Bug #14440: --jit does not work by default on OpenBSD due to use of gcc instead of clang

• Status: Closed
• Assignee: k0kubun (Takashi Kokubun)
• Target version: -
• ruby -v: ruby 2.6.0dev (2018-02-05 trunk 62211) [x86_64-openbsd]
• Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN

[jeremyevans0 (Jeremy Evans)]

On OpenBSD, when using just --jit, ruby issues a warning message to $stderr:

$ ruby --jit -e 'p 1'                
.ext/include/x86_64-openbsd/rb_mjit_min_header-2.6.0.h:2924: error: wrong number of arguments specified for '__deprecated__' attribute
compilation terminated due to -Wfatal-errors.
1

This is probably because MJIT doesn't work on old versions of GCC:

$ gcc -v
Reading specs from /usr/lib/gcc-lib/amd64-unknown-openbsd6.2/4.2.1/specs
Target: amd64-unknown-openbsd6.2
Configured with: OpenBSD/amd64 system compiler
Thread model: posix
gcc version 4.2.1 20070719

When using --jit --jit-cc=clang, there are no problems:

$ ruby --jit --jit-cc=clang -e 'p 1'
1

Either --jit should be made to work with older GCC versions, or older GCC versions should be skipped. It seems like for now, skipping older GCC versions would be easier.

[shevegen (Robert A. Heiler)]

Agreed. May be simpler to just notify the user which GCC versions are
currently supported; and if it works the modern GCC, one can look to
see that older GCC versions could also use --jit.

[k0kubun (Takashi Kokubun)]

Whether is the ruby compiled from gcc or clang? A known issue is that using MJIT header generated from different compiler may not work. So I may drop selecting cc in the future.

If the ruby is built from the old gcc and broken with --jit-cc=gcc, we need to fix it.

[jeremyevans0 (Jeremy Evans)]

k0kubun (Takashi Kokubun) wrote:

Whether is the ruby compiled from gcc or clang? A known issue is that using MJIT header generated from different compiler may not work. So I may drop selecting cc in the future.

If the ruby is built from the old gcc and broken with --jit-cc=gcc, we need to fix it.

clang is the system compiler on OpenBSD on the most common architectures. So it sounds like --jit should use clang by default in that case, since that is what is used to compile ruby itself.

[k0kubun (Takashi Kokubun)]

• Assignee set to k0kubun (Takashi Kokubun)

[k0kubun (Takashi Kokubun)]

• Status changed from Open to Closed

Applied in changeset trunk|r62230.

---

mjit.c: prefer using --jit-cc=clang if clang

is defined. This is basically for OpenBSD.

Failure on using the compiler which is
not used for Ruby compilation is not supported.

[Bug #14440]