Re: [Qemu-devel] [PATCH 04/10] tcg/mips: don't use global pointer

[Aurelien Jarno]

On Fri, Sep 21, 2012 at 11:18:39AM -0700, Richard Henderson wrote:
> On 09/21/2012 09:43 AM, Aurelien Jarno wrote:
> > Don't use the global pointer in TCG, in case helpers try access global
> > variables.
> 
> Err.. isn't the GP computed at the entry point of functions that need to use 
> it?

I read that GP should be preserved when checking the MIPS ABI for other
things. But you are right, GCC emit code to recompute GP at the entry point
of the function when used later. I guess I checked the wrong ABI.

> That said, under n32 and n64 abis it is call-saved; under o32 it's 
> call-clobbered.
> So by itself this is still a fix for new-abis, since we don't save it in the
> prologue.  OTOH, this does suggest an alternate solution... ;-)
> 

Supporting n32 or n64 implies a lot more things than that. So I guess
I'll just drop that patch for now.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net