About fpr usage in mips64

Heiher admin@heiher.info
Wed Nov 30 09:42:00 GMT 2011


The o32 abi programs could only use even-numbered floating-point
registers by appointment. The GCC generate assembly source  code using
odd-numbered floating-point register when I -march=mips64 and
-mabi=32. Every double floating-point instructions will use 32-bit
even/odd-numbered paired 64-bit fpr when 0 = bit FR in Status
register. However kernel set bit FR to a thread at loading ELF for N32
or 64 only. In other words, o32 abi process can't use odd-numbered
fpr.

How ought I to act? Thanks!

On Sun, Nov 27, 2011 at 1:20 PM, Ian Lance Taylor <iant@google.com> wrote:
> Heiher <admin@heiher.info> writes:
>
>> How to use even-numbered floating-point registers only in march=mips64
>> and mabi=o32 ?
>
> As far as I know there is no gcc option for that.  Why do you want to do
> that?  Does -msingle-float do what you want?
>
> I think it would be fairly easy to modify the source code to use only
> the even-numbered FP registers.
>
> Ian



-- 
Best regards!
Heiher



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