diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 7cbd617a2e..11fa336c7b 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -476,7 +476,8 @@ uint32_t ValueTable::lookup_or_add(Value* V) { if (CallInst* C = dyn_cast<CallInst>(V)) { if (C->getCalledFunction() && - AA->doesNotAccessMemory(C->getCalledFunction())) { + (AA->doesNotAccessMemory(C->getCalledFunction()) || + AA->onlyReadsMemory(C->getCalledFunction()))) { Expression e = create_expression(C); DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e); @@ -1038,6 +1039,22 @@ bool GVN::processInstruction(Instruction* I, } else if (currAvail.test(num)) { Value* repl = find_leader(currAvail, num); + if (CallInst* CI = dyn_cast<CallInst>(I)) { + AliasAnalysis& AA = getAnalysis<AliasAnalysis>(); + if (CI->getCalledFunction() && + !AA.doesNotAccessMemory(CI->getCalledFunction())) { + MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>(); + if (MD.getDependency(CI) != MD.getDependency(cast<CallInst>(repl))) { + // There must be an intervening may-alias store, so nothing from + // this point on will be able to be replaced with the preceding call + currAvail.erase(repl); + currAvail.insert(I); + + return false; + } + } + } + VN.erase(I); I->replaceAllUsesWith(repl); toErase.push_back(I); |