssumptionCache;
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class DominatorTree;
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class CodeExtractorAnalysisCache;
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/// A sequence of basic blocks.
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///
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/// A 0-sized SmallVector is slightly cheaper to move than a std::vector.
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using BlockSequence = SmallVector<BasicBlock *, 0>;
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class HotColdSplitting {
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public:
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HotColdSplitting(ProfileSummaryInfo *ProfSI,
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function_ref<BlockFrequencyInfo *(Function &)> GBFI,
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function_ref<TargetTransformInfo &(Function &)> GTTI,
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std::function<OptimizationRemarkEmitter &(Function &)> *GORE,
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function_ref<AssumptionCache *(Function &)> LAC)
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: PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE), LookupAC(LAC) {}
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bool run(Module &M);
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private:
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bool isFunctionCold(const Function &F) const;
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bool shouldOutlineFrom(const Function &F) const;
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bool outlineColdRegions(Function &F, bool HasProfileSummary);
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Function *extractColdRegion(const BlockSequence &Region,
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const CodeExtractorAnalysisCache &CEAC,
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DominatorTree &DT, BlockFrequencyInfo *BFI,
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TargetTransformInfo &TTI,
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OptimizationRemarkEmitter &ORE,
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AssumptionCache *AC, unsigned Count);
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ProfileSummaryInfo *PSI;
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function_ref<BlockFrequencyInfo *(Function &)> GetBFI;
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function_ref<TargetTransformInfo &(Function &)> GetTTI;
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std::function<OptimizationRemarkEmitter &(Function &)> *GetORE;
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function_ref<AssumptionCache *(Function &)> LookupAC;
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};
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/// Pass to outline cold regions.
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class HotColdSplittingPass : public PassInfoMixin<HotColdSplittingPass> {
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public:
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PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
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