Fix a PPC rlwimi instruction-selection bug
Under certain (evidently rare) circumstances, this code used to convert OR(a,
AND(x, y)) into OR(a, x). This was incorrect.
While there, I've added a comment to the code immediately above.
llvm-svn: 185201
diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 35f4b7c..f8d990c 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -447,10 +447,10 @@
unsigned SHOpc = Op1.getOperand(0).getOpcode();
if ((SHOpc == ISD::SHL || SHOpc == ISD::SRL) &&
isInt32Immediate(Op1.getOperand(0).getOperand(1), Value)) {
+ // Note that Value must be in range here (less than 32) because
+ // otherwise there would not be any bits set in InsertMask.
Op1 = Op1.getOperand(0).getOperand(0);
SH = (SHOpc == ISD::SHL) ? Value : 32 - Value;
- } else {
- Op1 = Op1.getOperand(0);
}
}