//===- LoopUnrollPass.h -----------------------------------------*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_SCALAR_LOOPUNROLLPASS_H
#define LLVM_TRANSFORMS_SCALAR_LOOPUNROLLPASS_H
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Support/CommandLine.h"
#include <optional>
namespace llvm {
extern cl::opt<bool> ForgetSCEVInLoopUnroll;
class Function;
class Loop;
class LPMUpdater;
/// Loop unroll pass that only does full loop unrolling and peeling.
class LoopFullUnrollPass : public PassInfoMixin<LoopFullUnrollPass> {
const int OptLevel;
/// If false, use a cost model to determine whether unrolling of a loop is
/// profitable. If true, only loops that explicitly request unrolling via
/// metadata are considered. All other loops are skipped.
const bool OnlyWhenForced;
/// If true, forget all loops when unrolling. If false, forget top-most loop
/// of the currently processed loops, which removes one entry at a time from
/// the internal SCEV records. For large loops, the former is faster.
const bool ForgetSCEV;
public:
explicit LoopFullUnrollPass(int OptLevel = 2, bool OnlyWhenForced = false,
bool ForgetSCEV = false)
: OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced),
ForgetSCEV(ForgetSCEV) {}
PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
LoopStandardAnalysisResults &AR, LPMUpdater &U);
};
/// A set of parameters used to control various transforms performed by the
/// LoopUnroll pass. Each of the boolean parameters can be set to:
/// true - enabling the transformation.
/// false - disabling the transformation.
/// None - relying on a global default.
///
/// There is also OptLevel parameter, which is used for additional loop unroll
/// tuning.
///
/// Intended use is to create a default object, modify parameters with
/// additional setters and then pass it to LoopUnrollPass.
///
struct LoopUnrollOptions {
std::optional<bool> AllowPartial;
std::optional<bool> AllowPeeling;
std::optional<bool> AllowRuntime;
std::optional<bool> AllowUpperBound;
std::optional<bool> AllowProfileBasedPeeling;
std::optional<unsigned> FullUnrollMaxCount;
int OptLevel;
/// If false, use a cost model to determine whether unrolling of a loop is
/// profitable. If true, only loops that explicitly request unrolling via
/// metadata are considered. All other loops are skipped.
bool OnlyWhenForced;
/// If true, forget all loops when unrolling. If false, forget top-most loop
/// of the currently processed loops, which removes one entry at a time from
/// the internal SCEV records. For large loops, the former is faster.
const bool ForgetSCEV;
LoopUnrollOptions(int OptLevel = 2, bool OnlyWhenForced = false,
bool ForgetSCEV = false)
: OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced),
ForgetSCEV(ForgetSCEV) {}
/// Enables or disables partial unrolling. When disabled only full unrolling
/// is allowed.
LoopUnrollOptions &setPartial(bool Partial) {
AllowPartial = Partial;
return *this;
}
/// Enables or disables unrolling of loops with runtime trip count.
LoopUnrollOptions &setRuntime(bool Runtime) {
AllowRuntime = Runtime;
return *this;
}
/// Enables or disables loop peeling.
LoopUnrollOptions &setPeeling(bool Peeling) {
AllowPeeling = Peeling;
return *this;
}
/// Enables or disables the use of trip count upper bound
/// in loop unrolling.
LoopUnrollOptions &setUpperBound(bool UpperBound) {
AllowUpperBound = UpperBound;
return *this;
}
// Sets "optimization level" tuning parameter for loop unrolling.
LoopUnrollOptions &setOptLevel(int O) {
OptLevel = O;
return *this;
}
// Enables or disables loop peeling basing on profile.
LoopUnrollOptions &setProfileBasedPeeling(int O) {
AllowProfileBasedPeeling = O;
return *this;
}
// Sets the max full unroll count.
LoopUnrollOptions &setFullUnrollMaxCount(unsigned O) {
FullUnrollMaxCount = O;
return *this;
}
};
/// Loop unroll pass that will support both full and partial unrolling.
/// It is a function pass to have access to function and module analyses.
/// It will also put loops into canonical form (simplified and LCSSA).
class LoopUnrollPass : public PassInfoMixin<LoopUnrollPass> {
LoopUnrollOptions UnrollOpts;
public:
/// This uses the target information (or flags) to control the thresholds for
/// different unrolling stategies but supports all of them.
explicit LoopUnrollPass(LoopUnrollOptions UnrollOpts = {})
: UnrollOpts(UnrollOpts) {}
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
void printPipeline(raw_ostream &OS,
function_ref<StringRef(StringRef)> MapClassName2PassName);
};
} // end namespace llvm
#endif // LLVM_TRANSFORMS_SCALAR_LOOPUNROLLPASS_H