[COMMITTED] tilegx: enable wordsize-64 support for ieee745 dbl-64.

[Joseph Myers]

On Tue, 23 Dec 2014, Chris Metcalf wrote:

> I missed this during the initial port.  Some testing shows that
> enabling this mode does, unsurprisingly, yield some nice speedups
> on the math functions in question.

I take it that the ABI on tilegx32 allows the lround alias to llround 
(that is, the upper 32 bits of a return value are unspecified, so that 
when an out-of-range value is passed in the return value always acts 
consistently like some value of type long rather than causing undefined 
behavior in the caller as it would if the ABI requires sign extension or 
zero extension but the result isn't properly extended)?  (That alias 
wouldn't be valid on MIPS n32, as all 32-bit values have to be 
sign-extended in registers - it's architecturally undefined how 32-bit 
instructions behave on 64-bit MIPS when given registers that aren't 
properly sign-extended.)

-- 
Joseph S. Myers
joseph@codesourcery.com