[PyCDE] Emit header guards for typedefs (#2221)

frontends/PyCDE/src/pycde/pycde_types.py

@@ -5,7 +5,7 @@
 from collections import OrderedDict
 
 import mlir.ir
-from circt.dialects import hw
+from circt.dialects import hw, sv
 import circt.support
 
 
@@ -60,15 +60,30 @@ class _Types:
     if not self.registered_aliases:
       return
 
-    type_scopes = [
-        op for op in mod.body.operations if isinstance(op, hw.TypeScopeOp)
-    ]
-    if len(type_scopes) == 0:
-      with mlir.ir.InsertionPoint.at_block_begin(mod.body):
-        type_scopes.append(hw.TypeScopeOp.create(self.TYPE_SCOPE))
+    type_scopes = list()
+    for op in mod.body.operations:
+      if isinstance(op, hw.TypeScopeOp):
+        type_scopes.append(op)
+        continue
+      if isinstance(op, sv.IfDefOp):
+        if len(op.elseRegion.blocks) == 0:
+          continue
+        for ifdef_op in op.elseRegion.blocks[0]:
+          if isinstance(ifdef_op, hw.TypeScopeOp):
+            type_scopes.append(ifdef_op)
+
+    assert len(type_scopes) <= 1
+    if len(type_scopes) == 1:
+      type_scope = type_scopes[0]
+    else:
+      guard_name = "__PYCDE_TYPES__"
+      ifdef = sv.IfDefOp(mlir.ir.StringAttr.get(guard_name),
+                         ip=mlir.ir.InsertionPoint.at_block_begin(mod.body))
+      with mlir.ir.InsertionPoint.at_block_begin(ifdef.elseRegion.blocks[0]):
+        sv.VerbatimOp(mlir.ir.StringAttr.get("`define " + guard_name), [],
+                      mlir.ir.ArrayAttr.get([]))
+        type_scope = hw.TypeScopeOp.create(self.TYPE_SCOPE)
 
-    assert len(type_scopes) == 1
-    type_scope = type_scopes[0]
     with mlir.ir.InsertionPoint(type_scope.body):
       for (name, type) in self.registered_aliases.items():
         declared_aliases = [

lib/Bindings/Python/CMakeLists.txt

@@ -108,7 +108,9 @@ declare_mlir_dialect_python_bindings(
   ADD_TO_PARENT CIRCTBindingsPythonSources.Dialects
   ROOT_DIR "${CMAKE_CURRENT_SOURCE_DIR}"
   TD_FILE circt/dialects/SVOps.td
-  SOURCES circt/dialects/sv.py
+  SOURCES
+    circt/dialects/sv.py
+    circt/dialects/_sv_ops_ext.py
   DIALECT_NAME sv)
 
 ################################################################################

lib/Bindings/Python/circt/dialects/_sv_ops_ext.py

@@ -0,0 +1,24 @@
+#  Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+#  See https://llvm.org/LICENSE.txt for license information.
+#  SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+import mlir.ir as _ir
+
+
+class IfDefOp:
+
+  def __init__(self, cond: _ir.Attribute, *, loc=None, ip=None):
+    operands = []
+    results = []
+    attributes = {"cond": cond}
+    regions = 2
+    super().__init__(
+        self.build_generic(attributes=attributes,
+                           results=results,
+                           operands=operands,
+                           successors=None,
+                           regions=regions,
+                           loc=loc,
+                           ip=ip))
+    self.regions[0].blocks.append()
+    self.regions[1].blocks.append()