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* [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program
[not found] <bug-40988-4@http.gcc.gnu.org/bugzilla/>
@ 2021-08-09 5:19 ` pinskia at gcc dot gnu.org
2024-04-03 22:35 ` pinskia at gcc dot gnu.org
2024-04-03 22:46 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-09 5:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40988
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect the inline-asm is broken, I am 90% sure of it.
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program
[not found] <bug-40988-4@http.gcc.gnu.org/bugzilla/>
2021-08-09 5:19 ` [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program pinskia at gcc dot gnu.org
@ 2024-04-03 22:35 ` pinskia at gcc dot gnu.org
2024-04-03 22:46 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-03 22:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40988
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So yes I was correct in saying the inline-asm was incorrect. it should have
been:
```
__asm__ __volatile__(
"btrl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit), "+m" (ADDR)
:"Ir" (nr) : "memory");
return oldbit;
```
as this both reads and write the memory.
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program
[not found] <bug-40988-4@http.gcc.gnu.org/bugzilla/>
2021-08-09 5:19 ` [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program pinskia at gcc dot gnu.org
2024-04-03 22:35 ` pinskia at gcc dot gnu.org
@ 2024-04-03 22:46 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-04-03 22:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40988
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
One more note the Linux kernel sources has been corrected already.
They do now:
asm volatile(__ASM_SIZE(btr) " %2,%1"
CC_SET(c)
: CC_OUT(c) (oldbit)
: ADDR, "Ir" (nr) : "memory");
return oldbit;
and
asm volatile(__ASM_SIZE(bts) " %1,%0" : : ADDR, "Ir" (nr) : "memory");
Which describes the same thing as "+" as the memory clobber says it will update
memory too.
Linux commit 5b77e95dd7790 changed it from "+" to the above.
Linux commit 92934bcbf96bc (in 2006 which was included in 2.6.16) fixed it to
be "+" so you must have copied the linux sources from FC6 and didn't look to
see if the Linux kernel header was updated in your FC11 system.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-08-09 5:19 ` [Bug target/40988] incorrect code when using ..._bit macros from asm/bitops.h in a loop in userspace program pinskia at gcc dot gnu.org
2024-04-03 22:35 ` pinskia at gcc dot gnu.org
2024-04-03 22:46 ` pinskia at gcc dot gnu.org
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