Re: [rfa/symtab] Move find_pc_section call to lookup_minimal_symbol_by_pc

[Andrew Cagney <cagney@gnu.org>]

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> Um, I'm not sure what is happening.  My GNU/Linux amd64 box appears to pass both times:

I've found the right machine (YelloDog 3.0), the attached appears to 
work on both yellow dog and IRIX (and Fedora Core).

The new patch modifies find_pc_partial_function supply the PC's section 
when available.

Look ok?

The problem was that the symbol lookup was finding a symbol from a 
previous section, instead of no symbol in the current section.  That 
leads to this test (using Joe's rewrite):

> +  if (ecs->stop_func_name == NULL
> +      && step_over_calls == STEP_OVER_UNDEBUGGABLE)
> +    {
> +      /* We couldn't determine where we stopped, so we just stepped
> +         inside undebuggable code.  Since we want to step over this
> +         kind of code, we keep going until the inferior returns from
> +         the current function.  */
> +      handle_step_into_function (ecs);
> +      return;
> +    }

not triggering.  ->stop_func_name had a non-NULL but bogus symbol name.

ok?
Andrew

PS: I think GDB has a few too many symbol lookup interfaces :-(


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2004-02-06  Andrew Cagney  <cagney@redhat.com>

	* blockframe.c (find_pc_partial_function): If find_pc_overlay
	fails, try find_pc_section.  Fix PR c++/1267.
	* minsyms.c (lookup_minimal_symbol_by_pc): Use find_pc_section
	instead of find_pc_mapped_section.
	(lookup_minimal_symbol_by_pc_section): If the SECTION is NULL, do
	not default to the section containing PC.  Fix PR symtab/1519.

Index: blockframe.c
===================================================================
RCS file: /cvs/src/src/gdb/blockframe.c,v
retrieving revision 1.87
diff -u -r1.87 blockframe.c
--- blockframe.c	4 Feb 2004 16:34:51 -0000	1.87
+++ blockframe.c	6 Feb 2004 18:42:16 -0000
@@ -507,10 +507,24 @@
 find_pc_partial_function (CORE_ADDR pc, char **name, CORE_ADDR *address,
 			  CORE_ADDR *endaddr)
 {
-  asection *section;
+  struct bfd_section *bfd_section;
 
-  section = find_pc_overlay (pc);
-  return find_pc_sect_partial_function (pc, section, name, address, endaddr);
+  /* To ensure that the symbol returned belongs to the correct setion
+     (and that the last [random] symbol from the previous section
+     isn't returned) try to find the section containing PC.  First try
+     the overlay code (which by default returns NULL); and second try
+     the normal section code (which almost always succeeds).  */
+  bfd_section = find_pc_overlay (pc);
+  if (bfd_section == NULL)
+    {
+      struct obj_section *obj_section = find_pc_section (pc);
+      if (obj_section == NULL)
+	bfd_section = NULL;
+      else
+	bfd_section = obj_section->the_bfd_section;
+    }
+  return find_pc_sect_partial_function (pc, bfd_section, name, address,
+					endaddr);
 }
 
 /* Return the innermost stack frame executing inside of BLOCK,
Index: minsyms.c
===================================================================
RCS file: /cvs/src/src/gdb/minsyms.c,v
retrieving revision 1.39
diff -u -r1.39 minsyms.c
--- minsyms.c	11 Nov 2003 20:04:52 -0000	1.39
+++ minsyms.c	6 Feb 2004 18:42:16 -0000
@@ -355,7 +355,7 @@
 
 /* Search through the minimal symbol table for each objfile and find
    the symbol whose address is the largest address that is still less
-   than or equal to PC, and matches SECTION (if non-null).  Returns a
+   than or equal to PC, and matches SECTION (if non-NULL).  Returns a
    pointer to the minimal symbol if such a symbol is found, or NULL if
    PC is not in a suitable range.  Note that we need to look through
    ALL the minimal symbol tables before deciding on the symbol that
@@ -374,20 +374,23 @@
   struct minimal_symbol *best_symbol = NULL;
   struct obj_section *pc_section;
 
-  /* pc has to be in a known section. This ensures that anything beyond
-     the end of the last segment doesn't appear to be part of the last
-     function in the last segment.  */
+  /* PC has to be in a known section.  This ensures that anything
+     beyond the end of the last segment doesn't appear to be part of
+     the last function in the last segment.  */
   pc_section = find_pc_section (pc);
   if (pc_section == NULL)
     return NULL;
 
-  /* If no section was specified, then just make sure that the PC is in
-     the same section as the minimal symbol we find.  */
-  if (section == NULL)
-    section = pc_section->the_bfd_section;
-
-  /* FIXME drow/2003-07-19: Should we also check that PC is in SECTION
-     if we were passed a non-NULL SECTION argument?  */
+  /* NOTE: cagney/2004-01-27: Removed code (added 2003-07-19) that was
+     trying to force the PC into a valid section as returned by
+     find_pc_section.  It broke IRIX 6.5 mdebug which relies on this
+     code returning an absolute symbol - the problem was that
+     find_pc_section wasn't returning an absolute section and hence
+     the code below would skip over absolute symbols.  Since the
+     original problem was with finding a frame's function, and that
+     uses [indirectly] lookup_minimal_symbol_by_pc, the original
+     problem has been fixed by having that function use
+     find_pc_section.  */
 
   for (objfile = object_files;
        objfile != NULL;
@@ -497,7 +500,13 @@
 struct minimal_symbol *
 lookup_minimal_symbol_by_pc (CORE_ADDR pc)
 {
-  return lookup_minimal_symbol_by_pc_section (pc, find_pc_mapped_section (pc));
+  /* NOTE: cagney/2004-01-27: This was using find_pc_mapped_section to
+     force the section but that (well unless you're doing overlay
+     debugging) always returns NULL making the call somewhat useless.  */
+  struct obj_section *section = find_pc_section (pc);
+  if (section == NULL)
+    return NULL;
+  return lookup_minimal_symbol_by_pc_section (pc, section->the_bfd_section);
 }
 \f