From: Richard Biener <richard.guenther@gmail.com>
To: Eric Botcazou <ebotcazou@adacore.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [patch] Fix PR middle-end/65958
Date: Wed, 18 Nov 2015 10:25:00 -0000 [thread overview]
Message-ID: <CAFiYyc2eRFafhB54BNcuGp+ZpAfZzRhvpg0+wU1F5qVxJ3eCXQ@mail.gmail.com> (raw)
In-Reply-To: <1750746.G8iFFmz9eE@polaris>
On Wed, Nov 18, 2015 at 11:06 AM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> Hi,
>
> this is the underlying issue of PR middle-end/65958: the compiler generates
> wrong code when alloca is used in conjunction with a VLA since the latter
> causes the stack space allocated to the former to be wrongly reclaimed.
> So the proposed fix is not to reclaim any stack space in this case.
>
> Bootstrapped/regtested on x86_64-suse-linux, OK for mainline and 5.x branch?
Ok. I wonder if we document GCCs VLA implementation somewhere so we can add
a note on the interaction with alloca.
Thanks,
Richard.
>
> 2015-11-18 Eric Botcazou <ebotcazou@adacore.com>
>
> PR middle-end/65958
> * gimplify.c (struct gimplify_ctx): Turn boolean fields into 1-bit
> fields, add keep_stack and reorder them.
> (gimplify_bind_expr): Save gimplify_ctxp->keep_stack on entry then
> set it to false. Do not insert a stack save/restore pair if it has
> been set to true by the gimplification of the statements.
> Restore it to the saved value on exit if it is still false.
> (gimplify_vla_decl): Do not set gimplify_ctxp->save_stack here.
> (gimplify_call_expr) <BUILT_IN_ALLOCA[_WITH_ALIGN]>: New case. Set
> either save_stack or keep_stack depending on CALL_ALLOCA_FOR_VAR_P.
>
>
> 2015-11-18 Eric Botcazou <ebotcazou@adacore.com>
>
> * gcc.dg/vla-24.c: New test.
>
> --
> Eric Botcazou
next prev parent reply other threads:[~2015-11-18 10:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-18 10:07 Eric Botcazou
2015-11-18 10:25 ` Richard Biener [this message]
2015-11-18 11:14 ` Eric Botcazou
2015-11-18 13:39 ` Richard Biener
2015-11-18 14:28 ` Eric Botcazou
2015-11-18 15:22 ` Richard Biener
2015-11-18 15:35 ` Eric Botcazou
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