[PATCH RFA] Fixup SYMBOL_SECTION for objfiles_relocate()

[Kevin Buettner <kevinb at cygnus dot com>]

I request permission to commit the patch below.

The OS for the project that I'm working on relocates the read/write
and the read-only sections by different amounts.  Thus it is critical
that objfile_relocate() actually have correct section indices during
the relocation process.

 I also discovered that for some symbol sym, SYMBOL_SECTION(sym) was
not providing the correct section index.  In fact, it was almost
always 0.  The same was true for partial symbols (upon which the same
macro magically works) as well.

The reason is that (at least for DWARF2) the SYMBOL_SECTION field
(section) was simply getting initialized to 0.  Furthermore, no
attempt was made to set things right later on.

The interesting thing is that SYMBOL_BFD_SECTION has exactly same
problem, but we have some code which attempts to set things right at
various points along the way.  The relevant functions are
fixup_symbol_section() and fixup_psymbol_section().  It seems to me
that we ought to be setting SYMBOL_SECTION at the same time that we're
setting BFD_SECTION and that is what the second hunk in the diff for
symtab.c is doing below.  [Thanks to Elena for bringing this to my
attention.]

Even once this is done, there is no guarantee that the symbols
and/or partial symbols will have been fixed up (with respect to
SYMBOL_SECTION) by the time that objfile_relocate() has been called.
So... now objfile_relocate() calls fixup_symbol_section() and
fixup_psymbol_section() as appropriate.

I'm not convinced that fixing these fields up at various random places
in the code where we need to access these fields is the right approach
to solving this problem.  It seems to me that it would be better to
attempt to set them correctly at the time that (or perhaps slightly
after) the symbol (or partial symbol) is created.  I made an attempt
at doing this, but I could not get it to work.  (Perhaps the minimal
symbols weren't available yet?) In any event, this is probably an
issue that the symbol table maintainers should consider in the future.
(grep for fixup_symbol_section() and look at all the places that
it's used.)

	* symtab.h (fixup_psymbol_section): Declare.
	* symtab.c (fixup_psymbol_section): Make extern.
	(fixup_section): Fix up section as well as bfd_section.
	* objfiles.c (objfile_relocate): Call fixup_symbol_section
	or fixup_psymbol_section before attempting to access
	the SYMBOL_SECTION component of a symbol or partial symbol.

Index: objfiles.c
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.c,v
retrieving revision 1.7
diff -u -p -r1.7 objfiles.c
--- objfiles.c	2000/07/30 01:48:26	1.7
+++ objfiles.c	2000/08/04 20:46:02
@@ -564,6 +564,9 @@ objfile_relocate (struct objfile *objfil
 	  for (j = 0; j < BLOCK_NSYMS (b); ++j)
 	    {
 	      struct symbol *sym = BLOCK_SYM (b, j);
+
+	      fixup_symbol_section (sym, objfile);
+
 	      /* The RS6000 code from which this was taken skipped
 	         any symbols in STRUCT_NAMESPACE or UNDEF_NAMESPACE.
 	         But I'm leaving out that test, on the theory that
@@ -606,15 +609,21 @@ objfile_relocate (struct objfile *objfil
     for (psym = objfile->global_psymbols.list;
 	 psym < objfile->global_psymbols.next;
 	 psym++)
-      if (SYMBOL_SECTION (*psym) >= 0)
-	SYMBOL_VALUE_ADDRESS (*psym) += ANOFFSET (delta,
-						  SYMBOL_SECTION (*psym));
+      {
+	fixup_psymbol_section (*psym, objfile);
+	if (SYMBOL_SECTION (*psym) >= 0)
+	  SYMBOL_VALUE_ADDRESS (*psym) += ANOFFSET (delta,
+						    SYMBOL_SECTION (*psym));
+      }
     for (psym = objfile->static_psymbols.list;
 	 psym < objfile->static_psymbols.next;
 	 psym++)
-      if (SYMBOL_SECTION (*psym) >= 0)
-	SYMBOL_VALUE_ADDRESS (*psym) += ANOFFSET (delta,
-						  SYMBOL_SECTION (*psym));
+      {
+	fixup_psymbol_section (*psym, objfile);
+	if (SYMBOL_SECTION (*psym) >= 0)
+	  SYMBOL_VALUE_ADDRESS (*psym) += ANOFFSET (delta,
+						    SYMBOL_SECTION (*psym));
+      }
   }
 
   {
Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.10
diff -u -p -r1.10 symtab.c
--- symtab.c	2000/07/30 01:48:27	1.10
+++ symtab.c	2000/08/04 20:46:07
@@ -81,10 +81,6 @@ static struct partial_symbol *lookup_par
 						     const char *, int,
 						     namespace_enum);
 
-static struct partial_symbol *fixup_psymbol_section (struct
-						     partial_symbol *,
-						     struct objfile *);
-
 static struct symtab *lookup_symtab_1 (char *);
 
 static void cplusplus_hint (char *);
@@ -520,7 +516,10 @@ fixup_section (struct general_symbol_inf
   msym = lookup_minimal_symbol (ginfo->name, NULL, objfile);
 
   if (msym)
-    ginfo->bfd_section = SYMBOL_BFD_SECTION (msym);
+    {
+      ginfo->bfd_section = SYMBOL_BFD_SECTION (msym);
+      ginfo->section = SYMBOL_SECTION (msym);
+    }
 }
 
 struct symbol *
@@ -537,7 +536,7 @@ fixup_symbol_section (struct symbol *sym
   return sym;
 }
 
-static struct partial_symbol *
+struct partial_symbol *
 fixup_psymbol_section (struct partial_symbol *psym, struct objfile *objfile)
 {
   if (!psym)
Index: symtab.h
===================================================================
RCS file: /cvs/src/src/gdb/symtab.h,v
retrieving revision 1.11
diff -u -p -r1.11 symtab.h
--- symtab.h	2000/06/05 20:49:53	1.11
+++ symtab.h	2000/08/04 20:46:09
@@ -1414,6 +1414,10 @@ extern int in_prologue (CORE_ADDR pc, CO
 extern struct symbol *fixup_symbol_section (struct symbol *,
 					    struct objfile *);
 
+extern struct partial_symbol *fixup_psymbol_section (struct partial_symbol
+						     *psym,
+						     struct objfile *objfile);
+
 /* Symbol searching */
 
 /* When using search_symbols, a list of the following structs is returned.