[APInt] Use lshrInPlace to replace lshr where possible

This patch uses lshrInPlace to replace code where the object that lshr is called on is being overwritten with the result.

This adds an lshrInPlace(const APInt &) version as well.

Differential Revision: https://reviews.llvm.org/D32155

llvm-svn: 300566

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 9cd19ee..2f66bc7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -546,8 +546,8 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
                                Depth + 1))
         return I;
       assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
-      KnownZero = KnownZero.lshr(ShiftAmt);
-      KnownOne  = KnownOne.lshr(ShiftAmt);
+      KnownZero.lshrInPlace(ShiftAmt);
+      KnownOne.lshrInPlace(ShiftAmt);
       if (ShiftAmt)
         KnownZero.setHighBits(ShiftAmt);  // high bits known zero.
     }
@@ -590,13 +590,13 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
       assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
       // Compute the new bits that are at the top now.
       APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
-      KnownZero = KnownZero.lshr(ShiftAmt);
-      KnownOne  = KnownOne.lshr(ShiftAmt);
+      KnownZero.lshrInPlace(ShiftAmt);
+      KnownOne.lshrInPlace(ShiftAmt);
 
       // Handle the sign bits.
       APInt SignBit(APInt::getSignBit(BitWidth));
       // Adjust to where it is now in the mask.
-      SignBit = SignBit.lshr(ShiftAmt);
+      SignBit.lshrInPlace(ShiftAmt);
 
       // If the input sign bit is known to be zero, or if none of the top bits
       // are demanded, turn this into an unsigned shift right.