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, 21 insertions, 15 deletions

diff --git a/gdb/avr-tdep.c b/gdb/avr-tdep.c
index ea259b9..0db1986 100644
--- a/gdb/avr-tdep.c
+++ b/gdb/avr-tdep.c
@@ -188,18 +188,18 @@ struct avr_unwind_cache
   trad_frame_saved_reg *saved_regs;
 };
 
-struct gdbarch_tdep
+struct avr_gdbarch_tdep : gdbarch_tdep
 {
   /* Number of bytes stored to the stack by call instructions.
      2 bytes for avr1-5 and avrxmega1-5, 3 bytes for avr6 and avrxmega6-7.  */
-  int call_length;
+  int call_length = 0;
 
   /* Type for void.  */
-  struct type *void_type;
+  struct type *void_type = nullptr;
   /* Type for a function returning void.  */
-  struct type *func_void_type;
+  struct type *func_void_type = nullptr;
   /* Type for a pointer to a function.  Used for the type of PC.  */
-  struct type *pc_type;
+  struct type *pc_type = nullptr;
 };
 
 /* Lookup the name of a register given it's number.  */
@@ -230,10 +230,14 @@ avr_register_type (struct gdbarch *gdbarch, int reg_nr)
 {
   if (reg_nr == AVR_PC_REGNUM)
     return builtin_type (gdbarch)->builtin_uint32;
+
+  avr_gdbarch_tdep *tdep = (avr_gdbarch_tdep *) gdbarch_tdep (gdbarch);
   if (reg_nr == AVR_PSEUDO_PC_REGNUM)
-    return gdbarch_tdep (gdbarch)->pc_type;
+    return tdep->pc_type;
+
   if (reg_nr == AVR_SP_REGNUM)
     return builtin_type (gdbarch)->builtin_data_ptr;
+
   return builtin_type (gdbarch)->builtin_uint8;
 }
 
@@ -745,13 +749,13 @@ avr_scan_prologue (struct gdbarch *gdbarch, CORE_ADDR pc_beg, CORE_ADDR pc_end,
   gdb_assert (vpc < AVR_MAX_PROLOGUE_SIZE);
 
   /* Handle static small stack allocation using rcall or push.  */
-
+  avr_gdbarch_tdep *tdep = (avr_gdbarch_tdep *) gdbarch_tdep (gdbarch);
   while (scan_stage == 1 && vpc < len)
     {
       insn = extract_unsigned_integer (&prologue[vpc], 2, byte_order);
       if (insn == 0xd000)	/* rcall .+0 */
 	{
-	  info->size += gdbarch_tdep (gdbarch)->call_length;
+	  info->size += tdep->call_length;
 	  vpc += 2;
 	}
       else if (insn == 0x920f || insn == 0x921f)  /* push r0 or push r1 */
@@ -984,7 +988,6 @@ avr_frame_unwind_cache (struct frame_info *this_frame,
   ULONGEST this_base;
   struct avr_unwind_cache *info;
   struct gdbarch *gdbarch;
-  struct gdbarch_tdep *tdep;
   int i;
 
   if (*this_prologue_cache)
@@ -1049,7 +1052,7 @@ avr_frame_unwind_cache (struct frame_info *this_frame,
 
   /* The previous frame's SP needed to be computed.  Save the computed
      value.  */
-  tdep = gdbarch_tdep (gdbarch);
+  avr_gdbarch_tdep *tdep = (avr_gdbarch_tdep *) gdbarch_tdep (gdbarch);
   info->saved_regs[AVR_SP_REGNUM].set_value (info->prev_sp
 					     - 1 + tdep->call_length);
 
@@ -1131,7 +1134,7 @@ avr_frame_prev_register (struct frame_info *this_frame,
 	  int i;
 	  gdb_byte buf[3];
 	  struct gdbarch *gdbarch = get_frame_arch (this_frame);
-	  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+	  avr_gdbarch_tdep *tdep = (avr_gdbarch_tdep *) gdbarch_tdep (gdbarch);
 
 	  read_memory (info->saved_regs[AVR_PC_REGNUM].addr (),
 		       buf, tdep->call_length);
@@ -1273,7 +1276,8 @@ avr_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 {
   int i;
   gdb_byte buf[3];
-  int call_length = gdbarch_tdep (gdbarch)->call_length;
+  avr_gdbarch_tdep *tdep = (avr_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  int call_length = tdep->call_length;
   CORE_ADDR return_pc = avr_convert_iaddr_to_raw (bp_addr);
   int regnum = AVR_ARGN_REGNUM;
   struct stack_item *si = NULL;
@@ -1424,7 +1428,6 @@ static struct gdbarch *
 avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 {
   struct gdbarch *gdbarch;
-  struct gdbarch_tdep *tdep;
   struct gdbarch_list *best_arch;
   int call_length;
 
@@ -1456,12 +1459,15 @@ avr_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
        best_arch != NULL;
        best_arch = gdbarch_list_lookup_by_info (best_arch->next, &info))
     {
-      if (gdbarch_tdep (best_arch->gdbarch)->call_length == call_length)
+      avr_gdbarch_tdep *tdep
+	= (avr_gdbarch_tdep *) gdbarch_tdep (best_arch->gdbarch);
+
+      if (tdep->call_length == call_length)
 	return best_arch->gdbarch;
     }
 
   /* None found, create a new architecture from the information provided.  */
-  tdep = XCNEW (struct gdbarch_tdep);
+  avr_gdbarch_tdep *tdep = new avr_gdbarch_tdep;
   gdbarch = gdbarch_alloc (&info, tdep);
   
   tdep->call_length = call_length;