Roman Lebedev 5a663bd77a [InstSimplify] Fix addo/subo undef folds (PR42209) ...

Fix folds of addo and subo with an undef operand to be:

`@llvm.{u,s}{add,sub}.with.overflow` all fold to `{ undef, false }`,
 as per LLVM undef rules.
Same for commuted variants.

Based on the original version of the patch by @nikic.

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42209 | PR42209 ]]

Differential Revision: https://reviews.llvm.org/D63065

llvm-svn: 363522

2019-06-16 20:39:45 +00:00

200 KiB

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