On May 10, 2020 4:59:17 AM PDT, David Laight wrote:
>From: Peter Anvin
>> Sent: 08 May 2020 18:32
>> On 2020-05-08 10:21, Nick Desaulniers wrote:
>> >>
>> >> One last suggestion. Add the "b" modifier to the mask operand:
>"orb
>> >> %b1, %0". That forces the compiler to use the 8-bit register
From: Peter Anvin
> Sent: 08 May 2020 18:32
> On 2020-05-08 10:21, Nick Desaulniers wrote:
> >>
> >> One last suggestion. Add the "b" modifier to the mask operand: "orb
> >> %b1, %0". That forces the compiler to use the 8-bit register name
> >> instead of trying to deduce the width from the
On 2020-05-08 10:21, Nick Desaulniers wrote:
>>
>> One last suggestion. Add the "b" modifier to the mask operand: "orb
>> %b1, %0". That forces the compiler to use the 8-bit register name
>> instead of trying to deduce the width from the input.
>
> Ah right:
>
On Thu, May 7, 2020 at 6:57 PM Brian Gerst wrote:
>
> On Thu, May 7, 2020 at 6:29 PM Nick Desaulniers
> wrote:
> >
> > On Thu, May 7, 2020 at 12:19 PM Nick Desaulniers
> > wrote:
> > >
> > > On Thu, May 7, 2020 at 7:00 AM Brian Gerst wrote:
> > > >
> > > > This change will make sparse happy
On Thu, May 7, 2020 at 6:29 PM Nick Desaulniers wrote:
>
> On Thu, May 7, 2020 at 12:19 PM Nick Desaulniers
> wrote:
> >
> > On Thu, May 7, 2020 at 7:00 AM Brian Gerst wrote:
> > >
> > > This change will make sparse happy and allow these cleanups:
> > > #define CONST_MASK(nr)
On Thu, May 7, 2020 at 12:19 PM Nick Desaulniers
wrote:
>
> On Thu, May 7, 2020 at 7:00 AM Brian Gerst wrote:
> >
> > This change will make sparse happy and allow these cleanups:
> > #define CONST_MASK(nr) ((u8)1 << ((nr) & 7))
>
> yep, this is more elegant, IMO. Will send a v3
On May 7, 2020 8:09:35 AM PDT, David Laight wrote:
>From: Brian Gerst
>> Sent: 07 May 2020 14:32
>...
>> I think the bug this worked around was that the compiler didn't
>detect
>> that CONST_MASK(nr) was also constant and doesn't need to be put into
>> a register. The question is does that bug
On May 7, 2020 6:32:24 AM PDT, Brian Gerst wrote:
>On Thu, May 7, 2020 at 3:02 AM wrote:
>>
>> On May 6, 2020 11:18:09 PM PDT, Brian Gerst
>wrote:
>> >On Tue, May 5, 2020 at 1:47 PM Nick Desaulniers
>> > wrote:
>> >>
>> >> From: Sedat Dilek
>> >>
>> >> It turns out that if your config tickles
On May 7, 2020 4:34:22 AM PDT, Peter Zijlstra wrote:
>On Tue, May 05, 2020 at 11:07:24AM -0700, h...@zytor.com wrote:
>> On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
> wrote:
>
>> >@@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long
>*addr)
>> >if (__builtin_constant_p(nr)) {
On Wed, May 6, 2020 at 11:18 PM Brian Gerst wrote:
>
> I think a better fix would be to make CONST_MASK() return a u8 value
> rather than have to cast on every use.
>
> Also I question the need for the "q" constraint. It was added in
> commit 437a0a54 as a workaround for GCC 3.4.4. Now that the
On Thu, May 7, 2020 at 7:00 AM Brian Gerst wrote:
>
> This change will make sparse happy and allow these cleanups:
> #define CONST_MASK(nr) ((u8)1 << ((nr) & 7))
yep, this is more elegant, IMO. Will send a v3 later with this
change. Looking at the uses of CONST_MASK, I noticed
From: Brian Gerst
> Sent: 07 May 2020 14:32
...
> I think the bug this worked around was that the compiler didn't detect
> that CONST_MASK(nr) was also constant and doesn't need to be put into
> a register. The question is does that bug still exist on compiler
> versions we care about?
Hmmm...
On Thu, May 7, 2020 at 7:38 AM Peter Zijlstra wrote:
>
> On Tue, May 05, 2020 at 11:07:24AM -0700, h...@zytor.com wrote:
> > On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
> > wrote:
>
> > >@@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long *addr)
> > > if
On Thu, May 7, 2020 at 3:02 AM wrote:
>
> On May 6, 2020 11:18:09 PM PDT, Brian Gerst wrote:
> >On Tue, May 5, 2020 at 1:47 PM Nick Desaulniers
> > wrote:
> >>
> >> From: Sedat Dilek
> >>
> >> It turns out that if your config tickles __builtin_constant_p via
> >> differences in choices to
On Tue, May 05, 2020 at 11:07:24AM -0700, h...@zytor.com wrote:
> On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
> wrote:
> >@@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long *addr)
> > if (__builtin_constant_p(nr)) {
> > asm volatile(LOCK_PREFIX "orb %1,%0"
> >
On Thu, May 7, 2020 at 10:50 AM David Laight wrote:
> From: Brian Gerst
> > Sent: 07 May 2020 07:18
> > I think a better fix would be to make CONST_MASK() return a u8 value
> > rather than have to cast on every use.
