Re: [PATCH] libgccjit: Fix ira cost segfault

[David Malcolm <dmalcolm@redhat.com>]

On Wed, 2024-01-10 at 09:30 -0500, David Malcolm wrote:
> On Thu, 2023-11-16 at 17:28 -0500, Antoni Boucher wrote:
> > Hi.
> > This patch fixes a segfault that happens when compiling librsvg
> > (more
> > specifically its dependency aho-corasick) with rustc_codegen_gcc
> > (bug
> > 112575).
> > I was not able to create a reproducer for this bug: I'm assuming I
> > might need to concat all the reproducers together in the same file
> > in
> > order to be able to reproduce the issue.
> 
> Hi Antoni
> 
> Thanks for the patch; sorry for missing it before.
> 
> CCing the i386 maintainers; quoting the patch here to give them
> context:

Oops; actually adding them to the CC this time; sorry.

> 
> > From e0f4f51682266bc9f507afdb64908ed3695a2f5e Mon Sep 17 00:00:00
> > 2001
> > From: Antoni Boucher <bouanto@zoho.com>
> > Date: Thu, 2 Nov 2023 17:18:35 -0400
> > Subject: [PATCH] libgccjit: Fix ira cost segfault
> > 
> > gcc/ChangeLog:
> >         PR jit/112575
> >         * config/i386/i386-options.cc
> > (ix86_option_override_internal):
> >         Cleanup target_attribute_cache.
> > ---
> >  gcc/config/i386/i386-options.cc | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/gcc/config/i386/i386-options.cc
> > b/gcc/config/i386/i386-options.cc
> > index df7d24352d1..f596c0fb53c 100644
> > --- a/gcc/config/i386/i386-options.cc
> > +++ b/gcc/config/i386/i386-options.cc
> > @@ -3070,6 +3070,12 @@ ix86_option_override_internal (bool
> > main_args_p,
> >         = opts->x_flag_unsafe_math_optimizations;
> >        target_option_default_node = target_option_current_node
> >          = build_target_option_node (opts, opts_set);
> > +      /* TODO: check if this is the correct location.  It should
> > probably be in
> > +        some finalizer function, but I don't
> > +        know if there's one.  */
> > +      target_attribute_cache[0] = NULL;
> > +      target_attribute_cache[1] = NULL;
> > +      target_attribute_cache[2] = NULL;
> >      }
> >  
> >    if (opts->x_flag_cf_protection != CF_NONE)
> > -- 
> > 2.42.1
> > 
> 
> Presumably this happens when there's more than one in-process
> invocation of the compiler code (via libgccjit).
> 
> > 
> > I'm also not sure I put the cleanup in the correct location.
> > Is there any finalizer function for target specific code?
> 
> As you know (but the i386 maintainers might not), to allow multiple
> in-
> process invocations of the compiler code (for libgccjit) we've been
> putting code to reset global state in various {filename_cc}_finalize
> functions called from toplev::finalize (see the end of toplev.cc).
> 
> There doesn't seem to be any kind of hook at this time for calling
> target-specific cleanups from toplev::finalize.
> 
> However, as of r14-4003-geaa8e8541349df ggc_common_finalize zeroes
> everything marked with GTY.  The array target_attribute_cache does
> have
> a GTY marking, so perhaps as of that commit this patch isn't
> necessary?
> 
> Otherwise, if special-casing this is required, sorry: I'm not
> familiar
> enough with i386-options.cc to know if the patch is correct.
> 
> > 
> > Thanks to fix this issue.
> 
> Dave