MFhead @ r292618

1 files changed, 5 insertions, 0 deletions

diff --git a/contrib/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/contrib/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index bf6e402..d4e666c 100644
--- a/contrib/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/contrib/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -309,6 +309,11 @@ PPCInstrInfo::commuteInstruction(MachineInstr *MI, bool NewMI) const {
   unsigned MB = MI->getOperand(4).getImm();
   unsigned ME = MI->getOperand(5).getImm();
 
+  // We can't commute a trivial mask (there is no way to represent an all-zero
+  // mask).
+  if (MB == 0 && ME == 31)
+    return nullptr;
+
   if (NewMI) {
     // Create a new instruction.
     unsigned Reg0 = ChangeReg0 ? Reg2 : MI->getOperand(0).getReg();