gdb: fix gdbarch_tdep ODR violation

I would like to be able to use non-trivial types in gdbarch_tdep types.
This is not possible at the moment (in theory), because of the one
definition rule.

To allow it, rename all gdbarch_tdep types to <arch>_gdbarch_tdep, and
make them inherit from a gdbarch_tdep base class.  The inheritance is
necessary to be able to pass pointers to all these <arch>_gdbarch_tdep
objects to gdbarch_alloc, which takes a pointer to gdbarch_tdep.

These objects are never deleted through a base class pointer, so I
didn't include a virtual destructor.  In the future, if gdbarch objects
deletable, I could imagine that the gdbarch_tdep objects could become
owned by the gdbarch objects, and then it would become useful to have a
virtual destructor (so that the gdbarch object can delete the owned
gdbarch_tdep object).  But that's not necessary right now.

It turns out that RISC-V already has a gdbarch_tdep that is
non-default-constructible, so that provides a good motivation for this
change.

Most changes are fairly straightforward, mostly needing to add some
casts all over the place.  There is however the xtensa architecture,
doing its own little weird thing to define its gdbarch_tdep.  I did my
best to adapt it, but I can't test those changes.

Change-Id: Ic001903f91ddd106bd6ca09a79dabe8df2d69f3b

1 files changed, 17 insertions, 13 deletions

diff --git a/gdb/v850-tdep.c b/gdb/v850-tdep.c
index f829f4db2dd..70f6d42a95b 100644
--- a/gdb/v850-tdep.c
+++ b/gdb/v850-tdep.c
@@ -264,15 +264,15 @@ enum v850_abi
 
 /* Architecture specific data.  */
 
-struct gdbarch_tdep
+struct v850_gdbarch_tdep : gdbarch_tdep
 {
   /* Fields from the ELF header.  */
-  int e_flags;
-  int e_machine;
+  int e_flags = 0;
+  int e_machine = 0;
 
   /* Which ABI are we using?  */
-  enum v850_abi abi;
-  int eight_byte_align;
+  enum v850_abi abi {};
+  int eight_byte_align = 0;
 };
 
 struct v850_frame_cache
@@ -510,8 +510,9 @@ v850_use_struct_convention (struct gdbarch *gdbarch, struct type *type)
 {
   int i;
   struct type *fld_type, *tgt_type;
+  v850_gdbarch_tdep *tdep = (v850_gdbarch_tdep *) gdbarch_tdep (gdbarch);
 
-  if (gdbarch_tdep (gdbarch)->abi == V850_ABI_RH850)
+  if (tdep->abi == V850_ABI_RH850)
     {
       if (v850_type_is_scalar (type) && TYPE_LENGTH(type) <= 8)
 	return 0;
@@ -1021,8 +1022,9 @@ v850_push_dummy_call (struct gdbarch *gdbarch,
   int argnum;
   int arg_space = 0;
   int stack_offset;
+  v850_gdbarch_tdep *tdep = (v850_gdbarch_tdep *) gdbarch_tdep (gdbarch);
 
-  if (gdbarch_tdep (gdbarch)->abi == V850_ABI_RH850)
+  if (tdep->abi == V850_ABI_RH850)
     stack_offset = 0;
   else
     {
@@ -1054,7 +1056,7 @@ v850_push_dummy_call (struct gdbarch *gdbarch,
       gdb_byte valbuf[v850_reg_size];
 
       if (!v850_type_is_scalar (value_type (*args))
-	 && gdbarch_tdep (gdbarch)->abi == V850_ABI_GCC
+	  && tdep->abi == V850_ABI_GCC
 	  && TYPE_LENGTH (value_type (*args)) > E_MAX_RETTYPE_SIZE_IN_REGS)
 	{
 	  store_unsigned_integer (valbuf, 4, byte_order,
@@ -1068,7 +1070,7 @@ v850_push_dummy_call (struct gdbarch *gdbarch,
 	  val = (gdb_byte *) value_contents (*args).data ();
 	}
 
-      if (gdbarch_tdep (gdbarch)->eight_byte_align
+      if (tdep->eight_byte_align
 	  && v850_eight_byte_align_p (value_type (*args)))
 	{
 	  if (argreg <= E_ARGLAST_REGNUM && (argreg & 1))
@@ -1348,7 +1350,6 @@ static struct gdbarch *
 v850_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 {
   struct gdbarch *gdbarch;
-  struct gdbarch_tdep *tdep;
   int e_flags, e_machine;
 
   /* Extract the elf_flags if available.  */
@@ -1371,13 +1372,16 @@ v850_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
        arches != NULL;
        arches = gdbarch_list_lookup_by_info (arches->next, &info))
     {
-      if (gdbarch_tdep (arches->gdbarch)->e_flags != e_flags
-	  || gdbarch_tdep (arches->gdbarch)->e_machine != e_machine)
+      v850_gdbarch_tdep *tdep
+	= (v850_gdbarch_tdep *) gdbarch_tdep (arches->gdbarch);
+
+      if (tdep->e_flags != e_flags || tdep->e_machine != e_machine)
 	continue;
 
       return arches->gdbarch;
     }
-  tdep = XCNEW (struct gdbarch_tdep);
+
+  v850_gdbarch_tdep *tdep = new v850_gdbarch_tdep;
   tdep->e_flags = e_flags;
   tdep->e_machine = e_machine;