On Sun, Oct 26, 2014 at 12:25 AM, Ludovic Courtès <l...@gnu.org> wrote:
> I think ATLAS should do like GMP, libc, etc.: build all the possible
> variants, and then use IFUNC or a similar mechanism to select the right
> variant at load time.
I would like to highlight two points:
1. there are many variants (see below).
2. even for the same configure time configuration, the build phase
does not necessarily produce identical libraries all the time. The
build phase tries many variants of algorithms, times them and picks
the best performing one. The result may be different depending on the
overall performance of the system such as on memory access time, and
several other factors.
Here the list of configure time variants:
$ ./xprint_enums
Architectural enums (Config's enum MACHTYPE):
0 = 'UNKNOWN'
1 = 'POWER3'
2 = 'POWER4'
3 = 'POWER5'
4 = 'PPCG4'
5 = 'PPCG5'
6 = 'POWER6'
7 = 'POWER7'
8 = 'POWERe6500'
9 = 'IBMz9'
10 = 'IBMz10'
11 = 'IBMz196'
12 = 'x86x87'
13 = 'x86SSE1'
14 = 'x86SSE2'
15 = 'x86SSE3'
16 = 'P5'
17 = 'P5MMX'
18 = 'PPRO'
19 = 'PII'
20 = 'PIII'
21 = 'PM'
22 = 'CoreSolo'
23 = 'CoreDuo'
24 = 'Core2Solo'
25 = 'Core2'
26 = 'Corei1'
27 = 'Corei2'
28 = 'Corei3'
29 = 'Atom'
30 = 'P4'
31 = 'P4E'
32 = 'Efficeon'
33 = 'K7'
34 = 'HAMMER'
35 = 'AMD64K10h'
36 = 'AMDLLANO'
37 = 'AMDDOZER'
38 = 'AMDDRIVER'
39 = 'UNKNOWNx86'
40 = 'IA64Itan'
41 = 'IA64Itan2'
42 = 'USI'
43 = 'USII'
44 = 'USIII'
45 = 'USIV'
46 = 'UST1'
47 = 'UST2'
48 = 'UnknownUS'
49 = 'MIPSR1xK'
50 = 'MIPSICE9'
51 = 'ARMv7'
Operating System enums (Config's enum OSTYPE):
0 = 'UNKNOWN'
1 = 'Linux'
2 = 'SunOS'
3 = 'SunOS4'
4 = 'OSF1'
5 = 'IRIX'
6 = 'AIX'
7 = 'Win9x'
8 = 'WinNT'
9 = 'Win64'
10 = 'HPUX'
11 = 'FreeBSD'
12 = 'OSX'
Compiler integer defines:
0 = 'ICC'
1 = 'SMC'
2 = 'DMC'
3 = 'SKC'
4 = 'DKC'
5 = 'XCC'
6 = 'GCC'
7 = 'F77'
ISA extensions are combined by adding their values together (bitvector):
none: 1
VSX: 2
AltiVec: 4
AVXMAC: 8
AVXFMA4: 16
AVX: 32
SSE3: 64
SSE2: 128
SSE1: 256
3DNow: 512
NEON: 1024
> That doesn’t answer your initial question, though. For now, I think
> it’s OK to let it do its configure-time tuning and add a statement in
> the description about substitutes, unless other packages depend on it
> (in the former case, people would be installing it explicitly, so they
> would most likely know what they’re doing.)
I'm preparing numpy/scipy and they depend on ATLAS. But initially it
will be independent.
Regards,
Fede
