[PATCH 0/3] Improvements to __ibm128 on PowerPC

[Michael Meissner <meissner@linux.ibm.com>]

The following 3 patches improve __ibm128 on the PowerPC GCC compiler:

The first patch allows the use of the __ibm128 keyword on non-VSX systems.
Originally, the __ibm128 keyword was only enabled when the IEEE 128-bit
floating point is enabled.  Sometime back in the GCC 12 development period,
Segher asked that the __ibm128 keyword be allowed in older systems that don't
support IEEE 128-bit.  This patch allows __ibm128 to be used if either IEEE
128-bit is enabled or long double used the IBM 128-bit format.

The second patch fixes PR target/105334.  This PR complains that the __ibm128
keyword is not defined on a system that uses IEEE 128-bit long double, but the
user used the -msoft-float option.  This patch removes the checks for hardware
floating point support in IBM 128-bit long double support, and also enables the
__ibm128 keyword.  The existing test gcc.target/powerpc/pr105334.c will now
pass on a system using IEEE 128-bit long double.

The third patch uses the 'w' suffix for __ibm128 constants.  It turns out we
had documented using the 'w' suffix for __ibm128, but we had never implemented
it.

I have tested these patches on the following systems:

    1)	LE Power10 using --with-cpu=power10 --with-long-double-format=ieee
    2)	LE Power10 using --with-cpu=power9  --with-long-double-format=ibm
    3)	LE Power10 using --with-cpu=power8  --with-long-double-format=ibm
    4)	LE Power10 using --with-cpu=power10 --with-long-double-format=ibm
    5)	LE Power9  using --with-cpu=power9  --with-long-double-format=ibm
    6)	BE Power8  using --with-cpu=power8  --with-long-double-format=ibm
    7)	BE Power8  using --with-cpu=power5  --with-long-double-format=ibm

There were no regressions in the build or in the tests.  On the power10 with
long double using the IEEE 128-bit format, pr105334.c now runs where it
previously failed.

Can I check these patches into the trunk?

Did we want to back port these changes to older GCC's?

-- 
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: meissner@linux.ibm.com