[3/3] x86: move (and rename) opcodespace attribute

Message ID 8aa94a23-664f-f3ed-fa90-2e0cfa963bd0@suse.com
State Accepted
Headers
Series x86: assorted opcode processing adjustments |

Checks

Context Check Description
snail/binutils-gdb-check success Github commit url

Commit Message

Jan Beulich Feb. 3, 2023, 7:33 a.m. UTC
  This really isn't a "modifier" and rather ought to live next to the base
opcode anyway. Use the bits we presently have available to fit in the
field, renaming it to opcode_space. As an intended side effect this
helps readability at the use sites, by shortening the references quite a
bit.

In generated code arrange for human readable output, by using the
SPACE_* constants there rather than raw numbers. This may aid debugging
down the road.
---
I'd like to do the same to opcodeprefix, but that's going to be more
intrusive, as we don't have spare bits left in a useful position
(fitting the field right after mnem_off isn't a good idea imo). Hence
I'm considering to do away with i386_opcode_modifier as a structure
altogether, which would tidy use sites quite a bit (like is the case
here). Plus it would shrink total struct size (when, at the same time,
reducing mnem_off to a 16-bit bitfield) and hence overall table size.
Thoughts anyone?
  

Patch

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -3203,8 +3203,8 @@  pte (insn_template *t)
   fprintf (stdout, " %d operands ", t->operands);
   if (opc_pfx[t->opcode_modifier.opcodeprefix])
     fprintf (stdout, "pfx %x ", opc_pfx[t->opcode_modifier.opcodeprefix]);
-  if (opc_spc[t->opcode_modifier.opcodespace])
-    fprintf (stdout, "space %s ", opc_spc[t->opcode_modifier.opcodespace]);
+  if (opc_spc[t->opcode_space])
+    fprintf (stdout, "space %s ", opc_spc[t->opcode_space]);
   fprintf (stdout, "opcode %x ", t->base_opcode);
   if (t->extension_opcode != None)
     fprintf (stdout, "ext %x ", t->extension_opcode);
@@ -3587,7 +3587,7 @@  build_vex_prefix (const insn_template *t
       && i.dir_encoding == dir_encoding_default
       && i.operands == i.reg_operands
       && operand_type_equal (&i.types[0], &i.types[i.operands - 1])
-      && i.tm.opcode_modifier.opcodespace == SPACE_0F
+      && i.tm.opcode_space == SPACE_0F
       && (i.tm.opcode_modifier.load || i.tm.opcode_modifier.d)
       && i.rex == REX_B)
     {
@@ -3633,7 +3633,7 @@  build_vex_prefix (const insn_template *t
       union i386_op temp_op;
       i386_operand_type temp_type;
 
-      gas_assert (i.tm.opcode_modifier.opcodespace == SPACE_0F);
+      gas_assert (i.tm.opcode_space == SPACE_0F);
       gas_assert (!i.tm.opcode_modifier.sae);
       gas_assert (operand_type_equal (&i.types[i.operands - 2],
                                       &i.types[i.operands - 3]));
@@ -3686,7 +3686,7 @@  build_vex_prefix (const insn_template *t
   /* Use 2-byte VEX prefix if possible.  */
   if (w == 0
       && i.vec_encoding != vex_encoding_vex3
-      && i.tm.opcode_modifier.opcodespace == SPACE_0F
+      && i.tm.opcode_space == SPACE_0F
       && (i.rex & (REX_W | REX_X | REX_B)) == 0)
     {
       /* 2-byte VEX prefix.  */
@@ -3707,7 +3707,7 @@  build_vex_prefix (const insn_template *t
       /* 3-byte VEX prefix.  */
       i.vex.length = 3;
 
-      switch (i.tm.opcode_modifier.opcodespace)
+      switch (i.tm.opcode_space)
 	{
 	case SPACE_0F:
 	case SPACE_0F38:
@@ -3725,7 +3725,7 @@  build_vex_prefix (const insn_template *t
 
