Re: [Tinycc-devel] Multiple, threaded LibTCC states

[Michael Matz]

Hello,

On Thu, 3 Dec 2020, Jonathan Levi wrote:

> I am using LibTCC to compile runtime defined functions for a rendering layer
> of a project of mine.  I compile many of these functions in parallel. 
> LibTCC is crashing with exit code -11, at what appears to be when execution
> is passed to LibTCC on multiple threads, at the same time.  It happens when
> I try to compile multiple functions at the same time, or compile a function
> at the same time as calling another already compiled function.  (Although
> calling multiple functions at the same time does not appear to exit.)
>
> Should LibTCC work in multiple threads?  I wonder whether I am just missing
> a dependency.

It's quite possible that there are still bugs with that, but in general it 
should work.  There's actually a testcase that compiles tcc with itself 
20 times with 20 threads, so that makes sure it normally works.

One thing to keep in mind: each thread must use a different top-level 
TCCState, i.e. tcc_new result, you can't share that one between threads 
(or at least can't use the same TCCState concurrently).  There is a little 
shared global state in TCC, but all accesses to that one are (supposed to 
be) protected by appropriate mutexes (fairly coaerse grained).

You also want to use the mob branch of tcc, not the 0.9.27 release.  And 
you may want to have a look at tests/libtcc_test_mt.c to see if you're 
using libtcc like that testcase does.


Ciao,
Michael.