On Thu, Jul 20, 2017 at 08:59:29AM +0200, Martin Liška wrote:
> Hello.
>
> Following patch does sharing of expansion for mem{p,}cpy and also strpcy
> (with a known constant as source)
> so that we use same type of expansion (direct insns emission, direct emission
> with a loop instruction and
> library call). As mentioned in the PR, glibc does not provide an optimized
> version for majority of targets.
>
> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
This broke e.g.
FAIL: gcc.dg/20050503-1.c scan-assembler-not call
on i686-linux, the result is significantly worse.
Also, while perhaps majority of targets don't provide optimized version,
some targets do, including i?86/x86_64, and if the memcpy would be expanded
as a call, it is much better to just emit mempcpy call instead.
Just look at the testcase, because of this misoptimization we suddenly can't
use a tail call.
Jakub