       /* The high 3 bits of the second VEX byte are 1's compliment
 	 of RXB bits from REX.  */
-      i.vex.bytes[1] = (~i.rex & 0x7) << 5 | i.tm.opcode_modifier.opcodespace;
+      i.vex.bytes[1] = (~i.rex & 0x7) << 5 | i.tm.opcode_space;
 
       i.vex.bytes[2] = (w << 7
 			| register_specifier << 3
@@ -3860,9 +3860,9 @@  build_evex_prefix (void)
 
   /* The high 3 bits of the second EVEX byte are 1's compliment of RXB
      bits from REX.  */
-  gas_assert (i.tm.opcode_modifier.opcodespace >= SPACE_0F);
-  gas_assert (i.tm.opcode_modifier.opcodespace <= SPACE_EVEXMAP6);
-  i.vex.bytes[1] = (~i.rex & 0x7) << 5 | i.tm.opcode_modifier.opcodespace;
+  gas_assert (i.tm.opcode_space >= SPACE_0F);
+  gas_assert (i.tm.opcode_space <= SPACE_EVEXMAP6);
+  i.vex.bytes[1] = (~i.rex & 0x7) << 5 | i.tm.opcode_space;
 
   /* The fifth bit of the second EVEX byte is 1's compliment of the
      REX_R bit in VREX.  */
@@ -4072,14 +4072,14 @@  encode_with_unaligned_vector_move (void)
     case 0x28:	/* Load instructions.  */
     case 0x29:	/* Store instructions.  */
       /* movaps/movapd/vmovaps/vmovapd.  */
-      if (i.tm.opcode_modifier.opcodespace == SPACE_0F
+      if (i.tm.opcode_space == SPACE_0F
 	  && i.tm.opcode_modifier.opcodeprefix <= PREFIX_0X66)
 	i.tm.base_opcode = 0x10 | (i.tm.base_opcode & 1);
       break;
     case 0x6f:	/* Load instructions.  */
     case 0x7f:	/* Store instructions.  */
       /* movdqa/vmovdqa/vmovdqa64/vmovdqa32. */
-      if (i.tm.opcode_modifier.opcodespace == SPACE_0F
+      if (i.tm.opcode_space == SPACE_0F
 	  && i.tm.opcode_modifier.opcodeprefix == PREFIX_0X66)
 	i.tm.opcode_modifier.opcodeprefix = PREFIX_0XF3;
       break;
@@ -4221,7 +4221,7 @@  optimize_encoding (void)
 	    {
 	      if (flag_code != CODE_32BIT)
 		return;
-	      i.tm.opcode_modifier.opcodespace = SPACE_0F;
+	      i.tm.opcode_space = SPACE_0F;
 	      i.tm.base_opcode = 0xb7;
 	    }
 	  else
@@ -4272,7 +4272,7 @@  optimize_encoding (void)
 	}
     }
   else if (flag_code == CODE_64BIT
-	   && i.tm.opcode_modifier.opcodespace == SPACE_BASE
+	   && i.tm.opcode_space == SPACE_BASE
 	   && ((i.types[1].bitfield.qword
 		&& i.reg_operands == 1
 		&& i.imm_operands == 1
@@ -4374,7 +4374,7 @@  optimize_encoding (void)
 		       || i.tm.cpu_flags.bitfield.cpuavx512vl
 		       || (i.tm.operand_types[2].bitfield.zmmword
 			   && i.types[2].bitfield.ymmword))))
-	   && i.tm.opcode_modifier.opcodespace == SPACE_0F
+	   && i.tm.opcode_space == SPACE_0F
 	   && ((i.tm.base_opcode | 2) == 0x57
 	       || i.tm.base_opcode == 0xdf
 	       || i.tm.base_opcode == 0xef
@@ -4545,7 +4545,7 @@  load_insn_p (void)
 	return 1;
     }
 
