Re: [patch] use .gnu.attributes to detect e500 machine type

[Aleksandar Ristovski <aristovski@qnx.com>]

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Joel, thank you for reviewing this.


Joel Brobecker wrote:
>> * rs6000-tdep.c (rs6000_gdbarch_init): Use .gnu.attributes to see
>> if this is a e500 binary (with SPE APU).
>> (powerpc_show_vector_abi): New function.
> 
> If you look at today's version of rs6000_gdbarch_init, you'll find
> that we're already checking the Tag_GNU_Power_ABI_Vector, and setting
> the tdep->vector_abi accordingly. It's actually conditionalized on
> HAVE_ELF, so we need at least to make sure that your testing of
> the .gnu.attributes sections gets conditionalized on HAVE_ELF as well.
> 
> However, I am wondering if it wouldn't be better to simply take
> advantage of the code that's already there. For that, you'll need
> to move the code up a bit, so that vector_abi gets set earlier.
> You can then use the resulting information to determine whether or
> not to fallback on the current approach of using .PPC.EMB.apuinfo.

With rearanged code, the patch is simpler, but functionally 
the same.

My original patch is broken into two, the one dealing with 
rs6000_gdbarch_init changes and using .gnu.attributes, and 
the other with printing "powerpc vector-abi" information.


Change logs:
	* rs6000-tdep.c (rs6000_gdbarch_init): Rearange the code to use
	.gnu.attributes to see if this is a e500 binary (with SPE APU).



	* rs6000-tdep.c (powerpc_show_vector_abi): New function.
	(_initialize_rs6000_tdep): Use powerpc_show_vector_abi.




Thank you,

Aleksandar

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Index: gdb/rs6000-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v
retrieving revision 1.328
diff -u -p -r1.328 rs6000-tdep.c
--- gdb/rs6000-tdep.c	22 Feb 2009 01:02:19 -0000	1.328
+++ gdb/rs6000-tdep.c	22 May 2009 19:15:42 -0000
@@ -3371,6 +3371,43 @@ rs6000_gdbarch_init (struct gdbarch_info
 	wordsize = 4;
     }
 
+#ifdef HAVE_ELF
+  if (soft_float_flag == AUTO_BOOLEAN_AUTO && from_elf_exec)
+    {
+      switch (bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
+					Tag_GNU_Power_ABI_FP))
+	{
+	case 1:
+	  soft_float_flag = AUTO_BOOLEAN_FALSE;
+	  break;
+	case 2:
+	  soft_float_flag = AUTO_BOOLEAN_TRUE;
+	  break;
+	default:
+	  break;
+	}
+    }
+
+  if (vector_abi == POWERPC_VEC_AUTO && from_elf_exec)
+    {
+      switch (bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
+					Tag_GNU_Power_ABI_Vector))
+	{
+	case 1:
+	  vector_abi = POWERPC_VEC_GENERIC;
+	  break;
+	case 2:
+	  vector_abi = POWERPC_VEC_ALTIVEC;
+	  break;
+	case 3:
+	  vector_abi = POWERPC_VEC_SPE;
+	  break;
+	default:
+	  break;
+	}
+    }
+#endif
+
   /* Get the architecture and machine from the BFD.  */
   arch = info.bfd_arch_info->arch;
   mach = info.bfd_arch_info->mach;
@@ -3383,16 +3420,14 @@ rs6000_gdbarch_init (struct gdbarch_info
      which version of it) can execute it. In our case we just look for
      the existance of the section.  */
 
-  if (info.abfd)
-    {
-      sect = bfd_get_section_by_name (info.abfd, ".PPC.EMB.apuinfo");
-      if (sect)
-	{
-	  arch = info.bfd_arch_info->arch;
-	  mach = bfd_mach_ppc_e500;
-	  bfd_default_set_arch_mach (&abfd, arch, mach);
-	  info.bfd_arch_info = bfd_get_arch_info (&abfd);
-	}
+  if (vector_abi == POWERPC_VEC_SPE
+      || (info.abfd
+	  && bfd_get_section_by_name (info.abfd, ".PPC.EMB.apuinfo") != NULL))
+    {
+      mach = bfd_mach_ppc_e500;
+      arch = info.bfd_arch_info->arch;
+      bfd_default_set_arch_mach (&abfd, arch, mach);
+      info.bfd_arch_info = bfd_get_arch_info (&abfd);
     }
 
