2014-10-25 22:09:46

by Steven Noonan

[permalink] [raw]
Subject: [PATCH] compiler-gcc*.h: remove inaccurate comment about 'asm goto' miscompiles

The bug referenced by the comment in this commit was not completely fixed in
GCC 4.8.2, as I mentioned in a thread back in February[1]. The conclusion at
that time was to make the quirk unconditional until the bug could be found and
fixed in GCC. Unfortunately, when I submitted the patch (commit a9f18034)
I left a comment in that claimed the bug was fixed in GCC 4.8.2+. This comment
is inaccurate, and should be removed.

[1] https://lkml.org/lkml/2014/2/12/797
Signed-off-by: Steven Noonan <[email protected]>
Cc: Ingo Molnar <[email protected]>
---
include/linux/compiler-gcc4.h | 1 -
include/linux/compiler-gcc5.h | 1 -
2 files changed, 2 deletions(-)

diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 2507fd2..d1a5582 100644
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -71,7 +71,6 @@
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- * Fixed in GCC 4.8.2 and later versions.
*
* (asm goto is automatically volatile - the naming reflects this.)
*/
diff --git a/include/linux/compiler-gcc5.h b/include/linux/compiler-gcc5.h
index cdd1cc2..c8c5659 100644
--- a/include/linux/compiler-gcc5.h
+++ b/include/linux/compiler-gcc5.h
@@ -53,7 +53,6 @@
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- * Fixed in GCC 4.8.2 and later versions.
*
* (asm goto is automatically volatile - the naming reflects this.)
*/
--
2.1.2


Subject: [tip:core/urgent] compiler/gcc4+: Remove inaccurate comment about 'asm goto' miscompiles

Commit-ID: 5631b8fba640a4ab2f8a954f63a603fa34eda96b
Gitweb: http://git.kernel.org/tip/5631b8fba640a4ab2f8a954f63a603fa34eda96b
Author: Steven Noonan <[email protected]>
AuthorDate: Sat, 25 Oct 2014 15:09:42 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Tue, 28 Oct 2014 11:03:40 +0100

compiler/gcc4+: Remove inaccurate comment about 'asm goto' miscompiles

The bug referenced by the comment in this commit was not
completely fixed in GCC 4.8.2, as I mentioned in a thread back
in February:

https://lkml.org/lkml/2014/2/12/797

The conclusion at that time was to make the quirk unconditional
until the bug could be found and fixed in GCC. Unfortunately,
when I submitted the patch (commit a9f18034) I left a comment
in that claimed the bug was fixed in GCC 4.8.2+.

This comment is inaccurate, and should be removed.

Signed-off-by: Steven Noonan <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Cc: Jakub Jelinek <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Cc: Ingo Molnar <[email protected]>
---
include/linux/compiler-gcc4.h | 1 -
include/linux/compiler-gcc5.h | 1 -
2 files changed, 2 deletions(-)

diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 2507fd2..d1a5582 100644
--- a/include/linux/compiler-gcc4.h
+++ b/include/linux/compiler-gcc4.h
@@ -71,7 +71,6 @@
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- * Fixed in GCC 4.8.2 and later versions.
*
* (asm goto is automatically volatile - the naming reflects this.)
*/
diff --git a/include/linux/compiler-gcc5.h b/include/linux/compiler-gcc5.h
index cdd1cc2..c8c5659 100644
--- a/include/linux/compiler-gcc5.h
+++ b/include/linux/compiler-gcc5.h
@@ -53,7 +53,6 @@
* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
- * Fixed in GCC 4.8.2 and later versions.
*
* (asm goto is automatically volatile - the naming reflects this.)
*/

2014-11-06 14:44:31

by Vlastimil Babka

[permalink] [raw]
Subject: Re: [PATCH] compiler-gcc*.h: remove inaccurate comment about 'asm goto' miscompiles

On 10/26/2014 12:09 AM, Steven Noonan wrote:
> The bug referenced by the comment in this commit was not completely fixed in
> GCC 4.8.2, as I mentioned in a thread back in February[1]. The conclusion at
> that time was to make the quirk unconditional until the bug could be found and
> fixed in GCC. Unfortunately, when I submitted the patch (commit a9f18034)
> I left a comment in that claimed the bug was fixed in GCC 4.8.2+. This comment
> is inaccurate, and should be removed.

I believe the original gcc bug was indeed fixed, but there's another bug [1] not
yet fixed, see also [2]. So maybe the new bug number should be added to the
comments?

Vlastimil

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61772
[2] https://lkml.org/lkml/2014/7/10/398

> [1] https://lkml.org/lkml/2014/2/12/797
> Signed-off-by: Steven Noonan <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> ---
> include/linux/compiler-gcc4.h | 1 -
> include/linux/compiler-gcc5.h | 1 -
> 2 files changed, 2 deletions(-)
>
> diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
> index 2507fd2..d1a5582 100644
> --- a/include/linux/compiler-gcc4.h
> +++ b/include/linux/compiler-gcc4.h
> @@ -71,7 +71,6 @@
> * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
> *
> * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
> - * Fixed in GCC 4.8.2 and later versions.
> *
> * (asm goto is automatically volatile - the naming reflects this.)
> */
> diff --git a/include/linux/compiler-gcc5.h b/include/linux/compiler-gcc5.h
> index cdd1cc2..c8c5659 100644
> --- a/include/linux/compiler-gcc5.h
> +++ b/include/linux/compiler-gcc5.h
> @@ -53,7 +53,6 @@
> * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
> *
> * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
> - * Fixed in GCC 4.8.2 and later versions.
> *
> * (asm goto is automatically volatile - the naming reflects this.)
> */
>