-  if (i.tm.opcode_modifier.opcodespace == SPACE_BASE)
+  if (i.tm.opcode_space == SPACE_BASE)
     {
       /* popf, popa.   */
       if (i.tm.base_opcode == 0x9d
@@ -4573,7 +4573,7 @@  load_insn_p (void)
       if (i.tm.mnem_off == MN_vldmxcsr)
 	return 1;
     }
-  else if (i.tm.opcode_modifier.opcodespace == SPACE_BASE)
+  else if (i.tm.opcode_space == SPACE_BASE)
     {
       /* test, not, neg, mul, imul, div, idiv.  */
       if (base_opcode == 0xf7 && i.tm.extension_opcode != 1)
@@ -4632,7 +4632,7 @@  load_insn_p (void)
 	  return 1;
 	}
     }
-  else if (i.tm.opcode_modifier.opcodespace == SPACE_0F)
+  else if (i.tm.opcode_space == SPACE_0F)
     {
       /* bt, bts, btr, btc.  */
       if (i.tm.base_opcode == 0xba
@@ -4670,7 +4670,7 @@  load_insn_p (void)
     dest--;
 
   /* add, or, adc, sbb, and, sub, xor, cmp, test, xchg.  */
-  if (i.tm.opcode_modifier.opcodespace == SPACE_BASE
+  if (i.tm.opcode_space == SPACE_BASE
       && ((base_opcode | 0x38) == 0x39
 	  || (base_opcode | 2) == 0x87))
     return 1;
@@ -4719,7 +4719,7 @@  insert_lfence_before (void)
 {
   char *p;
 
-  if (i.tm.opcode_modifier.opcodespace != SPACE_BASE)
+  if (i.tm.opcode_space != SPACE_BASE)
     return;
 
   if (i.tm.base_opcode == 0xff
@@ -4841,9 +4841,9 @@  static INLINE bool may_need_pass2 (const
   return t->opcode_modifier.sse2avx
 	 /* Note that all SSE2AVX templates have at least one operand.  */
 	 ? t->operand_types[t->operands - 1].bitfield.class == RegSIMD
-	 : (t->opcode_modifier.opcodespace == SPACE_0F
+	 : (t->opcode_space == SPACE_0F
 	    && (t->base_opcode | 1) == 0xbf)
-	   || (t->opcode_modifier.opcodespace == SPACE_BASE
+	   || (t->opcode_space == SPACE_BASE
 	       && t->base_opcode == 0x63);
 }
 
@@ -5116,8 +5116,8 @@  md_assemble (char *line)
   if (sse_check != check_none
       /* The opcode space check isn't strictly needed; it's there only to
 	 bypass the logic below when easily possible.  */
-      && t->opcode_modifier.opcodespace >= SPACE_0F
-      && t->opcode_modifier.opcodespace <= SPACE_0F3A
+      && t->opcode_space >= SPACE_0F
+      && t->opcode_space <= SPACE_0F3A
       && !i.tm.cpu_flags.bitfield.cpusse4a
       && !is_any_vex_encoding (t))
     {
@@ -5240,7 +5240,7 @@  md_assemble (char *line)
      instructions (base opcodes: 0x6c, 0x6e, 0xec, 0xee).  */
   if (i.input_output_operand
       && ((i.tm.base_opcode | 0x82) != 0xee
-	  || i.tm.opcode_modifier.opcodespace != SPACE_BASE))
+	  || i.tm.opcode_space != SPACE_BASE))
     {
       as_bad (_("input/output port address isn't allowed with `%s'"),
 	      insn_name (&i.tm));
@@ -5441,7 +5441,7 @@  md_assemble (char *line)
 static INLINE bool q_suffix_allowed(const insn_template *t)
 {
   return flag_code == CODE_64BIT
-	 || (t->opcode_modifier.opcodespace == SPACE_BASE
+	 || (t->opcode_space == SPACE_BASE
 	     && t->base_opcode == 0xdf
 	     && (t->extension_opcode & 1)) /* fild / fistp / fisttp */
 	 || t->mnem_off == MN_cmpxchg8b;
@@ -5678,7 +5678,7 @@  parse_insn (const char *line, char *mnem
 		  if (current_templates != NULL
 		      /* MOVS or CMPS */
 		      && (current_templates->start->base_opcode | 2) == 0xa6
-		      && current_templates->start->opcode_modifier.opcodespace
+		      && current_templates->start->opcode_space
 			 == SPACE_BASE
 		      && mnem_p[-2] == 's')
 		    {
@@ -6853,14 +6853,14 @@  match_template (char mnem_suffix)
 	     zero-extend %eax to %rax.  */
 	  if (flag_code == CODE_64BIT
 	      && t->base_opcode == 0x90
-	      && t->opcode_modifier.opcodespace == SPACE_BASE
+	      && t->opcode_space == SPACE_BASE
 	      && i.types[0].bitfield.instance == Accum
 	      && i.types[0].bitfield.dword
 	      && i.types[1].bitfield.instance == Accum)
 	    continue;
 
