Re: libgccjit 5.2 on Mac OSX Yosemite

[David Malcolm <dmalcolm@redhat.com>]

On Thu, 2015-08-13 at 22:04 +0100, Dibyendu Majumdar wrote:
> Dave,
> 
> I was able to get the JIT compiler working on Mac OS X Yosemite using
> your patch. Attached is the patched home-brew script I used.

Thanks; glad it's working.

As noted in the followup I posted, I've now committed the patch to both
branches.

I've also created this pull request:
  https://github.com/Homebrew/homebrew/pull/42924
requesting that they bring in your change to the homebrew gcc.rb recipe.



> When I reported the JIT compilation speed I reported earlier I forgot
> to mention that I was running on SSD disks. With laptop hard disk
> (5400 rpm) the JIT compiler is obviously even slower - the Lua Tests
> that ran in 1 second in interpreted mode took 1648 seconds in JIT
> mode. Timings below. I think that your work on getting rid of the
> process invocations should be given highest priority as JIT
> compilation times need to be improved significantly.

(nods)

If you get a chance to try gcc trunk, it might be interesting to try the
profiling hooks I added:
  https://gcc.gnu.org/ml/jit/2015-q3/msg00134.html

to see the libgccjit profile for Ravi.

In particular, I'm hoping that the Ravi profile is sufficiently similar
to that from test-benchmark.c so that my optimizations will benefit Ravi
(or maybe there are other unexpected things going on?)

Out of interest, how does this compare to LLVM.  IIRC you had said
libgccjit was taking about 5x longer than LLVM; is that still the case?

> Interpreted mode:
> 
> test done on 13/08/2015, at 21:23:43
> Lua 5.3
> 64-bit integers, 64-bit floats
> cleaning all!!!!
> ......    ---- total memory: 60.0K, max memory: 2.7M ----
> total time: 0.57s (wall time: 1s)
> 
> 
> JIT mode:
> testing date/time
> test done on 13/08/2015, at 21:51:11
> Lua 5.3
> 64-bit integers, 64-bit floats
> cleaning all!!!!
> ......    ---- total memory: 59.9K, max memory: 2.7M ----
> total time: 659.17s (wall time: 1648s)