http://sourceware.org/ml/gdb-patches/2012-05/msg01105.html

Subject: [RFA/commit 1/3] Revert "Search global symbols from the expression's block objfile first."

The search order used in this patch breaks global symbol lookups

for certain symbols when copy-relocation is used.  A slightly different

search order will be implemented later.

gdb/ChangeLog:

        Revert the following patch:

        * findvar.c (default_read_var_value): For LOC_UNRESOLVED symbols,

        try locating the symbol in the symbol's own objfile first, before

        extending the search to all objfiles.

        * symtab.c (lookup_symbol_aux_objfile): New function, extracted

        out of lookup_symbol_aux_symtabs.

        (lookup_symbol_aux_symtabs): Add new parameter "exclude_objfile".

        Replace extracted-out code by call to lookup_symbol_aux_objfile.

        Do not search EXCLUDE_OBJFILE.

        (lookup_static_symbol_aux): Update call to lookup_symbol_aux_symtabs.

        (lookup_symbol_global): Search for matches in the block's objfile

        first, before searching all other objfiles.

Will commit if patches #2 & #3 are OK.

---

 gdb/findvar.c |   10 +-----

 gdb/symtab.c  |  108 +++++++++++++++++----------------------------------------

 2 files changed, 33 insertions(+), 85 deletions(-)

diff --git a/gdb/findvar.c b/gdb/findvar.c

index ed7903c..9009e6f 100644

--- a/gdb/findvar.c

+++ b/gdb/findvar.c

@@ -562,15 +562,7 @@ default_read_var_value (struct symbol *var, struct frame_info *frame)

 	struct minimal_symbol *msym;

 	struct obj_section *obj_section;

-	/* First, try locating the associated minimal symbol within

-	   the same objfile.  This prevents us from selecting another

-	   symbol with the same name but located in a different objfile.  */

-	msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL,

-				      SYMBOL_SYMTAB (var)->objfile);

-	/* If the lookup failed, try expanding the search to all

-	   objfiles.  */

-	if (msym == NULL)

-	  msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL, NULL);

+	msym = lookup_minimal_symbol (SYMBOL_LINKAGE_NAME (var), NULL, NULL);

 	if (msym == NULL)

 	  error (_("No global symbol \"%s\"."), SYMBOL_LINKAGE_NAME (var));

 	if (overlay_debugging)

diff --git a/gdb/symtab.c b/gdb/symtab.c

index 85ddd1d..39d8c6f 100644

--- a/gdb/symtab.c

+++ b/gdb/symtab.c

@@ -95,8 +95,7 @@ struct symbol *lookup_symbol_aux_local (const char *name,

 static

 struct symbol *lookup_symbol_aux_symtabs (int block_index,

 					  const char *name,

-					  const domain_enum domain,

-					  struct objfile *exclude_objfile);

+					  const domain_enum domain);

 static

 struct symbol *lookup_symbol_aux_quick (struct objfile *objfile,

@@ -1360,7 +1359,7 @@ lookup_static_symbol_aux (const char *name, const domain_enum domain)

   struct objfile *objfile;

   struct symbol *sym;

-  sym = lookup_symbol_aux_symtabs (STATIC_BLOCK, name, domain, NULL);

+  sym = lookup_symbol_aux_symtabs (STATIC_BLOCK, name, domain);

   if (sym != NULL)

     return sym;

@@ -1499,61 +1498,40 @@ lookup_global_symbol_from_objfile (const struct objfile *main_objfile,

   return NULL;

 }

-/* Check to see if the symbol is defined in one of the OBJFILE's

-   symtabs.  BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,

+/* Check to see if the symbol is defined in one of the symtabs.

