alloca and labels as values

Marc Nieper-Wißkirchen marc@nieper-wisskirchen.de
Mon Jan 1 00:00:00 GMT 2018


> > Is `alloca' currently  possible with libgccjit? I haven't found
 > > anything
 > > about it in the documentation. If it isn't possible at the moment,
 > > I'd
 > > love to see it added to libgccjit very soon. (One use case would be
 > > a
 > > compiler like the Chicken Scheme compiler that employs Cheney-on-the-
 > > MTA
 > > where the youngest heap generation is allocated on the stack.)
 >
 > I haven't tested this, but I believe you ought to be able to access it
 > via the "__builtin_alloca" builtin, via something like:
 >
 >
 > gcc_jit_function *fn_alloca
 >   = gcc_jit_context_get_builtin_function (ctxt, "__builtin_alloca");
 >
 >
 > gcc_jit_rvalue *call =
 >         gcc_jit_context_new_call (ctxt,
 >                                   loc,
 >                                   fn_alloc_a,
 >                                   1, &size_t_arg);
 >
 >  gcc_jit_block_add_assignment (block, loc,
 >                                dst_lvalue,
 >                                call);
 >
 > ...or something like that.


That was helpful; thank you very much. I overlooked the procedure 
`gcc_jit_context_get_builtin_function' in the documentation. Is there a 
way to determine which builtins are supported by a specific version of 
the library or would I have to add a few scripts to my project's 
`configure.ac <http://configure.ac>' myself?

-- Marc

P.S.: Another thing I wasn't able to find so far was how to declare 
variables as thread local (i.e. GCC's __thread or C11's thread_local).



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