Add support for self-referencing phi nodes

include/sirit/sirit.h

@@ -90,6 +90,9 @@ public:
     /// Generate a new id for forward declarations
     [[nodiscard]] Id ForwardDeclarationId();
 
+    /// Returns the current generator id, useful for self-referencing phi nodes
+    [[nodiscard]] Id CurrentId() const noexcept;
+
     /// Assign a new id and return the old one, useful for defining forward declarations
     Id ExchangeCurrentId(Id new_current_id);
 

src/sirit.cpp

@@ -99,6 +99,10 @@ Id Module::ForwardDeclarationId() {
     return Id{++bound};
 }
 
+Id Module::CurrentId() const noexcept {
+    return Id{bound + 1};
+}
+
 Id Module::ExchangeCurrentId(Id new_current_id) {
     const std::uint32_t old_id = std::exchange(bound, new_current_id.value - 1);
     return Id{old_id + 1};