[llvm] r313792 - [InstCombine] Use APInt::getActiveBits() to avoid creating an APInt from a trailing zero count to do a comparison. NFCI

[Craig Topper via llvm-commits]

Author: ctopper
Date: Wed Sep 20 11:49:29 2017
New Revision: 313792

URL: http://llvm.org/viewvc/llvm-project?rev=313792&view=rev
Log:
[InstCombine] Use APInt::getActiveBits() to avoid creating an APInt from a trailing zero count to do a comparison. NFCI

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=313792&r1=313791&r2=313792&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Wed Sep 20 11:49:29 2017
@@ -1718,7 +1718,7 @@ Instruction *InstCombiner::foldICmpAndCo
   // result greater than C1.
   unsigned NumTZ = C2->countTrailingZeros();
   if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && NumTZ < C2->getBitWidth() &&
-      APInt::getOneBitSet(C2->getBitWidth(), NumTZ).ugt(*C1)) {
+      NumTZ >= C1->getActiveBits()) {
     Constant *Zero = Constant::getNullValue(And->getType());
     return new ICmpInst(ICmpInst::ICMP_NE, And, Zero);
   }