llvm/lib/CodeGen/MachineOptimizationRemarkEmitter.cpp
Brian Gesiak e3305284e8 [ORE] Add diagnostics hotness threshold
Summary:
Add an option to prevent diagnostics that do not meet a minimum hotness
threshold from being output. When generating optimization remarks for
large codebases with a ton of cold code paths, this option can be used
to limit the optimization remark output at a reasonable size. Discussion of
this change can be read here:
http://lists.llvm.org/pipermail/llvm-dev/2017-June/114377.html

Reviewers: anemet, davidxl, hfinkel

Reviewed By: anemet

Subscribers: qcolombet, javed.absar, fhahn, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D34867

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306912 91177308-0d34-0410-b5e6-96231b3b80d8
2017-06-30 23:14:53 +00:00

109 lines
3.6 KiB
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///===- MachineOptimizationRemarkEmitter.cpp - Opt Diagnostic -*- C++ -*---===//
///
/// The LLVM Compiler Infrastructure
///
/// This file is distributed under the University of Illinois Open Source
/// License. See LICENSE.TXT for details.
///
///===---------------------------------------------------------------------===//
/// \file
/// Optimization diagnostic interfaces for machine passes. It's packaged as an
/// analysis pass so that by using this service passes become dependent on MBFI
/// as well. MBFI is used to compute the "hotness" of the diagnostic message.
///
///===---------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
#include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/LLVMContext.h"
using namespace llvm;
DiagnosticInfoMIROptimization::MachineArgument::MachineArgument(
StringRef MKey, const MachineInstr &MI)
: Argument() {
Key = MKey;
raw_string_ostream OS(Val);
MI.print(OS, /*SkipOpers=*/false, /*SkipDebugLoc=*/true);
}
Optional<uint64_t>
MachineOptimizationRemarkEmitter::computeHotness(const MachineBasicBlock &MBB) {
if (!MBFI)
return None;
return MBFI->getBlockProfileCount(&MBB);
}
void MachineOptimizationRemarkEmitter::computeHotness(
DiagnosticInfoMIROptimization &Remark) {
const MachineBasicBlock *MBB = Remark.getBlock();
if (MBB)
Remark.setHotness(computeHotness(*MBB));
}
void MachineOptimizationRemarkEmitter::emit(
DiagnosticInfoOptimizationBase &OptDiagCommon) {
auto &OptDiag = cast<DiagnosticInfoMIROptimization>(OptDiagCommon);
computeHotness(OptDiag);
LLVMContext &Ctx = MF.getFunction()->getContext();
// If a diagnostic has a hotness value, then only emit it if its hotness
// meets the threshold.
if (OptDiag.getHotness() &&
*OptDiag.getHotness() < Ctx.getDiagnosticsHotnessThreshold()) {
return;
}
yaml::Output *Out = Ctx.getDiagnosticsOutputFile();
if (Out) {
auto *P = &const_cast<DiagnosticInfoOptimizationBase &>(OptDiagCommon);
*Out << P;
}
// FIXME: now that IsVerbose is part of DI, filtering for this will be moved
// from here to clang.
if (!OptDiag.isVerbose() || shouldEmitVerbose())
Ctx.diagnose(OptDiag);
}
MachineOptimizationRemarkEmitterPass::MachineOptimizationRemarkEmitterPass()
: MachineFunctionPass(ID) {
initializeMachineOptimizationRemarkEmitterPassPass(
*PassRegistry::getPassRegistry());
}
bool MachineOptimizationRemarkEmitterPass::runOnMachineFunction(
MachineFunction &MF) {
MachineBlockFrequencyInfo *MBFI;
if (MF.getFunction()->getContext().getDiagnosticsHotnessRequested())
MBFI = &getAnalysis<LazyMachineBlockFrequencyInfoPass>().getBFI();
else
MBFI = nullptr;
ORE = llvm::make_unique<MachineOptimizationRemarkEmitter>(MF, MBFI);
return false;
}
void MachineOptimizationRemarkEmitterPass::getAnalysisUsage(
AnalysisUsage &AU) const {
AU.addRequired<LazyMachineBlockFrequencyInfoPass>();
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
char MachineOptimizationRemarkEmitterPass::ID = 0;
static const char ore_name[] = "Machine Optimization Remark Emitter";
#define ORE_NAME "machine-opt-remark-emitter"
INITIALIZE_PASS_BEGIN(MachineOptimizationRemarkEmitterPass, ORE_NAME, ore_name,
false, true)
INITIALIZE_PASS_DEPENDENCY(LazyMachineBlockFrequencyInfoPass)
INITIALIZE_PASS_END(MachineOptimizationRemarkEmitterPass, ORE_NAME, ore_name,
false, true)