[PATCH 01/13] x86: re-arrange process_operands()

[Jan Beulich <jbeulich at suse dot com>]

Alter the sequence of conditions evaluated, without affecting the
overall result. This is going to help subsequent changes (and as a nice
side effect also slightly reduces overall indentation depth).

While doing this take the liberty of simplifying the calculation of the
operand index of the register operand in ShortForm handling.

gas/
2018-10-XX  Jan Beulich  <jbeulich@suse.com>

	* config/tc-i386.c (process_operands): Handle ShortForm insns
	later, splitting out their segment register sub-form.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -7079,63 +7079,7 @@ duplicate:
       i.reg_operands++;
     }
 
-  if (i.tm.opcode_modifier.shortform)
-    {
-      if (i.types[0].bitfield.sreg)
-	{
-	  if (flag_code != CODE_64BIT
-	      ? i.tm.base_opcode == POP_SEG_SHORT
-		&& i.op[0].regs->reg_num == 1
-	      : (i.tm.base_opcode | 1) == POP_SEG386_SHORT
-		&& i.op[0].regs->reg_num < 4)
-	    {
-	      as_bad (_("you can't `%s %s%s'"),
-		      i.tm.name, register_prefix, i.op[0].regs->reg_name);
-	      return 0;
-	    }
-	  if ( i.op[0].regs->reg_num > 3 && i.tm.opcode_length == 1 )
-	    {
-	      i.tm.base_opcode ^= POP_SEG_SHORT ^ POP_SEG386_SHORT;
-	      i.tm.opcode_length = 2;
-	    }
-	  i.tm.base_opcode |= (i.op[0].regs->reg_num << 3);
-	}
-      else
-	{
-	  /* The register or float register operand is in operand
-	     0 or 1.  */
-	  unsigned int op;
-
-	  if ((i.types[0].bitfield.reg && i.types[0].bitfield.tbyte)
-	      || operand_type_check (i.types[0], reg))
-	    op = 0;
-	  else
-	    op = 1;
-	  /* Register goes in low 3 bits of opcode.  */
-	  i.tm.base_opcode |= i.op[op].regs->reg_num;
-	  if ((i.op[op].regs->reg_flags & RegRex) != 0)
-	    i.rex |= REX_B;
-	  if (!quiet_warnings && i.tm.opcode_modifier.ugh)
-	    {
-	      /* Warn about some common errors, but press on regardless.
-		 The first case can be generated by gcc (<= 2.8.1).  */
-	      if (i.operands == 2)
-		{
-		  /* Reversed arguments on faddp, fsubp, etc.  */
-		  as_warn (_("translating to `%s %s%s,%s%s'"), i.tm.name,
-			   register_prefix, i.op[!intel_syntax].regs->reg_name,
-			   register_prefix, i.op[intel_syntax].regs->reg_name);
-		}
-	      else
-		{
-		  /* Extraneous `l' suffix on fp insn.  */
-		  as_warn (_("translating to `%s %s%s'"), i.tm.name,
-			   register_prefix, i.op[0].regs->reg_name);
-		}
-	    }
-	}
-    }
-  else if (i.tm.opcode_modifier.modrm)
+  if (i.tm.opcode_modifier.modrm)
     {
       /* The opcode is completed (modulo i.tm.extension_opcode which
 	 must be put into the modrm byte).  Now, we make the modrm and
@@ -7143,6 +7087,25 @@ duplicate:
 
       default_seg = build_modrm_byte ();
     }
+  else if (i.types[0].bitfield.sreg)
+    {
+      if (flag_code != CODE_64BIT
+	  ? i.tm.base_opcode == POP_SEG_SHORT
+	    && i.op[0].regs->reg_num == 1
+	  : (i.tm.base_opcode | 1) == POP_SEG386_SHORT
+	    && i.op[0].regs->reg_num < 4)
+	{
+	  as_bad (_("you can't `%s %s%s'"),
+		  i.tm.name, register_prefix, i.op[0].regs->reg_name);
+	  return 0;
+	}
+      if ( i.op[0].regs->reg_num > 3 && i.tm.opcode_length == 1 )
+	{
+	  i.tm.base_opcode ^= POP_SEG_SHORT ^ POP_SEG386_SHORT;
+	  i.tm.opcode_length = 2;
+	}
+      i.tm.base_opcode |= (i.op[0].regs->reg_num << 3);
+    }
   else if ((i.tm.base_opcode & ~0x3) == MOV_AX_DISP32)
     {
       default_seg = &ds;
@@ -7153,6 +7116,35 @@ duplicate:
 	 on one of their operands, the default segment is ds.  */
       default_seg = &ds;
     }
+  else if (i.tm.opcode_modifier.shortform)
+    {
+      /* The register or float register operand is in operand
+	 0 or 1.  */
+      unsigned int op = !i.tm.operand_types[0].bitfield.reg;
+
+      /* Register goes in low 3 bits of opcode.  */
+      i.tm.base_opcode |= i.op[op].regs->reg_num;
+      if ((i.op[op].regs->reg_flags & RegRex) != 0)
+	i.rex |= REX_B;
+      if (!quiet_warnings && i.tm.opcode_modifier.ugh)
+	{
+	  /* Warn about some common errors, but press on regardless.
+	     The first case can be generated by gcc (<= 2.8.1).  */
+	  if (i.operands == 2)
+	    {
+	      /* Reversed arguments on faddp, fsubp, etc.  */
+	      as_warn (_("translating to `%s %s%s,%s%s'"), i.tm.name,
+		       register_prefix, i.op[!intel_syntax].regs->reg_name,
+		       register_prefix, i.op[intel_syntax].regs->reg_name);
+	    }
+	  else
+	    {
+	      /* Extraneous `l' suffix on fp insn.  */
+	      as_warn (_("translating to `%s %s%s'"), i.tm.name,
+		       register_prefix, i.op[0].regs->reg_name);
+	    }
+	}
+    }
 
   if (i.tm.base_opcode == 0x8d /* lea */
       && i.seg[0]