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93054c1e87
Review feedback from r328165. Split out just the one function from the file that's used by Analysis. (As chandlerc pointed out, the original change only moved the header and not the implementation anyway - which was fine for the one function that was used (since it's a template/inlined in the header) but not in general) llvm-svn: 333954
81 lines
2.4 KiB
C++
81 lines
2.4 KiB
C++
//===- FlattenCFGPass.cpp - CFG Flatten Pass ----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements flattening of CFG.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Scalar.h"
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using namespace llvm;
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#define DEBUG_TYPE "flattencfg"
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namespace {
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struct FlattenCFGPass : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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public:
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FlattenCFGPass() : FunctionPass(ID) {
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initializeFlattenCFGPassPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<AAResultsWrapperPass>();
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}
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private:
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AliasAnalysis *AA;
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};
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}
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char FlattenCFGPass::ID = 0;
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INITIALIZE_PASS_BEGIN(FlattenCFGPass, "flattencfg", "Flatten the CFG", false,
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false)
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INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
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INITIALIZE_PASS_END(FlattenCFGPass, "flattencfg", "Flatten the CFG", false,
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false)
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// Public interface to the FlattenCFG pass
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FunctionPass *llvm::createFlattenCFGPass() { return new FlattenCFGPass(); }
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/// iterativelyFlattenCFG - Call FlattenCFG on all the blocks in the function,
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/// iterating until no more changes are made.
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static bool iterativelyFlattenCFG(Function &F, AliasAnalysis *AA) {
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bool Changed = false;
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bool LocalChange = true;
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while (LocalChange) {
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LocalChange = false;
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// Loop over all of the basic blocks and remove them if they are unneeded...
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//
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for (Function::iterator BBIt = F.begin(); BBIt != F.end();) {
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if (FlattenCFG(&*BBIt++, AA)) {
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LocalChange = true;
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}
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}
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Changed |= LocalChange;
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}
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return Changed;
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}
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bool FlattenCFGPass::runOnFunction(Function &F) {
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AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
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bool EverChanged = false;
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// iterativelyFlattenCFG can make some blocks dead.
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while (iterativelyFlattenCFG(F, AA)) {
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removeUnreachableBlocks(F);
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EverChanged = true;
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}
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return EverChanged;
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}
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