On 07/06/2018 06:08 AM, Christophe Lyon wrote:
> Hi Jeff,
>
> On Fri, 6 Jul 2018 at 05:44, Jeff Law <l...@redhat.com> wrote:
>>
>> As noted in BZ 86010 we can be more aggressive when trimming tails of
>> mem* or str* calls in gimple DSE since trimming a tail doesn't affect
>> alignment and residuals are usually handled pretty efficiently in libc.
>>
>> Additionally, if the total number of live bytes left is smaller than a
>> word, then it's highly likely we'll open-code the mem* or str* routine.
>> So we allow more aggressive trimming in that case too.
>>
>> What's left to be able to close out 86010 is to identify when a memory
>> store could be merged with a subsequent memset. I'm skeptical of the
>> importance of that optimization, though perhaps it comes up often enough
>> with structure initializations to be worth doing.
>>
>> Bootstrapped and regression tested on x86_64-linux-gnu. Installing on
>> the trunk.
>>
>
> This is causing a regression on arm and i686:
> gcc.dg/tree-ssa/pr30375.c: pattern found 0 times
> FAIL: gcc.dg/tree-ssa/pr30375.c scan-tree-dump-times dse1
> "MEM\\[\\(struct _s \\*\\)&signInfo \\+ [0-9]+B\\] = {}" 1
>
>> Jeff
Thanks. I'm on it.
jeff
