Re: [Qemu-devel] [patch] make qemu work with GCC 4

[Andreas Färber]

Hi Michael,

Am 28.08.2007 um 21:57 schrieb Michael Matz:

> the below patch let's qemu be compiled by GCC 4.2

Thanks for your effort!

> Here's some justification
>        of why that doesn't really cost performance: with three free  
> regs
>        GCC is already spilling like mad in the snippets, we just  
> trade one
>        of those memory accesses (to stack) with one other mem  
> access to
>        the cpu_state structure, which will be in cache.
>
>        Additionally I made sure that I put the least used Tx global  
> into
>        memory.  I haven't done much performance measurements but  
> noticed
>        no glaring problems.

Am I right to assume that compiling with gcc3 will still work with  
your patch? In that case your patch would enable qemu to run on gcc4- 
only platforms (where performance doesn't matter too much yet) while  
allowing to compile with gcc3 for performance reasons where necessary.

> The whole patch is against a 0.9.0-cvs version from 2007-07-09  
> (Alex might
> know the exact checkout date), so chances are that it still applies :)

What do you mean with 0.9.0-cvs? The 0.9.0 GCC4 patches for OSX/Intel  
don't apply to HEAD possibly due to some inline assembler changes,  
and if merged manually resulted in a crash...

Andreas