x86-asm: Reject some invalid arith imm8 instruction

There were two errors in the arithmetic imm8 instruction.  They accept
only REGW, and in case the user write a xxxb opcode that variant
needs to be rejected as well (it's not automatically rejected by REGW
in case the destination is memory).

1 files changed, 7 insertions, 0 deletions

diff --git a/i386-asm.c b/i386-asm.c
index 8baad47..b25bd42 100644
--- a/i386-asm.c
+++ b/i386-asm.c
@@ -552,7 +552,14 @@ ST_FUNC void asm_opcode(TCCState *s1, int opcode)
                 continue;
             s = (opcode - pa->sym) % NBWLX;
 	    if ((pa->instr_type & OPC_BWLX) == OPC_WLX)
+	      {
+		/* We need to reject the xxxb opcodes that we accepted above.
+		   Note that pa->sym for WLX opcodes is the 'w' token,
+		   to get the 'b' token subtract one.  */
+		if (((opcode - pa->sym + 1) % NBWLX) == 0)
+		    continue;
 	        s++;
+	      }
         } else if (pa->instr_type & OPC_SHIFT) {
             if (!(opcode >= pa->sym && opcode < pa->sym + 7*NBWLX))
                 continue;