Revert the part of 64623 that attempted to align the source in a

memcpy to match the alignment of the destination. It isn't necessary
for making loads and stores handled like the SSE loadu/storeu
intrinsics, and it was causing a performance regression in
MultiSource/Applications/JM/lencod.

The problem appears to have been a memcpy that copies from some
highly aligned array into an alloca; the alloca was then being
assigned a large alignment, which required codegen to perform
dynamic stack-pointer re-alignment, which forced the enclosing
function to have a frame pointer, which led to increased spilling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65289 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index cfd1bac..2b18640 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -9286,7 +9286,7 @@ unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
 
 Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
   unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
-  unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2), DstAlign);
+  unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
   unsigned MinAlign = std::min(DstAlign, SrcAlign);
   unsigned CopyAlign = MI->getAlignment()->getZExtValue();