[llvm] r301021 - [InstCombine] use isSubsetOf() for efficiency

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Fri Apr 21 14:16:52 2017
New Revision: 301021

URL: http://llvm.org/viewvc/llvm-project?rev=301021&view=rev
Log:
[InstCombine] use isSubsetOf() for efficiency

C | ~D == -1
~(C | ~D) == 0
~C & D == 0
D & ~C == 0
D.isSubsetOf(C)


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

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp?rev=301021&r1=301020&r2=301021&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp Fri Apr 21 14:16:52 2017
@@ -282,7 +282,7 @@ Value *InstCombiner::SimplifyDemandedUse
     // combining, SCEV, and codegen.
     const APInt *C;
     if (match(I->getOperand(1), m_APInt(C)) && !C->isAllOnesValue()) {
-      if ((*C | ~DemandedMask).isAllOnesValue()) {
+      if (DemandedMask.isSubsetOf(*C)) {
         // Force bits to 1 to create a 'not' op.
         I->setOperand(1, ConstantInt::getAllOnesValue(VTy));
         return I;