 	  if (t->base_opcode == MOV_AX_DISP32
-	      && t->opcode_modifier.opcodespace == SPACE_BASE
+	      && t->opcode_space == SPACE_BASE
 	      && t->mnem_off != MN_movabs)
 	    {
 	      /* Force 0x8b encoding for "mov foo@GOT, %eax".  */
@@ -6972,8 +6972,8 @@  match_template (char mnem_suffix)
 		  found_reverse_match = Opcode_VexW;
 		  goto check_operands_345;
 		}
-	      else if (t->opcode_modifier.opcodespace != SPACE_BASE
-		       && (t->opcode_modifier.opcodespace != SPACE_0F
+	      else if (t->opcode_space != SPACE_BASE
+		       && (t->opcode_space != SPACE_0F
 			   /* MOV to/from CR/DR/TR, as an exception, follow
 			      the base opcode space encoding model.  */
 			   || (t->base_opcode | 7) != 0x27))
@@ -7183,9 +7183,9 @@  process_suffix (void)
       unsigned int numop = i.operands;
 
       /* MOVSX/MOVZX */
-      is_movx = (i.tm.opcode_modifier.opcodespace == SPACE_0F
+      is_movx = (i.tm.opcode_space == SPACE_0F
 		 && (i.tm.base_opcode | 8) == 0xbe)
-		|| (i.tm.opcode_modifier.opcodespace == SPACE_BASE
+		|| (i.tm.opcode_space == SPACE_BASE
 		    && i.tm.base_opcode == 0x63
 		    && i.tm.cpu_flags.bitfield.cpu64);
 
@@ -7289,7 +7289,7 @@  process_suffix (void)
 	   && (i.tm.opcode_modifier.jump == JUMP_ABSOLUTE
 	       || i.tm.opcode_modifier.jump == JUMP_BYTE
 	       || i.tm.opcode_modifier.jump == JUMP_INTERSEGMENT
-	       || (i.tm.opcode_modifier.opcodespace == SPACE_0F
+	       || (i.tm.opcode_space == SPACE_0F
 		   && i.tm.base_opcode == 0x01 /* [ls][gi]dt */
 		   && i.tm.extension_opcode <= 3)))
     {
@@ -7511,7 +7511,7 @@  process_suffix (void)
 	     need rex64. */
 	  && ! (i.operands == 2
 		&& i.tm.base_opcode == 0x90
-		&& i.tm.opcode_modifier.opcodespace == SPACE_BASE
+		&& i.tm.opcode_space == SPACE_BASE
 		&& i.types[0].bitfield.instance == Accum
 		&& i.types[0].bitfield.qword
 		&& i.types[1].bitfield.instance == Accum))
@@ -8083,14 +8083,14 @@  process_operands (void)
 	  return 0;
 	}
       if (i.op[0].regs->reg_num > 3
-	  && i.tm.opcode_modifier.opcodespace == SPACE_BASE )
+	  && i.tm.opcode_space == SPACE_BASE )
 	{
 	  i.tm.base_opcode ^= (POP_SEG_SHORT ^ POP_SEG386_SHORT) & 0xff;
-	  i.tm.opcode_modifier.opcodespace = SPACE_0F;
+	  i.tm.opcode_space = SPACE_0F;
 	}
       i.tm.base_opcode |= (i.op[0].regs->reg_num << 3);
     }
-  else if (i.tm.opcode_modifier.opcodespace == SPACE_BASE
+  else if (i.tm.opcode_space == SPACE_BASE
 	   && (i.tm.base_opcode & ~3) == MOV_AX_DISP32)
     {
       default_seg = reg_ds;
@@ -9325,7 +9325,7 @@  maybe_fused_with_jcc_p (enum mf_cmp_kind
     return 0;
 
