Fix a recent regression. ClrOpcode is not set for i8; for i8, if
we want to clear %ah to zero before a division, just use a
zero-extending mov to %al. This fixes PR3366.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62691 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 9b42d00..c1d886c 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -1381,9 +1381,10 @@
SDValue Tmp0, Tmp1, Tmp2, Tmp3;
bool foldedLoad = TryFoldLoad(N, N1, Tmp0, Tmp1, Tmp2, Tmp3);
+ bool signBitIsZero = CurDAG->SignBitIsZero(N0);
SDValue InFlag;
- if (NVT == MVT::i8 && !isSigned) {
+ if (NVT == MVT::i8 && (!isSigned || signBitIsZero)) {
// Special case for div8, just use a move with zero extension to AX to
// clear the upper 8 bits (AH).
SDValue Tmp0, Tmp1, Tmp2, Tmp3, Move, Chain;
@@ -1405,7 +1406,7 @@
InFlag =
CurDAG->getCopyToReg(CurDAG->getEntryNode(),
LoReg, N0, SDValue()).getValue(1);
- if (isSigned && !CurDAG->SignBitIsZero(N0)) {
+ if (isSigned && !signBitIsZero) {
// Sign extend the low part into the high part.
InFlag =
SDValue(CurDAG->getTargetNode(SExtOpcode, MVT::Flag, InFlag), 0);