Index: opcodes/nios2-opc.c
===================================================================
RCS file: /cvs/src/src/opcodes/nios2-opc.c,v
retrieving revision 1.5
diff -u -p -r1.5 nios2-opc.c
--- opcodes/nios2-opc.c	24 Apr 2013 20:51:58 -0000	1.5
+++ opcodes/nios2-opc.c	9 Jun 2013 22:36:39 -0000
@@ -385,7 +385,7 @@ const struct nios2_opcode nios2_builtin_
    OP_MATCH_SUB, OP_MASK_ROPX | OP_MASK_ROP, 0, no_overflow},
   {"sync", "", "E", 0,
    OP_MATCH_SYNC, OP_MASK_SYNC, 0, no_overflow},
-  {"trap", "", "E", 0,
+  {"trap", "b", "b,E", 1,
    OP_MATCH_TRAP, OP_MASK_TRAP, 0, no_overflow},
   {"eret", "", "E", 0,
    OP_MATCH_ERET, OP_MASK, 0, no_overflow},
Index: gas/config/tc-nios2.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-nios2.c,v
retrieving revision 1.4
diff -u -p -r1.4 tc-nios2.c
--- gas/config/tc-nios2.c	24 Apr 2013 20:51:57 -0000	1.4
+++ gas/config/tc-nios2.c	9 Jun 2013 22:36:39 -0000
@@ -2078,7 +2078,11 @@ nios2_parse_args (nios2_insn_infoS *insn
 
   parsed_args[i] = NULL;
 
-  if (*parsestr != '\0' && insn->insn_nios2_opcode->match != OP_MATCH_BREAK)
+  /* The argument to break and trap instructions is optional; complain
+     for other cases of missing arguments.  */
+  if (*parsestr != '\0'
+      && insn->insn_nios2_opcode->match != OP_MATCH_BREAK
+      && insn->insn_nios2_opcode->match != OP_MATCH_TRAP)
     as_bad (_("missing argument"));
 }
 
Index: gas/testsuite/gas/nios2/trap.s
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/nios2/trap.s,v
retrieving revision 1.1
diff -u -p -r1.1 trap.s
--- gas/testsuite/gas/nios2/trap.s	6 Feb 2013 23:22:16 -0000	1.1
+++ gas/testsuite/gas/nios2/trap.s	9 Jun 2013 22:36:39 -0000
@@ -1,3 +1,6 @@
-# Source file used to test the ret instructions
+# Source file used to test the trap instructions
 foo:
 	trap
+	trap 0
+	trap 31
+	trap 14
Index: gas/testsuite/gas/nios2/trap.d
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/nios2/trap.d,v
retrieving revision 1.2
diff -u -p -r1.2 trap.d
--- gas/testsuite/gas/nios2/trap.d	12 Mar 2013 21:34:58 -0000	1.2
+++ gas/testsuite/gas/nios2/trap.d	9 Jun 2013 22:36:39 -0000
@@ -4,4 +4,7 @@
 .*: +file format elf32-littlenios2
 
 Disassembly of section .text:
-0+0000 <[^>]*> 003b683a 	trap
+0+0000 <[^>]*> 003b683a 	trap	0
+0+0004 <[^>]*> 003b683a 	trap	0
+0+0008 <[^>]*> 003b6ffa 	trap	31
+0+000c <[^>]*> 003b6bba 	trap	14