[llvm] r307185 - [Power9] Disable removing extra swaps on P9.

[Sean Fertile via llvm-commits]

Author: sfertile
Date: Wed Jul  5 11:37:10 2017
New Revision: 307185

URL: http://llvm.org/viewvc/llvm-project?rev=307185&view=rev
Log:
[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

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp

Modified: llvm/trunk/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp?rev=307185&r1=307184&r2=307185&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp Wed Jul  5 11:37:10 2017
@@ -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;