From: Richard Biener <richard.guenther@gmail.com>
To: gcc-patches@gcc.gnu.org,apinski@marvell.com
Cc: Andrew Pinski <apinski@marvell.com>
Subject: Re: [PATCH 2/2] Uninitialized padding in struct _dep.
Date: Thu, 16 Jan 2020 09:41:00 -0000 [thread overview]
Message-ID: <BCE65273-32F1-4F73-8CB5-E77E780516CE@gmail.com> (raw)
In-Reply-To: <1579151329-6088-2-git-send-email-apinski@marvell.com>
On January 16, 2020 6:08:49 AM GMT+01:00, apinski@marvell.com wrote:
>From: Andrew Pinski <apinski@marvell.com>
>
>In struct _dep, there is an implicit padding of 4bits. This
>bit-field padding is uninitialized when init_dep_1 is being called.
>This means we access uninitialized memory but never use it for
>anything. Adding an unused bit-field field and initializing it
>in init_dep_1 will improve code generation also as we initialize
>the whole 32bits now rather than just part of it.
>
>OK? Bootstrapped and tested on x86_64-linux-gnu.
OK.
Richard.
>Thanks,
>Andrew Pinski
>
>ChangeLog:
>* sched-int.h (_dep): Add unused bit-field field for the padding.
>* sched-deps.c (init_dep_1): Init unused field.
>
>Change-Id: I27000323e728f8a73189426e0b9a98c5235b8c55
>---
> gcc/sched-deps.c | 1 +
> gcc/sched-int.h | 2 ++
> 2 files changed, 3 insertions(+)
>
>diff --git a/gcc/sched-deps.c b/gcc/sched-deps.c
>index 9182aba5588..331af5ffdb3 100644
>--- a/gcc/sched-deps.c
>+++ b/gcc/sched-deps.c
>@@ -101,6 +101,7 @@ init_dep_1 (dep_t dep, rtx_insn *pro, rtx_insn
>*con, enum reg_note type, ds_t ds
> DEP_NONREG (dep) = 0;
> DEP_MULTIPLE (dep) = 0;
> DEP_REPLACE (dep) = NULL;
>+ dep->unused = 0;
> }
>
> /* Init DEP with the arguments.
>diff --git a/gcc/sched-int.h b/gcc/sched-int.h
>index 833b552a340..a847f876e65 100644
>--- a/gcc/sched-int.h
>+++ b/gcc/sched-int.h
>@@ -238,6 +238,8 @@ struct _dep
>/* Cached cost of the dependency. Make sure to update UNKNOWN_DEP_COST
> when changing the size of this field. */
> int cost:20;
>+
>+ unsigned unused:4;
> };
>
> #define UNKNOWN_DEP_COST ((int) ((unsigned int) -1 << 19))
next prev parent reply other threads:[~2020-01-16 8:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-16 7:08 [PATCH 1/2] Fix uninitialized field in expand_operand apinski
2020-01-16 7:32 ` [PATCH 2/2] Uninitialized padding in struct _dep apinski
2020-01-16 9:41 ` Richard Biener [this message]
2020-01-16 9:40 ` [PATCH 1/2] Fix uninitialized field in expand_operand Richard Biener
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