RISC-V: Move disassembler private data initialization

The original intent of this commit was to move disassembler's private data
initialization.  Since Nelson did the same in the commit 26e9197
("RISC-V: Minor improvements for dis-assembler."), this commit only moves
the initialization function (to fit much larger reorganization of the
disassembler).

Nelson's commit also allows storing mapping symbol and/or section-related
information to riscv_private_data.

In performance perspective, it also has a penalty.  However, it can be
easily paid back by other optimizations and it makes implementing
some optimizations easier.

Also, because xcalloc cannot fail (exit(1) occurs if the memory allocation
fails), the author temporarily removed the error handling here.

opcodes/ChangeLog:

	* riscv-dis.c (init_riscv_dis_private_data): Moved from
	riscv_init_disasm_info.
	(riscv_disassemble_insn): Move private data initialization to
	init_riscv_dis_private_data.  Remove unnecessary error handling.
	(riscv_init_disasm_info): Move to init_riscv_dis_private_data.
	(print_insn_riscv): Call init_riscv_dis_private_data.

opcodes/riscv-dis.c

@@ -233,6 +233,29 @@ init_riscv_dis_state_for_arch_and_options (void)
   is_arch_changed = false;
 }
 
+/* Initialize private data of the disassemble_info.  */
+
+static void
+init_riscv_dis_private_data (struct disassemble_info *info)
+{
+  struct riscv_private_data *pd;
+
+  pd = info->private_data = xcalloc (1, sizeof (struct riscv_private_data));
+  pd->gp = 0;
+  pd->print_addr = 0;
+  for (int i = 0; i < (int)ARRAY_SIZE (pd->hi_addr); i++)
+    pd->hi_addr[i] = -1;
+  pd->to_print_addr = false;
+  pd->has_gp = false;
+
+  for (int i = 0; i < info->symtab_size; i++)
+    if (strcmp (bfd_asymbol_name (info->symtab[i]), RISCV_GP_SYMBOL) == 0)
+      {
+	pd->gp = bfd_asymbol_value (info->symtab[i]);
+	pd->has_gp = true;
+      }
+}
+
 /* Update architecture for disassembler with its context.
    Call initialization functions if either:
    -  the architecture for current context is changed or
@@ -1280,34 +1303,6 @@ riscv_disassemble_data (bfd_vma memaddr ATTRIBUTE_UNUSED,
   return info->bytes_per_chunk;
 }
 
-static bool
-riscv_init_disasm_info (struct disassemble_info *info)
-{
-  int i;
-
-  struct riscv_private_data *pd =
-	xcalloc (1, sizeof (struct riscv_private_data));
-  pd->gp = 0;
-  pd->print_addr = 0;
-  for (i = 0; i < (int) ARRAY_SIZE (pd->hi_addr); i++)
-    pd->hi_addr[i] = -1;
-  pd->to_print_addr = false;
-  pd->has_gp = false;
-
-  for (i = 0; i < info->symtab_size; i++)
-    {
-      asymbol *sym = info->symtab[i];
-      if (strcmp (bfd_asymbol_name (sym), RISCV_GP_SYMBOL) == 0)
-	{
-	  pd->gp = bfd_asymbol_value (sym);
-	  pd->has_gp = true;
-	}
-    }
-
-  info->private_data = pd;
-  return true;
-}
-
 int
 print_insn_riscv (bfd_vma memaddr, struct disassemble_info *info)
 {
@@ -1319,13 +1314,14 @@ print_insn_riscv (bfd_vma memaddr, struct disassemble_info *info)
   int (*riscv_disassembler) (bfd_vma, insn_t, const bfd_byte *,
 			     struct disassemble_info *);
 
+  /* Initialize the private data.  */
+  if (info->private_data == NULL)
+    init_riscv_dis_private_data (info);
+
   /* Guess and update XLEN if we haven't determined it yet.  */
   if (xlen == 0)
     update_riscv_dis_xlen (info);
 
-  if (info->private_data == NULL && !riscv_init_disasm_info (info))
-    return -1;
-
   mstate = riscv_search_mapping_symbol (memaddr, info);
   /* Save the last mapping state.  */
   last_map_state = mstate;