[Patch] libffi-MIPS: More n64 fixes.

[David Daney]

Richard Sandiford wrote:
> David Daney <ddaney@avtrex.com> writes:
>   
>> As with my patch from yesterday, this patch  fixes several failures in
>> the libffi testsuite caused by the use of a 32 bit add instruction on a
>> 64 bit pointer value causing the upper 32 bits to be clobbered.  At the
>> same time I took the liberty of converting several 'add a,b,0' to 'move
>> a,b'.  Although these were not causing any immediate problems, I think
>> it makes the code more understandable.
>>     
>
> Agreed.  It also saves worrying about whether the value we're moving
> is really a 32-bit one.  However, I couldn't help noticing that all
> the moves could be folded into neighbouring instructions.  E.g.:
>
> 	REG_L	t4, 3*FFI_SIZEOF_ARG($fp)  # load the flags word
> 	move	t6, t4			   # and copy it into t6
>
> 	and	t4, ((1<<FFI_FLAG_BITS)-1)
>
> simplifies to:
>
> 	REG_L	t6, 3*FFI_SIZEOF_ARG($fp)  # load the flags word
>
> 	and	t4, t6, ((1<<FFI_FLAG_BITS)-1)
>
> while things like:
>
> 	move	t4, t6
> 	SRL	t4, 1*FFI_FLAG_BITS
>
> simplify to:
>
> 	SRL	t4, t6, 1*FFI_FLAG_BITS
>
> As well as being more efficient, it seems slightly more readable
> (at least to me).
>
> OK with that change, thanks.
>   
This is the version I committed:

2007-12-08  David Daney  <ddaney@avtrex.com>

        * src/mips/n32.S (ffi_call_N32):  Replace dadd with ADDU, dsub with
        SUBU, add with ADDU and use smaller code sequences.


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