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, 19 insertions, 18 deletions

diff --git a/gdb/frv-tdep.c b/gdb/frv-tdep.c
index e105c27..c74ea68 100644
--- a/gdb/frv-tdep.c
+++ b/gdb/frv-tdep.c
@@ -67,32 +67,33 @@ struct frv_unwind_cache		/* was struct frame_extra_info */
    of structures, each of which gives all the necessary info for one
    register.  Don't stick parallel arrays in here --- that's so
    Fortran.  */
-struct gdbarch_tdep
+struct frv_gdbarch_tdep : gdbarch_tdep
 {
   /* Which ABI is in use?  */
-  enum frv_abi frv_abi;
+  enum frv_abi frv_abi {};
 
   /* How many general-purpose registers does this variant have?  */
-  int num_gprs;
+  int num_gprs = 0;
 
   /* How many floating-point registers does this variant have?  */
-  int num_fprs;
+  int num_fprs = 0;
 
   /* How many hardware watchpoints can it support?  */
-  int num_hw_watchpoints;
+  int num_hw_watchpoints = 0;
 
   /* How many hardware breakpoints can it support?  */
-  int num_hw_breakpoints;
+  int num_hw_breakpoints = 0;
 
   /* Register names.  */
-  const char **register_names;
+  const char **register_names = nullptr;
 };
 
 /* Return the FR-V ABI associated with GDBARCH.  */
 enum frv_abi
 frv_abi (struct gdbarch *gdbarch)
 {
-  return gdbarch_tdep (gdbarch)->frv_abi;
+  frv_gdbarch_tdep *tdep = (frv_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  return tdep->frv_abi;
 }
 
 /* Fetch the interpreter and executable loadmap addresses (for shared
@@ -128,13 +129,12 @@ frv_fdpic_loadmap_addresses (struct gdbarch *gdbarch, CORE_ADDR *interp_addr,
 
 /* Allocate a new variant structure, and set up default values for all
    the fields.  */
-static struct gdbarch_tdep *
+static frv_gdbarch_tdep *
 new_variant (void)
 {
-  struct gdbarch_tdep *var;
   int r;
 
-  var = XCNEW (struct gdbarch_tdep);
+  frv_gdbarch_tdep *var = new frv_gdbarch_tdep;
 
   var->frv_abi = FRV_ABI_EABI;
   var->num_gprs = 64;
@@ -219,7 +219,7 @@ new_variant (void)
 /* Indicate that the variant VAR has NUM_GPRS general-purpose
    registers, and fill in the names array appropriately.  */
 static void
-set_variant_num_gprs (struct gdbarch_tdep *var, int num_gprs)
+set_variant_num_gprs (frv_gdbarch_tdep *var, int num_gprs)
 {
   int r;
 
@@ -238,7 +238,7 @@ set_variant_num_gprs (struct gdbarch_tdep *var, int num_gprs)
 /* Indicate that the variant VAR has NUM_FPRS floating-point
    registers, and fill in the names array appropriately.  */
 static void
-set_variant_num_fprs (struct gdbarch_tdep *var, int num_fprs)
+set_variant_num_fprs (frv_gdbarch_tdep *var, int num_fprs)
 {
   int r;
 
@@ -254,7 +254,7 @@ set_variant_num_fprs (struct gdbarch_tdep *var, int num_fprs)
 }
 
 static void
-set_variant_abi_fdpic (struct gdbarch_tdep *var)
+set_variant_abi_fdpic (frv_gdbarch_tdep *var)
 {
   var->frv_abi = FRV_ABI_FDPIC;
   var->register_names[fdpic_loadmap_exec_regnum] = xstrdup ("loadmap_exec");
@@ -263,7 +263,7 @@ set_variant_abi_fdpic (struct gdbarch_tdep *var)
 }
 
 static void
-set_variant_scratch_registers (struct gdbarch_tdep *var)
+set_variant_scratch_registers (frv_gdbarch_tdep *var)
 {
   var->register_names[scr0_regnum] = xstrdup ("scr0");
   var->register_names[scr1_regnum] = xstrdup ("scr1");
@@ -276,10 +276,12 @@ frv_register_name (struct gdbarch *gdbarch, int reg)
 {
   if (reg < 0)
     return "?toosmall?";
+
   if (reg >= frv_num_regs + frv_num_pseudo_regs)
     return "?toolarge?";
 
-  return gdbarch_tdep (gdbarch)->register_names[reg];
+  frv_gdbarch_tdep *tdep = (frv_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  return tdep->register_names[reg];
 }
 
 
@@ -1439,7 +1441,6 @@ static struct gdbarch *
 frv_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 {
   struct gdbarch *gdbarch;
-  struct gdbarch_tdep *var;
   int elf_flags = 0;
 
   /* Check to see if we've already built an appropriate architecture
@@ -1449,7 +1450,7 @@ frv_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
     return arches->gdbarch;
 
   /* Select the right tdep structure for this variant.  */
-  var = new_variant ();
+  frv_gdbarch_tdep *var = new_variant ();
   switch (info.bfd_arch_info->mach)
     {
     case bfd_mach_frv: