[pushed: r15-7126] jit: fix startup on aarch64

[David Malcolm]

On Wed, 2025-01-22 at 08:47 -0500, Antoni Boucher wrote:
> Hi David.

Hi Antoni

I went ahead and pushed this patch since without it even simple unit
tests like test-factorial.c were failing for me on aarch64; in
particular, the build of emacs was failing in Fedora's mass rebuild
with gcc 15, and the patch seems to be a minimal way to fix this.

> I had a patch for this here:
> https://github.com/antoyo/libgccjit/pull/20

Sorry for this getting stuck.  I see you marked that as "waiting for
review", but it looks like the patch there hasn't changed since my last
review within the github web UI; was that to signify that you were
hoping for an answer to the questions you asked on how to better
implement the fix?

> 
> The fact that you removed the debug_tree (and abort) will make it
> harder 
> to figure out what the missing types to handle are.
> This will also probably make it hard for people to understand why
> they 
> get a type error when calling a builtin function with an unsupported
> type.
> And as you can see in my PR, at least a few types were missing that
> you 
> didn't add in your patch.
> 
> Do you have a better solution for this?
> 
> I just thought about this potential solution: perhaps if we get an 
> unsupported type, we could add the builtin to an array instead of the
> hashmap: this way, we could tell the user that this builtin is not 
> currently supported.
> What are your thoughts on this?

I'll take another look at PR 117886 now and see if I can implement
something.

Dave


> 
> Thanks.
> 
> Le 2025-01-22 à 08 h 38, David Malcolm a écrit :
> > libgccjit fails on startup on aarch64 (and probably other archs).
> > 
> > The issues are that
> > 
> > (a) within jit_langhook_init the call to
> > targetm.init_builtins can use types that aren't representable
> > via jit::recording::type, and
> > 
> > (b) targetm.init_builtins can call lang_hooks.decls.pushdecl, which
> > although a no-op for libgccjit has a gcc_unreachable.
> > 
> > Fixed thusly.
> > 
> > Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
> > Pushed to trunk as r15-7126-g27470f9a818538.
> > 
> > gcc/jit/ChangeLog:
> > 	* dummy-frontend.cc (tree_type_to_jit_type): For
> > POINTER_TYPE,
> > 	bail out if the inner call to tree_type_to_jit_type fails.
> > 	Don't abort on unknown types.
> > 	(jit_langhook_pushdecl): Replace gcc_unreachable with
> > return of
> > 	NULL_TREE.
> > 
> > Signed-off-by: David Malcolm <dmalcolm@redhat.com>
> > ---
> >   gcc/jit/dummy-frontend.cc | 8 +++-----
> >   1 file changed, 3 insertions(+), 5 deletions(-)
> > 
> > diff --git a/gcc/jit/dummy-frontend.cc b/gcc/jit/dummy-frontend.cc
> > index 574851696311..1d0080d6fecb 100644
> > --- a/gcc/jit/dummy-frontend.cc
> > +++ b/gcc/jit/dummy-frontend.cc
> > @@ -1278,6 +1278,8 @@ recording::type* tree_type_to_jit_type (tree
> > type)
> >     {
> >       tree inner_type = TREE_TYPE (type);
> >       recording::type* element_type = tree_type_to_jit_type
> > (inner_type);
> > +    if (!element_type)
> > +      return nullptr;
> >       return element_type->get_pointer ();
> >     }
> >     else
> > @@ -1299,10 +1301,6 @@ recording::type* tree_type_to_jit_type (tree
> > type)
> >   	}
> >         }
> >       }
> > -
> > -    fprintf (stderr, "Unknown type:\n");
> > -    debug_tree (type);
> > -    abort ();
> >     }
> >   
> >     return NULL;
> > @@ -1372,7 +1370,7 @@ jit_langhook_global_bindings_p (void)
> >   static tree
> >   jit_langhook_pushdecl (tree decl ATTRIBUTE_UNUSED)
> >   {
> > -  gcc_unreachable ();
> > +  return NULL_TREE;
> >   }
> >   
> >   static tree
>