[llvm-dev] Missed strlen optimizations

[Dávid Bolvanský via llvm-dev]

Is:


2018-04-20 18:07 GMT+02:00 Dávid Bolvanský <david.bolvansky at gmail.com>:

> Hello,
>
> Code: https://godbolt.org/g/EG4Wi6
>
> unsigned fff3(void) {
>     char buf[10] = "";
>     return strlen(buf);
> }
>
> Since we are memset-ing before strlen call, we could replace strlen with
> just 0.
>
> Has LLVM any API to get "last instruction before strlen" which modifies
> strlen argument "buf"? So we can check "yes, it is memset there, replace
> strlen with zero" ?
>
>
> Thanks
>
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