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llvm-mirror/include/llvm/Transforms/IPO/HotColdSplitting.h
Hans Wennborg f6eeeaf04e Revert "[PM/CC1] Add -f[no-]split-cold-code CC1 option to toggle splitting"
This broke Chromium's PGO build, it seems because hot-cold-splitting got turned
on unintentionally. See comment on the code review for repro etc.

> This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
> the splitting pass to be toggled on/off. The current method of passing
> `-mllvm -hot-cold-split=true` to clang isn't ideal as it may not compose
> correctly (say, with `-O0` or `-Oz`).
>
> To implement the -fsplit-cold-code option, an attribute is applied to
> functions to indicate that they may be considered for splitting. This
> removes some complexity from the old/new PM pipeline builders, and
> behaves as expected when LTO is enabled.
>
> Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
> Differential Revision: https://reviews.llvm.org/D57265
> Reviewed By: Aditya Kumar, Vedant Kumar
> Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar

This reverts commit 273c299d5d649a0222fbde03c9a41e41913751b4.
2020-10-19 12:31:14 +02:00

70 lines
2.5 KiB
C++

//===- HotColdSplitting.h ---- Outline Cold Regions -------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//===----------------------------------------------------------------------===//
//
// This pass outlines cold regions to a separate function.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
#define LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H
#include "llvm/IR/PassManager.h"
namespace llvm {
class Module;
class ProfileSummaryInfo;
class BlockFrequencyInfo;
class TargetTransformInfo;
class OptimizationRemarkEmitter;
class AssumptionCache;
class DominatorTree;
class CodeExtractorAnalysisCache;
/// A sequence of basic blocks.
///
/// A 0-sized SmallVector is slightly cheaper to move than a std::vector.
using BlockSequence = SmallVector<BasicBlock *, 0>;
class HotColdSplitting {
public:
HotColdSplitting(ProfileSummaryInfo *ProfSI,
function_ref<BlockFrequencyInfo *(Function &)> GBFI,
function_ref<TargetTransformInfo &(Function &)> GTTI,
std::function<OptimizationRemarkEmitter &(Function &)> *GORE,
function_ref<AssumptionCache *(Function &)> LAC)
: PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE), LookupAC(LAC) {}
bool run(Module &M);
private:
bool isFunctionCold(const Function &F) const;
bool shouldOutlineFrom(const Function &F) const;
bool outlineColdRegions(Function &F, bool HasProfileSummary);
Function *extractColdRegion(const BlockSequence &Region,
const CodeExtractorAnalysisCache &CEAC,
DominatorTree &DT, BlockFrequencyInfo *BFI,
TargetTransformInfo &TTI,
OptimizationRemarkEmitter &ORE,
AssumptionCache *AC, unsigned Count);
ProfileSummaryInfo *PSI;
function_ref<BlockFrequencyInfo *(Function &)> GetBFI;
function_ref<TargetTransformInfo &(Function &)> GetTTI;
std::function<OptimizationRemarkEmitter &(Function &)> *GetORE;
function_ref<AssumptionCache *(Function &)> LookupAC;
};
/// Pass to outline cold regions.
class HotColdSplittingPass : public PassInfoMixin<HotColdSplittingPass> {
public:
PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
};
} // end namespace llvm
#endif // LLVM_TRANSFORMS_IPO_HOTCOLDSPLITTING_H