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Re: [PATCH] Fix PR/63841: empty constructor doesn't zero-initialize
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Teresa Johnson <tejohnson at google dot com>
- Cc: Andrew Pinski <pinskia at gmail dot com>, Xinliang David Li <davidxl at google dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 13 Nov 2014 22:45:14 +0100
- Subject: Re: [PATCH] Fix PR/63841: empty constructor doesn't zero-initialize
- Authentication-results: sourceware.org; auth=none
- References: <CAAe5K+Ve=h0BJ_VTwGsugzur4jrxMjZxrqqQttTr-FSf9sGGgw at mail dot gmail dot com> <CA+=Sn1m+QKApfX051u1_SW5KNtQ0YhFWa-D94wO6hqEY93CE2A at mail dot gmail dot com> <CAAe5K+U9C1_WUE=OA-1goTvUFSTOTeHoAyzzcfMyoDjDywEzPw at mail dot gmail dot com> <20141113143617 dot GR5026 at tucnak dot redhat dot com> <CAAe5K+WJnQ+QMT6xH9co=MpjCTEoW-VkR0fBn5wdnw00UXSpuA at mail dot gmail dot com> <20141113151258 dot GT5026 at tucnak dot redhat dot com> <CAAe5K+UwWtbVP57Z5Qm052gxTv8S4y_SnzciDddLoMDJmnSfHQ at mail dot gmail dot com> <CAAe5K+XYPbX2SextpQvkShsa8ms-4DkzEVT8S38tVo9T2T9BUQ at mail dot gmail dot com> <20141113205547 dot GZ5026 at tucnak dot redhat dot com> <CAAe5K+US+=C6QmhA5A_Jfd_e0-q=ZTxAqk=kXQVNJ7RJY6XByA at mail dot gmail dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Thu, Nov 13, 2014 at 01:33:07PM -0800, Teresa Johnson wrote:
> > Supposedly the printfs should have been removed and the #include <cstdio>
> > isn't needed then either. No need to clutter the test output and log files.
> > On the other side, tests should abort (); or __builtin_abort (); on failure,
> > not just return non-zero.
>
> Ok, sounds good. Here is the new patch. Confirmed that the test case
> passes with the fix, aborts without it.
>
> If this looks good I will also update the trunk version of the test.
LGTM, thanks.
Please commit also the tree-ssa-strlen.c change to the trunk, it will not
hurt.
> 2014-11-13 Teresa Johnson <tejohnson@google.com>
>
> gcc:
> PR tree-optimization/63841
> * tree-ssa-strlen.c (strlen_optimize_stmt): Ignore clobbers.
>
> 2014-11-13 Teresa Johnson <tejohnson@google.com>
>
> gcc/testsuite:
> PR tree-optimization/63841
> * testsuite/g++.dg/tree-ssa/pr63841.C: New test.
>
> Index: tree-ssa-strlen.c
> ===================================================================
> --- tree-ssa-strlen.c (revision 217503)
> +++ tree-ssa-strlen.c (working copy)
> @@ -1856,7 +1856,7 @@ strlen_optimize_stmt (gimple_stmt_iterator *gsi)
> break;
> }
> }
> - else if (is_gimple_assign (stmt))
> + else if (is_gimple_assign (stmt) && !gimple_clobber_p (stmt))
> {
> tree lhs = gimple_assign_lhs (stmt);
>
> Index: testsuite/g++.dg/tree-ssa/pr63841.C
> ===================================================================
> --- testsuite/g++.dg/tree-ssa/pr63841.C (revision 0)
> +++ testsuite/g++.dg/tree-ssa/pr63841.C (working copy)
> @@ -0,0 +1,35 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +#include <string>
> +
> +std::string __attribute__ ((noinline)) comp_test_write() {
> + std::string data;
> +
> + for (int i = 0; i < 2; ++i) {
> + char b = 1 >> (i * 8);
> + data.append(&b, 1);
> + }
> +
> + return data;
> +}
> +
> +std::string __attribute__ ((noinline)) comp_test_write_good() {
> + std::string data;
> +
> + char b;
> + for (int i = 0; i < 2; ++i) {
> + b = 1 >> (i * 8);
> + data.append(&b, 1);
> + }
> +
> + return data;
> +}
> +
> +int main() {
> + std::string good = comp_test_write_good();
> + std::string bad = comp_test_write();
> +
> + if (good != bad)
> + __builtin_abort ();
> +}
Jakub