>
> Or assign to a local variable - then it doesn't matter how
> the value is
On May 7, 2020 1:35:01 AM PDT, David Laight wrote:
>From: h...@zytor.com
>> Sent: 07 May 2020 08:59
>> On May 7, 2020 12:44:44 AM PDT, David Laight
> wrote:
>> >From: Brian Gerst
>> >> Sent: 07 May 2020 07:18
>> >...
>> >> > --- a/arch/x86/include/asm/bitops.h
>> >> > +++
From: h...@zytor.com
> Sent: 07 May 2020 08:59
> On May 7, 2020 12:44:44 AM PDT, David Laight wrote:
> >From: Brian Gerst
> >> Sent: 07 May 2020 07:18
> >...
> >> > --- a/arch/x86/include/asm/bitops.h
> >> > +++ b/arch/x86/include/asm/bitops.h
> >> > @@ -54,7 +54,7 @@ arch_set_bit(long nr,
On May 7, 2020 12:44:44 AM PDT, David Laight wrote:
>From: Brian Gerst
>> Sent: 07 May 2020 07:18
>...
>> > --- a/arch/x86/include/asm/bitops.h
>> > +++ b/arch/x86/include/asm/bitops.h
>> > @@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long
>*addr)
>> > if
From: Brian Gerst
> Sent: 07 May 2020 07:18
...
> > --- a/arch/x86/include/asm/bitops.h
> > +++ b/arch/x86/include/asm/bitops.h
> > @@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long *addr)
> > if (__builtin_constant_p(nr)) {
> > asm volatile(LOCK_PREFIX "orb
On May 6, 2020 11:18:09 PM PDT, Brian Gerst wrote:
>On Tue, May 5, 2020 at 1:47 PM Nick Desaulniers
> wrote:
>>
>> From: Sedat Dilek
>>
>> It turns out that if your config tickles __builtin_constant_p via
>> differences in choices to inline or not, this now produces invalid
>> assembly:
>>
>> $
On Tue, May 5, 2020 at 1:47 PM Nick Desaulniers wrote:
>
> From: Sedat Dilek
>
> It turns out that if your config tickles __builtin_constant_p via
> differences in choices to inline or not, this now produces invalid
> assembly:
>
> $ cat foo.c
> long a(long b, long c) {
> asm("orb\t%1, %0" :
Hi Nick,
> Ilie, may I put your authorship and signed off by tag on the V2?
Yes, of course. With the current global situation I took some time off
and didn't follow the latest discussion.
Feel free to credit/rework the code as you see fit.
Thanks,
I.H.
On Tue, May 5, 2020 at 9:30 PM Nathan Chancellor
wrote:
>
> On Tue, May 05, 2020 at 10:44:22AM -0700, Nick Desaulniers wrote:
> > This is easily reproducible via Clang+CONFIG_STAGING=y+CONFIG_VT6656=m,
> > or Clang+allyesconfig.
>
> For what it's worth, I don't see this with allyesconfig.
Oops,
On Tue, May 05, 2020 at 09:30:28PM -0700, Nathan Chancellor wrote:
> On Tue, May 05, 2020 at 10:44:22AM -0700, Nick Desaulniers wrote:
> > From: Sedat Dilek
> >
> > It turns out that if your config tickles __builtin_constant_p via
> > differences in choices to inline or not, this now produces
On Wed, May 6, 2020 at 6:30 AM Nathan Chancellor
wrote:
>
> On Tue, May 05, 2020 at 10:44:22AM -0700, Nick Desaulniers wrote:
> > From: Sedat Dilek
> >
> > It turns out that if your config tickles __builtin_constant_p via
> > differences in choices to inline or not, this now produces invalid
> >
On Tue, May 05, 2020 at 10:44:22AM -0700, Nick Desaulniers wrote:
> From: Sedat Dilek
>
> It turns out that if your config tickles __builtin_constant_p via
> differences in choices to inline or not, this now produces invalid
> assembly:
>
> $ cat foo.c
> long a(long b, long c) {
>
On Tue, May 5, 2020 at 11:07 AM wrote:
>
> On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
> wrote:
> >From: Sedat Dilek
> >
> >It turns out that if your config tickles __builtin_constant_p via
> >differences in choices to inline or not, this now produces invalid
> >assembly:
> >
> >$ cat
On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
wrote:
>From: Sedat Dilek
>
>It turns out that if your config tickles __builtin_constant_p via
>differences in choices to inline or not, this now produces invalid
>assembly:
>
>$ cat foo.c
>long a(long b, long c) {
> asm("orb\t%1, %0" : "+q"(c):
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