From c69bd733c02a4e0ca25f7a2d6b9b05168720d373 Mon Sep 17 00:00:00 2001
From: Tobias Grosser <grosser@fim.uni-passau.de>
Date: Wed, 13 Oct 2010 05:54:11 +0000
Subject: [PATCH] RegioInfo: Add getExpandedRegion().

getExpandedRegion() enables us to create non canonical regions. Those regions
can be used to define the largerst region, that fullfills a certain property.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116397 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/RegionInfo.h |  8 ++++++++
 lib/Analysis/RegionInfo.cpp        | 32 ++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/llvm/Analysis/RegionInfo.h b/include/llvm/Analysis/RegionInfo.h
index 1626abb36a0..f982b9f9ff3 100644
--- a/include/llvm/Analysis/RegionInfo.h
+++ b/include/llvm/Analysis/RegionInfo.h
@@ -292,6 +292,14 @@ public:
   /// @return The depth of the region.
   unsigned getDepth() const;
 
+  /// @brief Return a new (non canonical) region, that is obtained by joining
+  ///        this region with its predecessors.
+  ///
+  /// @return A region also starting at getEntry(), but reaching to the next
+  ///         basic block that forms with getEntry() a (non canonical) region.
+  ///         NULL if such a basic block does not exist.
+  Region *getExpandedRegion() const;
+
   /// @brief Is this a simple region?
   ///
   /// A region is simple if it has exactly one exit and one entry edge.
diff --git a/lib/Analysis/RegionInfo.cpp b/lib/Analysis/RegionInfo.cpp
index 0bf6aad48a8..2576d4ee14a 100644
--- a/lib/Analysis/RegionInfo.cpp
+++ b/lib/Analysis/RegionInfo.cpp
@@ -373,6 +373,38 @@ unsigned Region::getDepth() const {
   return Depth;
 }
 
+Region *Region::getExpandedRegion() const {
+  unsigned NumSuccessors = exit->getTerminator()->getNumSuccessors();
+
+  if (NumSuccessors == 0)
+    return NULL;
+
+  for (pred_iterator PI = pred_begin(getExit()), PE = pred_end(getExit());
+       PI != PE; ++PI)
+    if (!DT->dominates(getEntry(), *PI))
+      return NULL;
+
+  Region *R = RI->getRegionFor(exit);
+
+  if (R->getEntry() != exit) {
+    if (exit->getTerminator()->getNumSuccessors() == 1)
+      return new Region(getEntry(), *succ_begin(exit), RI, DT);
+    else
+      return NULL;
+  }
+
+  while (R->getParent() && R->getParent()->getEntry() == exit)
+    R = R->getParent();
+
+  if (!DT->dominates(getEntry(), R->getExit()))
+    for (pred_iterator PI = pred_begin(getExit()), PE = pred_end(getExit());
+         PI != PE; ++PI)
+    if (!DT->dominates(R->getExit(), *PI))
+      return NULL;
+
+  return new Region(getEntry(), R->getExit(), RI, DT);
+}
+
 void Region::print(raw_ostream &OS, bool print_tree, unsigned level) const {
   if (print_tree)
     OS.indent(level*2) << "[" << level << "] " << getNameStr();
-- 
2.34.1