diff options
-rw-r--r-- | include/llvm/LinkAllPasses.h | 1 | ||||
-rw-r--r-- | include/llvm/Transforms/Scalar.h | 5 | ||||
-rw-r--r-- | lib/Transforms/Scalar/MarkModRef.cpp | 69 |
3 files changed, 75 insertions, 0 deletions
diff --git a/include/llvm/LinkAllPasses.h b/include/llvm/LinkAllPasses.h index aabebf7..9e82e67 100644 --- a/include/llvm/LinkAllPasses.h +++ b/include/llvm/LinkAllPasses.h @@ -85,6 +85,7 @@ namespace { (void) llvm::createLowerInvokePass(); (void) llvm::createLowerSetJmpPass(); (void) llvm::createLowerSwitchPass(); + (void) llvm::createMarkModRefPass(); (void) llvm::createNoAAPass(); (void) llvm::createNoProfileInfoPass(); (void) llvm::createProfileLoaderPass(); diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h index 8799a6f..3cd4a5c 100644 --- a/include/llvm/Transforms/Scalar.h +++ b/include/llvm/Transforms/Scalar.h @@ -137,6 +137,11 @@ LoopPass *createLoopRotatePass(); // LoopPass *createLoopIndexSplitPass(); +//===----------------------------------------------------------------------===// +// +// MarkModRef - This pass marks functions readnone/readonly. +// +FunctionPass *createMarkModRefPass(); //===----------------------------------------------------------------------===// // diff --git a/lib/Transforms/Scalar/MarkModRef.cpp b/lib/Transforms/Scalar/MarkModRef.cpp new file mode 100644 index 0000000..e20278a --- /dev/null +++ b/lib/Transforms/Scalar/MarkModRef.cpp @@ -0,0 +1,69 @@ +//===--------- MarkModRef.cpp - Mark functions readnone/readonly ----------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass marks functions readnone/readonly based on the results of alias +// analysis. This requires a sufficiently powerful alias analysis, such as +// GlobalsModRef (invoke as "opt ... -globalsmodref-aa -markmodref ..."). +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "markmodref" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Function.h" +#include "llvm/Pass.h" +using namespace llvm; + +STATISTIC(NumReadNone, "Number of functions marked readnone"); +STATISTIC(NumReadOnly, "Number of functions marked readonly"); + +namespace { + struct VISIBILITY_HIDDEN MarkModRef : public FunctionPass { + static char ID; // Pass identification, replacement for typeid + MarkModRef() : FunctionPass((intptr_t)&ID) {} + + bool runOnFunction(Function &F); + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesCFG(); + AU.addRequired<AliasAnalysis>(); + AU.addPreserved<AliasAnalysis>(); + } + }; +} + +char MarkModRef::ID = 0; +static RegisterPass<MarkModRef> +X("markmodref", "Mark functions readnone/readonly"); + +bool MarkModRef::runOnFunction(Function &F) { + // FIXME: Wrong for functions with weak linkage. + if (F.doesNotAccessMemory()) + // Cannot do better. + return false; + + AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); + AliasAnalysis::ModRefBehavior ModRef = AA.getModRefBehavior(&F); + if (ModRef == AliasAnalysis::DoesNotAccessMemory) { + F.setDoesNotAccessMemory(); + NumReadNone++; + return true; + } else if (ModRef == AliasAnalysis::OnlyReadsMemory && !F.onlyReadsMemory()) { + F.setOnlyReadsMemory(); + NumReadOnly++; + return true; + } + return false; +} + +FunctionPass *llvm::createMarkModRefPass() { + return new MarkModRef(); +} |