RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

[Jaydeep Patil]

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Hi Rich,

> If simply using 'long' works, I think that's the cleanest/simplest
> solution. The union is uglier and less obvious what it's doing so I'd
> rather avoid it if we can.

From e91d41f84822377ef14c675094ad904d89dbd927 Mon Sep 17 00:00:00 2001
From: Jaydeep Patil <jaydeep.patil@imgtec.com>
Date: Wed, 9 Mar 2016 04:56:50 +0000
Subject: [PATCH 2/2] [MIPS64] Change a_sc_p for clang

---
arch/mips64/atomic_arch.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips64/atomic_arch.h b/arch/mips64/atomic_arch.h
index 8af6500..df35cf6 100644
--- a/arch/mips64/atomic_arch.h
+++ b/arch/mips64/atomic_arch.h
@@ -29,9 +29,9 @@ static inline void *a_ll_p(volatile long *p)
}

#define a_sc_p a_sc_p
-static inline void *a_sc_p(volatile long *p, void *v)
+static inline long a_sc_p(volatile long *p, void *v)
{
-       void *r;
+       long r;
        __asm__ __volatile__ (
                "scd %0, %1"
                : "=r"(r), "=m"(*p) : "0"(v) : "memory");
--
2.1.4

Regards,
Jaydeep

From: Jaydeep Patil
Sent: 08 March 2016 PM 03:40
To: Rich Felker (dalias@libc.org)
Cc: 'musl@lists.openwall.com'
Subject: RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

Added musl@lists.openwall.com<mailto:musl@lists.openwall.com> in Cc

From: Jaydeep Patil
Sent: 08 March 2016 PM 03:38
To: Rich Felker (dalias@libc.org)
Subject: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

Hi Rich,

Clang (3.9.0) generates following error for a_sc_p function in atomic_arch.h:

./arch/mips64/atomic_arch.h:37:29: error: unsupported inline asm: input with type 'long *' matching output with type 'int'

Could you please consider this patch to fix it?
-----

From 3e64da8f5db923a919cd5600e8031c158a0368a2 Mon Sep 17 00:00:00 2001
From: Jaydeep Patil <jaydeep.patil@imgtec.com>
Date: Tue, 8 Mar 2016 10:06:38 +0000
Subject: [PATCH] [MIPS64] Fix Clang error

---
arch/mips64/atomic_arch.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips64/atomic_arch.h b/arch/mips64/atomic_arch.h
index 49d9884..8af6500 100644
--- a/arch/mips64/atomic_arch.h
+++ b/arch/mips64/atomic_arch.h
@@ -29,9 +29,9 @@ static inline void *a_ll_p(volatile long *p)
}

#define a_sc_p a_sc_p
-static inline int a_sc_p(volatile long *p, void *v)
+static inline void *a_sc_p(volatile long *p, void *v)
{
-       int r;
+       void *r;
        __asm__ __volatile__ (
                "scd %0, %1"
                : "=r"(r), "=m"(*p) : "0"(v) : "memory");
--
2.1.4

Thanks,
Jaydeep


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Re: RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

[Rich Felker (dalias@libc.org)]

On Wed, Mar 09, 2016 at 05:00:42AM +0000, Jaydeep Patil wrote:
> Hi Rich,
> 
> > If simply using 'long' works, I think that's the cleanest/simplest
> > solution. The union is uglier and less obvious what it's doing so I'd
> > rather avoid it if we can.
> 
> >From e91d41f84822377ef14c675094ad904d89dbd927 Mon Sep 17 00:00:00 2001
> From: Jaydeep Patil <jaydeep.patil@imgtec.com>
> Date: Wed, 9 Mar 2016 04:56:50 +0000
> Subject: [PATCH 2/2] [MIPS64] Change a_sc_p for clang
> 
> ---
> arch/mips64/atomic_arch.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips64/atomic_arch.h b/arch/mips64/atomic_arch.h
> index 8af6500..df35cf6 100644
> --- a/arch/mips64/atomic_arch.h
> +++ b/arch/mips64/atomic_arch.h
> @@ -29,9 +29,9 @@ static inline void *a_ll_p(volatile long *p)
> }
> 
> #define a_sc_p a_sc_p
> -static inline void *a_sc_p(volatile long *p, void *v)
> +static inline long a_sc_p(volatile long *p, void *v)
> {
> -       void *r;
> +       long r;
>         __asm__ __volatile__ (
>                 "scd %0, %1"
>                 : "=r"(r), "=m"(*p) : "0"(v) : "memory");

I've committed this fix and also fixed the pointer types to match the
actual types they operate on.

