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*From*: David Edelsohn <dje dot gcc at gmail dot com>*To*: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>*Date*: Thu, 24 Apr 2014 14:42:45 -0400*Subject*: Re: [PATCH], Add DFP, extended divide, BCD builtins to PowerPC*Authentication-results*: sourceware.org; auth=none*References*: <20140422202119 dot GA6785 at ibm-tiger dot the-meissners dot org>

On Tue, Apr 22, 2014 at 4:21 PM, Michael Meissner <meissner@linux.vnet.ibm.com> wrote: > 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. This patch is okay. Please allow a few days on trunk before backporting to ensure that it does not expose problem on other configurations. The div[dw]e instructions could be utilized by divtidi3 and divdisi3, but GCC does not have the infrastructure for that. Thanks, David

**References**:**[PATCH], Add DFP, extended divide, BCD builtins to PowerPC***From:*Michael Meissner

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