Introduce IDs for regions (phate#1494)

Author: phate

.github/golden/hls-test-suite/decoupled/mergesort_decouple.cycles

@@ -1 +1 @@
-193602
+193558

jlm/rvsdg/graph.cpp

@@ -71,7 +71,8 @@ GraphExport::Create(Output & origin, std::string name)
 Graph::~Graph() noexcept = default;
 
 Graph::Graph()
-    : RootRegion_(new Region(nullptr, this))
+    : nextRegionId_(0),
+      RootRegion_(new Region(nullptr, this))
 {}
 
 std::unique_ptr<Graph>

jlm/rvsdg/graph.hpp

@@ -78,6 +78,20 @@ class Graph final
 
   Graph();
 
+  /**
+   * @return A unique identifier for a region within this graph.
+   *
+   * @note This method is automatically invoked when a region is created.
+   * The identifier is only unique within this graph.
+   */
+  [[nodiscard]] Region::Id
+  generateRegionId() noexcept
+  {
+    const auto regionId = nextRegionId_;
+    nextRegionId_++;
+    return regionId;
+  }
+
   /**
    * @return The root region of the graph.
    */
@@ -117,6 +131,7 @@ class Graph final
   ExtractTailNodes(const Graph & rvsdg);
 
 private:
+  Region::Id nextRegionId_;
   std::unique_ptr<Region> RootRegion_;
 };
 

jlm/rvsdg/region.cpp

@@ -145,7 +145,8 @@ Region::~Region() noexcept
 }
 
 Region::Region(Region *, Graph * graph)
-    : index_(0),
+    : id_(graph->generateRegionId()),
+      index_(0),
       graph_(graph),
       nextNodeId_(0),
       node_(nullptr),
@@ -154,8 +155,9 @@ Region::Region(Region *, Graph * graph)
       numNodes_(0)
 {}
 
-Region::Region(rvsdg::StructuralNode * node, size_t index)
-    : index_(index),
+Region::Region(StructuralNode * node, const size_t index)
+    : id_(node->graph()->generateRegionId()),
+      index_(index),
       graph_(node->graph()),
       nextNodeId_(0),
       node_(node),

jlm/rvsdg/region.hpp

@@ -241,6 +241,8 @@ class Region
   using BottomNodeConstRange = util::IteratorRange<BottomNodeConstIterator>;
 
 public:
+  using Id = uint64_t;
+
   ~Region() noexcept;
 
   Region(rvsdg::Region * parent, Graph * graph);
@@ -252,6 +254,17 @@ class Region
   Region &
   operator=(const Region &) = delete;
 
+  /**
+   * @return The unique identifier of the region instance within the graph.
+   *
+   * \see Graph::generateRegionId()
+   */
+  [[nodiscard]] Id
+  getRegionId() const noexcept
+  {
+    return id_;
+  }
+
   /**
    * @return Returns an iterator range for iterating through the arguments of the region.
    */
@@ -733,6 +746,7 @@ class Region
   [[nodiscard]] static std::string
   ToString(const util::Annotation & annotation, char labelValueSeparator);
 
+  Id id_;
   size_t index_;
   Graph * graph_;
   Node::Id nextNodeId_;