[PowerPC] Compute the MMO offset for an unaligned load with signed arithmetic
If you compute the MMO offset using unsigned arithmetic, you end up with a
large positive offset instead of a small negative one. In theory, this could
cause bad instruction-scheduling decisions later.
I noticed this by inspection from the debug output, and using that for the
regression test is the best I can do right now.
llvm-svn: 246805
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 40a80d6..116ecb4 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -10302,7 +10302,8 @@
// original unaligned load.
MachineFunction &MF = DAG.getMachineFunction();
MachineMemOperand *BaseMMO =
- MF.getMachineMemOperand(LD->getMemOperand(), -MemVT.getStoreSize()+1,
+ MF.getMachineMemOperand(LD->getMemOperand(),
+ -(long)MemVT.getStoreSize()+1,
2*MemVT.getStoreSize()-1);
// Create the new base load.