[PATCH], Add DFP, extended divide, BCD builtins to PowerPC

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

This patch adds the last set of instructions in the ISA 2.05 (power6), ISA 2.06
(power7), and ISA 2.07 (power8) specifications as builtins.  As far as I know,
this completes the set of user space instructions that users might want to use
to the GCC compiler.  In addition, I added some 128-bit pack and unpack
functions for the use of library maintainers that need to deal with the 128-bit
types as two 64-bit words.

The builtins added are:

1. Extended divide instructions added in ISA 2.06:
==================================================

int __builtin_divwe (int, int);
int __builtin_divweo (int, int);
unsigned int __builtin_divweu (unsigned int, unsigned int);
unsigned int __builtin_divweuo (unsigned int, unsigned int);

long __builtin_divde (long, long);
long __builtin_divdeo (long, long);
unsigned long __builtin_divdeu (unsigned long, unsigned long);
unsigned long __builtin_divdeuo (unsigned long, unsigned long);

2. BCD instructions added in ISA 2.06:
======================================

unsigned int cdtbcd (unsigned int);
unsigned int cbcdtd (unsigned int);
unsigned int addg6s (unsigned int, unsigned int);

3. Decimal floating point instructions added in ISA 2.05:
=========================================================

_Decimal64 __builtin_dxex (_Decimal64);
_Decimal128 __builtin_dxexq (_Decimal128);
_Decimal64 __builtin_ddedpd (int, _Decimal64);
_Decimal128 __builtin_ddedpdq (int, _Decimal128);
_Decimal64 __builtin_denbcd (int, _Decimal64);
_Decimal128 __builtin_denbcdq (int, _Decimal128);
_Decimal64 __builtin_diex (_Decimal64, _Decimal64);
_Decimal128 _builtin_diexq (_Decimal128, _Decimal128);
_Decimal64 __builtin_dscli (_Decimal64, int);
_Decimal128 __builitn_dscliq (_Decimal128, int);
_Decimal64 __builtin_dscri (_Decimal64, int);
_Decimal128 __builitn_dscriq (_Decimal128, int);

4. 128-bit pack/unpack functions:
=================================

double __builtin_unpack_longdouble (long double, int);
double __builtin_longdouble_dw0 (long double);
double __builtin_longdouble_dw1 (long double);
long double __builtin_pack_longdouble (double, double);

unsigned long long __builtin_unpack_dec128 (_Decimal128, int);
_Decimal128 __builtin_pack_dec128 (unsigned long long, unsigned long long);

unsigned long long __builtin_unpack_vector_int128 (vector __int128_t, int);
vector __int128_t __builtin_pack_vector_int128 (unsigned long long,
                                                unsigned long long);

5. BCD add/subtract instructions added in ISA 2.07:
===================================================

vector __int128_t __builtin_bcdadd (vector __int128_t, vector__int128_t);
int __builtin_bcdadd_lt (vector __int128_t, vector__int128_t);
int __builtin_bcdadd_eq (vector __int128_t, vector__int128_t);
int __builtin_bcdadd_gt (vector __int128_t, vector__int128_t);
int __builtin_bcdadd_ov (vector __int128_t, vector__int128_t);
vector __int128_t bcdsub (vector __int128_t, vector__int128_t);
int __builtin_bcdsub_lt (vector __int128_t, vector__int128_t);
int __builtin_bcdsub_eq (vector __int128_t, vector__int128_t);
int __builtin_bcdsub_gt (vector __int128_t, vector__int128_t);
int __builtin_bcdsub_ov (vector __int128_t, vector__int128_t);

Note, there are two minor bugs that I found in writing the test cases, that I
will submit as bugzillas to be fixed eventually.

The first bug is the PowerPC extension: 'vector __int128_t' does not seem to
work with LTO, which shows up when I wrote the test pack01.c.  I suspect this
is some problem with the way 'vector' is implemented as a conditional keyword,
along with the C family private type __int128_t that doesn't work together.  I
used the vector_size attribute instead of the 'vector' keyword to work around
this.

The second bug is that pack01.c won't generate the correct code on power7
little endian (the words get swapped in going between GPRs and VSX registers).
On power8 it works, since we have the direct move instructions.  Since little
endian powerpc 64-bit is officially only supported on power8 and above, I just
made the test require power8.

I've done bootstrap and make check with no regressions on power7 big endian,
power8 big endian, and power8 little endian systems.  Can I install the
patches?  I would prefer to upgrade both 4.8 and 4.9 as well, since we have
moved the power8 enablement to those branches.

If thse patches are too big, I can re-forumulate them as a series of smaller
patches.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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