[SelectionDAG] Use the inlined APInt shift methods since we've already bounds checked the shift.

The version that takes APInt is out of line. The 'unsigned' version optimizes for the common case of single word APInts.

llvm-svn: 319628

1 files changed, 11 insertions, 8 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index b456b74abd3..0b59af2fa10 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2463,27 +2463,30 @@ void SelectionDAG::computeKnownBits(SDValue Op, KnownBits &Known,
   case ISD::SHL:
     if (const APInt *ShAmt = getValidShiftAmountConstant(Op)) {
       computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
-      Known.Zero <<= *ShAmt;
-      Known.One <<= *ShAmt;
+      unsigned Shift = ShAmt->getZExtValue();
+      Known.Zero <<= Shift;
+      Known.One <<= Shift;
       // Low bits are known zero.
-      Known.Zero.setLowBits(ShAmt->getZExtValue());
+      Known.Zero.setLowBits(Shift);
     }
     break;
   case ISD::SRL:
     if (const APInt *ShAmt = getValidShiftAmountConstant(Op)) {
       computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
-      Known.Zero.lshrInPlace(*ShAmt);
-      Known.One.lshrInPlace(*ShAmt);
+      unsigned Shift = ShAmt->getZExtValue();
+      Known.Zero.lshrInPlace(Shift);
+      Known.One.lshrInPlace(Shift);
       // High bits are known zero.
-      Known.Zero.setHighBits(ShAmt->getZExtValue());
+      Known.Zero.setHighBits(Shift);
     }
     break;
   case ISD::SRA:
     if (const APInt *ShAmt = getValidShiftAmountConstant(Op)) {
       computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
+      unsigned Shift = ShAmt->getZExtValue();
       // Sign extend known zero/one bit (else is unknown).
-      Known.Zero.ashrInPlace(*ShAmt);
-      Known.One.ashrInPlace(*ShAmt);
+      Known.Zero.ashrInPlace(Shift);
+      Known.One.ashrInPlace(Shift);
     }
     break;
   case ISD::SIGN_EXTEND_INREG: {