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//===- llvm/Transforms/Utils/UnrollLoop.h - Unrolling utilities -*- 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 file defines some loop unrolling utilities. It does not define any
// actual pass or policy, but provides a single function to perform loop
// unrolling.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H
#define LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Support/InstructionCost.h"
namespace llvm {
class AssumptionCache;
class AAResults;
class BasicBlock;
class BlockFrequencyInfo;
class DependenceInfo;
class DominatorTree;
class Loop;
class LoopInfo;
class MDNode;
class ProfileSummaryInfo;
class OptimizationRemarkEmitter;
class ScalarEvolution;
class StringRef;
class Value;
using NewLoopsMap = SmallDenseMap<const Loop *, Loop *, 4>;
/// @{
/// Metadata attribute names
const char *const LLVMLoopUnrollFollowupAll = "llvm.loop.unroll.followup_all";
const char *const LLVMLoopUnrollFollowupUnrolled =
"llvm.loop.unroll.followup_unrolled";
const char *const LLVMLoopUnrollFollowupRemainder =
"llvm.loop.unroll.followup_remainder";
/// @}
const Loop* addClonedBlockToLoopInfo(BasicBlock *OriginalBB,
BasicBlock *ClonedBB, LoopInfo *LI,
NewLoopsMap &NewLoops);
/// Represents the result of a \c UnrollLoop invocation.
enum class LoopUnrollResult {
/// The loop was not modified.
Unmodified,
/// The loop was partially unrolled -- we still have a loop, but with a
/// smaller trip count. We may also have emitted epilogue loop if the loop
/// had a non-constant trip count.
PartiallyUnrolled,
/// The loop was fully unrolled into straight-line code. We no longer have
/// any back-edges.
FullyUnrolled
};
struct UnrollLoopOptions {
unsigned Count;
bool Force;
bool Runtime;
bool AllowExpensiveTripCount;
bool UnrollRemainder;
bool ForgetAllSCEV;
const Instruction *Heart = nullptr;
};
LoopUnrollResult UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
ScalarEvolution *SE, DominatorTree *DT,
AssumptionCache *AC,
const llvm::TargetTransformInfo *TTI,
OptimizationRemarkEmitter *ORE, bool PreserveLCSSA,
Loop **RemainderLoop = nullptr,
AAResults *AA = nullptr);
bool UnrollRuntimeLoopRemainder(
Loop *L, unsigned Count, bool AllowExpensiveTripCount,
bool UseEpilogRemainder, bool UnrollRemainder, bool ForgetAllSCEV,
LoopInfo *LI, ScalarEvolution *SE, DominatorTree *DT, AssumptionCache *AC,
const TargetTransformInfo *TTI, bool PreserveLCSSA,
Loop **ResultLoop = nullptr);
LoopUnrollResult UnrollAndJamLoop(Loop *L, unsigned Count, unsigned TripCount,
unsigned TripMultiple, bool UnrollRemainder,
LoopInfo *LI, ScalarEvolution *SE,
DominatorTree *DT, AssumptionCache *AC,
const TargetTransformInfo *TTI,
OptimizationRemarkEmitter *ORE,
Loop **EpilogueLoop = nullptr);
bool isSafeToUnrollAndJam(Loop *L, ScalarEvolution &SE, DominatorTree &DT,
DependenceInfo &DI, LoopInfo &LI);
void simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
ScalarEvolution *SE, DominatorTree *DT,
AssumptionCache *AC,
const TargetTransformInfo *TTI,
AAResults *AA = nullptr);
MDNode *GetUnrollMetadata(MDNode *LoopID, StringRef Name);
TargetTransformInfo::UnrollingPreferences gatherUnrollingPreferences(
Loop *L, ScalarEvolution &SE, const TargetTransformInfo &TTI,
BlockFrequencyInfo *BFI, ProfileSummaryInfo *PSI,
llvm::OptimizationRemarkEmitter &ORE, int OptLevel,
std::optional<unsigned> UserThreshold, std::optional<unsigned> UserCount,
std::optional<bool> UserAllowPartial, std::optional<bool> UserRuntime,
std::optional<bool> UserUpperBound,
std::optional<unsigned> UserFullUnrollMaxCount);
/// Produce an estimate of the unrolled cost of the specified loop. This
/// is used to a) produce a cost estimate for partial unrolling and b) to
/// cheaply estimate cost for full unrolling when we don't want to symbolically
/// evaluate all iterations.
class UnrollCostEstimator {
InstructionCost LoopSize;
bool NotDuplicatable;
public:
unsigned NumInlineCandidates;
ConvergenceKind Convergence;
bool ConvergenceAllowsRuntime;
UnrollCostEstimator(const Loop *L, const TargetTransformInfo &TTI,
const SmallPtrSetImpl<const Value *> &EphValues,
unsigned BEInsns);
/// Whether it is legal to unroll this loop.
bool canUnroll() const;
uint64_t getRolledLoopSize() const { return *LoopSize.getValue(); }
/// Returns loop size estimation for unrolled loop, given the unrolling
/// configuration specified by UP.
uint64_t
getUnrolledLoopSize(const TargetTransformInfo::UnrollingPreferences &UP,
unsigned CountOverwrite = 0) const;
};
bool computeUnrollCount(Loop *L, const TargetTransformInfo &TTI,
DominatorTree &DT, LoopInfo *LI, AssumptionCache *AC,
ScalarEvolution &SE,
const SmallPtrSetImpl<const Value *> &EphValues,
OptimizationRemarkEmitter *ORE, unsigned TripCount,
unsigned MaxTripCount, bool MaxOrZero,
unsigned TripMultiple, const UnrollCostEstimator &UCE,
TargetTransformInfo::UnrollingPreferences &UP,
TargetTransformInfo::PeelingPreferences &PP,
bool &UseUpperBound);
} // end namespace llvm
#endif // LLVM_TRANSFORMS_UTILS_UNROLLLOOP_H
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