x86: drop stale Mem enumerator

This was supposed to also be removed by c48dadc9a8 ('x86: drop "mem"
operand type attribute').  It's odd enough that this hasn't caused
build issues, considering the careful use of OTunused (apparently to
avoid "missing initializer" warnings).

To avoid such happening again introduce compile time consistency
checks.

opcodes/ChangeLog

@@ -1,3 +1,11 @@
+2019-07-17  Jan Beulich  <jbeulich@suse.com>
+
+	* i386-gen.c (static_assert): Define.
+	(main): Use it.
+	* i386-opc.h (Opcode_Modifier_Max): Rename to ...
+	(Opcode_Modifier_Num): ... this.
+	(Mem): Delete.
+
 2019-07-16  Jan Beulich  <jbeulich@suse.com>
 
 	* i386-gen.c (operand_types): Move RegMem ...

opcodes/i386-gen.c

@@ -30,6 +30,10 @@
 #include <libintl.h>
 #define _(String) gettext (String)
 
+/* Build-time checks are preferrable over runtime ones.  Use this construct
+   in preference where possible.  */
+#define static_assert(e) ((void)sizeof (struct { int _:1 - 2 * !(e); }))
+
 static const char *program_name = NULL;
 static int debug = 0;
 
@@ -1665,9 +1669,13 @@ main (int argc, char **argv)
 
   /* Check the unused bitfield in i386_cpu_flags.  */
 #ifdef CpuUnused
+  static_assert (ARRAY_SIZE (cpu_flags) == CpuMax + 2);
+
   if ((cpumax - 1) != CpuMax)
     fail (_("CpuMax != %d!\n"), cpumax);
 #else
+  static_assert (ARRAY_SIZE (cpu_flags) == CpuMax + 1);
+
   if (cpumax != CpuMax)
     fail (_("CpuMax != %d!\n"), cpumax);
 
@@ -1676,8 +1684,14 @@ main (int argc, char **argv)
     fail (_("%d unused bits in i386_cpu_flags.\n"), c);
 #endif
 
+  static_assert (ARRAY_SIZE (opcode_modifiers) == Opcode_Modifier_Num);
+
   /* Check the unused bitfield in i386_operand_type.  */
-#ifndef OTUnused
+#ifdef OTUnused
+  static_assert (ARRAY_SIZE (operand_types) == OTNum + 1);
+#else
+  static_assert (ARRAY_SIZE (operand_types) == OTNum);
+
   c = OTNumOfBits - OTMax - 1;
   if (c)
     fail (_("%d unused bits in i386_operand_type.\n"), c);

opcodes/i386-opc.h

@@ -626,7 +626,7 @@ enum
   /* Intel64.  */
   Intel64,
   /* The last bitfield in i386_opcode_modifier.  */
-  Opcode_Modifier_Max
+  Opcode_Modifier_Num
 };
 
 typedef struct i386_opcode_modifier
@@ -757,8 +757,6 @@ enum
   JumpAbsolute,
   /* String insn operand with fixed es segment */
   EsSeg,
-  /* Memory.  */
-  Mem,
   /* BYTE size. */
   Byte,
   /* WORD size. 2 byte */