+   BLOCK_INDEX should be either GLOBAL_BLOCK or STATIC_BLOCK,

    depending on whether or not we want to search global symbols or

    static symbols.  */

 static struct symbol *

-lookup_symbol_aux_objfile (struct objfile *objfile, int block_index,

-			   const char *name, const domain_enum domain)

-{

-  struct symbol *sym = NULL;

-  struct blockvector *bv;

-  const struct block *block;

-  struct symtab *s;

-

-  if (objfile->sf)

-    objfile->sf->qf->pre_expand_symtabs_matching (objfile, block_index,

-						  name, domain);

-

-  ALL_OBJFILE_SYMTABS (objfile, s)

-    if (s->primary)

-      {

-	bv = BLOCKVECTOR (s);

-	block = BLOCKVECTOR_BLOCK (bv, block_index);

-	sym = lookup_block_symbol (block, name, domain);

-	if (sym)

-	  {

-	    block_found = block;

-	    return fixup_symbol_section (sym, objfile);

-	  }

-      }

-

-  return NULL;

-}

-

-/* Same as lookup_symbol_aux_objfile, except that it searches all

-   objfiles except for EXCLUDE_OBJFILE.  Return the first match found.

-

-   If EXCLUDE_OBJFILE is NULL, then all objfiles are searched.  */

-

-static struct symbol *

 lookup_symbol_aux_symtabs (int block_index, const char *name,

-			   const domain_enum domain,

-			   struct objfile *exclude_objfile)

+			   const domain_enum domain)

 {

   struct symbol *sym;

   struct objfile *objfile;

+  struct blockvector *bv;

+  const struct block *block;

+  struct symtab *s;

   ALL_OBJFILES (objfile)

   {

-    if (objfile != exclude_objfile)

-      {

-	sym = lookup_symbol_aux_objfile (objfile, block_index, name, domain);

-	if (sym)

-	  return sym;

-      }

+    if (objfile->sf)

+      objfile->sf->qf->pre_expand_symtabs_matching (objfile,

+						    block_index,

+						    name, domain);

+

+    ALL_OBJFILE_SYMTABS (objfile, s)

+      if (s->primary)

+	{

+	  bv = BLOCKVECTOR (s);

+	  block = BLOCKVECTOR_BLOCK (bv, block_index);

+	  sym = lookup_block_symbol (block, name, domain);

+	  if (sym)

+	    {

+	      block_found = block;

+	      return fixup_symbol_section (sym, objfile);

+	    }

+	}

   }

   return NULL;

@@ -1679,46 +1657,24 @@ lookup_symbol_global (const char *name,

 		      const domain_enum domain)

 {

   struct symbol *sym = NULL;

-  struct objfile *block_objfile = NULL;

   struct objfile *objfile = NULL;

   /* Call library-specific lookup procedure.  */

-  block_objfile = lookup_objfile_from_block (block);

-  if (block_objfile != NULL)

-    sym = solib_global_lookup (block_objfile, name, domain);

+  objfile = lookup_objfile_from_block (block);

+  if (objfile != NULL)

+    sym = solib_global_lookup (objfile, name, domain);

   if (sym != NULL)

     return sym;

-  /* If BLOCK_OBJFILE is not NULL, then search this objfile first.

-     In case the global symbol is defined in multiple objfiles,

-     we have a better chance of finding the most relevant symbol.  */

-

-  if (block_objfile != NULL)

-    {

-      sym = lookup_symbol_aux_objfile (block_objfile, GLOBAL_BLOCK,

-				       name, domain);

-      if (sym == NULL)

-	sym = lookup_symbol_aux_quick (block_objfile, GLOBAL_BLOCK,

-				       name, domain);

-      if (sym != NULL)

-	return sym;

-    }

-

-  /* Symbol not found in the BLOCK_OBJFILE, so try all the other

-     objfiles, starting with symtabs first, and then partial symtabs.  */

-

-  sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, domain, block_objfile);

+  sym = lookup_symbol_aux_symtabs (GLOBAL_BLOCK, name, domain);

   if (sym != NULL)

     return sym;

   ALL_OBJFILES (objfile)

   {

-    if (objfile != block_objfile)

-      {

-	sym = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK, name, domain);

-	if (sym)

-	  return sym;

-      }

+    sym = lookup_symbol_aux_quick (objfile, GLOBAL_BLOCK, name, domain);

+    if (sym)

+      return sym;

   }

   return NULL;

-- 

1.7.1