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From: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To: Ramsay Jones <ramsay@ramsayjones.plus.com>
Cc: linux-sparse@vger.kernel.org
Subject: Re: [PATCH 04/12] builtin: evaluate __sync_*_fetch*()
Date: Mon, 19 Oct 2020 06:44:39 +0200
Message-ID: <20201019044439.pcj7ucxjfm762tx4@ltop.local> (raw)
In-Reply-To: <c19eba37-af33-a852-a286-a6ecf23d77ea@ramsayjones.plus.com>

On Mon, Oct 19, 2020 at 12:59:01AM +0100, Ramsay Jones wrote:
> On 17/10/2020 23:56, Luc Van Oostenryck wrote:
> > diff --git a/builtin.c b/builtin.c
> > index 880dd54f647e..5e490830e147 100644
> > --- a/builtin.c
> > +++ b/builtin.c
> > @@ -627,23 +627,23 @@ static const struct builtin_fn builtins_common[] = {
> >  	{ "__builtin___vsnprintf_chk", &int_ctype, 0, { &string_ctype, size_t_ctype, &int_ctype, size_t_ctype, &const_string_ctype, va_list_ctype }},
> >  	{ "__builtin___vsprintf_chk", &int_ctype, 0, { &string_ctype, &int_ctype, size_t_ctype, &const_string_ctype, va_list_ctype }},
> >  
> > -	{ "__sync_add_and_fetch", &int_ctype, 1, { &ptr_ctype }},
> > -	{ "__sync_and_and_fetch", &int_ctype, 1, { &ptr_ctype }},
> > +	{ "__sync_add_and_fetch", NULL, 1, { vol_ptr, &dyntype }, .op = &atomic_op },
> > +	{ "__sync_and_and_fetch", NULL, 1, { vol_ptr, &dyntype }, .op = &atomic_op },
> 
> Hmm, I get that the return type is derived from the type of the first
> argument, but I don't see where that return type is checked/assigned
> to the function return type. :( So, why are these set to NULL, but ...
> 
> >  	{ "__sync_bool_compare_and_swap", &bool_ctype, 1, { vol_ptr, &dyntype, &dyntype }, .op = &atomic_op},
> 
> ... this one isn't?

Well, yes, __sync_bool_compare_and_swap() is defined as returning a bool,
so it can directly specified here. For the other functions, for example
__sync_add_and_fetch(), the return type must indeed be deduced form the
type of the first argument. It is set at the end of eval_atomic_common()

	if (!expr->ctype)       // __sync_val_compare_and_swap()
                expr->ctype = ctype;

The comment should be removed or replaced by a real one.

I'll clarify that. Thanks for noticng this.
-- Luc

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-17 22:56 [PATCH 00/12] fix and complete the evaluation of atomic builtins Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 01/12] builtin: add generic .args method Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 02/12] builtin: add builtin type for volatile void * Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 03/12] builtin: make eval_sync_compare_and_swap() more generic Luc Van Oostenryck
2020-10-18 21:31   ` Ramsay Jones
2020-10-19  4:59     ` Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 04/12] builtin: evaluate __sync_*_fetch*() Luc Van Oostenryck
2020-10-18 23:59   ` Ramsay Jones
2020-10-19  4:44     ` Luc Van Oostenryck [this message]
2020-10-17 22:56 ` [PATCH 05/12] builtin: fix evaluation of __sync_lock_release Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 06/12] builtin: __sync_synchronize() too is variadic Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 07/12] builtin: add predefines for __ATOMIC_RELAXED & friends Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 08/12] builtin: add support for __atomic_add_fetch(), Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 09/12] builtin: add support for others generic atomic builtins Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 10/12] builtin: add builtin type: [volatile] pointer to bool Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 11/12] builtin: add support for __atomic_clear() Luc Van Oostenryck
2020-10-17 22:56 ` [PATCH 12/12] builtin: add support for remaining atomic builtins Luc Van Oostenryck

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