[Octave-patch-tracker] [patch #8395] Work-in-progress port of Octave JIT to libgccjit

[David Malcolm]

URL:
  <http://savannah.gnu.org/patch/?8395>

                 Summary: Work-in-progress port of Octave JIT to libgccjit
                 Project: GNU Octave
            Submitted by: dmalcolm
            Submitted on: Fri 14 Mar 2014 10:52:30 PM GMT
                Category: None
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any

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Details:

I've been experimentally porting Octave's existing JIT to libgccjit:
  http://gcc.gnu.org/wiki/JIT

I thought it was time I posted what I have.  It compiles and runs, though
there are plenty of issues.

Notes:
  * I split out HAVE_LLVM to HAVE_JIT, HAVE_LLVM, and HAVE_GCCJIT

  * both the LLVM *and* gccjit implementations are built within the same
    build.  This is clearly overkill, but is handy for debugging in that
    one can compare what each of the two implementation produces.

    The resulting preprocessor gunk is deeply ugly.  Perhaps it could be
    simplified by making choice of JIT backend be a configure-time thing,
    rather than trying to support both within one process.

  * jit.tst runs, but I had to hack out some of the tests for now.  It
    tries to run both the LLVM and gccjit compiler on the IR.  It then
    tries to run the gccjit-built code, if that succeeded; failing that
    the LLVM-built code.

    It fails near the end here:
      jit fail: Too many parameter to function
        ***** testif HAVE_JIT
       jit_failure_count (0)
       assert (id (1), 1);
       assert (id (1+1i), 1+1i);
       assert (id (1, 2), 1);
       assert (jit_failure_count, 0);
      !!!!! test failed
      ASSERT errors for:  assert (jit_failure_count,0)
    in type-inference on the id (1, 2) I believe, before my code; do other
    people see this?

  * I've only implemented JIT-compilation of loops for now, not functions.
    I hope the latter is fairly easy to add, but I wanted to post
    something.

  * lots of FIXMEs, TODOs and other cruft; sorry (e.g. the configure.ac
    "test", which for now just hardcodes a location of a libgccjit
    checkout)

  * libgccjit currently requires function names to be valid C
    identifiers, so I changed some functions to obey this restriction

  * there's a name-mangling issue with gripe_divide_by_zero, which for me
    gets name-mangled by the C++ compiler (to "_Z20gripe_divide_by_zerov").
    For now I have a horrible hack I'm applying on the libgccjit side which
    special-cases this, and applies the mangling when referencing this
    symbol (am attaching it)

Clearly this isn't ready yet, but I wanted some feedback from the Octave
maintainers on the direction of this.



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File Attachments:


-------------------------------------------------------
Date: Fri 14 Mar 2014 10:52:30 PM GMT  Name:
port-of-octave-jit-to-libgccjit.patch  Size: 121kB   By: dmalcolm
Work-in-progress port of Octave JIT to libgccjit (patch against
&quot;default&quot;)
<http://savannah.gnu.org/patch/download.php?file_id=30906>

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