commit fc947bcfba2fc8bc9cc4f8750d1d74c5bf24ee08
author Craig Topper <craig.topper@gmail.com> Tue Apr 18 17:14:21 2017 +0000
committer Craig Topper <craig.topper@gmail.com> Tue Apr 18 17:14:21 2017 +0000
tree 725abbf8e51f075df0b067b5c735c54e9471ae0e
parent ec9deb7f548a7d045ce630308e2d2c84cd3087b9

[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

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 69484f4..7ed999f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -839,7 +839,8 @@
     // Length bits.
     if (CI0) {
       APInt Elt = CI0->getValue();
-      Elt = Elt.lshr(Index).zextOrTrunc(Length);
+      Elt.lshrInPlace(Index);
+      Elt = Elt.zextOrTrunc(Length);
       return LowConstantHighUndef(Elt.getZExtValue());
     }
 
@@ -1036,7 +1037,7 @@
     // The PD variants uses bit 1 to select per-lane element index, so
     // shift down to convert to generic shuffle mask index.
     if (IsPD)
-      Index = Index.lshr(1);
+      Index.lshrInPlace(1);
 
     // The _256 variants are a bit trickier since the mask bits always index
     // into the corresponding 128 half. In order to convert to a generic

llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 9aa679c..cb6145c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -370,7 +370,7 @@
         MaskV <<= Op1C->getZExtValue();
       else {
         assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
-        MaskV = MaskV.lshr(Op1C->getZExtValue());
+        MaskV.lshrInPlace(Op1C->getZExtValue());
       }
 
       // shift1 & 0x00FF

llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp

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 @@
                                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 @@
       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.