Move AARCH64 ILP32 rejection handling

For AARCH64 ILP32, we reject compatibility too
early on to support gdb ILP32.  This patch
moves ILP32 rejection from compatible
to elfNN_aarch64_merge_private_bfd_data
which allows aarch64 and aarch64:ilp32
to be handled correctly with gdb.
An added bonus is that we can have an error
message on why two object files are rejected.

OK?  Tested both binutils and gdb.

Thanks,
Andrew Pinski

2016-08-31  Andrew Pinski  <apinski@cavium.com>

	* cpu-aarch64.c (compatible):
	Don't reject different mach or ILP32 here.
	* elfnn-aarch64.c (elfNN_aarch64_merge_private_bfd_data):
	Add an error message on why endianess is rejected.
	Reject different ILP32/LP64 settings.

Signed-off-by: Andrew Pinski <apinski@cavium.com>

3 files changed, 27 insertions, 26 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 59dfb2c..77b2b6b 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2016-08-31  Andrew Pinski  <apinski@cavium.com>
+
+	* cpu-aarch64.c (compatible):
+	Don't reject different mach or ILP32 here.
+	* elfnn-aarch64.c (elfNN_aarch64_merge_private_bfd_data):
+	Add an error message on why endianess is rejected.
+	Reject different ILP32/LP64 settings.
+
 2016-08-31  Alan Modra  <amodra@gmail.com>
 
 	* elf64-ppc.c (group_sections): Delete stub14_group_size.  Instead,
diff --git a/bfd/cpu-aarch64.c b/bfd/cpu-aarch64.c
index 596d241..6fb9133 100644
--- a/bfd/cpu-aarch64.c
+++ b/bfd/cpu-aarch64.c
@@ -34,31 +34,9 @@ compatible (const bfd_arch_info_type * a, const bfd_arch_info_type * b)
   if (a->arch != b->arch)
     return NULL;
 
-  /* If a & b are for the same machine then all is well.  */
-  if (a->mach == b->mach)
-    return a;
-
-  /* Don't allow mixing ilp32 with lp64.  */
-  if ((a->mach & bfd_mach_aarch64_ilp32) != (b->mach & bfd_mach_aarch64_ilp32))
-    return NULL;
-
-  /* Otherwise if either a or b is the 'default' machine
-     then it can be polymorphed into the other.  */
-  if (a->the_default)
-    return b;
-
-  if (b->the_default)
-    return a;
-
-  /* So far all newer cores are
-     supersets of previous cores.  */
-  if (a->mach < b->mach)
-    return b;
-  else if (a->mach > b->mach)
-    return a;
-
-  /* Never reached!  */
-  return NULL;
+  /* Machine compatibility is checked in
+     elfNN_aarch64_merge_private_bfd_data.  */
+  return a;
 }
 
 static struct
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 3435a3d..1e27501 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -6530,11 +6530,26 @@ elfNN_aarch64_merge_private_bfd_data (bfd *ibfd, bfd *obfd)
 
   /* Check if we have the same endianess.  */
   if (!_bfd_generic_verify_endian_match (ibfd, obfd))
-    return FALSE;
+    {
+      (*_bfd_error_handler)
+	(_("%B: endianness incompatible with that of the selected emulation"),
+	 ibfd);
+      return FALSE;
+    }
 
   if (!is_aarch64_elf (ibfd) || !is_aarch64_elf (obfd))
     return TRUE;
 
+  /* Don't allow mixing ilp32 with lp64.  */
+  if ((bfd_get_arch_info (ibfd)->mach & bfd_mach_aarch64_ilp32)
+      != (bfd_get_arch_info (obfd)->mach & bfd_mach_aarch64_ilp32))
+    {
+      (*_bfd_error_handler)
+	(_("%B: ABI is incompatible with that of the selected emulation: \"%s\" != \"%s\""),
+	 ibfd, bfd_get_target (ibfd), bfd_get_target (obfd));
+      return FALSE;
+    }
+
   /* The input BFD must have had its flags initialised.  */
   /* The following seems bogus to me -- The flags are initialized in
      the assembler but I don't think an elf_flags_init field is