optimize ~(~X >>s Y) --> (X >>s Y), patch by Edmund Grimley

Evans!

llvm-svn: 93884

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index af300fc3577..fa7bb12ff21 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1751,6 +1751,11 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
             return BinaryOperator::CreateOr(NotX, NotY);
           return BinaryOperator::CreateAnd(NotX, NotY);
         }
+
+      } else if (Op0I->getOpcode() == Instruction::AShr) {
+        // ~(~X >>s Y) --> (X >>s Y)
+        if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0)))
+          return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1));
       }
     }
   }