On Fri, Oct 31, 2014 at 12:19 PM, Marek Polacek-3 [via gcc]
<ml-node+s1065356n1085049...@n5.nabble.com> wrote:
> On Thu, Oct 30, 2014 at 07:47:52PM +0100, Marek Polacek wrote:
>
>> This patch tries to optimize away redundant UBSAN_NULL checks.
>> It walks the statements, looks for UBSAN_NULL calls and keeps
>> track of pointers and statements checking that pointer in a
>> hash map. Now, if we can prove that some UBSAN_NULL stmt is
>> dominated by other one which requires the same or less strict
>> alignment, there's no point in keeping this check around and
>> expanding it.
>>
>> optimize_checks should be enhanced to handle other {ub,a,t}san
>> checks as well - which is what I'm going to work on next.
>
> (Strike this version. I'm working on a variant that walks the dominator
> tree first to get better optimizations.)
Just curious how much speedup did you get from this? I've tried
similar optimizations and got pitiful 3% speedup.
-Y
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