FYI: don't use obsavestring on a constant string

[Tom Tromey <tromey at redhat dot com>]

I'm checking this in.

I noticed a few places in gdb that call obsavestring on a constant
string.  I can't think of any reason to ever do this.  This patch
removes all such calls.

Built and regtested on x86-64 (compile farm).

Tom

2009-11-05  Tom Tromey  <tromey@redhat.com>

	* symtab.h (SYMBOL_SET_LINKAGE_NAME): Update comment.
	* symfile.c (allocate_symtab): Don't use obsavestring on a
	constant string.
	* stabsread.c (define_symbol): Don't use obsavestring on a
	constant string.
	* mdebugread.c (parse_type): Don't use obsavestring on a constant
	string.
	(new_symtab): Likewise.
	* elfread.c (elf_symtab_read): Don't use obsavestring on a
	constant string.

diff --git a/gdb/elfread.c b/gdb/elfread.c
index 131d7d2..29b7c0c 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -231,8 +231,9 @@ elf_symtab_read (struct objfile *objfile, int type,
   /* If filesym is nonzero, it points to a file symbol, but we haven't
      seen any section info for it yet.  */
   asymbol *filesym = 0;
-  /* Name of filesym, as saved on the objfile_obstack.  */
-  char *filesymname = obsavestring ("", 0, &objfile->objfile_obstack);
+  /* Name of filesym.  This is either a constant string or is saved on
+     the objfile's obstack.  */
+  char *filesymname = "";
   struct dbx_symfile_info *dbx = objfile->deprecated_sym_stab_info;
   int stripped = (bfd_get_symcount (objfile->obfd) == 0);
 
diff --git a/gdb/mdebugread.c b/gdb/mdebugread.c
index aac82e9..7d29b97 100644
--- a/gdb/mdebugread.c
+++ b/gdb/mdebugread.c
@@ -1746,12 +1746,10 @@ parse_type (int fd, union aux_ext *ax, unsigned int aux_index, int *bs,
       TYPE_NFIELDS (tp) = 2;
       TYPE_FIELDS (tp) = ((struct field *)
 			  TYPE_ALLOC (tp, 2 * sizeof (struct field)));
-      TYPE_FIELD_NAME (tp, 0) = obsavestring ("Low", strlen ("Low"),
-					    &current_objfile->objfile_obstack);
+      TYPE_FIELD_NAME (tp, 0) = "Low";
       TYPE_LOW_BOUND (tp) = AUX_GET_DNLOW (bigend, ax);
       ax++;
-      TYPE_FIELD_NAME (tp, 1) = obsavestring ("High", strlen ("High"),
-					    &current_objfile->objfile_obstack);
+      TYPE_FIELD_NAME (tp, 1) = "High";
       TYPE_HIGH_BOUND (tp) = AUX_GET_DNHIGH (bigend, ax);
       ax++;
     }
@@ -4680,8 +4678,7 @@ new_symtab (char *name, int maxlines, struct objfile *objfile)
     BLOCKVECTOR_BLOCK (BLOCKVECTOR (s), GLOBAL_BLOCK);
 
   s->free_code = free_linetable;
-  s->debugformat = obsavestring ("ECOFF", 5,
-				 &objfile->objfile_obstack);
+  s->debugformat = "ECOFF";
   return (s);
 }
 
diff --git a/gdb/stabsread.c b/gdb/stabsread.c
index e62bb15..274fe1a 100644
--- a/gdb/stabsread.c
+++ b/gdb/stabsread.c
@@ -673,18 +673,14 @@ define_symbol (CORE_ADDR valu, char *string, int desc, int type,
       switch (string[1])
 	{
 	case 't':
-	  SYMBOL_SET_LINKAGE_NAME
-	    (sym, obsavestring ("this", strlen ("this"),
-				&objfile->objfile_obstack));
+	  SYMBOL_SET_LINKAGE_NAME (sym, "this");
 	  break;
 
 	case 'v':		/* $vtbl_ptr_type */
 	  goto normal;
 
 	case 'e':
-	  SYMBOL_SET_LINKAGE_NAME
-	    (sym, obsavestring ("eh_throw", strlen ("eh_throw"),
-				&objfile->objfile_obstack));
+	  SYMBOL_SET_LINKAGE_NAME (sym, "eh_throw");
 	  break;
 
 	case '_':
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 1e57c69..626aa54 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -2750,8 +2750,7 @@ allocate_symtab (char *filename, struct objfile *objfile)
 				   &objfile->objfile_obstack);
   symtab->fullname = NULL;
   symtab->language = deduce_language_from_filename (filename);
-  symtab->debugformat = obsavestring ("unknown", 7,
-				      &objfile->objfile_obstack);
+  symtab->debugformat = "unknown";
 
   /* Hook it to the objfile it comes from */
 
diff --git a/gdb/symtab.h b/gdb/symtab.h
index acb8510..2bc3dd5 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -185,7 +185,8 @@ extern void symbol_init_language_specific (struct general_symbol_info *symbol,
 /* Set just the linkage name of a symbol; do not try to demangle
    it.  Used for constructs which do not have a mangled name,
    e.g. struct tags.  Unlike SYMBOL_SET_NAMES, linkage_name must
-   be terminated and already on the objfile's obstack.  */
+   be terminated and either already on the objfile's obstack or
+   permanently allocated.  */
 #define SYMBOL_SET_LINKAGE_NAME(symbol,linkage_name) \
   (symbol)->ginfo.name = (linkage_name)