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055646cac9
moved before another instruction. Summary:Added an API to check if an instruction can be safely moved before another instruction. In future PRs, we will like to add support of moving instructions between blocks that are not control flow equivalent, and add other APIs to enhance usability, e.g. moving basic blocks, moving list of instructions... Loop Fusion will be its first user. When there is intervening code in between two loops, fusion is currently unable to fuse them. Loop Fusion can use this utility to check if the intervening code can be safely moved before or after the two loops, and move them, then it can successfully fuse them. Reviewer:kbarton,jdoerfert,Meinersbur,bmahjour,etiotto Reviewed By:bmahjour Subscribers:mgorny,hiraditya,llvm-commits Tag:LLVM Differential Revision:https://reviews.llvm.org/D70049
114 lines
3.6 KiB
C++
114 lines
3.6 KiB
C++
//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the post-dominator construction algorithms.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/PostDominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "postdomtree"
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#ifdef EXPENSIVE_CHECKS
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static constexpr bool ExpensiveChecksEnabled = true;
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#else
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static constexpr bool ExpensiveChecksEnabled = false;
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#endif
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//===----------------------------------------------------------------------===//
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// PostDominatorTree Implementation
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//===----------------------------------------------------------------------===//
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char PostDominatorTreeWrapperPass::ID = 0;
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PostDominatorTreeWrapperPass::PostDominatorTreeWrapperPass()
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: FunctionPass(ID) {
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initializePostDominatorTreeWrapperPassPass(*PassRegistry::getPassRegistry());
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}
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INITIALIZE_PASS(PostDominatorTreeWrapperPass, "postdomtree",
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"Post-Dominator Tree Construction", true, true)
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bool PostDominatorTree::invalidate(Function &F, const PreservedAnalyses &PA,
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FunctionAnalysisManager::Invalidator &) {
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// Check whether the analysis, all analyses on functions, or the function's
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// CFG have been preserved.
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auto PAC = PA.getChecker<PostDominatorTreeAnalysis>();
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return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
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PAC.preservedSet<CFGAnalyses>());
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}
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bool PostDominatorTree::dominates(const Instruction *I1,
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const Instruction *I2) const {
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assert(I1 && I2 && "Expecting valid I1 and I2");
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const BasicBlock *BB1 = I1->getParent();
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const BasicBlock *BB2 = I2->getParent();
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if (BB1 != BB2)
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return Base::dominates(BB1, BB2);
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// PHINodes in a block are unordered.
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if (isa<PHINode>(I1) && isa<PHINode>(I2))
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return false;
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// Loop through the basic block until we find I1 or I2.
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BasicBlock::const_iterator I = BB1->begin();
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for (; &*I != I1 && &*I != I2; ++I)
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/*empty*/;
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return &*I == I2;
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}
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bool PostDominatorTreeWrapperPass::runOnFunction(Function &F) {
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DT.recalculate(F);
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return false;
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}
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void PostDominatorTreeWrapperPass::verifyAnalysis() const {
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if (VerifyDomInfo)
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assert(DT.verify(PostDominatorTree::VerificationLevel::Full));
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else if (ExpensiveChecksEnabled)
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assert(DT.verify(PostDominatorTree::VerificationLevel::Basic));
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}
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void PostDominatorTreeWrapperPass::print(raw_ostream &OS, const Module *) const {
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DT.print(OS);
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}
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FunctionPass* llvm::createPostDomTree() {
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return new PostDominatorTreeWrapperPass();
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}
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AnalysisKey PostDominatorTreeAnalysis::Key;
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PostDominatorTree PostDominatorTreeAnalysis::run(Function &F,
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FunctionAnalysisManager &) {
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PostDominatorTree PDT(F);
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return PDT;
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}
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PostDominatorTreePrinterPass::PostDominatorTreePrinterPass(raw_ostream &OS)
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: OS(OS) {}
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PreservedAnalyses
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PostDominatorTreePrinterPass::run(Function &F, FunctionAnalysisManager &AM) {
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OS << "PostDominatorTree for function: " << F.getName() << "\n";
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AM.getResult<PostDominatorTreeAnalysis>(F).print(OS);
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return PreservedAnalyses::all();
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}
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