Re: [xine-devel] Re: [testsuite] compilation failure : greedyh.asm

[Miguel F. <mfr...@gm...>]

hi Hans, Thibaut,

On 6/4/05, Hans-Dieter Kosch <hd...@t-...> wrote:
> The older compilers do not understand the syntax
>    __asm__ ( "command %[name0]" : : [name0] "x"(arg0) )
> They only understand
>    __asm__ ( "command %0" : : "x"(arg0) )

interesting. i wasn't aware of this newer syntax.
it is definitely much better - having to remember the argument order is stu=
pid.

> This is really not very elegant, but maybe there's a workaround with
> #define and/or #ifdef ?

yes and no.

i tried what you suggest, adding #defines:
#define asmLastAvg            "%0"
#define asmL1                 "%1"
#define asmL3                 "%2"
#define asmL2P                "%3"
... and so on.

unfortunately it still doesn't fix compilation on gcc 2.95. now it
triggers a different gcc's idiosyncrasy: "more than 10 operands in
`asm'". some web searching revealed the following interesting
discussion (basically gcc folks considered that %[0-9] followed by
numbers was a valid syntax).

http://gcc.gnu.org/ml/gcc-bugs/2000-03/msg01000.html
http://gcc.gnu.org/ml/gcc-bugs/2000-03/msg01001.html

it seems that newer gcc's don't suffer from this "documented limitation".

now back to 2005, we have basically two options:

1) require gcc > 3.x for compiling xine.
2) converting some of these arguments to access variables directly.
the problem is that it requires moving these variables to static
globals, and i don't know if it would have any impact on performance.
greedyh.asm comment says: "in tight loop some vars are accessed faster
in local storage"

i will investigate implementing (2). any ideas/comments would be appreciate=
d.

Miguel