Re: [Qemu-devel] WE NEED GCC 4 please

[Andreas Färber]

Am 21.01.2008 um 12:18 schrieb Johannes Schindelin:

> The miniops right now are implemented as plain C commands.  If the  
> "good"
> gcc guys would not have insisted on not having an option to force the
> "ret" or "jmp" statement at the end of the function, we could use  
> them for
> _all_ processors.
>
> As it is, Fabrice's code generator will most likely be something  
> similar
> to Paul's qops, which means that you have to invent a "primitive C" in
> which to write the miniops, and you will have to write a backend for
> _each_ and _every_ host CPU you support.

Has anyone looked into the idea of manually generating machine  
instructions through preprocessor macros at runtime, then jumping  
there? That's what the Mono JIT does, leaving C compilers completely  
out of the picture.

But apart from it being lots of work to start from scratch and for  
each and every host CPU, if translating at instruction level rather  
than method level it would require lots of jumps between instruction  
decoding and generated instructions though.

Andreas