[PATCH 1/3] x86: consistently convert to byte registers for TEST w/ imm optimization

[Jan Beulich]

Commit ac0ab1842d ("i386: Also check R12-R15 registers when optimizing
testq to testb") didn't go quite far enough: In order to avoid confusing
other code registers would better be converted to byte ones uniformly.

gas/
2019-12-XX  Jan Beulich  <jbeulich@suse.com>

	* config/tc-i386.c (optimize_encoding): Generalize register
	transformation for TEST optimization.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -3932,17 +3932,16 @@ optimize_encoding (void)
 	  i.types[1].bitfield.byte = 1;
 	  /* Ignore the suffix.  */
 	  i.suffix = 0;
-	  if (base_regnum >= 4)
-	    {
-	      /* Handle SP, BP, SI, DI and R12-R15 registers.  */
-	      if (i.types[1].bitfield.word)
-		j = 16;
-	      else if (i.types[1].bitfield.dword)
-		j = 32;
-	      else
-		j = 48;
-	      i.op[1].regs -= j;
-	    }
+	  /* Convert to byte registers.  */
+	  if (i.types[1].bitfield.word)
+	    j = 16;
+	  else if (i.types[1].bitfield.dword)
+	    j = 32;
+	  else
+	    j = 48;
+	  if (!(i.op[1].regs->reg_flags & RegRex) && base_regnum < 4)
+	    j += 8;
+	  i.op[1].regs -= j;
 	}
     }
   else if (flag_code == CODE_64BIT