diff --git a/lib/cretonne/meta/cdsl/formats.py b/lib/cretonne/meta/cdsl/formats.py
index 4b7d512ff1..aa7d384b7c 100644
--- a/lib/cretonne/meta/cdsl/formats.py
+++ b/lib/cretonne/meta/cdsl/formats.py
@@ -68,11 +68,7 @@ class InstructionFormat(object):
         # `has_value_list` is set.
         self.num_value_operands = 0
 
-        self.kinds = tuple(self._process_member_names(kinds))
-
-        # Which of self.kinds are `value`?
-        self.value_operands = tuple(
-                i for i, k in enumerate(self.kinds) if k is VALUE)
+        sig_kinds = tuple(self._process_member_names(kinds))
 
         # The typevar_operand argument must point to a 'value' operand.
         self.typevar_operand = kwargs.get('typevar_operand', None)  # type: int
@@ -85,7 +81,7 @@ class InstructionFormat(object):
             self.typevar_operand = 0
 
         # Compute a signature for the global registry.
-        sig = (self.multiple_results, self.kinds)
+        sig = (self.multiple_results, sig_kinds)
         if sig in InstructionFormat._registry:
             raise RuntimeError(
                 "Format '{}' has the same signature as existing format '{}'"
diff --git a/lib/cretonne/meta/cdsl/instructions.py b/lib/cretonne/meta/cdsl/instructions.py
index 85581edde2..30596fd1fb 100644
--- a/lib/cretonne/meta/cdsl/instructions.py
+++ b/lib/cretonne/meta/cdsl/instructions.py
@@ -154,7 +154,7 @@ class Instruction(object):
         variables.
         """
         poly_ins = [
-                i for i in self.format.value_operands
+                i for i in self.value_opnums
                 if self.ins[i].typevar.free_typevar()]
         poly_outs = [
                 i for i, o in enumerate(self.outs)
@@ -206,8 +206,8 @@ class Instruction(object):
         """
         other_tvs = []
         # Check value inputs.
-        for opidx in self.format.value_operands:
-            typ = self.ins[opidx].typevar
+        for opnum in self.value_opnums:
+            typ = self.ins[opnum].typevar
             tv = typ.free_typevar()
             # Non-polymorphic or derived form ctrl_typevar is OK.
             if tv is None or tv is ctrl_typevar:
@@ -216,7 +216,7 @@ class Instruction(object):
             if typ is not tv:
                 raise RuntimeError(
                         "{}: type variable {} must be derived from {}"
-                        .format(self.ins[opidx], typ.name, ctrl_typevar))
+                        .format(self.ins[opnum], typ.name, ctrl_typevar))
             # Other free type variables can only be used once each.
             if tv in other_tvs:
                 raise RuntimeError(
diff --git a/lib/cretonne/meta/cdsl/isa.py b/lib/cretonne/meta/cdsl/isa.py
index 7e4c09e58d..ef667015ce 100644
--- a/lib/cretonne/meta/cdsl/isa.py
+++ b/lib/cretonne/meta/cdsl/isa.py
@@ -176,7 +176,8 @@ class EncRecipe(object):
         self.number = None  # type: int
 
         self.ins = self._verify_constraints(ins)
-        assert len(self.ins) == len(format.value_operands)
+        if not format.has_value_list:
+            assert len(self.ins) == format.num_value_operands
         self.outs = self._verify_constraints(outs)
         if len(self.outs) > 1:
             assert format.multiple_results
@@ -193,7 +194,9 @@ class EncRecipe(object):
             if isinstance(c, int):
                 # An integer constraint is bound to a value operand.
                 # Check that it is in range.
-                assert c >= 0 and c < len(self.format.value_operands)
+                assert c >= 0
+                if not format.has_value_list:
+                    assert c < self.format.num_value_operands
             else:
                 assert isinstance(c, RegClass) or isinstance(c, Register)
         return seq
diff --git a/lib/cretonne/meta/cdsl/xform.py b/lib/cretonne/meta/cdsl/xform.py
index deca293e50..21c6103bcd 100644
--- a/lib/cretonne/meta/cdsl/xform.py
+++ b/lib/cretonne/meta/cdsl/xform.py
@@ -224,7 +224,7 @@ class XForm(object):
                     ctrl_var = d.defs[inst.value_results[0]]
 
             # Reconcile arguments with the requirements of `inst`.
-            for opnum in inst.format.value_operands:
+            for opnum in inst.value_opnums:
                 inst_tv = inst.ins[opnum].typevar
                 v = d.expr.args[opnum]
                 if isinstance(v, Var):
diff --git a/lib/cretonne/meta/gen_instr.py b/lib/cretonne/meta/gen_instr.py
index 567cfa16f6..e6cd265118 100644
--- a/lib/cretonne/meta/gen_instr.py
+++ b/lib/cretonne/meta/gen_instr.py
@@ -411,9 +411,9 @@ def gen_type_constraints(fmt, instrs):
             for idx in i.value_results:
                 constraints.append(
                         get_constraint(i.outs[idx], ctrl_typevar, type_sets))
-            for idx in i.format.value_operands:
+            for opnum in i.value_opnums:
                 constraints.append(
-                        get_constraint(i.ins[idx], ctrl_typevar, type_sets))
+                        get_constraint(i.ins[opnum], ctrl_typevar, type_sets))
             offset = operand_seqs.add(constraints)
             fixed_results = len(i.value_results)
             # Can the controlling type variable be inferred from the designated