   /* No opcodes outside of base encoding space.  */
-  if (i.tm.opcode_modifier.opcodespace != SPACE_BASE)
+  if (i.tm.opcode_space != SPACE_BASE)
     return 0;
 
   /* add, sub without add/sub m, imm.  */
@@ -9449,7 +9449,7 @@  add_branch_padding_frag_p (enum align_br
   if (!align_branch_power
       || now_seg == absolute_section
       || !cpu_arch_flags.bitfield.cpui386
-      || i.tm.opcode_modifier.opcodespace != SPACE_BASE)
+      || i.tm.opcode_space != SPACE_BASE)
     return 0;
 
   add_padding = 0;
@@ -9611,7 +9611,7 @@  output_insn (void)
 	  /* LAHF-SAHF insns in 64-bit mode.  */
 	  || (flag_code == CODE_64BIT
 	      && (i.tm.base_opcode | 1) == 0x9f
-	      && i.tm.opcode_modifier.opcodespace == SPACE_BASE))
+	      && i.tm.opcode_space == SPACE_BASE))
 	x86_isa_1_used |= GNU_PROPERTY_X86_ISA_1_V2;
       if (i.tm.cpu_flags.bitfield.cpuavx
 	  || i.tm.cpu_flags.bitfield.cpuavx2
@@ -9870,7 +9870,7 @@  output_insn (void)
       /* Now the opcode; be careful about word order here!  */
       j = i.opcode_length;
       if (!i.vex.length)
-	switch (i.tm.opcode_modifier.opcodespace)
+	switch (i.tm.opcode_space)
 	  {
 	  case SPACE_BASE:
 	    break;
@@ -9895,11 +9895,11 @@  output_insn (void)
 	{
 	  p = frag_more (j);
 	  if (!i.vex.length
-	      && i.tm.opcode_modifier.opcodespace != SPACE_BASE)
+	      && i.tm.opcode_space != SPACE_BASE)
 	    {
 	      *p++ = 0x0f;
-	      if (i.tm.opcode_modifier.opcodespace != SPACE_0F)
-		*p++ = i.tm.opcode_modifier.opcodespace == SPACE_0F38
+	      if (i.tm.opcode_space != SPACE_0F)
+		*p++ = i.tm.opcode_space == SPACE_0F38
 		       ? 0x38 : 0x3a;
 	    }
 
@@ -9971,7 +9971,7 @@  output_insn (void)
 
