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Re: [PATCH] Fix up memset handling in DSE (PR rtl-optimization/69891)
- From: Richard Biener <rguenther at suse dot de>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Eric Botcazou <ebotcazou at adacore dot com>, Jeff Law <law at redhat dot com>, Bernd Schmidt <bschmidt at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 26 Feb 2016 13:51:10 +0100 (CET)
- Subject: Re: [PATCH] Fix up memset handling in DSE (PR rtl-optimization/69891)
- Authentication-results: sourceware.org; auth=none
- References: <20160226121041 dot GB3017 at tucnak dot redhat dot com>
On Fri, 26 Feb 2016, Jakub Jelinek wrote:
> Hi!
>
> As analyzed by Eric, DSE mishandles memset calls if it can't figure out what
> the arguments to memset exactly are (it handles only register arguments
> right now), or if the second or third arguments are not CONST_INTs.
> In that case we don't call record_store, because we don't know what to call
> it on; but we need to treat it as a wild store, which is handled by the
> clear_rhs_from_active_local_stores () function (which record_store also uses
> if it can't figure out what exactly is being overwritten).
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?
Ok.
Thanks,
Richard.
> 2016-02-26 Jakub Jelinek <jakub@redhat.com>
> Eric Botcazou <ebotcazou@adacore.com>
>
> PR rtl-optimization/69891
> * dse.c (scan_insn): If we can't figure out memset arguments
> or they are non-constant, call clear_rhs_from_active_local_stores.
>
> * gcc.target/i386/pr69891.c: New test.
>
> --- gcc/dse.c.jj 2016-01-19 13:32:12.000000000 +0100
> +++ gcc/dse.c 2016-02-26 11:03:36.694206088 +0100
> @@ -2556,6 +2556,8 @@ scan_insn (bb_info_t bb_info, rtx_insn *
> active_local_stores = insn_info;
> }
> }
> + else
> + clear_rhs_from_active_local_stores ();
> }
> }
> else if (SIBLING_CALL_P (insn) && reload_completed)
> --- gcc/testsuite/gcc.target/i386/pr69891.c.jj 2016-02-26 11:09:45.492079225 +0100
> +++ gcc/testsuite/gcc.target/i386/pr69891.c 2016-02-26 11:10:58.941058170 +0100
> @@ -0,0 +1,30 @@
> +/* PR rtl-optimization/69891 */
> +/* { dg-do run } */
> +/* { dg-options "-O -fno-tree-fre -mstringop-strategy=libcall -Wno-psabi" } */
> +/* { dg-additional-options "-mno-sse" { target ia32 } } */
> +
> +typedef unsigned short A;
> +typedef unsigned short B __attribute__ ((vector_size (32)));
> +typedef unsigned int C;
> +typedef unsigned int D __attribute__ ((vector_size (32)));
> +typedef unsigned long long E;
> +typedef unsigned long long F __attribute__ ((vector_size (32)));
> +
> +__attribute__((noinline, noclone)) unsigned
> +foo(D a, B b, D c, F d)
> +{
> + b /= (B) {1, -c[0]} | 1;
> + c[0] |= 7;
> + a %= c | 1;
> + c ^= c;
> + return a[0] + b[15] + c[0] + d[3];
> +}
> +
> +int
> +main ()
> +{
> + unsigned x = foo ((D) {}, (B) {}, (D) {}, (F) {});
> + if (x != 0)
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)