* real.h (EXP_BITS): Make room for...
(struct real_value): ... added canonical bit.
(struct real_format): Added pnan.
(mips_single_format, mips_double_format, mips_extended_format,
mips_quad_format): New.
* real.c: Copy p to pnan in all formats.
(get_canonical_qnan, get_canonical_snan): Set canonical bit.
(real_nan): Use pnan to compute significand's shift.
(real_identical): Disregard significand in canonical
NaNs.
(real_hash): Likewise.  Take signalling into account.
(encode_ieee_single, encode_ieee_double, encode_ieee_quad):
Disregard significand bits in canonical NaNs.  Set all bits of
canonical NaN if !qnan_msb_set.
(encode_ibm_extended, decode_ibm_extended): Likewise.  Use
qnan_msb_set to tell the base double format.
(ibm_extended_format): Use 53 as pnan.
(mips_single_format, mips_double_format, mips_extended_format,
mips_quad_format): Copied from the corresponding ieee/ibm
formats, with qnan_msb_set false.
* config/mips/iris6.h (MIPS_TFMODE_FORMAT): Use mips_extended_format.
* config/mips/linux64.h (MIPS_TFMODE_FORMAT): Use mips_quad_format.
* config/mips/mips.c (override_options): Use mips_single_format
and mips_double_format.  Default TFmode to mips_quad_format.
* config/mips/t-linux64 (tp-bit.c): Define QUIET_NAN_NEGATED.
* config/mips/t-irix6: Likewise.
* config/mips/t-mips (fp-bit.c, dp-bit.c): Likewise.
* config/fp-bit.c (pack_d, unpack_d): Obey it.

From-SVN: r65146