Add comments about DstAlign and SrcAlign.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100132 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 3 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 5d6e571..11d6ec1 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1070,9 +1070,12 @@ unsigned X86TargetLowering::getByValTypeAlignment(const Type *Ty) const {
 }
 
 /// getOptimalMemOpType - Returns the target specific optimal type for load
-/// and store operations as a result of memset, memcpy, and memmove
-/// lowering. It returns MVT::iAny if SelectionDAG should be responsible for
-/// determining it.
+/// and store operations as a result of memset, memcpy, and memmove lowering.
+/// If DstAlign is zero that means it's safe to destination alignment can
+/// satisfy any constraint. Similarly if SrcAlign is zero it means there
+/// isn't a need to check it against alignment requirement, probably because
+/// the source does not need to be loaded. It returns EVT::Other if
+/// SelectionDAG should be responsible for determining it.
 EVT
 X86TargetLowering::getOptimalMemOpType(uint64_t Size,
                                        unsigned DstAlign, unsigned SrcAlign,