Re: Native compiler - passing command line options to C compiler

[Eli Zaretskii]

> From: Arthur Miller <arthur.miller@live.com>
> Date: Sun, 29 Aug 2021 23:47:56 +0200
> 
> after the few mails the other day, I wasn't really sure if Andrea is going to
> implement it and when. I thought it was rather a tedious manual labour and 
> maybe
> not so important, so I took me a liberty to implement this myself in my own, 
> so
> called, personal copy of Eamcs sources.

Thanks.

> I am not sure if I have done it correctly though, I appreciate if Andrea have
> time to take a look; I have just mainly copied your code for backend options. 
> It
> seems to work for me, with a minor remark: When I pass a valid option, 
> "native",
> in place where it should go, I get an invalid option error. Gcc even lists it 
> in
> the error message as a valid option. Another option "skylake" works just 
> fine. This seems to vary between flags. I am not sure if this is some encoding
> error from Emacs to libgccjit, or if it is some bug in libgccjit, or is it 
> just
> my brain having dumps.

I guess -march=native is something handled by GCC itself, and here we
don't have it?  If you want to be sure, ask this question on the GCC
list, or report as a bug to their Bugzilla.

> +break your code. Use at own risk.
                  ^^
Two spaces between sentences.

> +DEFUN ("comp-native-compiler-options-effective-p",
> +       Fcomp_native_compiler_options_effective_p,
> +       Scomp_native_compiler_options_effective_p,
> +       0, 0, 0,
> +       doc: /* Return t if `comp-native-compiler-options' is effective.  */)
> +  (void)
> +{
> +#if defined (LIBGCCJIT_HAVE_gcc_jit_context_add_command_line_option)  \
> +  || defined (WINDOWSNT)  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
> +  if (gcc_jit_context_add_command_line_option)
> +    return Qt;
> +#endif

The emphasized part doesn't look right: we did that elsewhere because
the options we pass there work around bugs that happen also in
versions that don't report libgccjit version.  But here this is not
needed, and the version check isn't present anyway.  So the WINDOWSNT
special handling should be removed, I think.

> +static void
> +add_compiler_options (void)
> +{
> +  Lisp_Object options = Fsymbol_value (Qnative_comp_compiler_options);
> +
> +#if defined (LIBGCCJIT_HAVE_gcc_jit_context_add_command_line_option) \
> +  || defined (WINDOWSNT)
> +  load_gccjit_if_necessary (true);
> +  if (!NILP (Fcomp_native_compiler_options_effective_p ()))

Likewise here.  And since Fcomp_native_compiler_options_effective_p
already does this test, why did you need to have another test outside
it?

> +  /* Captured `comp-native-driver-options' because file-local.  */
> +#if defined (LIBGCCJIT_HAVE_gcc_jit_context_add_command_line_option) \
> +  || defined (WINDOWSNT)
> +  options = comp.compiler_options;
> +  if (!NILP (Fcomp_native_compiler_options_effective_p ()))
> +    FOR_EACH_TAIL (options)
> +      gcc_jit_context_add_command_line_option (comp.ctxt,
> +                                               /* FIXME: Need to encode
> +                                                  this, but how? either
> +                                                  ENCODE_FILE or
> +                                                  ENCODE_SYSTEM.  */
> +                                               SSDATA (XCAR (options)));
> +#endif

Likewise here.