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Diffstat (limited to 'lib/Transforms/Scalar/EarlyCSE.cpp')
-rw-r--r-- | lib/Transforms/Scalar/EarlyCSE.cpp | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/EarlyCSE.cpp b/lib/Transforms/Scalar/EarlyCSE.cpp new file mode 100644 index 0000000000..4445404f6c --- /dev/null +++ b/lib/Transforms/Scalar/EarlyCSE.cpp @@ -0,0 +1,62 @@ +//===- EarlyCSE.cpp - Simple and fast CSE pass ----------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass performs a simple dominator tree walk that eliminates trivially +// redundant instructions. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "early-cse" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Pass.h" +using namespace llvm; + +namespace { +/// EarlyCSE - This pass does a simple depth-first walk over the dominator +/// tree, eliminating trivially redundant instructions and using instsimplify +/// to canonicalize things as it goes. It is intended to be fast and catch +/// obvious cases so that instcombine and other passes are more effective. It +/// is expected that a later pass of GVN will catch the interesting/hard +/// cases. +class EarlyCSE : public FunctionPass { +public: + static char ID; + explicit EarlyCSE() + : FunctionPass(ID) { + initializeEarlyCSEPass(*PassRegistry::getPassRegistry()); + } + + bool runOnFunction(Function &F); + +private: + // This transformation requires dominator postdominator info + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired<DominatorTree>(); + AU.setPreservesCFG(); + } +}; +} + +char EarlyCSE::ID = 0; + +// createEarlyCSEPass - The public interface to this file. +FunctionPass *llvm::createEarlyCSEPass() { + return new EarlyCSE(); +} + +INITIALIZE_PASS_BEGIN(EarlyCSE, "early-cse", "Early CSE", false, false) +INITIALIZE_PASS_DEPENDENCY(DominatorTree) +INITIALIZE_PASS_END(EarlyCSE, "early-cse", "Early CSE", false, false) + +bool EarlyCSE::runOnFunction(Function &F) { + DominatorTree &DT = getAnalysis<DominatorTree>(); + (void)DT; + return false; +} |