x86-64: refuse "high" 8-bit regs with .insn and VEX/XOP/EVEX encodings

Much like REX, those encodings - if permitting 8-bit regs at all, i.e.
only starting with APX - permit use of "new" 8-bit registers only. %ah,
%ch, %dh, and %bh cannot be encoded and hence should be rejected.

Permit their use outside of 64-bit code though, as "new" registers
simply don't exist there.

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 6e2f6e51457086bb4c21ca07435124dc047df1da..cdd3b55c655d0ffc9698785774d1259d2529bc3d 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -11485,6 +11485,16 @@ s_insn (int dummy ATTRIBUTE_UNUSED)
 
       for (j = i.imm_operands; j < i.operands; ++j)
        {
+         /* Look for 8-bit operands that use old registers.  */
+         if (i.vec_encoding != vex_encoding_default
+             && flag_code == CODE_64BIT
+             && i.types[j].bitfield.class == Reg
+             && i.types[j].bitfield.byte
+             && !(i.op[j].regs->reg_flags & RegRex64)
+             && i.op[j].regs->reg_num > 3)
+           as_bad (_("can't encode register '%s%s' with VEX/XOP/EVEX"),
+                   register_prefix, i.op[j].regs->reg_name);
+
          i.types[j].bitfield.instance = InstanceNone;
 
          if (operand_type_check (i.types[j], disp))