 	      /* Count prefixes for extended opcode maps.  */
 	      if (!i.vex.length)
-		switch (i.tm.opcode_modifier.opcodespace)
+		switch (i.tm.opcode_space)
 		  {
 		  case SPACE_BASE:
 		    break;
@@ -10209,7 +10209,7 @@  output_disp (fragS *insn_start_frag, off
 			  && i.rm.regmem == 5))
 		  && (i.rm.mode == 2
 		      || (i.rm.mode == 0 && i.rm.regmem == 5))
-		  && i.tm.opcode_modifier.opcodespace == SPACE_BASE
+		  && i.tm.opcode_space == SPACE_BASE
 		  && ((i.operands == 1
 		       && i.tm.base_opcode == 0xff
 		       && (i.rm.reg == 2 || i.rm.reg == 4))
--- a/opcodes/i386-gen.c
+++ b/opcodes/i386-gen.c
@@ -430,7 +430,6 @@  static bitfield opcode_modifiers[] =
   BITFIELD (Vex),
   BITFIELD (VexVVVV),
   BITFIELD (VexW),
-  BITFIELD (OpcodeSpace),
   BITFIELD (OpcodePrefix),
   BITFIELD (VexSources),
   BITFIELD (SIB),
@@ -957,10 +956,24 @@  get_element_size (char **opnd, int linen
 
 static void
 process_i386_opcode_modifier (FILE *table, char *mod, unsigned int space,
-			      unsigned int prefix, char **opnd, int lineno)
+			      unsigned int prefix, const char *extension_opcode,
+			      char **opnd, int lineno)
 {
   char *str, *next, *last;
   bitfield modifiers [ARRAY_SIZE (opcode_modifiers)];
+  static const char *const spaces[] = {
+#define SPACE(n) [SPACE_##n] = #n
+    SPACE(BASE),
+    SPACE(0F),
+    SPACE(0F38),
+    SPACE(0F3A),
+    SPACE(EVEXMAP5),
+    SPACE(EVEXMAP6),
+    SPACE(XOP08),
+    SPACE(XOP09),
+    SPACE(XOP0A),
+#undef SPACE
+  };
 
   active_isstring = 0;
 
@@ -978,6 +991,34 @@  process_i386_opcode_modifier (FILE *tabl
 	  if (str)
 	    {
 	      int val = 1;
+
+	      if (strncmp(str, "OpcodeSpace", 11) == 0)
+		{
+		  char *end;
+
+		  if (str[11] != '=')
+		    fail ("%s:%d: Missing value for `OpcodeSpace'\n",
+			  filename, lineno);
+
+		  val = strtol (str + 12, &end, 0);
+		  if (*end)
+		    fail ("%s:%d: Bogus value `%s' for `OpcodeSpace'\n",
+			  filename, lineno, end);
+
+		  if (space)
+		    {
+		      if (val != space)
+			fail ("%s:%d: Conflicting opcode space specifications\n",
+			      filename, lineno);
+		      fprintf (stderr,
+			       "%s:%d: Warning: redundant opcode space specification\n",
+			       filename, lineno);
+		    }
+
+		  space = val;
+		  continue;
+		}
+
 	      if (strcasecmp(str, "Broadcast") == 0)
 		val = get_element_size (opnd, lineno) + BYTE_BROADCAST;
 	      else if (strcasecmp(str, "Disp8MemShift") == 0)
@@ -1002,19 +1043,6 @@  process_i386_opcode_modifier (FILE *tabl
 	    }
 	}
 
-      if (space)
-	{
-	  if (!modifiers[OpcodeSpace].value)
-	    modifiers[OpcodeSpace].value = space;
-	  else if (modifiers[OpcodeSpace].value != space)
-	    fail ("%s:%d: Conflicting opcode space specifications\n",
-		  filename, lineno);
-	  else
-	    fprintf (stderr,
-		     "%s:%d: Warning: redundant opcode space specification\n",
-		     filename, lineno);
-	}
-
       if (prefix)
 	{
 	  if (!modifiers[OpcodePrefix].value)
@@ -1038,6 +1066,13 @@  process_i386_opcode_modifier (FILE *tabl
 		 "%s: %d: W modifier without Word/Dword/Qword operand(s)\n",
 		 filename, lineno);
     }
+
+  if (space >= ARRAY_SIZE (spaces) || !spaces[space])
+    fail ("%s:%d: Unknown opcode space %u\n", filename, lineno, space);
+
+  fprintf (table, " SPACE_%s, %s,\n",
+	   spaces[space], extension_opcode ? extension_opcode : "None");
+
   output_opcode_modifier (table, modifiers, ARRAY_SIZE (modifiers));
 }
 
