From: H. Peter Anvin <hpa@zytor.com>
Date: Fri, 24 Oct 2025 13:12:39 +0000 (+0200)
Subject: z80, gas: follow historical assemblers and allow "op A,x" and "op x"
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f861f82cd9f058ecbe8133fad950bf237a3c66d1;p=thirdparty%2Fbinutils-gdb.git

z80, gas: follow historical assemblers and allow "op A,x" and "op x"

For arithmetic ops, Z80 syntax wants "op A,x" for ADD, ADC and SBC and
"op x" for SUB, AND, OR, XOR, and CP. Many historical assemblers
simply treat them orthogonally; allowing but not requiring the "A,"
operand for any of these operations. This is widely used in legacy
source code, and there is no reason not to.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---

diff --git a/gas/config/tc-z80.c b/gas/config/tc-z80.c
index add28a39119..72689256f0f 100644
--- a/gas/config/tc-z80.c
+++ b/gas/config/tc-z80.c
@@ -1463,9 +1463,8 @@ emit_s (char prefix, char opcode, const char *args)
 
   p = parse_exp (args, & arg_s);
   if (*p == ',' && arg_s.X_md == 0 && arg_s.X_op == O_register && arg_s.X_add_number == REG_A)
-    { /* possible instruction in generic format op A,x */
-      if (!(ins_ok & INS_EZ80) && !sdcc_compat)
-        ill_op ();
+    {
+      /* Allow both op A,x and op x */
       ++p;
       p = parse_exp (p, & arg_s);
     }
@@ -1473,30 +1472,6 @@ emit_s (char prefix, char opcode, const char *args)
   return p;
 }
 
-static const char *
-emit_sub (char prefix, char opcode, const char *args)
-{
-  expressionS arg_s;
-  const char *p;
-
-  if (!(ins_ok & INS_GBZ80))
-    return emit_s (prefix, opcode, args);
-  p = parse_exp (args, & arg_s);
-  if (*p++ != ',')
-    {
-      error (_("bad instruction syntax"));
-      return p;
-    }
-
-  if (arg_s.X_md != 0 || arg_s.X_op != O_register || arg_s.X_add_number != REG_A)
-    ill_op ();
-
-  p = parse_exp (p, & arg_s);
-
-  emit_sx (prefix, opcode, & arg_s);
-  return p;
-}
-
 static const char *
 emit_swap (char prefix, char opcode, const char *args)
 {
@@ -1731,8 +1706,8 @@ emit_adc (char prefix, char opcode, const char * args)
   p = parse_exp (args, &term);
   if (*p++ != ',')
     {
-      error (_("bad instruction syntax"));
-      return p;
+      /* "op x" -> "op A,x" */
+      return emit_s (prefix, opcode, args);
     }
 
   if ((term.X_md) || (term.X_op != O_register))
@@ -1774,8 +1749,8 @@ emit_add (char prefix, char opcode, const char * args)
   p = parse_exp (args, &term);
   if (*p++ != ',')
     {
-      error (_("bad instruction syntax"));
-      return p;
+      /* "op x" -> "op A,x" */
+      return emit_s (prefix, opcode, args);
     }
 
   if ((term.X_md) || (term.X_op != O_register))
@@ -3389,7 +3364,7 @@ static int
 assemble_suffix (const char **suffix)
 {
   static
-  const char sf[8][4] = 
+  const char sf[8][4] =
     {
       "il",
       "is",
@@ -3664,7 +3639,7 @@ static table_t instab[] =
   { "srl",  0xCB, 0x38, emit_mr,   INS_ALL },
   { "stmix",0xED, 0x7D, emit_insn, INS_EZ80 },
   { "stop", 0x00, 0x10, emit_insn, INS_GBZ80 },
-  { "sub",  0x00, 0x90, emit_sub,  INS_ALL },
+  { "sub",  0x00, 0x90, emit_s,    INS_ALL },
   { "swap", 0xCB, 0x30, emit_swap, INS_GBZ80|INS_Z80N },
   { "swapnib",0xED,0x23,emit_insn, INS_Z80N },
   { "test", 0xED, 0x27, emit_insn_n, INS_Z80N },