[SelectionDAG] ComputeNumSignBits - use Valid Min/Max shift amount helpers directly...

We are calling getValidShiftAmountConstant first followed by getValidMinimumShiftAmountConstant/getValidMaximumShiftAmountConstant if that failed. But both are used in the same way in ComputeNumSignBits and the Min/Max variants call getValidShiftAmountConstant internally anyhow.

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3cba91a..232b1ea 100644 (file)
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3657,23 +3657,17 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
   case ISD::SRA:
     Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
     // SRA X, C -> adds C sign bits.
-    if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts))
-      Tmp = std::min<uint64_t>(Tmp + ShAmt->getZExtValue(), VTBits);
-    else if (const APInt *ShAmt =
-                 getValidMinimumShiftAmountConstant(Op, DemandedElts))
+    if (const APInt *ShAmt =
+            getValidMinimumShiftAmountConstant(Op, DemandedElts))
       Tmp = std::min<uint64_t>(Tmp + ShAmt->getZExtValue(), VTBits);
     return Tmp;
   case ISD::SHL:
-    if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts)) {
+    if (const APInt *ShAmt =
+            getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
       // shl destroys sign bits, ensure it doesn't shift out all sign bits.
       Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
       if (ShAmt->ult(Tmp))
         return Tmp - ShAmt->getZExtValue();
-    } else if (const APInt *ShAmt =
-                   getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
-      Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
-      if (ShAmt->ult(Tmp))
-        return Tmp - ShAmt->getZExtValue();
     }
     break;
   case ISD::AND: