Re: PATCH: fine-tuning for can_store_by_pieces

[Sandra Loosemore <sandra@codesourcery.com>]

Andrew Pinski wrote:
> On 8/15/07, Sandra Loosemore <sandra@codesourcery.com> wrote:
>> On MIPS we can get better code by having can_store_by_pieces differentiate
>> between the cases where it's used for memset operations, and those where it's
>> used to copy a string constant.  This patch introduces new SET_RATIO and
>> SET_BY_PIECES_P macros, with appropriate defaults to preserve the existing
>> behavior.  I checked other targets and made the ones that override the default
>> STORE_BY_PIECES_P clone the same definition for SET_BY_PIECES_P.
> 
> Are you sure that the cause of the real issue here is not really PR
> 31150?  

I don't think so.  Nigel originally developed this patch against gcc 3.4; I just 
verified that it still does something useful for current mainline.

> I don't think copying string constants and memcpy/memset
> should be different in terms of heuristics.
> 
> It seems if you gave a testcase where this is profitable, it would be
> better to judge this patch (and maybe a testcase for the testsuite
> also).

I'll see if I can come up with something specific, or perhaps Nigel has a test case.

-Sandra