Subzero: Translation-time improvements in the register allocator.

src/IceRegAlloc.h

 //===- subzero/src/IceRegAlloc.h - Linear-scan reg. allocation --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the data structures used during linear-scan
@@ skipping 23 matching lines @@
     return range().endsBefore(Other.range());
   }
   bool overlaps(const LiveRangeWrapper &Other) const {
     const bool UseTrimmed = true;
     return range().overlaps(Other.range(), UseTrimmed);
   }
   bool overlapsStart(const LiveRangeWrapper &Other) const {
     const bool UseTrimmed = true;
     return range().overlapsInst(Other.range().getStart(), UseTrimmed);
   }
-  Variable *const Var;
+  Variable *Var;
   void dump(const Cfg *Func) const;
 
 private:
   // LiveRangeWrapper(const LiveRangeWrapper &) = delete;
-  LiveRangeWrapper &operator=(const LiveRangeWrapper &) = delete;
+  // LiveRangeWrapper &operator=(const LiveRangeWrapper &) = delete;
 };
 
 class LinearScan {
 public:
   LinearScan(Cfg *Func) : Func(Func) {}
   void scan(const llvm::SmallBitVector &RegMask);
   void dump(Cfg *Func) const;
 
 private:
   Cfg *const Func;
-  // RangeCompare is the comparator for sorting an LiveRangeWrapper
-  // by starting point in a std::set<>.  Ties are broken by variable
-  // number so that sorting is stable.
-  struct RangeCompare {
-    bool operator()(const LiveRangeWrapper &L,
-                    const LiveRangeWrapper &R) const {
-      InstNumberT Lstart = L.Var->getLiveRange().getStart();
-      InstNumberT Rstart = R.Var->getLiveRange().getStart();
-      if (Lstart == Rstart)
-        return L.Var->getIndex() < R.Var->getIndex();
-      return Lstart < Rstart;
-    }
-  };
-  typedef std::set<LiveRangeWrapper, RangeCompare> OrderedRanges;
+  typedef std::vector<LiveRangeWrapper> OrderedRanges;
   typedef std::list<LiveRangeWrapper> UnorderedRanges;
   OrderedRanges Unhandled;
   // UnhandledPrecolored is a subset of Unhandled, specially collected
   // for faster processing.
   OrderedRanges UnhandledPrecolored;
   UnorderedRanges Active, Inactive, Handled;
   LinearScan(const LinearScan &) = delete;
   LinearScan &operator=(const LinearScan &) = delete;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEREGALLOC_H