llvm-project/polly/lib/Transform/CodePreparation.cpp
Reid Kleckner 05da2fe521 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

121 lines
3.7 KiB
C++

//===---- CodePreparation.cpp - Code preparation for Scop Detection -------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// The Polly code preparation pass is executed before SCoP detection. Its
// currently only splits the entry block of the SCoP to make room for alloc
// instructions as they are generated during code generation.
//
// XXX: In the future, we should remove the need for this pass entirely and
// instead add this spitting to the code generation pass.
//
//===----------------------------------------------------------------------===//
#include "polly/CodePreparation.h"
#include "polly/LinkAllPasses.h"
#include "polly/Support/ScopHelper.h"
#include "llvm/Analysis/DominanceFrontier.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
using namespace polly;
namespace {
/// Prepare the IR for the scop detection.
///
class CodePreparation : public FunctionPass {
CodePreparation(const CodePreparation &) = delete;
const CodePreparation &operator=(const CodePreparation &) = delete;
LoopInfo *LI;
ScalarEvolution *SE;
void clear();
public:
static char ID;
explicit CodePreparation() : FunctionPass(ID) {}
~CodePreparation();
/// @name FunctionPass interface.
//@{
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual void releaseMemory();
virtual bool runOnFunction(Function &F);
virtual void print(raw_ostream &OS, const Module *) const;
//@}
};
} // namespace
PreservedAnalyses CodePreparationPass::run(Function &F,
FunctionAnalysisManager &FAM) {
// Find first non-alloca instruction. Every basic block has a non-alloca
// instruction, as every well formed basic block has a terminator.
auto &EntryBlock = F.getEntryBlock();
BasicBlock::iterator I = EntryBlock.begin();
while (isa<AllocaInst>(I))
++I;
auto &DT = FAM.getResult<DominatorTreeAnalysis>(F);
auto &LI = FAM.getResult<LoopAnalysis>(F);
// splitBlock updates DT, LI and RI.
splitEntryBlockForAlloca(&EntryBlock, &DT, &LI, nullptr);
PreservedAnalyses PA;
PA.preserve<DominatorTreeAnalysis>();
PA.preserve<LoopAnalysis>();
return PA;
}
void CodePreparation::clear() {}
CodePreparation::~CodePreparation() { clear(); }
void CodePreparation::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LoopInfoWrapperPass>();
AU.addRequired<ScalarEvolutionWrapperPass>();
AU.addPreserved<LoopInfoWrapperPass>();
AU.addPreserved<RegionInfoPass>();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<DominanceFrontierWrapperPass>();
}
bool CodePreparation::runOnFunction(Function &F) {
if (skipFunction(F))
return false;
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
splitEntryBlockForAlloca(&F.getEntryBlock(), this);
return true;
}
void CodePreparation::releaseMemory() { clear(); }
void CodePreparation::print(raw_ostream &OS, const Module *) const {}
char CodePreparation::ID = 0;
char &polly::CodePreparationID = CodePreparation::ID;
Pass *polly::createCodePreparationPass() { return new CodePreparation(); }
INITIALIZE_PASS_BEGIN(CodePreparation, "polly-prepare",
"Polly - Prepare code for polly", false, false)
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_END(CodePreparation, "polly-prepare",
"Polly - Prepare code for polly", false, false)