From f4a0c81371553d45b3536d29d73a1aee8216db66 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Fri, 17 Dec 2010 18:13:52 +0000
Subject: [PATCH] Add MachineLoopRange comparators for sorting loop lists by
 number and by area.

llvm-svn: 122073
---
 include/llvm/CodeGen/MachineLoopRanges.h | 19 +++++++++++++
 lib/CodeGen/MachineLoopRanges.cpp        | 35 ++++++++++++++++++++++--
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/include/llvm/CodeGen/MachineLoopRanges.h b/include/llvm/CodeGen/MachineLoopRanges.h
index 730b729dba7..3f2f24194a4 100644
--- a/include/llvm/CodeGen/MachineLoopRanges.h
+++ b/include/llvm/CodeGen/MachineLoopRanges.h
@@ -42,6 +42,9 @@ private:
   /// Bit 0 = inside loop block.
   Map Intervals;
 
+  /// Loop area as measured by SlotIndex::distance.
+  unsigned Area;
+
   /// Create a MachineLoopRange, only accessible to MachineLoopRanges.
   MachineLoopRange(const MachineLoop*, Allocator&, SlotIndexes&);
 
@@ -50,11 +53,27 @@ public:
   /// inteructions.
   bool overlaps(SlotIndex Start, SlotIndex Stop);
 
+  /// getNumber - Return the loop number. This is the same as the number of the
+  /// header block.
+  unsigned getNumber() const;
+
+  /// getArea - Return the loop area. This number is approximately proportional
+  /// to the number of instructions in the loop.
+  unsigned getArea() const { return Area; }
+
   /// getMap - Allow public read-only access for IntervalMapOverlaps.
   const Map &getMap() { return Intervals; }
 
   /// print - Print loop ranges on OS.
   void print(raw_ostream&) const;
+
+  /// byNumber - Comparator for array_pod_sort that sorts a list of
+  /// MachineLoopRange pointers by number.
+  static int byNumber(const void*, const void*);
+
+  /// byAreaDesc - Comparator for array_pod_sort that sorts a list of
+  /// MachineLoopRange pointers by descending area, then by number.
+  static int byAreaDesc(const void*, const void*);
 };
 
 raw_ostream &operator<<(raw_ostream&, const MachineLoopRange&);
diff --git a/lib/CodeGen/MachineLoopRanges.cpp b/lib/CodeGen/MachineLoopRanges.cpp
index 9ee6c5bd125..17fe67f6504 100644
--- a/lib/CodeGen/MachineLoopRanges.cpp
+++ b/lib/CodeGen/MachineLoopRanges.cpp
@@ -57,12 +57,13 @@ MachineLoopRange *MachineLoopRanges::getLoopRange(const MachineLoop *Loop) {
 MachineLoopRange::MachineLoopRange(const MachineLoop *loop,
                                    MachineLoopRange::Allocator &alloc,
                                    SlotIndexes &Indexes)
-  : Loop(loop), Intervals(alloc) {
+  : Loop(loop), Intervals(alloc), Area(0) {
   // Compute loop coverage.
   for (MachineLoop::block_iterator I = Loop->block_begin(),
          E = Loop->block_end(); I != E; ++I) {
     const std::pair<SlotIndex, SlotIndex> &Range = Indexes.getMBBRange(*I);
     Intervals.insert(Range.first, Range.second, 1u);
+    Area += Range.first.distance(Range.second);
   }
 }
 
@@ -73,8 +74,38 @@ bool MachineLoopRange::overlaps(SlotIndex Start, SlotIndex Stop) {
   return I.valid() && Stop > I.start();
 }
 
+unsigned MachineLoopRange::getNumber() const {
+  return Loop->getHeader()->getNumber();
+}
+
+/// byNumber - Comparator for array_pod_sort that sorts a list of
+/// MachineLoopRange pointers by number.
+int MachineLoopRange::byNumber(const void *pa, const void *pb) {
+  const MachineLoopRange *a = *static_cast<MachineLoopRange *const *>(pa);
+  const MachineLoopRange *b = *static_cast<MachineLoopRange *const *>(pb);
+  unsigned na = a->getNumber();
+  unsigned nb = b->getNumber();
+  if (na < nb)
+    return -1;
+  if (na > nb)
+    return 1;
+  return 0;
+}
+
+/// byAreaDesc - Comparator for array_pod_sort that sorts a list of
+/// MachineLoopRange pointers by:
+/// 1. Descending area.
+/// 2. Ascending number.
+int MachineLoopRange::byAreaDesc(const void *pa, const void *pb) {
+  const MachineLoopRange *a = *static_cast<MachineLoopRange *const *>(pa);
+  const MachineLoopRange *b = *static_cast<MachineLoopRange *const *>(pb);
+  if (a->getArea() != b->getArea())
+    return a->getArea() > b->getArea() ? -1 : 1;
+  return byNumber(pa, pb);
+}
+
 void MachineLoopRange::print(raw_ostream &OS) const {
-  OS << "Loop#" << Loop->getHeader()->getNumber() << " =";
+  OS << "Loop#" << getNumber() << " =";
   for (Map::const_iterator I = Intervals.begin(); I.valid(); ++I)
     OS << " [" << I.start() << ';' << I.stop() << ')';
 }