From mboxrd@z Thu Jan  1 00:00:00 1970
From: Josh Triplett <josh@freedesktop.org>
Subject: Re: barrier macro
Date: Tue, 01 May 2007 20:17:53 -0700
Message-ID: <463802E1.4030303@freedesktop.org>
References: <20070501153448.a65c81c2.rdunlap@xenotime.net>
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To: Randy Dunlap <rdunlap@xenotime.net>
Cc: linux-sparse@vger.kernel.org

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Randy Dunlap wrote:
> (using sparse 0.3)
>=20
> ./compiler-gcc.h:10:#define barrier() __asm__ __volatile__("": : :"memo=
ry")
>=20
> causes this output:
>=20
> net/sunrpc/xprtsock.c:640:2: error: Expected ( after asm
> net/sunrpc/xprtsock.c:640:2: error: got __volatile__
> net/sunrpc/xprtsock.c:640:2: error: typename in expression
> net/sunrpc/xprtsock.c:640:2: error: Expected ) in function call
> net/sunrpc/xprtsock.c:640:2: error: got :
>=20
>=20
> Maybe sparse could allow modifiers between asm|__asm__ and the
> (...) ?

Sparse specifically allows volatile, and double-underscore variants, betw=
een the asm keyword and the open parenthesis:

static struct token *parse_asm_statement(struct token *token, struct stat=
ement *stmt)
{
        token =3D token->next;
        stmt->type =3D STMT_ASM;
        if (match_idents(token, &__volatile___ident, &__volatile_ident, &=
volatile_ident, NULL)) {
                token =3D token->next;
        }
        token =3D expect(token, '(', "after asm");
[...]


I cannot reproduce your report with the following test case (just added t=
o git
as validation/asm-volatile.c):

#define barrier() __asm__ __volatile__("": : :"memory")

static void f(void)
{
        barrier();
}


Perhaps something else has caused the problem.  Could you please generate=
 a
preprocessed file with "make net/sunrpc/xprtsock.i", and strip it down to=
 a
minimal test case that still generates the Sparse warning?

- Josh Triplett


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