[Power9] Disable removing extra swaps on P9.

On power 8 we sometimes insert swaps to deal with the difference between
Little-Endian and Big-Endian. The swap removal pass is supposed to clean up
these swaps. On power 9 we don't need this pass since we do not need to insert
the swaps in the first place.

Commiting on behalf of Stefan Pintilie.
Differential Revision: https://reviews.llvm.org/D34627

llvm-svn: 307185

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp b/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
index 491eaf326a5..7d34efd4af3 100644
--- a/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
+++ b/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
@@ -195,8 +195,10 @@ public:
       return false;
 
     // If we don't have VSX on the subtarget, don't do anything.
+    // Also, on Power 9 the load and store ops preserve element order and so
+    // the swaps are not required.
     const PPCSubtarget &STI = MF.getSubtarget<PPCSubtarget>();
-    if (!STI.hasVSX())
+    if (!STI.hasVSX() || !STI.needsSwapsForVSXMemOps())
       return false;
 
     bool Changed = false;