   /* Find a default target description which describes our register
@@ -3629,43 +3664,6 @@ rs6000_gdbarch_init (struct gdbarch_info
       return NULL;
     }
 
-#ifdef HAVE_ELF
-  if (soft_float_flag == AUTO_BOOLEAN_AUTO && from_elf_exec)
-    {
-      switch (bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
-					Tag_GNU_Power_ABI_FP))
-	{
-	case 1:
-	  soft_float_flag = AUTO_BOOLEAN_FALSE;
-	  break;
-	case 2:
-	  soft_float_flag = AUTO_BOOLEAN_TRUE;
-	  break;
-	default:
-	  break;
-	}
-    }
-
-  if (vector_abi == POWERPC_VEC_AUTO && from_elf_exec)
-    {
-      switch (bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
-					Tag_GNU_Power_ABI_Vector))
-	{
-	case 1:
-	  vector_abi = POWERPC_VEC_GENERIC;
-	  break;
-	case 2:
-	  vector_abi = POWERPC_VEC_ALTIVEC;
-	  break;
-	case 3:
-	  vector_abi = POWERPC_VEC_SPE;
-	  break;
-	default:
-	  break;
-	}
-    }
-#endif
-
   if (soft_float_flag == AUTO_BOOLEAN_TRUE)
     soft_float = 1;
   else if (soft_float_flag == AUTO_BOOLEAN_FALSE)

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Index: gdb/rs6000-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v
retrieving revision 1.328
diff -u -p -r1.328 rs6000-tdep.c
--- gdb/rs6000-tdep.c	22 Feb 2009 01:02:19 -0000	1.328
+++ gdb/rs6000-tdep.c	22 May 2009 18:43:14 -0000
@@ -4003,6 +4029,36 @@ powerpc_set_vector_abi (char *args, int 
     internal_error (__FILE__, __LINE__, "could not update architecture");
 }
 
+static void
+powerpc_show_vector_abi (struct ui_file *file,
+			 int from_tty,
+			 struct cmd_list_element *c,
+			 const char *value)
+{
+  struct gdbarch *gdbarch = current_gdbarch;
+  enum powerpc_vector_abi tdep_vector_abi;
+  int global_msg_only = 0;
+
+  if (gdbarch == NULL)
+    global_msg_only = 1;
+  else 
+    {
+      tdep_vector_abi = gdbarch_tdep (gdbarch)->vector_abi;
+      if (strcmp (powerpc_vector_abi_string,
+		  powerpc_vector_strings[tdep_vector_abi]) == 0)
+	global_msg_only = 1;
+    }
+
+  if (global_msg_only)
+    printf_unfiltered ("The vector ABI is \"%s\"\n",
+		       powerpc_vector_abi_string);
+  else
+    printf_unfiltered ("\
+The vector ABI in use is \"%s\". Default setting is \"%s\".\n",
+		       powerpc_vector_strings[tdep_vector_abi],
+		       powerpc_vector_abi_string); 
+}
+
 /* Initialization code.  */
 
 extern initialize_file_ftype _initialize_rs6000_tdep; /* -Wmissing-prototypes */
@@ -4056,6 +4112,6 @@ _initialize_rs6000_tdep (void)
 			&powerpc_vector_abi_string,
 			_("Set the vector ABI."),
 			_("Show the vector ABI."),
-			NULL, powerpc_set_vector_abi, NULL,
+			NULL, powerpc_set_vector_abi, powerpc_show_vector_abi,
 			&setpowerpccmdlist, &showpowerpccmdlist);
 }