@@ -1257,13 +1292,12 @@  output_i386_opcode (FILE *table, const c
 	  filename, lineno, name, 2 * length, opcode);
 
   ident = mkident (name);
-  fprintf (table, "  { MN_%s, 0x%0*llx%s, %lu, %s,\n",
-	   ident, 2 * (int)length, opcode, end, i,
-	   extension_opcode ? extension_opcode : "None");
+  fprintf (table, "  { MN_%s, 0x%0*llx%s, %u,",
+	   ident, 2 * (int)length, opcode, end, i);
   free (ident);
 
   process_i386_opcode_modifier (table, opcode_modifier, space, prefix,
-				operand_types, lineno);
+				extension_opcode, operand_types, lineno);
 
   process_i386_cpu_flag (table, cpu_flags, NULL, ",", "    ", lineno, CpuMax);
 
--- a/opcodes/i386-opc.h
+++ b/opcodes/i386-opc.h
@@ -605,28 +605,6 @@  enum
 #define VEXW1	2
 #define VEXWIG	3
   VexW,
-  /* Opcode encoding space (values chosen to be usable directly in
-     VEX/XOP mmmmm and EVEX mm fields):
-     0: Base opcode space.
-     1: 0F opcode prefix / space.
-     2: 0F38 opcode prefix / space.
-     3: 0F3A opcode prefix / space.
-     5: EVEXMAP5 opcode prefix / space.
-     6: EVEXMAP6 opcode prefix / space.
-     8: XOP 08 opcode space.
-     9: XOP 09 opcode space.
-     A: XOP 0A opcode space.
-   */
-#define SPACE_BASE	0
-#define SPACE_0F	1
-#define SPACE_0F38	2
-#define SPACE_0F3A	3
-#define SPACE_EVEXMAP5	5
-#define SPACE_EVEXMAP6	6
-#define SPACE_XOP08	8
-#define SPACE_XOP09	9
-#define SPACE_XOP0A	0xA
-  OpcodeSpace,
   /* Opcode prefix (values chosen to be usable directly in
      VEX/XOP/EVEX pp fields):
      0: None
@@ -759,7 +737,6 @@  typedef struct i386_opcode_modifier
   unsigned int vex:2;
   unsigned int vexvvvv:2;
   unsigned int vexw:2;
-  unsigned int opcodespace:4;
   unsigned int opcodeprefix:2;
   unsigned int vexsources:2;
   unsigned int sib:3;
@@ -942,8 +919,29 @@  typedef struct insn_template
   /* how many operands */
   unsigned int operands:3;
 
-  /* spare bits */
-  unsigned int :4;
+  /* opcode space */
+  unsigned int opcode_space:4;
+  /* Opcode encoding space (values chosen to be usable directly in
+     VEX/XOP mmmmm and EVEX mm fields):
+     0: Base opcode space.
+     1: 0F opcode prefix / space.
+     2: 0F38 opcode prefix / space.
+     3: 0F3A opcode prefix / space.
+     5: EVEXMAP5 opcode prefix / space.
+     6: EVEXMAP6 opcode prefix / space.
+     8: XOP 08 opcode space.
+     9: XOP 09 opcode space.
+     A: XOP 0A opcode space.
+   */
+#define SPACE_BASE	0
+#define SPACE_0F	1
+#define SPACE_0F38	2
+#define SPACE_0F3A	3
+#define SPACE_EVEXMAP5	5
+#define SPACE_EVEXMAP6	6
+#define SPACE_XOP08	8
+#define SPACE_XOP09	9
+#define SPACE_XOP0A	0xA
 
 /* (Fake) base opcode value for pseudo prefixes.  */
 #define PSEUDO_PREFIX 0