From: Sanjay Patel <spatel@rotateright.com>
Date: Fri, 21 Apr 2017 19:16:52 +0000 (+0000)
Subject: [InstCombine] use isSubsetOf() for efficiency
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=39af0db425b756e9c641c5ec4e9ba03d964655e1;p=llvm

[InstCombine] use isSubsetOf() for efficiency

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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301021 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index d7e709c9cca..10faf478676 100644
--- a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -282,7 +282,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     // 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;