Revert "Add the nsw flag when we detect that an add will not signed overflow."

This reverts commit r210029.

It was not correctly handling cases where LHS and RHS had multiple but different
sign bits.

llvm-svn: 210048

1 files changed, 0 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 4d8a1efd64e..c37a9cf2ef9 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1191,11 +1191,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
       return BinaryOperator::CreateOr(A, B);
   }
 
-  if (!I.hasNoSignedWrap() && WillNotOverflowSignedAdd(LHS, RHS)) {
-    Changed = true;
-    I.setHasNoSignedWrap(true);
-  }
-
   return Changed ? &I : nullptr;
 }