1662c200a5
Make this dependent only on the minsize attribute and drop the pipeline handling. Rename the enable-loop-header-duplication option to enable-loop-header-duplication-at-minsize to clarify that it controls header duplication at minsize only (in other cases it is enabled by default, independently of this option).
108 lines
4.2 KiB
C++
108 lines
4.2 KiB
C++
//===- LoopRotation.cpp - Loop Rotation Pass ------------------------------===//
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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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//
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// This file implements Loop Rotation Pass.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar/LoopRotation.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/LazyBlockFrequencyInfo.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/MemorySSA.h"
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#include "llvm/Analysis/MemorySSAUpdater.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/LoopRotationUtils.h"
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#include "llvm/Transforms/Utils/LoopUtils.h"
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#include <optional>
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using namespace llvm;
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#define DEBUG_TYPE "loop-rotate"
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static cl::opt<unsigned> DefaultRotationThreshold(
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"rotation-max-header-size", cl::init(16), cl::Hidden,
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cl::desc("The default maximum header size for automatic loop rotation"));
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static cl::opt<bool> PrepareForLTOOption(
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"rotation-prepare-for-lto", cl::init(false), cl::Hidden,
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cl::desc("Run loop-rotation in the prepare-for-lto stage. This option "
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"should be used for testing only."));
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// Experimentally allow loop header duplication. This should allow for better
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// optimization at Oz, since loop-idiom recognition can then recognize things
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// like memcpy. If this ends up being useful for many targets, we should drop
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// this flag and make a code generation option that can be controlled
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// independent of the opt level and exposed through the frontend.
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static cl::opt<bool> EnableLoopHeaderDuplicationAtMinSize(
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"enable-loop-header-duplication-at-minsize", cl::init(false), cl::Hidden,
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cl::desc("Enable loop header duplication even for minsize"));
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LoopRotatePass::LoopRotatePass(bool EnableHeaderDuplication, bool PrepareForLTO,
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bool CheckExitCount)
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: EnableHeaderDuplication(EnableHeaderDuplication),
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PrepareForLTO(PrepareForLTO), CheckExitCount(CheckExitCount) {}
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void LoopRotatePass::printPipeline(
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raw_ostream &OS, function_ref<StringRef(StringRef)> MapClassName2PassName) {
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static_cast<PassInfoMixin<LoopRotatePass> *>(this)->printPipeline(
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OS, MapClassName2PassName);
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OS << "<";
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if (!EnableHeaderDuplication)
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OS << "no-";
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OS << "header-duplication;";
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if (!PrepareForLTO)
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OS << "no-";
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OS << "prepare-for-lto;";
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if (!CheckExitCount)
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OS << "no-";
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OS << "check-exit-count";
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OS << ">";
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}
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PreservedAnalyses LoopRotatePass::run(Loop &L, LoopAnalysisManager &AM,
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LoopStandardAnalysisResults &AR,
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LPMUpdater &) {
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// Vectorization requires loop-rotation. Use default threshold for loops the
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// user explicitly marked for vectorization, even when header duplication is
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// disabled.
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int Threshold = EnableHeaderDuplication &&
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(!L.getHeader()->getParent()->hasMinSize() ||
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EnableLoopHeaderDuplicationAtMinSize ||
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hasVectorizeTransformation(&L) == TM_ForcedByUser)
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? DefaultRotationThreshold
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: 0;
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const DataLayout &DL = L.getHeader()->getDataLayout();
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const SimplifyQuery SQ = getBestSimplifyQuery(AR, DL);
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std::optional<MemorySSAUpdater> MSSAU;
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if (AR.MSSA)
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MSSAU = MemorySSAUpdater(AR.MSSA);
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bool Changed =
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LoopRotation(&L, &AR.LI, &AR.TTI, &AR.AC, &AR.DT, &AR.SE,
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MSSAU ? &*MSSAU : nullptr, SQ, false, Threshold, false,
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PrepareForLTO || PrepareForLTOOption, CheckExitCount);
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if (!Changed)
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return PreservedAnalyses::all();
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if (AR.MSSA && VerifyMemorySSA)
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AR.MSSA->verifyMemorySSA();
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auto PA = getLoopPassPreservedAnalyses();
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if (AR.MSSA)
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PA.preserve<MemorySSAAnalysis>();
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return PA;
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}
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