Re: [RFC] lookup problem in blockframe.c:inside_main_func()

[Joel Brobecker <brobecker@gnat.com>]

[-- Attachment #1: Type: text/plain, Size: 1748 bytes --]

> Oh... I see that Ada already has an interface for selecting a list of
> symbols.  Another bit that doesn't belong anywhere near the
> language-specific code, if you'll permit some historical ranting.

I agree. My holy grail would be to push all the code doing symbol
lookups for Ada, or rather the 90% part of it that's almost a copy/paste
of the C code. But this is not something that I have been looking at,
because Paul Hilfinger was more familiar with this part and its
historical legacy.

> > >   Or you could
> > > just use the minsym version, and then call find_pc_function.
> > 
> > That's a good idea, I think. Lookup the minsym.... Hmmm, let me explore
> > this path. Thanks!
> 
> Follow along with the code immediately above in the same function. 

I don't understand you suggestion, there isn't much code above the
part I'd like to change. Maybe below?

In any case, attached is the patch that I came up with. I tested it
on x86-linux RH9.0 using the stock gcc/g++ there. No regression found.
Would it be acceptable for inclusion? I can also add a dated comments
explaining why we are doing it that way instead of using lookup_symbol.

> Beware, right now that minsym code may find the one which demangles to
> main; but that should change.

Hmmm, did I do it the right way, or did I open a bad door? In the latter
case, is there a way for me to make sure I find the right one? It seems
pretty easy to verify that I did find the right own by comparing
main_name() against the SYMBOL_LINKAGE_NAME, but that still would not
help us find the right symbol :-).

2003-10-06  J. Brobecker  <brobecker@gnat.com>

	* blockframe.c (inside_main_func): No longer use symbol_lookup()
        to lookup the main function symbol.

Thanks,
-- 
Joel

[-- Attachment #2: blockframe.c.diff --]
[-- Type: text/plain, Size: 1805 bytes --]

Index: blockframe.c
===================================================================
RCS file: /cvs/src/src/gdb/blockframe.c,v
retrieving revision 1.80
diff -u -p -r1.80 blockframe.c
--- blockframe.c	14 Sep 2003 16:32:12 -0000	1.80
+++ blockframe.c	7 Oct 2003 01:56:40 -0000
@@ -83,22 +83,27 @@ deprecated_inside_entry_file (CORE_ADDR 
 int
 inside_main_func (CORE_ADDR pc)
 {
+  struct minimal_symbol *msymbol;
+
   if (pc == 0)
     return 1;
   if (symfile_objfile == 0)
     return 0;
 
+  msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
+
   /* If the addr range is not set up at symbol reading time, set it up
      now.  This is for DEPRECATED_FRAME_CHAIN_VALID_ALTERNATE. I do
      this for coff, because it is unable to set it up and symbol
      reading time. */
 
-  if (symfile_objfile->ei.main_func_lowpc == INVALID_ENTRY_LOWPC &&
-      symfile_objfile->ei.main_func_highpc == INVALID_ENTRY_HIGHPC)
+  if (msymbol != NULL
+      && symfile_objfile->ei.main_func_lowpc == INVALID_ENTRY_LOWPC
+      && symfile_objfile->ei.main_func_highpc == INVALID_ENTRY_HIGHPC)
     {
-      struct symbol *mainsym;
+      struct symbol *mainsym
+        = find_pc_function (SYMBOL_VALUE_ADDRESS (msymbol));
 
-      mainsym = lookup_symbol (main_name (), NULL, VAR_DOMAIN, NULL, NULL);
       if (mainsym && SYMBOL_CLASS (mainsym) == LOC_BLOCK)
 	{
 	  symfile_objfile->ei.main_func_lowpc =
@@ -111,8 +116,6 @@ inside_main_func (CORE_ADDR pc)
   /* Not in the normal symbol tables, see if "main" is in the partial
      symbol table.  If it's not, then give up.  */
   {
-    struct minimal_symbol *msymbol
-      = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
     if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_text)
       {
 	struct obj_section *osect