From 0f001a470175b1f06dba8be4b1c077326953922d Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Fri, 21 Apr 2017 19:16:52 +0000
Subject: [PATCH] [InstCombine] use isSubsetOf() for efficiency

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

llvm-svn: 301021
---
 llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index d7e709c9cca1..10faf4786764 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/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;