Name of symbol missing when printing global variable's address

The build_address_symbolic funnction filters out data symbols if
their size is set to zero.  But the problem is that the COFF symbol
table (for instance) does not provide any size information, leaving
the size to its default value of zero, thus always triggering
the filter.

This shows up when trying to print the address of a global variable
when debugging a Windows executable, for instance.

gdb/ChangeLog:

        * symtab.h (struct minimal_symbol) [has_size]: New field.
        (MSYMBOL_SIZE): Adjust to forbid macro from being used as lvalue.
        (SET_MSYMBOL_SIZE, MSYMBOL_HAS_SIZE): New macros.
        * printcmd.c (build_address_symbolic): Only filter out zero-sized
        minimal symbols if the symbol's size is actually known.
        * minsyms.c (prim_record_minimal_symbol_full): Adjust setting
        of msymbol's size field.  Add comment.
        * elfread.c (elf_symtab_read, elf_rel_plt_read): Use
        SET_MSYMBOL_SIZE to set the minimal symbol size.

5 files changed, 32 insertions, 5 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 449d4fb..333eb6e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,17 @@
 2012-09-11  Joel Brobecker  <brobecker@adacore.com>
 
+	* symtab.h (struct minimal_symbol) [has_size]: New field.
+	(MSYMBOL_SIZE): Adjust to forbid macro from being used as lvalue.
+	(SET_MSYMBOL_SIZE, MSYMBOL_HAS_SIZE): New macros.
+	* printcmd.c (build_address_symbolic): Only filter out zero-sized
+	minimal symbols if the symbol's size is actually known.
+	* minsyms.c (prim_record_minimal_symbol_full): Adjust setting
+	of msymbol's size field.  Add comment.
+	* elfread.c (elf_symtab_read, elf_rel_plt_read): Use
+	SET_MSYMBOL_SIZE to set the minimal symbol size.
+
+2012-09-11  Joel Brobecker  <brobecker@adacore.com>
+
 	* minsyms.c (install_minimal_symbols): Use memset to fill entire
 	minimal_symbol struct object, rather than setting some of its
 	fields one by one.
diff --git a/gdb/elfread.c b/gdb/elfread.c
index f3967d7..516cbd0 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -570,7 +570,7 @@ elf_symtab_read (struct objfile *objfile, int type,
 		elf_sym = (elf_symbol_type *) sym->udata.p;
 
 	      if (elf_sym)
-		MSYMBOL_SIZE(msym) = elf_sym->internal_elf_sym.st_size;
+		SET_MSYMBOL_SIZE (msym, elf_sym->internal_elf_sym.st_size);
 
 	      msym->filename = filesymname;
 	      gdbarch_elf_make_msymbol_special (gdbarch, sym, msym);
@@ -594,7 +594,7 @@ elf_symtab_read (struct objfile *objfile, int type,
 						  sym->section, objfile);
 		  if (mtramp)
 		    {
-		      MSYMBOL_SIZE (mtramp) = MSYMBOL_SIZE (msym);
+		      SET_MSYMBOL_SIZE (mtramp, MSYMBOL_SIZE (msym));
 		      mtramp->created_by_gdb = 1;
 		      mtramp->filename = filesymname;
 		      gdbarch_elf_make_msymbol_special (gdbarch, sym, mtramp);
@@ -689,7 +689,7 @@ elf_rel_plt_read (struct objfile *objfile, asymbol **dyn_symbol_table)
                                     1, address, mst_slot_got_plt, got_plt,
 				    objfile);
       if (msym)
-	MSYMBOL_SIZE (msym) = ptr_size;
+	SET_MSYMBOL_SIZE (msym, ptr_size);
     }
 
   do_cleanups (back_to);
diff --git a/gdb/minsyms.c b/gdb/minsyms.c
index b6df4ea..a3a376c 100644
--- a/gdb/minsyms.c
+++ b/gdb/minsyms.c
@@ -937,7 +937,9 @@ prim_record_minimal_symbol_full (const char *name, int name_len, int copy_name,
   MSYMBOL_TYPE (msymbol) = ms_type;
   MSYMBOL_TARGET_FLAG_1 (msymbol) = 0;
   MSYMBOL_TARGET_FLAG_2 (msymbol) = 0;
-  MSYMBOL_SIZE (msymbol) = 0;
+  /* Do not use the SET_MSYMBOL_SIZE macro to initialize the size,
+     as it would also set the has_size flag.  */
+  msymbol->size = 0;
 
   /* The hash pointers must be cleared! If they're not,
      add_minsym_to_hash_table will NOT add this msymbol to the hash table.  */
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index d5b5b63..9e8cd65 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -680,6 +680,7 @@ build_address_symbolic (struct gdbarch *gdbarch,
     }
 
   if (msymbol != NULL
+      && MSYMBOL_HAS_SIZE (msymbol)
       && MSYMBOL_SIZE (msymbol) == 0
       && MSYMBOL_TYPE (msymbol) != mst_text
       && MSYMBOL_TYPE (msymbol) != mst_text_gnu_ifunc
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 76120a3..041d8cf 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -348,6 +348,11 @@ struct minimal_symbol
   unsigned int target_flag_1 : 1;
   unsigned int target_flag_2 : 1;
 
+  /* Nonzero iff the size of the minimal symbol has been set.
+     Symbol size information can sometimes not be determined, because
+     the object file format may not carry that piece of information.  */
+  unsigned int has_size : 1;
+
   /* Minimal symbols with the same hash key are kept on a linked
      list.  This is the link.  */
 
@@ -361,7 +366,14 @@ struct minimal_symbol
 
 #define MSYMBOL_TARGET_FLAG_1(msymbol)  (msymbol)->target_flag_1
 #define MSYMBOL_TARGET_FLAG_2(msymbol)  (msymbol)->target_flag_2
-#define MSYMBOL_SIZE(msymbol)		(msymbol)->size
+#define MSYMBOL_SIZE(msymbol)		((msymbol)->size + 0)
+#define SET_MSYMBOL_SIZE(msymbol, sz)		\
+  do						\
+    {						\
+      (msymbol)->size = sz;			\
+      (msymbol)->has_size = 1;			\
+    } while (0)
+#define MSYMBOL_HAS_SIZE(msymbol)	((msymbol)->has_size + 0)
 #define MSYMBOL_TYPE(msymbol)		(msymbol)->type
 
 #include "minsyms.h"