Re: [Qemu-devel] [PATCH V4 00/11] Qemu MIPS ASE DSP Support

[Richard Henderson]

On 03/30/2012 07:42 AM, Richard Henderson wrote:
> All of your helpers, whereever they receive or return a register value, need 
> to use
> type target_ulong and the DEF_HELPER lines need to use "tl".  All of the 
> mips32
> helpers you've written so far that return values need to make sure to 
> sign-extend
> their results from 32-bits.

Hmm, actually I wonder if that's the best advice.

It looks like your translated code isn't going to work well with r0.

I suspect it would be better to add a gen_load_gpr32 function for the
translator that (1) sets 0 for r0, (2a) copies the register for mips32,
and (2b) truncates the register for mips64.  That way 32-bit hosts do
not need to use 64-bit arithmetic when unnecessary.  You'd need a
gen_store_gpr32 function as well, which for mips64 sign-extends the value.


r~