llvm-project/llvm/lib/Analysis/DominanceFrontier.cpp

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//===- DominanceFrontier.cpp - Dominance Frontier Calculation -------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/DominanceFrontier.h"
#include "llvm/Analysis/DominanceFrontierImpl.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace llvm {
template class DominanceFrontierBase<BasicBlock, false>;
template class DominanceFrontierBase<BasicBlock, true>;
template class ForwardDominanceFrontierBase<BasicBlock>;
} // end namespace llvm
char DominanceFrontierWrapperPass::ID = 0;
INITIALIZE_PASS_BEGIN(DominanceFrontierWrapperPass, "domfrontier",
"Dominance Frontier Construction", true, true)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_END(DominanceFrontierWrapperPass, "domfrontier",
"Dominance Frontier Construction", true, true)
DominanceFrontierWrapperPass::DominanceFrontierWrapperPass()
: FunctionPass(ID), DF() {
initializeDominanceFrontierWrapperPassPass(*PassRegistry::getPassRegistry());
}
void DominanceFrontierWrapperPass::releaseMemory() {
DF.releaseMemory();
}
bool DominanceFrontierWrapperPass::runOnFunction(Function &) {
releaseMemory();
DF.analyze(getAnalysis<DominatorTreeWrapperPass>().getDomTree());
return false;
}
void DominanceFrontierWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<DominatorTreeWrapperPass>();
}
void DominanceFrontierWrapperPass::print(raw_ostream &OS, const Module *) const {
DF.print(OS);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void DominanceFrontierWrapperPass::dump() const {
print(dbgs());
}
#endif
/// Handle invalidation explicitly.
bool DominanceFrontier::invalidate(Function &F, const PreservedAnalyses &PA,
FunctionAnalysisManager::Invalidator &) {
// Check whether the analysis, all analyses on functions, or the function's
// CFG have been preserved.
auto PAC = PA.getChecker<DominanceFrontierAnalysis>();
return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
PAC.preservedSet<CFGAnalyses>());
}
[PM] Change the static object whose address is used to uniquely identify analyses to have a common type which is enforced rather than using a char object and a `void *` type when used as an identifier. This has a number of advantages. First, it at least helps some of the confusion raised in Justin Lebar's code review of why `void *` was being used everywhere by having a stronger type that connects to documentation about this. However, perhaps more importantly, it addresses a serious issue where the alignment of these pointer-like identifiers was unknown. This made it hard to use them in pointer-like data structures. We were already dodging this in dangerous ways to create the "all analyses" entry. In a subsequent patch I attempted to use these with TinyPtrVector and things fell apart in a very bad way. And it isn't just a compile time or type system issue. Worse than that, the actual alignment of these pointer-like opaque identifiers wasn't guaranteed to be a useful alignment as they were just characters. This change introduces a type to use as the "key" object whose address forms the opaque identifier. This both forces the objects to have proper alignment, and provides type checking that we get it right everywhere. It also makes the types somewhat less mysterious than `void *`. We could go one step further and introduce a truly opaque pointer-like type to return from the `ID()` static function rather than returning `AnalysisKey *`, but that didn't seem to be a clear win so this is just the initial change to get to a reliably typed and aligned object serving is a key for all the analyses. Thanks to Richard Smith and Justin Lebar for helping pick plausible names and avoid making this refactoring many times. =] And thanks to Sean for the super fast review! While here, I've tried to move away from the "PassID" nomenclature entirely as it wasn't really helping and is overloaded with old pass manager constructs. Now we have IDs for analyses, and key objects whose address can be used as IDs. Where possible and clear I've shortened this to just "ID". In a few places I kept "AnalysisID" to make it clear what was being identified. Differential Revision: https://reviews.llvm.org/D27031 llvm-svn: 287783
2016-11-24 01:53:26 +08:00
AnalysisKey DominanceFrontierAnalysis::Key;
DominanceFrontier DominanceFrontierAnalysis::run(Function &F,
FunctionAnalysisManager &AM) {
DominanceFrontier DF;
DF.analyze(AM.getResult<DominatorTreeAnalysis>(F));
return DF;
}
DominanceFrontierPrinterPass::DominanceFrontierPrinterPass(raw_ostream &OS)
: OS(OS) {}
PreservedAnalyses
DominanceFrontierPrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
OS << "DominanceFrontier for function: " << F.getName() << "\n";
AM.getResult<DominanceFrontierAnalysis>(F).print(OS);
return PreservedAnalyses::all();
}