If we're changing the source of a memcpy we need to use the alignment

of the source, not the original alignment since it may no longer
be valid.

Fixes rdar://8400094


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114781 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher 2010-09-25 00:57:26 +00:00
parent 576a3968a2
commit c69a000470

View File

@ -697,14 +697,16 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) {
M->getParent()->getParent()->getParent(),
M->getIntrinsicID(), ArgTys, 3);
// Make sure to use the alignment of the source since we're changing the
// location we're reading from.
// TODO: Is this worth it if we're creating a less aligned memcpy? For
// example we could be moving from movaps -> movq on x86.
Value *Args[5] = {
M->getRawDest(), MDep->getRawSource(), M->getLength(),
M->getAlignmentCst(), M->getVolatileCst()
MDep->getAlignmentCst(), M->getVolatileCst()
};
CallInst *C = CallInst::Create(MemCpyFun, Args, Args+5, "", M);
// If C and M don't interfere, then this is a valid transformation. If they
// did, this would mean that the two sources overlap, which would be bad.
if (MD.getDependency(C) == dep) {