[PyCDE] Fix casting bug

Must pad or truncate before `hwarith.cast`.

frontends/PyCDE/src/pycde/signals.py

@@ -134,7 +134,7 @@ def _namehint_attrname(self):
     return "sv.namehint"
 
   @property
-  def name(self):
+  def name(self) -> Optional[str]:
     owner = self.value.owner
     if hasattr(owner,
                "attributes") and self._namehint_attrname in owner.attributes:
@@ -146,6 +146,7 @@ def name(self):
       return mod_type.input_names[block_arg.arg_number]
     if hasattr(self, "_name"):
       return self._name
+    return None
 
   @name.setter
   def name(self, new: str):
@@ -306,6 +307,12 @@ class BitsSignal(BitVectorSignal):
   """Operations on signless ints (bits). These will all return signless values -
   a user is expected to reapply signedness semantics if needed."""
 
+  def _exec_cast(self, targetValueType, type_getter, width: int = None):
+    if width is not None and width != self.type.width:
+      return self.pad_or_truncate(width)._exec_cast(targetValueType,
+                                                    type_getter)
+    return super()._exec_cast(targetValueType, type_getter)
+
   @singledispatchmethod
   def __getitem__(self, idxOrSlice: Union[int, slice]) -> BitVectorSignal:
     lo, hi = get_slice_bounds(len(self), idxOrSlice)

frontends/PyCDE/test/test_hwarith.py

@@ -119,13 +119,18 @@ def construct(ports):
 
 
 # CHECK:  hw.module @Casting(in %in0 : i16)
-# CHECK-NEXT:    %0 = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> si16
-# CHECK-NEXT:    %1 = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> ui16
-# CHECK-NEXT:    %2 = hwarith.cast %0 {{({sv.namehint = ".*"} )?}}: (si16) -> i16
-# CHECK-NEXT:    %3 = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> si8
-# CHECK-NEXT:    %4 = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> ui8
-# CHECK-NEXT:    %5 = hwarith.cast %0 {{({sv.namehint = ".*"} )?}}: (si16) -> i8
-# CHECK-NEXT:    %6 = hwarith.cast %0 {{({sv.namehint = ".*"} )?}}: (si16) -> si24
+# CHECK-NEXT:    [[R0:%.+]] = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> si16
+# CHECK-NEXT:    [[R1:%.+]] = hwarith.cast %in0 {{({sv.namehint = ".*"} )?}}: (i16) -> ui16
+# CHECK-NEXT:    [[R2:%.+]] = hwarith.cast [[R0]] {{({sv.namehint = ".*"} )?}}: (si16) -> i16
+# CHECK-NEXT:    [[R11:%.+]] = comb.extract %in0 from 0 : (i16) -> i8
+# CHECK-NEXT:    [[R3:%.+]] = hwarith.cast [[R11]] {{({sv.namehint = ".*"} )?}}: (i8) -> si8
+# CHECK-NEXT:    [[R12:%.+]] = comb.extract %in0 from 0 : (i16) -> i8
+# CHECK-NEXT:    [[R4:%.+]] = hwarith.cast [[R12]] {{({sv.namehint = ".*"} )?}}: (i8) -> ui8
+# CHECK-NEXT:    [[R5:%.+]] = hwarith.cast [[R0]] {{({sv.namehint = ".*"} )?}}: (si16) -> i8
+# CHECK-NEXT:    [[R6:%.+]] = hwarith.cast [[R0]] {{({sv.namehint = ".*"} )?}}: (si16) -> si24
+# CHECK-NEXT:    [[Rc0_i16:%.+]] = hw.constant 0 : i16
+# CHECK-NEXT:    [[R9:%.+]] = comb.concat [[Rc0_i16]], %in0 {{({sv.namehint = ".*"} )?}}: i16, i16
+# CHECK-NEXT:    [[R10:%.+]] = hwarith.cast [[R9]] {{({sv.namehint = ".*"} )?}}: (i32) -> ui32
 # CHECK-NEXT:    hw.output
 @unittestmodule(run_passes=True)
 class Casting(Module):
@@ -140,6 +145,7 @@ def construct(ports):
     in0u8 = ports.in0.as_uint(8)
     in0s_i8 = in0s.as_bits(8)
     in0s_s24 = in0s.as_sint(24)
+    in0s_u32 = ports.in0.as_uint(32)
 
 
 # -----