diff -r c88a5644d81a -r eb586b1cf8ca src/arch/isa_parser.py
--- a/src/arch/isa_parser.py	Wed Jun 29 03:57:55 2011 -0700
+++ b/src/arch/isa_parser.py	Wed Jun 29 03:58:47 2011 -0700
@@ -1792,23 +1792,28 @@
         """Generate operandTypeMap from the user's 'def operand_types'
         statement."""
         operand_type = {}
-        for (ext, (desc, size)) in user_dict.iteritems():
-            if desc == 'signed int':
-                ctype = 'int%d_t' % size
-            elif desc == 'unsigned int':
-                ctype = 'uint%d_t' % size
-            elif desc == 'float':
-                if size == 32:
-                    ctype = 'float'
-                elif size == 64:
-                    ctype = 'double'
-            elif desc == 'twin64 int':
-                ctype = 'Twin64_t'
-            elif desc == 'twin32 int':
-                ctype = 'Twin32_t'
-            if ctype == '':
-                error(parser, lineno,
-                      'Unrecognized type description "%s" in user_dict')
+        for (ext, val) in user_dict.iteritems():
+            ctype = ''
+            if isinstance(val, (list, tuple)):
+                (desc, size) = val
+                if desc == 'signed int':
+                    ctype = 'int%d_t' % size
+                elif desc == 'unsigned int':
+                    ctype = 'uint%d_t' % size
+                elif desc == 'float':
+                    if size == 32:
+                        ctype = 'float'
+                    elif size == 64:
+                        ctype = 'double'
+                elif desc == 'twin64 int':
+                    ctype = 'Twin64_t'
+                elif desc == 'twin32 int':
+                    ctype = 'Twin32_t'
+                if ctype == '':
+                    error(self, lineno,
+                          'Unrecognized type description "%s" in user_dict')
+            else:
+                ctype = val
             operand_type[ext] = ctype
 
         self.operandTypeMap = operand_type