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Re: Inline sqrt for ia64
Richard Henderson <rth@redhat.com> writes:
> On Sun, Oct 26, 2003 at 01:57:03AM -0700, Zack Weinberg wrote:
>> + [ ;; exponent of +1/2 in r2
>> + (set (match_dup 2) (const_int 65534))
>> + ;; +1/2 in f8
>> + (set (match_dup 3)
>> + (unspec:XF [(match_dup 2)] UNSPEC_SETF_EXP))
>
> FYI, I've considered defining an HFmode for ia64 that could
> implement this optimization automatically. The HFmode would
> be defined such that it has 16 bits of exponent and 0 bits
> of fraction.
>
> With this SETF_EXP operation represented as extendhfxf, etc,
> the code in compress_float_constant would automatically
> notice when this optimization applies.
That's a cute idea, but I wonder if it's overkill for the purpose.
And wouldn't you then have to define arithmetic operations on this
rather peculiar mode?
zw