[Mesa-dev] [PATCH v4 4/8] gallium/auxiliary: add inc and dec alternative with return (v2)

[Ilia Mirkin]

On Mon, Nov 17, 2014 at 10:58 AM, Axel Davy <axel.davy at ens.fr> wrote:
> From: Christoph Bumiller <christoph.bumiller at speed.at>
>
> At this moment we use only zero or positive values.
>
> v2: Implement it for also for Solaris, MSVC assembly
>     and enable for other combinations.
>
> Signed-off-by: David Heidelberg <david at ixit.cz>
> ---
>  src/gallium/auxiliary/util/u_atomic.h | 78 +++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
>
> diff --git a/src/gallium/auxiliary/util/u_atomic.h b/src/gallium/auxiliary/util/u_atomic.h
> index 2f2b42b..f177b60 100644
> --- a/src/gallium/auxiliary/util/u_atomic.h
> +++ b/src/gallium/auxiliary/util/u_atomic.h
> @@ -69,6 +69,18 @@ p_atomic_dec(int32_t *v)
>  }
>
>  static INLINE int32_t
> +p_atomic_inc_return(int32_t *v)
> +{
> +   return __sync_add_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
> +p_atomic_dec_return(int32_t *v)
> +{
> +   return __sync_sub_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
>  p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  {
>     return __sync_val_compare_and_swap(v, old, _new);
> @@ -116,6 +128,18 @@ p_atomic_dec(int32_t *v)
>  }
>
>  static INLINE int32_t
> +p_atomic_inc_return(int32_t *v)
> +{
> +   return __sync_add_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
> +p_atomic_dec_return(int32_t *v)
> +{
> +   return __sync_sub_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
>  p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  {
>     return __sync_val_compare_and_swap(v, old, _new);
> @@ -161,6 +185,18 @@ p_atomic_dec(int32_t *v)
>  }
>
>  static INLINE int32_t
> +p_atomic_inc_return(int32_t *v)
> +{
> +   return __sync_add_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
> +p_atomic_dec_return(int32_t *v)
> +{
> +   return __sync_sub_and_fetch(v, 1);
> +}
> +
> +static INLINE int32_t
>  p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  {
>     return __sync_val_compare_and_swap(v, old, _new);
> @@ -186,6 +222,8 @@ p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  #define p_atomic_dec_zero(_v) ((boolean) --(*(_v)))
>  #define p_atomic_inc(_v) ((void) (*(_v))++)
>  #define p_atomic_dec(_v) ((void) (*(_v))--)
> +#define p_atomic_inc_return(_v) ((*(_v))++)
> +#define p_atomic_dec_return(_v) ((*(_v))--)
>  #define p_atomic_cmpxchg(_v, old, _new) (*(_v) == old ? *(_v) = (_new) : *(_v))
>
>  #endif
> @@ -237,6 +275,32 @@ p_atomic_dec(int32_t *v)
>  }
>
>  static INLINE int32_t
> +p_atomic_inc_return(int32_t *v)
> +{
> +   int32_t i;
> +
> +   __asm {
> +      mov       eax, [v]
> +      lock inc  dword ptr [eax]
> +      mov       [i], eax
> +   }
> +   return i;
> +}
> +
> +static INLINE int32_t
> +p_atomic_dec_return(int32_t *v)
> +{
> +   int32_t i;
> +
> +   __asm {
> +      mov       eax, [v]
> +      lock dec  dword ptr [eax]
> +      mov       [i], eax
> +   }
> +   return i;

Both of these seem wrong. "mov [i], eax" -- eax contains the address
of the value, not the value itself, which you're trying to return. I'm
actually not 100% sure how to implement this offhand, but there's a
gcc builting primitive for it, so it must be easy. Just reading [eax]
doesn't seem like it'd work since another thread may have already
decremented it by then. I think this needs to be done as a cmpxchg
type of deal...

> +}
> +
> +static INLINE int32_t
>  p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  {
>     int32_t orig;
> @@ -288,6 +352,12 @@ p_atomic_inc(int32_t *v)
>     _InterlockedIncrement((long *)v);
>  }
>
> +static INLINE int32_t
> +p_atomic_inc_return(int32_t *v)
> +{
> +   return _InterlockedIncrement((long *)v);
> +}
> +
>  static INLINE void
>  p_atomic_dec(int32_t *v)
>  {
> @@ -295,6 +365,12 @@ p_atomic_dec(int32_t *v)
>  }
>
>  static INLINE int32_t
> +p_atomic_dec_return(int32_t *v)
> +{
> +   return _InterlockedDecrement((long *)v);
> +}
> +
> +static INLINE int32_t
>  p_atomic_cmpxchg(int32_t *v, int32_t old, int32_t _new)
>  {
>     return _InterlockedCompareExchange((long *)v, _new, old);
> @@ -329,6 +405,8 @@ p_atomic_dec_zero(int32_t *v)
>
>  #define p_atomic_inc(_v) atomic_inc_32((uint32_t *) _v)
>  #define p_atomic_dec(_v) atomic_dec_32((uint32_t *) _v)
> +#define p_atomic_inc_return(_v) atomic_inc_32_nv((uint32_t *) _v)
> +#define p_atomic_dec_return(_v) atomic_dec_32_nv((uint32_t *) _v)
>
>  #define p_atomic_cmpxchg(_v, _old, _new) \
>         atomic_cas_32( (uint32_t *) _v, (uint32_t) _old, (uint32_t) _new)
> --
> 2.1.0
>
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