Re: [Mesa3d-dev] dynamic code generation with gcc

[Stephen J B. <sj...@li...>]

On 8 Mar 2001, Josh Vanderhoof wrote:

> Keith Whitwell <ke...@va...> writes:
> 
> > You may want to avoid sharing the nv-specific stuff, but any progress on otf
> > codegen has lots of application beyond that extension -- I can think of a
> > dozen uses for something like this.
> 
> What would you guys think of putting stuff like this in Mesa?
 
<snip compile-on-the-fly stuff>

I think the problems are significant:

  1) Whilst it'll (perhaps) improve frame rates once the code
     has been compiled, you could easily get a several-second
     pause when you first refer to something that triggers this
     action.  In some applications, that would be disasterous.

  2) You are depending on picking a valid compiler correctly and
     that there is a compiler on the system at all.  There are
     many (and growing) platforms where software-only-Mesa might
     make sense (eg http://www.agendacomputing.com - a Linux-based
     PDA) where no compiler exists on the target machine.

I believe that when SGI do this kind of thing in their Windoze
software-OpenGL, they were generating x86 machine code directly
into memory without using compilers or even assemblers.  That's
a viable technique...at least for the most popular CPU types.

----
Steve Baker                      (817)619-2657 (Vox/Vox-Mail)
L3Com/Link Simulation & Training (817)619-2466 (Fax)
Work: sj...@li...           http://www.link.com
Home: sjb...@ai...       http://web2.airmail.net/sjbaker1