[vlc-devel] commit: contrib: turn off Thumb ISA for libavcodec and libmad ( Rémi Denis-Courmont )

Rafaël Carré rafael.carre at gmail.com
Sat Aug 29 22:12:28 CEST 2009

On Sat, 29 Aug 2009 22:06:38 +0300
"Rémi Denis-Courmont" <remi at remlab.net> wrote:

> I guess avcodec uses fancy ASM instructions outside of Thumb-2.

You can't use inline asm when asking GCC to build thumb because you
don't know if it will use ARM or THUMB instruction set for a specific

A solution would be to build the files containing inline ARM asm with
-mno-thumb -mthumb-interwork but you'd have to check every file

Last but not least: thumb is quite limited and considered slower than
ARM code (note thumb-2 appears to be generally faster than thumb) so
it's not advised for multimedia routines especially when you have loads
of memory available and code size doesn't matter that much.

Rafaël Carré
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