PPCDAGToDAGISel::isRunOfOnes should return false on zero
This fixes a bug (found by csmith) at -O0 where we attempt to create a RLWIMI
with an out-of-range operand. Most uses of the isRunOfOnes function are guarded
by a condition that the value is not zero. This was not true in two places, and
in both places a zero input would result in an out-of-rage MB value (= 32).
To fix this, isRunOfOnes returns false on a zero input (and I've remove one
now-redundant guard).
llvm-svn: 186101
diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 901d369..475bde1 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -330,6 +330,9 @@
}
bool PPCDAGToDAGISel::isRunOfOnes(unsigned Val, unsigned &MB, unsigned &ME) {
+ if (!Val)
+ return false;
+
if (isShiftedMask_32(Val)) {
// look for the first non-zero bit
MB = countLeadingZeros(Val);
@@ -435,7 +438,7 @@
}
unsigned MB, ME;
- if (InsertMask && isRunOfOnes(InsertMask, MB, ME)) {
+ if (isRunOfOnes(InsertMask, MB, ME)) {
SDValue Tmp1, Tmp2;
if ((Op1Opc == ISD::SHL || Op1Opc == ISD::SRL) &&