Re: The problem with stabs and sign extension

["H . J . Lu" <hjl@lucon.org>]

On Wed, Aug 08, 2001 at 04:14:21PM -0700, H . J . Lu wrote:
> On Wed, Aug 08, 2001 at 02:12:07PM -0700, Daniel Jacobowitz wrote:
> > The problem seems, to my inexperienced eye, to be in stabsread.c:
> > 
> > #define INTERNALIZE_SYMBOL(intern, extern, abfd)                        \
> >   {                                                                     \
> >     (intern).n_type = bfd_h_get_8 (abfd, (extern)->e_type);             \
> >     (intern).n_strx = bfd_h_get_32 (abfd, (extern)->e_strx);            \
> >     (intern).n_desc = bfd_h_get_16 (abfd, (extern)->e_desc);            \
> >     (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);          \
> >   }
> > 
> > n_value is a CORE_ADDR.  bfd_h_get_32 returns a bfd_vma, without doing sign
> > extension.  For MIPS, we want sign extension to have happened here.  Right? 
> > It does if we're reading mdebug in (because ECOFF_SIGNED_32 is defined in
> > BFD).
> > 
> > On the other hand, I'm sure other targets don't want sign extension here. 
> > How should we handle this?
> 

With this patch, I can do

# gdb vmlinux
...
(gdb) print printk
$1 = {int (char *)} 0x8011c5b0 <printk>
(gdb) list printk
250     printk.c: No such file or directory.
        in printk.c


H.J.
----
2001-08-08  H.J. Lu  (hjl@gnu.org)

	* dbxread.c (COERCE32): New.
	(SWAP_SYMBOL): Removed.
	(INTERNALIZE_SYMBOL): Check sign extended vma.
	(read_ofile_symtab): Set text_offset with COERCE32.

--- gdb/dbxread.c.vma	Fri Jul 13 12:12:34 2001
+++ gdb/dbxread.c	Wed Aug  8 16:49:09 2001
@@ -109,6 +109,10 @@ struct symloc
 #define SYMBOL_OFFSET(p) (SYMLOC(p)->symbol_offset)
 #define STRING_OFFSET(p) (SYMLOC(p)->string_offset)
 #define FILE_STRING_OFFSET(p) (SYMLOC(p)->file_string_offset)
+
+/* Sign extension to bfd_signed_vma.  */
+#define COERCE32(x) \
+  ((bfd_signed_vma) (long) (((unsigned long) (x) ^ 0x80000000) - 0x80000000))
 \f
 
 /* Remember what we deduced to be the source language of this psymtab. */
@@ -946,22 +950,15 @@ fill_symbuf (bfd *sym_bfd)
   symbuf_read += nbytes;
 }
 
-#define SWAP_SYMBOL(symp, abfd) \
-  { \
-    (symp)->n_strx = bfd_h_get_32(abfd,			\
-				(unsigned char *)&(symp)->n_strx);	\
-    (symp)->n_desc = bfd_h_get_16 (abfd,			\
-				(unsigned char *)&(symp)->n_desc);  	\
-    (symp)->n_value = bfd_h_get_32 (abfd,			\
-				(unsigned char *)&(symp)->n_value); 	\
-  }
-
 #define INTERNALIZE_SYMBOL(intern, extern, abfd)			\
   {									\
     (intern).n_type = bfd_h_get_8 (abfd, (extern)->e_type);		\
     (intern).n_strx = bfd_h_get_32 (abfd, (extern)->e_strx);		\
     (intern).n_desc = bfd_h_get_16 (abfd, (extern)->e_desc);  		\
-    (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);		\
+    if (bfd_get_sign_extend_vma (abfd))					\
+      (intern).n_value = bfd_h_get_signed_32 (abfd, (extern)->e_value);	\
+    else								\
+      (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);	\
   }
 
 /* Invariant: The symbol pointed to by symbuf_idx is the first one
@@ -1687,7 +1684,7 @@ read_ofile_symtab (struct partial_symtab
   objfile = pst->objfile;
   sym_offset = LDSYMOFF (pst);
   sym_size = LDSYMLEN (pst);
-  text_offset = pst->textlow;
+  text_offset = COERCE32 (pst->textlow);
   text_size = pst->texthigh - pst->textlow;
   /* This cannot be simply objfile->section_offsets because of
      elfstab_offset_sections() which initializes the psymtab section