Date: Sun, 11 Jun 2017 18:45:00 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: [PATCH] s390x: Add single instruction math functions * Rich Felker <dalias@...c.org> [2017-06-11 11:04:38 -0400]: > On Sun, Jun 11, 2017 at 12:19:55PM +0200, Szabolcs Nagy wrote: > > * Rich Felker <dalias@...c.org> [2017-06-10 22:20:44 -0400]: > > > On Sat, Jun 10, 2017 at 05:48:05PM -0400, David Edelsohn wrote: > > > > When I worked with Bobby Bingham to create the s390x port of Musl, I > > > > said that he could assume newer processors. Also, I don't believe > > > > that LLVM supports the earlier processors. I believe that he assumed > > > > some more recent instructions in other parts of the code. > > > > > > That seems doubtful; the amount of asm in musl is minimal and unlikely > > > to benefit from later ISA levels; all the instructions I see look like > > > very basic stuff that would always have been available. > > > > > > Now, what likely is accurate is your claim that nobody is using musl > > > on lower ISA levels, so maybe it doesn't matter. > > > > well i am using s390x musl with lower isa level for compile tests > > > > and it seems gas rejects unrecognized opcodes so the new inline > > asm does not compile for me. > > > > i think either musl configure should make sure the cc targets > > the right isa level or the code should handle it with ifdefs > > Do you know the right predefined macros to check the ISA level? David, > any objection to including the #if/#ifdef since at least someone seems > to want ability to build for minimum ISA level? > i see no diff between s390x-linux-musl-gcc -E -dM - and s390x-linux-musl-gcc -E -dM -march=z196 - so it's not possible to tell at compile time, but the asm is different so configure can detect it: $ s390x-linux-musl-gcc -S -xc /dev/null -o - .machinemode zarch .machine "z900" .ident "GCC: (GNU) 6.3.0" .section .note.GNU-stack,"",@progbits $ s390x-linux-musl-gcc -S -xc /dev/null -o - -march=z196 .machinemode zarch .machine "z196" .ident "GCC: (GNU) 6.3.0" .section .note.GNU-stack,"",@progbits
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