https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96983
--- Comment #18 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #17)
> const poly_uint16_pod mode_precision[NUM_MACHINE_MODES] =
> {
> ...
> { 4 * BITS_PER_UNIT }, /* SF */
> { 8 * BITS_PER_UNIT }, /* DF */
> { 126 }, /* KF */
> { 127 }, /* TF */
> { 128 }, /* IF */
> ...
>
> Why aren't KFmode, IFmode and TFmode all 128??? Mike?
This comes from rs6000-modes.h:
/* We order the 3 128-bit floating point types so that IFmode (IBM 128-bit
floating point) is the 128-bit floating point type with the highest
precision (128 bits). This so that machine independent parts of the
compiler do not try to widen IFmode to TFmode on ISA 3.0 (power9) that has
hardware support for IEEE 128-bit. We set TFmode (long double mode) in
between, and KFmode (explicit __float128) below it.
We won't encounter conversion from IEEE 128-bit to IBM 128-bit because we
don't have insns to support the IBM 128-bit aritmetic operations. */
#ifndef RS6000_MODES_H
#define RS6000_MODES_H 1
#define FLOAT_PRECISION_IFmode 128
#define FLOAT_PRECISION_TFmode 127
#define FLOAT_PRECISION_KFmode 126
