[HW] Added methods to operate on in and inout ports (#4023)

Co-authored-by: Fabian Schuiki <fabian@schuiki.ch>

include/circt/Dialect/HW/HWStructure.td

@@ -87,6 +87,9 @@ def HWModuleOp : HWModuleOpBase<"module",
       return getAllModulePortInfos(*this);
     }
 
+    /// Returns the number of in or inout ports.
+    size_t getNumInOrInoutPorts() { return getArgumentTypes().size(); }
+
     /// Return the PortInfo for the specified input or inout port.
     PortInfo getInOrInoutPort(size_t i) {
       return getModuleInOrInoutPort(*this, i);
@@ -97,6 +100,29 @@ def HWModuleOp : HWModuleOpBase<"module",
       return getModuleOutputPort(*this, i);
     }
 
+    /// Append an input with a given name and type to the port list.
+    /// If the name is not unique, a unique name is created and returned.
+    std::pair<StringAttr, BlockArgument>
+    appendInput(const Twine &name, Type ty) {
+      return insertInput(getNumInOrInoutPorts(), name, ty);
+    }
+
+    std::pair<StringAttr, BlockArgument>
+    appendInput(StringAttr name, Type ty) {
+      return insertInput(getNumInOrInoutPorts(), name.getValue(), ty);
+    }
+
+    /// Insert an input with a given name and type into the port list.
+    /// The input is added at the specified index.
+    std::pair<StringAttr, BlockArgument>
+    insertInput(unsigned index, StringAttr name, Type ty);
+
+    std::pair<StringAttr, BlockArgument>
+    insertInput(unsigned index, const Twine &name, Type ty) {
+      ::mlir::StringAttr nameAttr = ::mlir::StringAttr::get(getContext(), name);
+      return insertInput(index, nameAttr, ty);
+    }
+
     /// Inserts a list of output ports into the port list at a specific
     /// location, shifting all subsequent ports.  Rewrites the output op
     /// to return the associated values.

lib/Dialect/HW/HWOps.cpp

@@ -17,10 +17,13 @@
 #include "circt/Dialect/HW/HWSymCache.h"
 #include "circt/Dialect/HW/HWVisitors.h"
 #include "circt/Dialect/HW/ModuleImplementation.h"
+#include "circt/Support/Namespace.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/FunctionImplementation.h"
 #include "mlir/IR/PatternMatch.h"
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/StringSet.h"
 
 using namespace circt;
 using namespace hw;
@@ -1133,6 +1136,25 @@ LogicalResult HWModuleOp::verify() { return verifyModuleCommon(*this); }
 
 LogicalResult HWModuleExternOp::verify() { return verifyModuleCommon(*this); }
 
+std::pair<StringAttr, BlockArgument>
+HWModuleOp::insertInput(unsigned index, StringAttr name, Type ty) {
+  // Find a unique name for the wire.
+  Namespace ns;
+  for (auto port : getAllPorts())
+    ns.newName(port.name.getValue());
+  auto nameAttr = StringAttr::get(getContext(), ns.newName(name.getValue()));
+
+  // Create a new port for the host clock.
+  PortInfo port;
+  port.name = nameAttr;
+  port.direction = PortDirection::INPUT;
+  port.type = ty;
+  insertPorts({std::make_pair(index, port)}, {});
+
+  // Add a new argument.
+  return {nameAttr, getBody().getArgument(index)};
+}
+
 void HWModuleOp::insertOutputs(unsigned index,
                                ArrayRef<std::pair<StringAttr, Value>> outputs) {