[gstreamer-bugs] [Bug 584174] Problems with tvtime assembler

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-good | Ver: 0.10.26

Brian Cameron changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEEDINFO




------- Comment #5 from Brian Cameron  2009-06-02 22:26 UTC -------

Ignore the "inline extern int" issue for now.  Based on discussions with the
Sun Studio compiler team, I am fairly sure this is a Sun Studio compiler bug.

However, we are having more problems compiling the deinterlace assembler code.
When compiling linear.c, I see these errors:

ube: Sun Compiler Common 12.1 SunOS_i386 2009/04/15

assertion failed in function gra_renumber_instrs() @ gra.c:7962
assert(mit_dest_reg_kind_(lf_op_(curr_instr)) == B_REGISTER)

cc: ube failed for linear.c

In talking with the Sun Studio team, they suspect that this problem is caused
by these lines in deinterlace_scanline_linear_mmxext:

    movntq_r2m (mm0, *out);
    movntq_r2m (mm2, *(out + 8));
    movntq_r2m (mm4, *(out + 16));
    movntq_r2m (mm6, *(out + 24));

This gets translated to lines like:

    __asm__ __volatile__ ( "movntq" " %%" "mm0" ", %0" : "=X" ( * out ) : );

Note that X-constraint means "Any operand whatsoever is allowed." (from
gcc.gnu.org)

This is not true: "movntq" accept a *memory* operand only.

The fact that gcc generate correct code is accidental: if you try to build
absolutely equivalent code then you will get the same errors even with gcc

    char ch_out = *out;
    __asm__ __volatile__ ( "movntq" " %%" "mm0" ", %0" : "=X" ( ch_out ) : );
    *out = ch_out;

We have different behavior with gcc and SunStudio because SunStudio in some
cases does not organize access to arguments optimally.

This is way above my head, and I am hoping that the GStreamer maintainers may
have an idea about how to fix this?Thanks for taking the time to report this
bug.


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