Re: [PATCH] Non-working jit patch for debug-early (was Re: [patch 0/10] debug-early merge)

[Aldy Hernandez <aldyh@redhat.com>]

On 05/08/2015 10:38 AM, David Malcolm wrote:

> I tested your branch (at 09263eae7c260c305fa19ffa186afd1d89654fb8) with
> the jit configuration from the docs:
>
> ../src/configure \
>   --enable-host-shared \
>     --enable-languages=jit,c++ \
>     --disable-bootstrap \
>     --enable-checking=release \
>     --prefix=$PREFIX
>
> Sadly, the jit "frontend" fails to compile:

Whoops.  My bad.  I was unaware `jit' needed to be added to 
--enable-languages.  I thought it was tested automatically.

>
> ../../src/gcc/jit/jit-playback.c: In member function ‘void
> gcc::jit::playback::context::write_global_decls_2()’:
> ../../src/gcc/jit/jit-playback.c:710:20: error: ‘const struct
> gcc_debug_hooks’ has no member named ‘global_decl’
>         debug_hooks->global_decl (decl);

The basic idea is that if your globals do NOT make it to 
rest_of_decl_compilation(), you need to call 
debug_hooks->early_global_decl() on them manually after parsing.

On the other hand, if your functions do NOT make it to the symbol table 
then you also need to call debug_hooks->early_global_decl() on them 
after parsing (see finalize_compilation_unit()).

The call to debug_hooks->late_global_decl() should be handled 
automagically.  I mean, I assume your symbols (functions and globals, 
etc) make it to the symbol table, in which case they'll be picked up by 
either compile_file() or by analyze_functions().  The latter in case the 
symbol was optimized away and is about to be removed from the symbol table.

Does this help?  If it doesn't, I can gladly take over this on Monday.

>                      ^
> since the "global_decl" debug hook has gone away.  I see that
>    LANG_HOOKS_WRITE_GLOBALS
> also is no more, and this leads to various code in the jit becoming
> dead:
> ../../src/gcc/jit/dummy-frontend.c:225:1: warning: ‘void
> jit_langhook_write_globals()’ defined but not used [-Wunused-function]
>
>
> The attached patch gets it to compile, and eliminates the now-dead code,
> but it's not clear to me how global variables are meant to be created in
> the debug-early world.

Thanks for working on this.

Aldy