Re: [RFA] mips-irix SEGV: long doubles are 128 bits long on IRIX

[cgd@broadcom.com]

At Thu, 22 Jul 2004 00:49:31 +0000 (UTC), "Daniel Jacobowitz" wrote:
> I don't think NetBSD even supports mips64.  Not in GCC HEAD, at least.

NetBSD doesn't support n32 or n64, or have any real support for
'mips64' at all, at this time (AFAIK).


> According to GCC long double is 128-bit for all n64 and n32 targets.

Note that the actual 'long double' format is *different* between
Linux and IRIX, AFAIK.

On Linux (w/ glibc), it's 128 bits in the typical IEEE format -- I
don't recall what the exact terminology or specification for 128-bit
IEEE-style value is, tho.  (like normal double, but wider mantissa and
wider exponent.)

On IRIX, if i recall correctly, 'long double' is implemented as a
*pair of doubles*, which allows one to get somewhat-extended
precision, but doesn't allow the complete range of 128-bit IEEE-style.
(I imagine the benefit is, you can do at least some of the 'long
double' ops w/ 'double' FP ops in HW.  So, better speed... maybe.)



cgd