Re: barrier macro

[Josh Triplett <josh@freedesktop.org>]

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Randy Dunlap wrote:
> (using sparse 0.3)
> 
> ./compiler-gcc.h:10:#define barrier() __asm__ __volatile__("": : :"memory")
> 
> causes this output:
> 
> 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 :
> 
> 
> Maybe sparse could allow modifiers between asm|__asm__ and the
> (...) ?

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

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


I cannot reproduce your report with the following test case (just added to 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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