[X86] SimplifyDemandedBitsForTargetNode - cleanup SSE shift-by-immediate handlers. NFC.

Cleanup the SHLI/SRLI/SRAI handlers to be more consistent - prep for a future patch.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -43375,8 +43375,9 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
   }
   case X86ISD::VSHLI: {
     SDValue Op0 = Op.getOperand(0);
+    SDValue Op1 = Op.getOperand(1);
 
-    unsigned ShAmt = Op.getConstantOperandVal(1);
+    unsigned ShAmt = Op1->getAsZExtVal();
     if (ShAmt >= BitWidth)
       break;
 
@@ -43420,14 +43421,17 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
     return false;
   }
   case X86ISD::VSRLI: {
-    unsigned ShAmt = Op.getConstantOperandVal(1);
+    SDValue Op0 = Op.getOperand(0);
+    SDValue Op1 = Op.getOperand(1);
+
+    unsigned ShAmt = Op1->getAsZExtVal();
     if (ShAmt >= BitWidth)
       break;
 
     APInt DemandedMask = OriginalDemandedBits << ShAmt;
 
-    if (SimplifyDemandedBits(Op.getOperand(0), DemandedMask,
-                             OriginalDemandedElts, Known, TLO, Depth + 1))
+    if (SimplifyDemandedBits(Op0, DemandedMask, OriginalDemandedElts, Known,
+                             TLO, Depth + 1))
       return true;
 
     Known.Zero.lshrInPlace(ShAmt);
@@ -43452,8 +43456,7 @@ bool X86TargetLowering::SimplifyDemandedBitsForTargetNode(
       return TLO.CombineTo(Op, Op0);
 
     // fold (VSRAI (VSHLI X, C1), C1) --> X iff NumSignBits(X) > C1
-    if (Op0.getOpcode() == X86ISD::VSHLI &&
-        Op.getOperand(1) == Op0.getOperand(1)) {
+    if (Op0.getOpcode() == X86ISD::VSHLI && Op1 == Op0.getOperand(1)) {
       SDValue Op00 = Op0.getOperand(0);
       unsigned NumSignBits =
           TLO.DAG.ComputeNumSignBits(Op00, OriginalDemandedElts);