Displaying 2 results from an estimated 2 matches for "31633_".
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31633
2017 May 26
3
Poison/Undef at CodeGen level Was: [poison] is select-of-select to logic+select allowed?
...gt; Just because there’s no explicit poison in SDAG, just having nsw is
>> sufficient to cause miscompilations when combined with other
>> transformations.
>> See, for example, this bug report for InstCombine regarding
>> select+nsw:_https://bugs.llvm.org/show_bug.cgi?id=31633_
>
> Poison/Undef at the CodeGen level is a very interesting discussion! I
> don't think there is any documentation about posion/undef at the
> CodeGen level and I haven't discussed this much with others, so I'd
> like to hear further feedback:
>
> - I think we sh...
2017 May 23
6
[poison] is select-of-select to logic+select allowed?
Regarding the patches, there are two concerns AFAICT:
1. It’s a new instruction and as usual when introducing a new instruction it will require work for some time until most optimizations know about it, and to get rid of any potential perf regression. No big deal; we just need to do the work (and we have already done some of it).
2. The patch was written by a student, which may not have time to