Re: [patch, fortran] Load scalar intent-in variables at the beginning of procedures

[Janne Blomqvist]

On Thu, Nov 21, 2019 at 12:18 AM Janne Blomqvist
<blomqvist.ja...@gmail.com> wrote:
>
> On Wed, Nov 20, 2019 at 11:35 PM Thomas König <t...@tkoenig.net> wrote:
> > (Why do we zero %eax
> > before each call? It should not be a variadic call right?)
>
> Not sure. Maybe some belt and suspenders thing? I guess someone better
> versed in ABI minutiae knows better. It's not Fortran-specific though,
> the C frontend does the same when calling a void function.

Ah, scratch that, it is some varargs-thing, I had forgot that a C
function with no arguments or lacking a prototype is considered a
varargs. The code

void foo();
void bar(void);

void testfoo()
{
foo();
}

void testbar()
{
bar();
}

void testunprototyped()
{
baz();
}


generates code (elided scaffolding):

testfoo:
    xorl %eax, %eax
    jmp foo
testbar:
    jmp bar
testunprototyped:
    xorl %eax, %eax
    jmp baz


So probably this is due to the Fortran procedures lacking an interface
being considered varargs by the caller.  Starts to smell like some
leftover from PR 87689?

-- 
Janne Blomqvist