[PATCH] D115670: Correct behavior of Vector boolean-operations, implement vector operator-

[Craig Topper via Phabricator via cfe-commits]

craig.topper added inline comments.


================
Comment at: clang/lib/AST/ExprConstant.cpp:2915
   case BO_EQ:
-    Result = (LHSValue == RHSValue);
+    Result = -(LHSValue == RHSValue);
     break;
----------------
erichkeane wrote:
> efriedma wrote:
> > Using "operator=" to assign an int to an APInt is going to lead to weird/confusing results.  For example, I think this produces the wrong result if you have an int128_t vector.
> Can you clarify your comment? The result type of one of these compare-ops is either an i8 or an i32 I think, so I would expect it to 'just work', right?  
> 
> What problem of operator= on an APInt gives the wrong result?  I guess I've never seen/don't know how to repro what you mean.
> 
> I DID try to get a test wtih a 'compare op' on an __int128 vector, but that ends up asserting in GetSignedVectorType
Don't compare ops produce a result with the same number of bits as the input? If the compare is a vector of int128 the result should also be a vector of int128. APInt::operator= takes a uint64_t as input and will zero extend it to 128 bits. I think we want to sign extend here.

I assume the APInt for result already been given its bit width before this call?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115670/new/

https://reviews.llvm.org/D115670