diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp index ea29fca346a..9c16ae417c4 100644 --- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp +++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp @@ -688,11 +688,14 @@ bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep, if (DepSize < MSize) return false; - // Finally, we have to make sure that the dest of the second does not - // alias the source of the first. + Intrinsic::ID ResultFn = Intrinsic::memcpy; + + // If the dest of the second might alias the source of the first, then the + // source and dest might overlap. We still want to eliminate the intermediate + // value, but we have to generate a memmove instead of memcpy. AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); if (!AA.isNoAlias(M->getRawDest(), MSize, MDep->getRawSource(), DepSize)) - return false; + ResultFn = Intrinsic::memmove; // If all checks passed, then we can transform these memcpy's const Type *ArgTys[3] = { @@ -702,7 +705,7 @@ bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep, }; Function *MemCpyFun = Intrinsic::getDeclaration(M->getParent()->getParent()->getParent(), - M->getIntrinsicID(), ArgTys, 3); + ResultFn, ArgTys, 3); // Make sure to use the lesser of the alignment of the source and the dest // since we're changing where we're reading from, but don't want to increase |
