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llvm-mirror/lib/CodeGen/LazyMachineBlockFrequencyInfo.cpp
Reid Kleckner 68092989f3 Sink all InitializePasses.h includes
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.

I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
  recompiles    touches affected_files  header
  342380        95      3604    llvm/include/llvm/ADT/STLExtras.h
  314730        234     1345    llvm/include/llvm/InitializePasses.h
  307036        118     2602    llvm/include/llvm/ADT/APInt.h
  213049        59      3611    llvm/include/llvm/Support/MathExtras.h
  170422        47      3626    llvm/include/llvm/Support/Compiler.h
  162225        45      3605    llvm/include/llvm/ADT/Optional.h
  158319        63      2513    llvm/include/llvm/ADT/Triple.h
  140322        39      3598    llvm/include/llvm/ADT/StringRef.h
  137647        59      2333    llvm/include/llvm/Support/Error.h
  131619        73      1803    llvm/include/llvm/Support/FileSystem.h

Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.

Reviewers: bkramer, asbirlea, bollu, jdoerfert

Differential Revision: https://reviews.llvm.org/D70211
2019-11-13 16:34:37 -08:00

98 lines
3.4 KiB
C++

///===- LazyMachineBlockFrequencyInfo.cpp - Lazy Machine Block Frequency --===//
///
/// 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
///
///===---------------------------------------------------------------------===//
/// \file
/// This is an alternative analysis pass to MachineBlockFrequencyInfo. The
/// difference is that with this pass the block frequencies are not computed
/// when the analysis pass is executed but rather when the BFI result is
/// explicitly requested by the analysis client.
///
///===---------------------------------------------------------------------===//
#include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
#define DEBUG_TYPE "lazy-machine-block-freq"
INITIALIZE_PASS_BEGIN(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
"Lazy Machine Block Frequency Analysis", true, true)
INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_END(LazyMachineBlockFrequencyInfoPass, DEBUG_TYPE,
"Lazy Machine Block Frequency Analysis", true, true)
char LazyMachineBlockFrequencyInfoPass::ID = 0;
LazyMachineBlockFrequencyInfoPass::LazyMachineBlockFrequencyInfoPass()
: MachineFunctionPass(ID) {
initializeLazyMachineBlockFrequencyInfoPassPass(
*PassRegistry::getPassRegistry());
}
void LazyMachineBlockFrequencyInfoPass::print(raw_ostream &OS,
const Module *M) const {
getBFI().print(OS, M);
}
void LazyMachineBlockFrequencyInfoPass::getAnalysisUsage(
AnalysisUsage &AU) const {
AU.addRequired<MachineBranchProbabilityInfo>();
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
void LazyMachineBlockFrequencyInfoPass::releaseMemory() {
OwnedMBFI.reset();
OwnedMLI.reset();
OwnedMDT.reset();
}
MachineBlockFrequencyInfo &
LazyMachineBlockFrequencyInfoPass::calculateIfNotAvailable() const {
auto *MBFI = getAnalysisIfAvailable<MachineBlockFrequencyInfo>();
if (MBFI) {
LLVM_DEBUG(dbgs() << "MachineBlockFrequencyInfo is available\n");
return *MBFI;
}
auto &MBPI = getAnalysis<MachineBranchProbabilityInfo>();
auto *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
auto *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
LLVM_DEBUG(dbgs() << "Building MachineBlockFrequencyInfo on the fly\n");
LLVM_DEBUG(if (MLI) dbgs() << "LoopInfo is available\n");
if (!MLI) {
LLVM_DEBUG(dbgs() << "Building LoopInfo on the fly\n");
// First create a dominator tree.
LLVM_DEBUG(if (MDT) dbgs() << "DominatorTree is available\n");
if (!MDT) {
LLVM_DEBUG(dbgs() << "Building DominatorTree on the fly\n");
OwnedMDT = std::make_unique<MachineDominatorTree>();
OwnedMDT->getBase().recalculate(*MF);
MDT = OwnedMDT.get();
}
// Generate LoopInfo from it.
OwnedMLI = std::make_unique<MachineLoopInfo>();
OwnedMLI->getBase().analyze(MDT->getBase());
MLI = OwnedMLI.get();
}
OwnedMBFI = std::make_unique<MachineBlockFrequencyInfo>();
OwnedMBFI->calculate(*MF, MBPI, *MLI);
return *OwnedMBFI.get();
}
bool LazyMachineBlockFrequencyInfoPass::runOnMachineFunction(
MachineFunction &F) {
MF = &F;
return false;
}