RegionInfo: Add helpers to replace entry/exit recursively

Contributed by: Star Tan <[email protected]>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179157 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/RegionInfo.h

@@ -266,6 +266,24 @@ class Region : public RegionNode {
   /// @param BB  The new exit basic block of the region.
   void replaceExit(BasicBlock *BB);
 
+  /// @brief Recursively replace the entry basic block of the region.
+  ///
+  /// This function replaces the entry basic block with a new basic block. It
+  /// also updates all child regions that have the same entry basic block as
+  /// this region.
+  ///
+  /// @param NewEntry The new entry basic block.
+  void replaceEntryRecursive(BasicBlock *NewEntry);
+
+  /// @brief Recursively replace the exit basic block of the region.
+  ///
+  /// This function replaces the exit basic block with a new basic block. It
+  /// also updates all child regions that have the same exit basic block as
+  /// this region.
+  ///
+  /// @param NewExit The new exit basic block.
+  void replaceExitRecursive(BasicBlock *NewExit);
+
   /// @brief Get the exit BasicBlock of the Region.
   /// @return The exit BasicBlock of the Region, NULL if this is the TopLevel
   ///         Region.

lib/Analysis/RegionInfo.cpp

@@ -79,6 +79,38 @@ void Region::replaceExit(BasicBlock *BB) {
   exit = BB;
 }
 
+void Region::replaceEntryRecursive(BasicBlock *NewEntry) {
+  std::vector<Region *> RegionQueue;
+  BasicBlock *OldEntry = getEntry();
+
+  RegionQueue.push_back(this);
+  while (!RegionQueue.empty()) {
+    Region *R = RegionQueue.back();
+    RegionQueue.pop_back();
+
+    R->replaceEntry(NewEntry);
+    for (Region::const_iterator RI = R->begin(), RE = R->end(); RI != RE; ++RI)
+      if ((*RI)->getEntry() == OldEntry)
+        RegionQueue.push_back(*RI);
+  }
+}
+
+void Region::replaceExitRecursive(BasicBlock *NewExit) {
+  std::vector<Region *> RegionQueue;
+  BasicBlock *OldExit = getExit();
+
+  RegionQueue.push_back(this);
+  while (!RegionQueue.empty()) {
+    Region *R = RegionQueue.back();
+    RegionQueue.pop_back();
+
+    R->replaceExit(NewExit);
+    for (Region::const_iterator RI = R->begin(), RE = R->end(); RI != RE; ++RI)
+      if ((*RI)->getExit() == OldExit)
+        RegionQueue.push_back(*RI);
+  }
+}
+
 bool Region::contains(const BasicBlock *B) const {
   BasicBlock *BB = const_cast<BasicBlock*>(B);