Re: [RFA] Nullified garbage-collected global variables

[Jerome Guitton <guitton@adacore.com>]

Tom Tromey (tromey@redhat.com):

> >>>>> "Jerome" == Jerome Guitton <guitton@adacore.com> writes:
> 
> Jerome> 	* dwarf2read.c (add_partial_symbol): Do not add a global variable if
> Jerome> 	its adress is null. Add comment to explain why.
> Jerome> 	(new_symbol): Ditto.
> 
> This is ok.  Thanks.

Thank you. I was actually polishing my tests when I realized that I was
missing a case (partial symbols for static variables). I've modified
my patch to handle it; it actually makes it cleaner, I think.

Unless you object, I will commit this new version.


gdb/ChangeLog:

	* dwarf2read.c (add_partial_symbol): Do not add a global variable if
	its adress is null. Add comment to explain why.
	(new_symbol): Ditto.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 288d777..80222c3 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -3421,7 +3421,19 @@ add_partial_symbol (struct partial_die_info *pdi, struct dwarf2_cu *cu)
 	}
       break;
     case DW_TAG_variable:
-      if (pdi->is_external)
+      if (pdi->locdesc)
+	addr = decode_locdesc (pdi->locdesc, cu);
+
+      if (pdi->locdesc
+	  && addr == 0
+	  && !dwarf2_per_objfile->has_section_at_zero)
+	{
+	  /* A global or static variable may also have been stripped
+	     out by the linker if unused, in which case its address
+	     will be nullified; do not add such variables into partial
+	     symbol table then.  */
+	}
+      else if (pdi->is_external)
 	{
 	  /* Global Variable.
 	     Don't enter into the minimal symbol tables as there is
@@ -3436,8 +3448,6 @@ add_partial_symbol (struct partial_die_info *pdi, struct dwarf2_cu *cu)
 	     used by GDB, but it comes in handy for debugging partial symbol
 	     table building.  */
 
-	  if (pdi->locdesc)
-	    addr = decode_locdesc (pdi->locdesc, cu);
 	  if (pdi->locdesc || pdi->has_type)
 	    psym = add_psymbol_to_list (actual_name, strlen (actual_name),
 					built_actual_name,
@@ -3455,7 +3465,6 @@ add_partial_symbol (struct partial_die_info *pdi, struct dwarf2_cu *cu)
 		xfree (actual_name);
 	      return;
 	    }
-	  addr = decode_locdesc (pdi->locdesc, cu);
 	  /*prim_record_minimal_symbol (actual_name, addr + baseaddr,
 	     mst_file_data, objfile); */
 	  psym = add_psymbol_to_list (actual_name, strlen (actual_name),
@@ -9860,7 +9869,16 @@ new_symbol (struct die_info *die, struct type *type, struct dwarf2_cu *cu)
 	    {
 	      var_decode_location (attr, sym, cu);
 	      attr2 = dwarf2_attr (die, DW_AT_external, cu);
-	      if (attr2 && (DW_UNSND (attr2) != 0))
+	      if (SYMBOL_CLASS (sym) == LOC_STATIC
+		  && SYMBOL_VALUE_ADDRESS (sym) == 0
+		  && !dwarf2_per_objfile->has_section_at_zero)
+		{
+		  /* When a static variable is eliminated by the linker,
+		     the corresponding debug information is not stripped
+		     out, but the variable address is set to null;
+		     do not add such variables into symbol table.  */
+		}
+	      else if (attr2 && (DW_UNSND (attr2) != 0))
 		{
 		  struct pending **list_to_add;