RFA: MIPS ABI selection

[Daniel Jacobowitz]

On Sun, Jun 09, 2002 at 03:15:16PM -0400, Andrew Cagney wrote:
> >The current state of the world in GCC says: a handful of setups default to
> >unique ABIs, but the global default is O32.  The default is also to pass no
> >ABI flags to the assembler.
> >
> >elf64.h, iris6.h, isa3264.h, and r3900.h override this.  Irix defaults to
> >N32 and passing -n32 which presumably tags binaries; plus the irix
> >configuration in GDB can handle this.  elf64.h does not do pass any flags
> >but defaults to O64.  isa3264.h defaults to MEABI and appears not to tag
> >binaries.  r3900.h defaults to EABI and untagged binaries.
> >
> >That's mipsisa32-*-elf*, mips64*-*-elf*, mipstx39*-*-elf*,
> >mips-sgi-irix5cross64, and mips-sgi-irix6*.
> >
> >So what's a debugger to do?  Right now, we try to infer things from our
> >header files, but only little details of the ABI.  In particular, we never
> >infer O32 correctly.  Better would be to match GCC; that's quite
> >straightforward.
> 
> 
> >I skipped mipsisa32-*-elf*, because GDB doesn't support MEABI.  So this
> >patch fixes the defaults for mips64*-*-elf* and mipstx39*-*-elf*, and a
> >little tweaking for IRIX.  It then adds a global O32 default.  In the
> >process I found another way that GCC tags binaries with their ABI: a
> >".mdebug.abi32", etc. section.  I handle that too.  All appears to work 
> >like
> >a charm.  We even get warnings for MEABI etc. binaries.
> >
> >Andrew, this look OK?
> 
> Hmm, this contains several changes:
> 
> 
> -- The function mips_find_abi_section() that better identifies the ABI.
> 
> Yes.  This is definitly a good idea and approved.

Committed this version.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer

2002-06-08  Daniel Jacobowitz  <drow@mvista.com>

	* mips-tdep.c (mips_find_abi_section): New function.
	(mips_gdbarch_init): Call it.

Index: mips-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-tdep.c,v
retrieving revision 1.74
diff -u -p -r1.74 mips-tdep.c
--- mips-tdep.c	21 May 2002 15:36:03 -0000	1.74
+++ mips-tdep.c	9 Jun 2002 03:09:50 -0000
@@ -4126,6 +4126,32 @@ mips_integer_to_address (struct type *ty
 				 TYPE_LENGTH (builtin_type_void_data_ptr));
 }
 
+static void
+mips_find_abi_section (bfd *abfd, asection *sect, void *obj)
+{
+  enum mips_abi *abip = (enum mips_abi *) obj;
+  const char *name = bfd_get_section_name (abfd, sect);
+
+  if (*abip != MIPS_ABI_UNKNOWN)
+    return;
+
+  if (strncmp (name, ".mdebug.", 8) != 0)
+    return;
+
+  if (strcmp (name, ".mdebug.abi32") == 0)
+    *abip = MIPS_ABI_O32;
+  else if (strcmp (name, ".mdebug.abiN32") == 0)
+    *abip = MIPS_ABI_N32;
+  else if (strcmp (name, ".mdebug.abiO64") == 0)
+    *abip = MIPS_ABI_O64;
+  else if (strcmp (name, ".mdebug.eabi32") == 0)
+    *abip = MIPS_ABI_EABI32;
+  else if (strcmp (name, ".mdebug.eabi64") == 0)
+    *abip = MIPS_ABI_EABI64;
+  else
+    warning ("unsupported ABI %s.", name + 8);
+}
+
 static struct gdbarch *
 mips_gdbarch_init (struct gdbarch_info info,
 		   struct gdbarch_list *arches)
@@ -4180,6 +4206,10 @@ mips_gdbarch_init (struct gdbarch_info i
       break;
     }
 
+  /* GCC creates a pseudo-section whose name describes the ABI.  */
+  if (mips_abi == MIPS_ABI_UNKNOWN && info.abfd != NULL)
+    bfd_map_over_sections (info.abfd, mips_find_abi_section, &mips_abi);
+
   /* Try the architecture for any hint of the corect ABI */
   if (mips_abi == MIPS_ABI_UNKNOWN
       && info.bfd_arch_info != NULL