[llvm] r356549 - [X86] Use getConstantOperandAPInt to detect out-of-range shifts.

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Wed Mar 20 04:41:52 2019
New Revision: 356549

URL: http://llvm.org/viewvc/llvm-project?rev=356549&view=rev
Log:
[X86] Use getConstantOperandAPInt to detect out-of-range shifts.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=356549&r1=356548&r2=356549&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Mar 20 04:41:52 2019
@@ -41161,11 +41161,12 @@ static SDValue combineCMP(SDNode *N, Sel
       onlyZeroFlagUsed(SDValue(N, 0))) {
     EVT VT = Op.getValueType();
     unsigned BitWidth = VT.getSizeInBits();
-    unsigned ShAmt = Op.getConstantOperandVal(1);
-    if (ShAmt < BitWidth) { // Avoid undefined shifts.
+    const APInt &ShAmt = Op.getConstantOperandAPInt(1);
+    if (ShAmt.ult(BitWidth)) { // Avoid undefined shifts.
+      unsigned MaskBits = BitWidth - ShAmt.getZExtValue();
       APInt Mask = Op.getOpcode() == ISD::SRL
-                       ? APInt::getHighBitsSet(BitWidth, BitWidth - ShAmt)
-                       : APInt::getLowBitsSet(BitWidth, BitWidth - ShAmt);
+                       ? APInt::getHighBitsSet(BitWidth, MaskBits)
+                       : APInt::getLowBitsSet(BitWidth, MaskBits);
       if (Mask.isSignedIntN(32)) {
         Op = DAG.getNode(ISD::AND, dl, VT, Op.getOperand(0),
                          DAG.getConstant(Mask, dl, VT));
@@ -41175,7 +41176,6 @@ static SDValue combineCMP(SDNode *N, Sel
     }
   }
 
-
   // Look for a truncate with a single use.
   if (Op.getOpcode() != ISD::TRUNCATE || !Op.hasOneUse())
     return SDValue();