https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #16 from David Brown ---
(In reply to Xi Ruoyao from comment #8)
> (In reply to David Brown from comment #7)
>
> > There is no intention to make "asm volatile" a barrier, as you get with a
> > memory clobber. The intention is to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
Segher Boessenkool changed:
What|Removed |Added
Status|ASSIGNED|RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #14 from Segher Boessenkool ---
Author: segher
Date: Wed Oct 18 21:15:24 2017
New Revision: 253871
URL: https://gcc.gnu.org/viewcvs?rev=253871=gcc=rev
Log:
ira: volatile asm's are not moveable (PR82602)
A volatile asm statement can
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #13 from Segher Boessenkool ---
Author: segher
Date: Wed Oct 18 21:13:16 2017
New Revision: 253870
URL: https://gcc.gnu.org/viewcvs?rev=253870=gcc=rev
Log:
ira: volatile asm's are not moveable (PR82602)
A volatile asm statement can
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #12 from Segher Boessenkool ---
Author: segher
Date: Wed Oct 18 21:08:18 2017
New Revision: 253869
URL: https://gcc.gnu.org/viewcvs?rev=253869=gcc=rev
Log:
ira: volatile asm's are not moveable (PR82602)
A volatile asm statement can
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #11 from Segher Boessenkool ---
(In reply to Bernd Edlinger from comment #10)
> Yes, and moreover foo() could access non-volatile memory.
> And only a memory clobber can prevent the compiler from
> using cached values.
But you
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #10 from Bernd Edlinger ---
Yes, and moreover foo() could access non-volatile memory.
And only a memory clobber can prevent the compiler from
using cached values.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #9 from Segher Boessenkool ---
You cannot do that if you do not know what foo() does (it could for
example contain another volatile asm). But yes, the code as written
is not so great.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #8 from Xi Ruoyao ---
(In reply to David Brown from comment #7)
> There is no intention to make "asm volatile" a barrier, as you get with a
> memory clobber. The intention is to stop it moving past other volatile code
> (such as
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #7 from David Brown ---
(In reply to Xi Ruoyao from comment #3)
There is no intention to make "asm volatile" a barrier, as you get with a
memory clobber. The intention is to stop it moving past other volatile code
(such as other asm
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #6 from Segher Boessenkool ---
(In reply to Xi Ruoyao from comment #3)
> I'm still not convinced this is a bug. For example, all kernel code
> uses `asm volatile ("" ::: "memory")` as barrier to stop GCC to reorder code
> through
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
Bernd Edlinger changed:
What|Removed |Added
CC||bernd.edlinger at hotmail dot
de
---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
--- Comment #4 from Xi Ruoyao ---
By the way, in kernel code (compiler-gcc.h) there is a comment:
/* The "volatile" is due to gcc bugs */
#define barrier() __asm__ __volatile__("": : :"memory")
So the developer(s) actually think "volatile" is
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
Xi Ruoyao changed:
What|Removed |Added
CC||ryxi at stu dot xidian.edu.cn
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
David Brown changed:
What|Removed |Added
CC||david at westcontrol dot com
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
Segher Boessenkool changed:
What|Removed |Added
Status|NEW |ASSIGNED
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602
Segher Boessenkool changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed|
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