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llvm-mirror/lib/IR/PseudoProbe.cpp
Hongtao Yu 7fbb587058 [CSSPGO] Undoing the concept of dangling pseudo probe
As a follow-up to https://reviews.llvm.org/D104129, I'm cleaning up the danling probe related code in both the compiler and llvm-profgen.

I'm seeing a 5% size win for the pseudo_probe section for SPEC2017 and 10% for Ciner. Certain benchmark such as 602.gcc has a 20% size win. No obvious difference seen on build time for SPEC2017 and Cinder.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D104477
2021-06-18 15:14:11 -07:00

110 lines
4.1 KiB
C++

//===- PseudoProbe.cpp - Pseudo Probe Helpers -----------------------------===//
//
// 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 implements the helpers to manipulate pseudo probe IR intrinsic
// calls.
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/PseudoProbe.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include <unordered_set>
using namespace llvm;
namespace llvm {
Optional<PseudoProbe> extractProbeFromDiscriminator(const Instruction &Inst) {
assert(isa<CallBase>(&Inst) && !isa<IntrinsicInst>(&Inst) &&
"Only call instructions should have pseudo probe encodes as their "
"Dwarf discriminators");
if (const DebugLoc &DLoc = Inst.getDebugLoc()) {
const DILocation *DIL = DLoc;
auto Discriminator = DIL->getDiscriminator();
if (DILocation::isPseudoProbeDiscriminator(Discriminator)) {
PseudoProbe Probe;
Probe.Id =
PseudoProbeDwarfDiscriminator::extractProbeIndex(Discriminator);
Probe.Type =
PseudoProbeDwarfDiscriminator::extractProbeType(Discriminator);
Probe.Attr =
PseudoProbeDwarfDiscriminator::extractProbeAttributes(Discriminator);
Probe.Factor =
PseudoProbeDwarfDiscriminator::extractProbeFactor(Discriminator) /
(float)PseudoProbeDwarfDiscriminator::FullDistributionFactor;
return Probe;
}
}
return None;
}
Optional<PseudoProbe> extractProbe(const Instruction &Inst) {
if (const auto *II = dyn_cast<PseudoProbeInst>(&Inst)) {
PseudoProbe Probe;
Probe.Id = II->getIndex()->getZExtValue();
Probe.Type = (uint32_t)PseudoProbeType::Block;
Probe.Attr = II->getAttributes()->getZExtValue();
Probe.Factor = II->getFactor()->getZExtValue() /
(float)PseudoProbeFullDistributionFactor;
return Probe;
}
if (isa<CallBase>(&Inst) && !isa<IntrinsicInst>(&Inst))
return extractProbeFromDiscriminator(Inst);
return None;
}
void setProbeDistributionFactor(Instruction &Inst, float Factor) {
assert(Factor >= 0 && Factor <= 1 &&
"Distribution factor must be in [0, 1.0]");
if (auto *II = dyn_cast<PseudoProbeInst>(&Inst)) {
IRBuilder<> Builder(&Inst);
uint64_t IntFactor = PseudoProbeFullDistributionFactor;
if (Factor < 1)
IntFactor *= Factor;
auto OrigFactor = II->getFactor()->getZExtValue();
if (IntFactor != OrigFactor)
II->replaceUsesOfWith(II->getFactor(), Builder.getInt64(IntFactor));
} else if (isa<CallBase>(&Inst) && !isa<IntrinsicInst>(&Inst)) {
if (const DebugLoc &DLoc = Inst.getDebugLoc()) {
const DILocation *DIL = DLoc;
auto Discriminator = DIL->getDiscriminator();
if (DILocation::isPseudoProbeDiscriminator(Discriminator)) {
auto Index =
PseudoProbeDwarfDiscriminator::extractProbeIndex(Discriminator);
auto Type =
PseudoProbeDwarfDiscriminator::extractProbeType(Discriminator);
auto Attr = PseudoProbeDwarfDiscriminator::extractProbeAttributes(
Discriminator);
// Round small factors to 0 to avoid over-counting.
uint32_t IntFactor =
PseudoProbeDwarfDiscriminator::FullDistributionFactor;
if (Factor < 1)
IntFactor *= Factor;
uint32_t V = PseudoProbeDwarfDiscriminator::packProbeData(
Index, Type, Attr, IntFactor);
DIL = DIL->cloneWithDiscriminator(V);
Inst.setDebugLoc(DIL);
}
}
}
}
void addPseudoProbeAttribute(PseudoProbeInst &Inst,
PseudoProbeAttributes Attr) {
IRBuilder<> Builder(&Inst);
uint32_t OldAttr = Inst.getAttributes()->getZExtValue();
uint32_t NewAttr = OldAttr | (uint32_t)Attr;
if (OldAttr != NewAttr)
Inst.replaceUsesOfWith(Inst.getAttributes(), Builder.getInt32(NewAttr));
}
} // namespace llvm