[PATCH] D60426: [InstCombine] prevent possible miscompile with negate+sdiv of vector op

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/test/Transforms/InstCombine/div.ll:820
 ;
   %div = sdiv <2 x i8> %x, <i8 -1, i8 1>
   %neg = sub <2 x i8> zeroinitializer, %div
----------------
spatel wrote:
> lebedev.ri wrote:
> > Could also add a test for SINT_MIN (yes, i have seen the next test here)
> Do you mean a splat of SINT_MIN (that's above here) or something else?
I actually initially misread `@negate_sdiv_vec_signed_min_elt`, i thought it was:
```
define <2 x i8> @negate_sdiv_vec_signed_min_and_one_elt(<2 x i8> %x) {
  %div = sdiv <2 x i8> %x, <i8 1, i8 -128>
  %neg = sub <2 x i8> zeroinitializer, %div
  ret <2 x i8> %neg
}
```
and i was going to suggest to add the test that is already in `@negate_sdiv_vec_signed_min_elt`.
So now i guess i'd suggest maybe adding test from this comment.


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  https://reviews.llvm.org/D60426/new/

https://reviews.llvm.org/D60426