[PATCH] Remove lto_global_var_decls, simplify necessary analysis for PR60060

[Richard Biener]

On Wed, 5 Feb 2014, Jan Hubicka wrote:

> > 
> > When looking at PR60060, outputting the declaration debug info for
> > a local static variable twice (once via BLOCK_VARS and once via
> > calling the debug hook on all globals) I noticed that the
> > rest_of_decl_compilation call in materialize_cgraph always works
> > on the empty lto_global_var_decls vector (we only populate it
> > later).  That results in the opportunity to effectively remove it
> > and in lto_write_globals walk over the defined vars in the
> > varpool instead.
> > 
> > Eventually the fix for PR60060 is to not push TREE_ASM_WRITTEN
> > decls there (but I'm not sure of other side-effects of that ...).
> > 
> > Thus, this cleanup first.
> > 
> > LTO bootstrap / regtest running on x86_64-unknown-linux-gnu.
> > 
> > Ok?
> 
> Seems OK to me.  I always had an impression that this machinery exists to
> make decls that are revmoed fro symbol table (optimized out) to land the
> debug info, but I think this is mostly broken by partitioning anyway, right?
> Do we stream them at all?

No, we don't stream those.  We'd need to stream what the FEs think
are the globals (lang_hooks.getdecls()) and somehow partition them
and ship them somewhere.

Richard.
 
> Honza
> > 
> > Thanks,
> > Richard.
> > 
> > 2014-02-05  Richard Biener  <rguenther@suse.de>
> > 
> > 	lto/
> > 	* lto.h (lto_global_var_decls): Remove.
> > 	* lto-lang.c (lto_init): Do not allocate lto_global_var_decls.
> > 	(lto_write_globals): Do nothing in WPA stage, gather globals from
> > 	the varpool here ...
> > 	* lto.c (lto_main): ... not here.
> > 	(materialize_cgraph): Do not call rest_of_decl_compilation
> > 	on the empty lto_global_var_decls vector.
> > 	(lto_global_var_decls): Remove.
> > 
> > Index: gcc/lto/lto-lang.c
> > ===================================================================
> > *** gcc/lto/lto-lang.c	(revision 207497)
> > --- gcc/lto/lto-lang.c	(working copy)
> > *************** lto_getdecls (void)
> > *** 1075,1085 ****
> >   static void
> >   lto_write_globals (void)
> >   {
> > !   tree *vec = lto_global_var_decls->address ();
> > !   int len = lto_global_var_decls->length ();
> >     wrapup_global_declarations (vec, len);
> >     emit_debug_global_declarations (vec, len);
> > !   vec_free (lto_global_var_decls);
> >   }
> >   
> >   static tree
> > --- 1075,1094 ----
> >   static void
> >   lto_write_globals (void)
> >   {
> > !   if (flag_wpa)
> > !     return;
> > ! 
> > !   /* Record the global variables.  */
> > !   vec<tree> lto_global_var_decls = vNULL;
> > !   varpool_node *vnode;
> > !   FOR_EACH_DEFINED_VARIABLE (vnode)
> > !     lto_global_var_decls.safe_push (vnode->decl);
> > ! 
> > !   tree *vec = lto_global_var_decls.address ();
> > !   int len = lto_global_var_decls.length ();
> >     wrapup_global_declarations (vec, len);
> >     emit_debug_global_declarations (vec, len);
> > !   lto_global_var_decls.release ();
> >   }
> >   
> >   static tree
> > *************** lto_init (void)
> > *** 1218,1224 ****
> >   #undef NAME_TYPE
> >   
> >     /* Initialize LTO-specific data structures.  */
> > -   vec_alloc (lto_global_var_decls, 256);
> >     in_lto_p = true;
> >   
> >     return true;
> > --- 1227,1232 ----
> > Index: gcc/lto/lto.c
> > ===================================================================
> > *** gcc/lto/lto.c	(revision 207497)
> > --- gcc/lto/lto.c	(working copy)
> > *************** along with GCC; see the file COPYING3.
> > *** 50,57 ****
> >   #include "context.h"
> >   #include "pass_manager.h"
> >   
> > - /* Vector to keep track of external variables we've seen so far.  */
> > - vec<tree, va_gc> *lto_global_var_decls;
> >   
> >   static GTY(()) tree first_personality_decl;
> >   
> > --- 50,55 ----
> > *************** read_cgraph_and_symbols (unsigned nfiles
> > *** 3009,3017 ****
> >   static void
> >   materialize_cgraph (void)
> >   {
> > -   tree decl;
> >     struct cgraph_node *node; 
> > -   unsigned i;
> >     timevar_id_t lto_timer;
> >   
> >     if (!quiet_flag)
> > --- 3007,3013 ----
> > *************** materialize_cgraph (void)
> > *** 3043,3052 ****
> >     current_function_decl = NULL;
> >     set_cfun (NULL);
> >   
> > -   /* Inform the middle end about the global variables we have seen.  */
> > -   FOR_EACH_VEC_ELT (*lto_global_var_decls, i, decl)
> > -     rest_of_decl_compilation (decl, 1, 0);
> > - 
> >     if (!quiet_flag)
> >       fprintf (stderr, "\n");
> >   
> > --- 3039,3044 ----
> > *************** lto_main (void)
> > *** 3309,3316 ****
> >   	do_whole_program_analysis ();
> >         else
> >   	{
> > - 	  varpool_node *vnode;
> > - 
> >   	  timevar_start (TV_PHASE_OPT_GEN);
> >   
> >   	  materialize_cgraph ();
> > --- 3301,3306 ----
> > *************** lto_main (void)
> > *** 3330,3339 ****
> >   	     this.  */
> >   	  if (flag_lto_report || (flag_wpa && flag_lto_report_wpa))
> >   	    print_lto_report_1 ();
> > - 
> > - 	  /* Record the global variables.  */
> > - 	  FOR_EACH_DEFINED_VARIABLE (vnode)
> > - 	    vec_safe_push (lto_global_var_decls, vnode->decl);
> >   	}
> >       }
> >   
> > --- 3320,3325 ----
> > Index: gcc/lto/lto.h
> > ===================================================================
> > *** gcc/lto/lto.h	(revision 207497)
> > --- gcc/lto/lto.h	(working copy)
> > *************** extern tree lto_eh_personality (void);
> > *** 41,49 ****
> >   extern void lto_main (void);
> >   extern void lto_read_all_file_options (void);
> >   
> > - /* In lto-symtab.c  */
> > - extern GTY(()) vec<tree, va_gc> *lto_global_var_decls;
> > - 
> >   /* In lto-elf.c or lto-coff.c  */
> >   extern lto_file *lto_obj_file_open (const char *filename, bool writable);
> >   extern void lto_obj_file_close (lto_file *file);
> > --- 41,46 ----
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer