Re: wish: gcc_jit_type_get_atomic

[Basile Starynkevitch <basile@starynkevitch.net>]

On 05/20/2016 01:46 PM, Basile Starynkevitch wrote:
>
> My feeling (but I might be wrong) is that GCCJIT should give some way 
> to retrieve that __ATOMIC_SEQ_CST. Apparently it is a magic 
> preprocessor symbol (perhaps GCC specific!) implemented in 
> gcc/cppbuiltin.c (near line 68, defined as MEMMODEL_SEQ_CST); but if I 
> understand correctly GCCJIT does not give access to the compiler's 
> magic preprocessor symbols.
>
> I feel that GCCJIT might want to have a function like
> int gccjit_atomic_seq_cst_value(); // value of __ATOMIC_SEQ_CST in the 
> GCC used by GCCJIT
> or perhaps a more general function
> int gccjit_compiler_magic_int(const char*);
> that I would call as gccjit_compiler_magic_int("__ATOMIC_SEQ_CST");

FWIW, there is a dirty hack to get that. On a Debian system with both 
libgccjit-6-dev & gcc-6-plugin-dev packages installed the 
/usr/lib/gcc/x86_64-linux-gnu/6/plugin/include/coretypes.h header file 
(provided by libgccjit-6-dev) defines an enum memmodel with 
MEMMODEL_SEQ_CST = 5; So I guess that I could use that MEMMODEL_SEQ_CST 
as an argument to gcc_jit_context_new_rvalue_from_int.

But some distributions don't package GCC plugin headers (in particular, 
in the past, some GCC versions on some Redhat systems disabled plugins 
in GCC; I don't know if that is true today). And at least, it is not 
documented that GCCJIT is related to GCC plugins.

Regards.

-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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