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//===- OptimizationRemarkEmitter.h - Optimization Diagnostic ----*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Optimization diagnostic interfaces. It's packaged as an analysis pass so
// that by using this service passes become dependent on BFI as well. BFI is
// used to compute the "hotness" of the diagnostic message.
#include "llvm/ADT/Optional.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
namespace llvm {
class DebugLoc;
class Loop;
class Pass;
class Twine;
class Value;
/// The optimization diagnostic interface.
/// It allows reporting when optimizations are performed and when they are not
/// along with the reasons for it. Hotness information of the corresponding
/// code region can be included in the remark if DiagnosticsHotnessRequested is
/// enabled in the LLVM context.
class OptimizationRemarkEmitter {
OptimizationRemarkEmitter(const Function *F, BlockFrequencyInfo *BFI)
: F(F), BFI(BFI) {}
/// This variant can be used to generate ORE on demand (without the
/// analysis pass).
/// Note that this ctor has a very different cost depending on whether
/// F->getContext().getDiagnosticsHotnessRequested() is on or not. If it's off
/// the operation is free.
/// Whereas if DiagnosticsHotnessRequested is on, it is fairly expensive
/// operation since BFI and all its required analyses are computed. This is
/// for example useful for CGSCC passes that can't use function analyses
/// passes in the old PM.
OptimizationRemarkEmitter(const Function *F);
OptimizationRemarkEmitter(OptimizationRemarkEmitter &&Arg)
: F(Arg.F), BFI(Arg.BFI) {}
OptimizationRemarkEmitter &operator=(OptimizationRemarkEmitter &&RHS) {
F = RHS.F;
return *this;
/// Handle invalidation events in the new pass manager.
bool invalidate(Function &F, const PreservedAnalyses &PA,
FunctionAnalysisManager::Invalidator &Inv);
/// Output the remark via the diagnostic handler and to the
/// optimization record file.
void emit(DiagnosticInfoOptimizationBase &OptDiag);
/// Take a lambda that returns a remark which will be emitted. Second
/// argument is only used to restrict this to functions.
template <typename T>
void emit(T RemarkBuilder, decltype(RemarkBuilder()) * = nullptr) {
// Avoid building the remark unless we know there are at least *some*
// remarks enabled. We can't currently check whether remarks are requested
// for the calling pass since that requires actually building the remark.
if (F->getContext().getDiagnosticsOutputFile() ||
F->getContext().getDiagHandlerPtr()->isAnyRemarkEnabled()) {
auto R = RemarkBuilder();
emit((DiagnosticInfoOptimizationBase &)R);
/// Whether we allow for extra compile-time budget to perform more
/// analysis to produce fewer false positives.
/// This is useful when reporting missed optimizations. In this case we can
/// use the extra analysis (1) to filter trivial false positives or (2) to
/// provide more context so that non-trivial false positives can be quickly
/// detected by the user.
bool allowExtraAnalysis(StringRef PassName) const {
return (F->getContext().getDiagnosticsOutputFile() ||
const Function *F;
BlockFrequencyInfo *BFI;
/// If we generate BFI on demand, we need to free it when ORE is freed.
std::unique_ptr<BlockFrequencyInfo> OwnedBFI;
/// Compute hotness from IR value (currently assumed to be a block) if PGO is
/// available.
Optional<uint64_t> computeHotness(const Value *V);
/// Similar but use value from \p OptDiag and update hotness there.
void computeHotness(DiagnosticInfoIROptimization &OptDiag);
/// Only allow verbose messages if we know we're filtering by hotness
/// (BFI is only set in this case).
bool shouldEmitVerbose() { return BFI != nullptr; }
OptimizationRemarkEmitter(const OptimizationRemarkEmitter &) = delete;
void operator=(const OptimizationRemarkEmitter &) = delete;
/// Add a small namespace to avoid name clashes with the classes used in
/// the streaming interface. We want these to be short for better
/// write/readability.
namespace ore {
using NV = DiagnosticInfoOptimizationBase::Argument;
using setIsVerbose = DiagnosticInfoOptimizationBase::setIsVerbose;
using setExtraArgs = DiagnosticInfoOptimizationBase::setExtraArgs;
/// OptimizationRemarkEmitter legacy analysis pass
/// Note that this pass shouldn't generally be marked as preserved by other
/// passes. It's holding onto BFI, so if the pass does not preserve BFI, BFI
/// could be freed.
class OptimizationRemarkEmitterWrapperPass : public FunctionPass {
std::unique_ptr<OptimizationRemarkEmitter> ORE;
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
OptimizationRemarkEmitter &getORE() {
assert(ORE && "pass not run yet");
return *ORE;
static char ID;
class OptimizationRemarkEmitterAnalysis
: public AnalysisInfoMixin<OptimizationRemarkEmitterAnalysis> {
friend AnalysisInfoMixin<OptimizationRemarkEmitterAnalysis>;
static AnalysisKey Key;
/// Provide the result typedef for this analysis pass.
typedef OptimizationRemarkEmitter Result;
/// Run the analysis pass over a function and produce BFI.
Result run(Function &F, FunctionAnalysisManager &AM);