[rfa] lookup_symbol_aux_minsym
David Carlton
carlton@math.stanford.edu
Wed Dec 4 14:57:00 GMT 2002
On Wed, 4 Dec 2002 14:39:34 -0500, Elena Zannoni <ezannoni@redhat.com> said:
> OK, I think we should use find_pc_sect_symtab after all.
Yes, given Jim's comments that clearly seems better.
> I found some info....
Thanks!
> Approved, modulus the fortran, etc comments.
Committed; I'm including what I committed at the bottom if this
message. It differs from my original patch only in the comment at the
bottom, which is now the HP version of the comment plus some
explanation before it including your Fortran info.
David Carlton
carlton@math.stanford.edu
2002-11-05 David Carlton <carlton@math.stanford.edu>
* symtab.c (lookup_symbol_aux): Move minsym code into a separate
function.
(lookup_symbol_aux_minsyms): New function.
Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.78
diff -u -p -r1.78 symtab.c
--- symtab.c 6 Nov 2002 23:27:58 -0000 1.78
+++ symtab.c 4 Dec 2002 20:52:15 -0000
@@ -103,6 +103,14 @@ struct symbol *lookup_symbol_aux_psymtab
const namespace_enum namespace,
struct symtab **symtab);
+static
+struct symbol *lookup_symbol_aux_minsyms (const char *name,
+ const char *mangled_name,
+ const namespace_enum namespace,
+ int *is_a_field_of_this,
+ struct symtab **symtab,
+ int *force_return);
+
static struct symbol *find_active_alias (struct symbol *sym, CORE_ADDR addr);
/* This flag is used in hppa-tdep.c, and set in hp-symtab-read.c */
@@ -786,9 +794,14 @@ lookup_symbol_aux (const char *name, con
int *is_a_field_of_this, struct symtab **symtab)
{
struct symbol *sym;
- struct symtab *s = NULL;
- struct blockvector *bv;
- struct minimal_symbol *msymbol;
+
+ /* FIXME: carlton/2002-11-05: This variable is here so that
+ lookup_symbol_aux will sometimes return NULL after receiving a
+ NULL return value from lookup_symbol_aux_minsyms, without
+ proceeding on to the partial symtab and static variable tests. I
+ suspect that that's a bad idea. */
+
+ int force_return;
/* Search specified block and its superiors. */
@@ -875,65 +888,14 @@ lookup_symbol_aux (const char *name, con
a mangled variable that is stored in one of the minimal symbol tables.
Eventually, all global symbols might be resolved in this way. */
- if (namespace == VAR_NAMESPACE)
- {
- msymbol = lookup_minimal_symbol (name, NULL, NULL);
- if (msymbol != NULL)
- {
- s = find_pc_sect_symtab (SYMBOL_VALUE_ADDRESS (msymbol),
- SYMBOL_BFD_SECTION (msymbol));
- if (s != NULL)
- {
- /* This is a function which has a symtab for its address. */
- bv = BLOCKVECTOR (s);
- block = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+ force_return = 0;
- /* This call used to pass `SYMBOL_NAME (msymbol)' as the
- `name' argument to lookup_block_symbol. But the name
- of a minimal symbol is always mangled, so that seems
- to be clearly the wrong thing to pass as the
- unmangled name. */
- sym = lookup_block_symbol (block, name, mangled_name, namespace);
- /* We kept static functions in minimal symbol table as well as
- in static scope. We want to find them in the symbol table. */
- if (!sym)
- {
- block = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
- sym = lookup_block_symbol (block, name,
- mangled_name, namespace);
- }
-
- /* sym == 0 if symbol was found in the minimal symbol table
- but not in the symtab.
- Return 0 to use the msymbol definition of "foo_".
-
- This happens for Fortran "foo_" symbols,
- which are "foo" in the symtab.
-
- This can also happen if "asm" is used to make a
- regular symbol but not a debugging symbol, e.g.
- asm(".globl _main");
- asm("_main:");
- */
-
- if (symtab != NULL)
- *symtab = s;
- return fixup_symbol_section (sym, s->objfile);
- }
- else if (MSYMBOL_TYPE (msymbol) != mst_text
- && MSYMBOL_TYPE (msymbol) != mst_file_text
- && !STREQ (name, SYMBOL_NAME (msymbol)))
- {
- /* This is a mangled variable, look it up by its
- mangled name. */
- return lookup_symbol_aux (SYMBOL_NAME (msymbol), mangled_name, NULL,
- namespace, is_a_field_of_this, symtab);
- }
- /* There are no debug symbols for this file, or we are looking
- for an unmangled variable.
