[PATCH] Make mempcpy more optimal (PR middle-end/70140).

[H.J. Lu]

On Wed, Jul 19, 2017 at 11:59 PM, Martin Liška <mliska@suse.cz> 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.
>
> Ready to be installed?
> Martin
>
> gcc/testsuite/ChangeLog:
>
> 2017-07-17  Martin Liska  <mliska@suse.cz>
>
>         PR middle-end/70140
>         * gcc.dg/string-opt-1.c: Adjust test-case to scan for memcpy.
>
> gcc/ChangeLog:
>
> 2017-07-17  Martin Liska  <mliska@suse.cz>
>
>         PR middle-end/70140
>         * builtins.c (expand_builtin_memcpy_args): Remove.
>         (expand_builtin_memcpy): Call newly added function
>         expand_builtin_memory_copy_args.
>         (expand_builtin_memcpy_with_bounds): Likewise.
>         (expand_builtin_mempcpy): Remove last argument.
>         (expand_builtin_mempcpy_with_bounds): Likewise.
>         (expand_builtin_memory_copy_args): New function created from
>         expand_builtin_mempcpy_args with small modifications.
>         (expand_builtin_mempcpy_args): Remove.
>         (expand_builtin_stpcpy): Remove unused argument.
>         (expand_builtin): Likewise.
>         (expand_builtin_with_bounds): Likewise.
> ---
>  gcc/builtins.c                      | 268 ++++++++++++++----------------------
>  gcc/testsuite/gcc.dg/string-opt-1.c |  51 ++++++-
>  2 files changed, 147 insertions(+), 172 deletions(-)
>
>

I got many mempcpy test failures on Fedora 26/x86-64:

#0  0xf7ddef50 in abort () from /lib/libc.so.6
#1  0x08048a95 in test (buf3=0x804b060 <buf1>, buf4=0x804b0e0 <buf1+128> "",
    buf6=0x8048d3c "rstuvwxyz", n=0)
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy-2.c:49
#2  0x08048b77 in main_test ()
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy-2.c:152
#3  0x08048bc7 in main ()
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/lib/main.c:10
(gdb) f 1
#1  0x08048a95 in test (buf3=0x804b060 <buf1>, buf4=0x804b0e0 <buf1+128> "",
    buf6=0x8048d3c "rstuvwxyz", n=0)
    at /export/gnu/import/git/sources/gcc/gcc/testsuite/gcc.c-torture/execute/builtins/mempcpy-2.c:49
49    abort ();
(gdb)


-- 
H.J.