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f785676f2a
all of the features in the current working draft of the upcoming C++ standard, provisionally named C++1y. The code generator's performance is greatly increased, and the loop auto-vectorizer is now enabled at -Os and -O2 in addition to -O3. The PowerPC backend has made several major improvements to code generation quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ backends have all seen major feature work. Release notes for llvm and clang can be found here: <http://llvm.org/releases/3.4/docs/ReleaseNotes.html> <http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html> MFC after: 1 month
79 lines
2.3 KiB
C++
79 lines
2.3 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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#define DEBUG_TYPE "flattencfg"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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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);
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void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<AliasAnalysis>();
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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_AG_DEPENDENCY(AliasAnalysis)
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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<AliasAnalysis>();
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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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