- Try to find a matching static symbol below. */
- }
- }
+ sym = lookup_symbol_aux_minsyms (name, mangled_name,
+ namespace, is_a_field_of_this,
+ symtab, &force_return);
+
+ if (sym != NULL || force_return == 1)
+ return sym;
#endif
@@ -975,87 +937,15 @@ lookup_symbol_aux (const char *name, con
the static check in this case?
*/
- if (namespace == VAR_NAMESPACE)
- {
- msymbol = lookup_minimal_symbol (name, NULL, NULL);
- if (msymbol != NULL)
- {
- /* OK, we found a minimal symbol in spite of not
- * finding any symbol. There are various possible
- * explanations for this. One possibility is the symbol
- * exists in code not compiled -g. Another possibility
- * is that the 'psymtab' isn't doing its job.
- * A third possibility, related to #2, is that we were confused
- * by name-mangling. For instance, maybe the psymtab isn't
- * doing its job because it only know about demangled
- * names, but we were given a mangled name...
- */
-
- /* We first use the address in the msymbol to try to
- * locate the appropriate symtab. Note that find_pc_symtab()
- * has a side-effect of doing psymtab-to-symtab expansion,
- * for the found symtab.
- */
- s = find_pc_symtab (SYMBOL_VALUE_ADDRESS (msymbol));
- if (s != NULL)
- {
- bv = BLOCKVECTOR (s);
- block = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
- /* This call used to pass `SYMBOL_NAME (msymbol)' as the
- `name' argument to lookup_block_symbol. But the name
- of a minimal symbol is always mangled, so that seems
- to be clearly the wrong thing to pass as the
- unmangled name. */
- sym = lookup_block_symbol (block, name, mangled_name, namespace);
- /* We kept static functions in minimal symbol table as well as
- in static scope. We want to find them in the symbol table. */
- if (!sym)
- {
- block = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
- sym = lookup_block_symbol (block, name,
- mangled_name, namespace);
- }
- /* If we found one, return it */
- if (sym)
- {
- if (symtab != NULL)
- *symtab = s;
- return sym;
- }
-
- /* If we get here with sym == 0, the symbol was
- found in the minimal symbol table
- but not in the symtab.
- Fall through and return 0 to use the msymbol
- definition of "foo_".
- (Note that outer code generally follows up a call
- to this routine with a call to lookup_minimal_symbol(),
- so a 0 return means we'll just flow into that other routine).
- This happens for Fortran "foo_" symbols,
- which are "foo" in the symtab.
+ force_return = 0;
- This can also happen if "asm" is used to make a
- regular symbol but not a debugging symbol, e.g.
- asm(".globl _main");
- asm("_main:");
- */
- }
-
- /* If the lookup-by-address fails, try repeating the
- * entire lookup process with the symbol name from
- * the msymbol (if different from the original symbol name).
