Add comments about DstAlign and SrcAlign.

llvm-svn: 100132

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index d043ec626a2..e67666d8048 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -5539,6 +5539,13 @@ PPCTargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
   return false;
 }
 
+/// getOptimalMemOpType - Returns the target specific optimal type for load
+/// 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 PPCTargetLowering::getOptimalMemOpType(uint64_t Size,
                                            unsigned DstAlign, unsigned SrcAlign,
                                            bool SafeToUseFP,