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, 18 insertions, 14 deletions

diff --git a/gdb/msp430-tdep.c b/gdb/msp430-tdep.c
index c1b0c4c..f3c44b7 100644
--- a/gdb/msp430-tdep.c
+++ b/gdb/msp430-tdep.c
@@ -104,19 +104,19 @@ enum
 
 /* Architecture specific data.  */
 
-struct gdbarch_tdep
+struct msp430_gdbarch_tdep : gdbarch_tdep
 {
   /* The ELF header flags specify the multilib used.  */
-  int elf_flags;
+  int elf_flags = 0;
 
   /* One of MSP_ISA_MSP430 or MSP_ISA_MSP430X.  */
-  int isa;
+  int isa = 0;
 
   /* One of MSP_SMALL_CODE_MODEL or MSP_LARGE_CODE_MODEL.  If, at
      some point, we support different data models too, we'll probably
      structure things so that we can combine values using logical
      "or".  */
-  int code_model;
+  int code_model = 0;
 };
 
 /* This structure holds the results of a prologue analysis.  */
@@ -340,7 +340,8 @@ msp430_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc,
   int rn;
   pv_t reg[MSP430_NUM_TOTAL_REGS];
   CORE_ADDR after_last_frame_setup_insn = start_pc;
-  int code_model = gdbarch_tdep (gdbarch)->code_model;
+  msp430_gdbarch_tdep *tdep = (msp430_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  int code_model = tdep->code_model;
   int sz;
 
   memset (result, 0, sizeof (*result));
@@ -568,7 +569,8 @@ msp430_return_value (struct gdbarch *gdbarch,
 {
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   LONGEST valtype_len = TYPE_LENGTH (valtype);
-  int code_model = gdbarch_tdep (gdbarch)->code_model;
+  msp430_gdbarch_tdep *tdep = (msp430_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  int code_model = tdep->code_model;
 
   if (TYPE_LENGTH (valtype) > 8
       || valtype->code () == TYPE_CODE_STRUCT
@@ -648,7 +650,8 @@ msp430_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
   int write_pass;
   int sp_off = 0;
   CORE_ADDR cfa;
-  int code_model = gdbarch_tdep (gdbarch)->code_model;
+  msp430_gdbarch_tdep *tdep = (msp430_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  int code_model = tdep->code_model;
 
   struct type *func_type = value_type (function);
 
@@ -766,8 +769,7 @@ msp430_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 
   /* Push the return address.  */
   {
-    int sz = (gdbarch_tdep (gdbarch)->code_model == MSP_SMALL_CODE_MODEL)
-      ? 2 : 4;
+    int sz = tdep->code_model == MSP_SMALL_CODE_MODEL ? 2 : 4;
     sp = sp - sz;
     write_memory_unsigned_integer (sp, sz, byte_order, bp_addr);
   }
@@ -811,7 +813,8 @@ msp430_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
 
   stub_name = bms.minsym->linkage_name ();
 
-  if (gdbarch_tdep (gdbarch)->code_model == MSP_SMALL_CODE_MODEL
+  msp430_gdbarch_tdep *tdep = (msp430_gdbarch_tdep *) gdbarch_tdep (gdbarch);
+  if (tdep->code_model == MSP_SMALL_CODE_MODEL
       && msp430_in_return_stub (gdbarch, pc, stub_name))
     {
       CORE_ADDR sp = get_frame_register_unsigned (frame, MSP430_SP_REGNUM);
@@ -830,7 +833,6 @@ static struct gdbarch *
 msp430_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 {
   struct gdbarch *gdbarch;
-  struct gdbarch_tdep *tdep;
   int elf_flags, isa, code_model;
 
   /* Extract the elf_flags if available.  */
@@ -873,7 +875,8 @@ msp430_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 	  struct gdbarch *ca = get_current_arch ();
 	  if (ca && gdbarch_bfd_arch_info (ca)->arch == bfd_arch_msp430)
 	    {
-	      struct gdbarch_tdep *ca_tdep = gdbarch_tdep (ca);
+	      msp430_gdbarch_tdep *ca_tdep
+		= (msp430_gdbarch_tdep *) gdbarch_tdep (ca);
 
 	      elf_flags = ca_tdep->elf_flags;
 	      isa = ca_tdep->isa;
@@ -899,7 +902,8 @@ msp430_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
        arches != NULL;
        arches = gdbarch_list_lookup_by_info (arches->next, &info))
     {
-      struct gdbarch_tdep *candidate_tdep = gdbarch_tdep (arches->gdbarch);
+      msp430_gdbarch_tdep *candidate_tdep
+	= (msp430_gdbarch_tdep *) gdbarch_tdep (arches->gdbarch);
 
       if (candidate_tdep->elf_flags != elf_flags
 	  || candidate_tdep->isa != isa
@@ -911,7 +915,7 @@ msp430_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 
   /* None found, create a new architecture from the information
      provided.  */
-  tdep = XCNEW (struct gdbarch_tdep);
+  msp430_gdbarch_tdep *tdep = new msp430_gdbarch_tdep;
   gdbarch = gdbarch_alloc (&info, tdep);
   tdep->elf_flags = elf_flags;
   tdep->isa = isa;