- */
- else if (MSYMBOL_TYPE (msymbol) != mst_text
- && MSYMBOL_TYPE (msymbol) != mst_file_text
- && !STREQ (name, SYMBOL_NAME (msymbol)))
- {
- return lookup_symbol_aux (SYMBOL_NAME (msymbol), mangled_name,
- NULL, namespace, is_a_field_of_this,
- symtab);
- }
- }
- }
+ sym = lookup_symbol_aux_minsyms (name, mangled_name,
+ namespace, is_a_field_of_this,
+ symtab, &force_return);
+
+ if (sym != NULL || force_return == 1)
+ return sym;
#endif
@@ -1198,6 +1088,130 @@ lookup_symbol_aux_psymtabs (int block_in
return fixup_symbol_section (sym, objfile);
}
}
+
+ return NULL;
+}
+
+/* Check for the possibility of the symbol being a function or a
+ mangled variable that is stored in one of the minimal symbol
+ tables. Eventually, all global symbols might be resolved in this
+ way. */
+
+static struct symbol *
+lookup_symbol_aux_minsyms (const char *name,
+ const char *mangled_name,
+ const namespace_enum namespace,
+ int *is_a_field_of_this,
+ struct symtab **symtab,
+ int *force_return)
+{
+ struct symbol *sym;
+ struct blockvector *bv;
+ const struct block *block;
+ struct minimal_symbol *msymbol;
+ struct symtab *s;
+
+ if (namespace == VAR_NAMESPACE)
+ {
+ msymbol = lookup_minimal_symbol (name, NULL, NULL);
+
+ if (msymbol != NULL)
+ {
+ /* OK, we found a minimal symbol in spite of not finding any
+ symbol. There are various possible explanations for
+ this. One possibility is the symbol exists in code not
+ compiled -g. Another possibility is that the 'psymtab'
+ isn't doing its job. A third possibility, related to #2,
+ is that we were confused by name-mangling. For instance,
+ maybe the psymtab isn't doing its job because it only
+ know about demangled names, but we were given a mangled
+ name... */
+
+ /* We first use the address in the msymbol to try to locate
+ the appropriate symtab. Note that find_pc_sect_symtab()
+ has a side-effect of doing psymtab-to-symtab expansion,
+ for the found symtab. */
+ s = find_pc_sect_symtab (SYMBOL_VALUE_ADDRESS (msymbol),
+ SYMBOL_BFD_SECTION (msymbol));
+ if (s != NULL)
+ {
+ /* This is a function which has a symtab for its address. */
+ bv = BLOCKVECTOR (s);
+ block = BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK);
+
+ /* This call used to pass `SYMBOL_NAME (msymbol)' as the
+ `name' argument to lookup_block_symbol. But the name
+ of a minimal symbol is always mangled, so that seems
+ to be clearly the wrong thing to pass as the
+ unmangled name. */
+ sym =
+ lookup_block_symbol (block, name, mangled_name, namespace);
+ /* We kept static functions in minimal symbol table as well as
+ in static scope. We want to find them in the symbol table. */
+ if (!sym)
+ {
+ block = BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK);
+ sym = lookup_block_symbol (block, name,
+ mangled_name, namespace);
+ }
+
+ /* NOTE: carlton/2002-12-04: The following comment was
+ taken from a time when two versions of this function
+ were part of the body of lookup_symbol_aux: this
+ comment was taken from the version of the function
+ that was #ifdef HPUXHPPA, and the comment was right
+ before the 'return NULL' part of lookup_symbol_aux.
+ (Hence the "Fall through and return 0" comment.)
+ Elena did some digging into the situation for
+ Fortran, and she reports:
+
+ "I asked around (thanks to Jeff Knaggs), and I think
+ the story for Fortran goes like this:
+
+ "Apparently, in older Fortrans, '_' was not part of
+ the user namespace. g77 attached a final '_' to
+ procedure names as the exported symbols for linkage
+ (foo_) , but the symbols went in the debug info just
+ like 'foo'. The rationale behind this is not
+ completely clear, and maybe it was done to other
+ symbols as well, not just procedures." */
+
+ /* If we get here with sym == 0, the symbol was
+ found in the minimal symbol table
+ but not in the symtab.
+ Fall through and return 0 to use the msymbol
+ definition of "foo_".
+ (Note that outer code generally follows up a call
+ to this routine with a call to lookup_minimal_symbol(),
+ so a 0 return means we'll just flow into that other routine).
+
+ This happens for Fortran "foo_" symbols,
+ which are "foo" in the symtab.
+
+ This can also happen if "asm" is used to make a
+ regular symbol but not a debugging symbol, e.g.
+ asm(".globl _main");
+ asm("_main:");
+ */
+
+ if (symtab != NULL && sym != NULL)
+ *symtab = s;
+ *force_return = 1;
+ return fixup_symbol_section (sym, s->objfile);
+ }
+ else if (MSYMBOL_TYPE (msymbol) != mst_text
+ && MSYMBOL_TYPE (msymbol) != mst_file_text
+ && !STREQ (name, SYMBOL_NAME (msymbol)))
+ {
+ /* This is a mangled variable, look it up by its
+ mangled name. */
+ *force_return = 1;
+ return lookup_symbol_aux (SYMBOL_NAME (msymbol), mangled_name,
+ NULL, namespace, is_a_field_of_this,
+ symtab);
+ }
+ }
+ }
return NULL;
}
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