Rich

Re: RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

[Szabolcs Nagy]

* Rich Felker (dalias@libc.org) <dalias@libc.org> [2016-03-08 12:26:50 -0500]:
> On Tue, Mar 08, 2016 at 12:26:13PM +0100, Szabolcs Nagy wrote:
> > * Jaydeep Patil <Jaydeep.Patil@imgtec.com> [2016-03-08 10:09:43 +0000]:
> > > 
> > > ./arch/mips64/atomic_arch.h:37:29: error: unsupported inline asm: input with type 'long *' matching output with type 'int'
> > > 
> > 
> > clang probably should not complain about this
> > 
> > (it's possible to have the output in the low 32bit of a 64bit input reg
> > and then you do want mismatching input/output types for the same reg)
> 
> I can imagine it being problematic on other archs where the register
> names are different for 32-bit and 64-bit versions -- %0 couldn't
> expand to both. Isn't there a similar ugly issue on aarch64's
> atomic_arch.h?
> 

in aarch64 asm wN is the 32bit part of gpr N and xN is the whole 64bit.
(width is not part of the mnemonics, but the operands in most cases).

in gcc inline asm %w0 prints wN and %x0 prints xN for gpr operands,
plain %0 is the same as %x0 for gprs but works for other operands too.

aarch64 gcc does not complain if you pass int for a 64bit operand or long
for 32bit one (that's why we had a bug in atomic_arch.h, i forgot the 'w'),
but this sdc input-output operand would work.

> > > #define a_sc_p a_sc_p
> > > -static inline int a_sc_p(volatile long *p, void *v)
> > > +static inline void *a_sc_p(volatile long *p, void *v)
> > > {
> > > -       int r;
> > > +       void *r;
> > >         __asm__ __volatile__ (
> > >                 "scd %0, %1"
> > >                 : "=r"(r), "=m"(*p) : "0"(v) : "memory");
> > 
> > the return type should be int (1 on success, 0 on failure)
> > 
> > e.g. you can use 'long r' instead of 'int r'
> > 
> > if clang still complains then maybe
> > 
> > 	union {void *v; long r;} u = {v};
> > 	__asm__ __volatile__ (
> > 		"scd %0, %1" : "+r"(u.v), "=m"(*p) :: "memory");
> > 	return u.r;
> 
> If simply using 'long' works, I think that's the cleanest/simplest
> solution. The union is uglier and less obvious what it's doing so I'd
> rather avoid it if we can.
> 
> Rich

Re: RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

[Rich Felker (dalias@libc.org)]

On Tue, Mar 08, 2016 at 12:26:13PM +0100, Szabolcs Nagy wrote:
> * Jaydeep Patil <Jaydeep.Patil@imgtec.com> [2016-03-08 10:09:43 +0000]:
> > 
> > ./arch/mips64/atomic_arch.h:37:29: error: unsupported inline asm: input with type 'long *' matching output with type 'int'
> > 
> 
> clang probably should not complain about this
> 
> (it's possible to have the output in the low 32bit of a 64bit input reg
> and then you do want mismatching input/output types for the same reg)

I can imagine it being problematic on other archs where the register
names are different for 32-bit and 64-bit versions -- %0 couldn't
expand to both. Isn't there a similar ugly issue on aarch64's
atomic_arch.h?

> > #define a_sc_p a_sc_p
> > -static inline int a_sc_p(volatile long *p, void *v)
> > +static inline void *a_sc_p(volatile long *p, void *v)
> > {
> > -       int r;
> > +       void *r;
> >         __asm__ __volatile__ (
> >                 "scd %0, %1"
> >                 : "=r"(r), "=m"(*p) : "0"(v) : "memory");
> 
> the return type should be int (1 on success, 0 on failure)
> 
> e.g. you can use 'long r' instead of 'int r'
> 
> if clang still complains then maybe
> 
> 	union {void *v; long r;} u = {v};
> 	__asm__ __volatile__ (
> 		"scd %0, %1" : "+r"(u.v), "=m"(*p) :: "memory");
> 	return u.r;

If simply using 'long' works, I think that's the cleanest/simplest
solution. The union is uglier and less obvious what it's doing so I'd
rather avoid it if we can.

Rich

Re: RE: [PATCH] MIPS64 atomic_arch.h Clang complains about input type

[Szabolcs Nagy]

* Jaydeep Patil <Jaydeep.Patil@imgtec.com> [2016-03-08 10:09:43 +0000]:
> 
> ./arch/mips64/atomic_arch.h:37:29: error: unsupported inline asm: input with type 'long *' matching output with type 'int'
> 

clang probably should not complain about this

(it's possible to have the output in the low 32bit of a 64bit input reg
and then you do want mismatching input/output types for the same reg)

> #define a_sc_p a_sc_p
> -static inline int a_sc_p(volatile long *p, void *v)
> +static inline void *a_sc_p(volatile long *p, void *v)
> {
> -       int r;
> +       void *r;
>         __asm__ __volatile__ (
>                 "scd %0, %1"
>                 : "=r"(r), "=m"(*p) : "0"(v) : "memory");

the return type should be int (1 on success, 0 on failure)

e.g. you can use 'long r' instead of 'int r'

if clang still complains then maybe

	union {void *v; long r;} u = {v};
	__asm__ __volatile__ (
		"scd %0, %1" : "+r"(u.v), "=m"(*p) :: "memory");
	return u.r;