[Builder] Add index from/to Float/Fixed/UFixed type casting

allo/ir/builder.py

@@ -356,6 +356,7 @@ def build_cast_op(ctx, op, src_type, res_type, shape=None):
         if type(res_type) is type(src_type) and res_type == src_type:
             return op
 
+        # Single-step type conversions
         cast_map = {
             # Index <-> UInt/Int
             (Int, Index): arith_d.IndexCastOp,
@@ -367,9 +368,6 @@ def build_cast_op(ctx, op, src_type, res_type, shape=None):
             (UInt, Float): arith_d.UIToFPOp,
             (Float, Int): arith_d.FPToSIOp,
             (Float, UInt): arith_d.FPToUIOp,
-            # FP to Index is not supported in MLIR
-            # (Float, Index): RuntimeError,
-            # (Index, Float): RuntimeError,
             # Float <-> Fixed/UFixed
             (Float, Fixed): allo_d.FloatToFixedOp,
             (Float, UFixed): allo_d.FloatToFixedOp,
@@ -402,6 +400,16 @@ def build_cast_op(ctx, op, src_type, res_type, shape=None):
                 IntegerType.get_signless(32), op.result, ip=ctx.get_ip()
             )
             opcls = arith_d.SIToFPOp  # proceed to build cast to float
+        elif isinstance(src_type, Index) and isinstance(res_type, (Fixed, UFixed)):
+            op = arith_d.IndexCastOp(
+                IntegerType.get_signless(32), op.result, ip=ctx.get_ip()
+            )
+            opcls = allo_d.IntToFixedOp  # proceed to build cast to float
+        elif isinstance(src_type, (Fixed, UFixed)) and isinstance(res_type, Index):
+            op = allo_d.FixedToIntOp(
+                IntegerType.get_signless(32), op.result, ip=ctx.get_ip()
+            )
+            opcls = arith_d.IndexCastOp
         elif isinstance(src_type, (Int, UInt)) and isinstance(res_type, (Int, UInt)):
             if src_type.bits > res_type.bits:
                 opcls = arith_d.TruncIOp

tests/test_types.py

@@ -14,6 +14,7 @@
     uint1,
     int32,
     float32,
+    index,
 )
 import allo.ir.types as T
 
@@ -42,6 +43,44 @@ def kernel(a: int32) -> float32:
     assert mod(1) == kernel(1)
 
 
+def test_index_fixed_casting():
+    def test_one_cast(fixed):
+        def kernel(a: fixed) -> float32:
+            sum_val: fixed = 0.0
+            ret_val: float32 = 0.0
+            for step in range(10):
+                sum_val += step
+            ret_val = sum_val
+            return ret_val
+
+        s = allo.customize(kernel)
+        mod = s.build()
+        assert mod(1) == kernel(1)
+
+    for i in range(1, 20):
+        test_one_cast(Fixed(32, i))
+        test_one_cast(UFixed(32, i))
+
+
+def test_fixed_index_casting():
+
+    def test_one_cast(fixed):
+        def kernel(a: float32) -> int32:
+            a_fix: fixed = a
+            a_idx: index = a_fix
+            b: index = 2
+            ret: int32 = a_idx + b
+            return ret
+
+        s = allo.customize(kernel)
+        mod = s.build()
+        assert mod(2.0) == kernel(2.0)
+
+    for i in range(1, 20):
+        test_one_cast(Fixed(32, i))
+        test_one_cast(UFixed(32, i))
+
+
 def test_large_bitwidth():
     def kernel(a: Int(65536)[1], b: Int(345)[1], c: Int(65536)[1]):
         c[0] = a[0] + b[0]