Introduce a new data structure, the SparseMultiSet, and changes to the MI scheduler to use it.

A SparseMultiSet adds multiset behavior to SparseSet, while retaining SparseSet's desirable properties. Essentially, SparseMultiSet provides multiset behavior by storing its dense data in doubly linked lists that are inlined into the dense vector. This allows it to provide good data locality as well as vector-like constant-time clear() and fast constant time find(), insert(), and erase(). It also allows SparseMultiSet to have a builtin recycler rather than keeping SparseSet's behavior of always swapping upon removal, which allows it to preserve more iterators. It's often a better alternative to a SparseSet of a growable container or vector-of-vector.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173064 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 46 deletions

diff --git a/include/llvm/CodeGen/ScheduleDAGInstrs.h b/include/llvm/CodeGen/ScheduleDAGInstrs.h
index 8b841e2..94abec2 100644
--- a/include/llvm/CodeGen/ScheduleDAGInstrs.h
+++ b/include/llvm/CodeGen/ScheduleDAGInstrs.h
@@ -17,6 +17,7 @@
 
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SparseSet.h"
+#include "llvm/ADT/SparseMultiSet.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/ScheduleDAG.h"
@@ -48,56 +49,18 @@ namespace llvm {
   struct PhysRegSUOper {
     SUnit *SU;
     int OpIdx;
+    unsigned Reg;
 
-    PhysRegSUOper(SUnit *su, int op): SU(su), OpIdx(op) {}
-  };
-
-  /// Combine a SparseSet with a 1x1 vector to track physical registers.
-  /// The SparseSet allows iterating over the (few) live registers for quickly
-  /// comparing against a regmask or clearing the set.
-  ///
-  /// Storage for the map is allocated once for the pass. The map can be
-  /// cleared between scheduling regions without freeing unused entries.
-  class Reg2SUnitsMap {
-    SparseSet<unsigned> PhysRegSet;
-    std::vector<std::vector<PhysRegSUOper> > SUnits;
-  public:
-    typedef SparseSet<unsigned>::const_iterator const_iterator;
-
-    // Allow iteration over register numbers (keys) in the map. If needed, we
-    // can provide an iterator over SUnits (values) as well.
-    const_iterator reg_begin() const { return PhysRegSet.begin(); }
-    const_iterator reg_end() const { return PhysRegSet.end(); }
-
-    /// Initialize the map with the number of registers.
-    /// If the map is already large enough, no allocation occurs.
-    /// For simplicity we expect the map to be empty().
-    void setRegLimit(unsigned Limit);
-
-    /// Returns true if the map is empty.
-    bool empty() const { return PhysRegSet.empty(); }
+    PhysRegSUOper(SUnit *su, int op, unsigned R): SU(su), OpIdx(op), Reg(R) {}
 
-    /// Clear the map without deallocating storage.
-    void clear();
-
-    bool contains(unsigned Reg) const { return PhysRegSet.count(Reg); }
-
-    /// If this register is mapped, return its existing SUnits vector.
-    /// Otherwise map the register and return an empty SUnits vector.
-    std::vector<PhysRegSUOper> &operator[](unsigned Reg) {
-      bool New = PhysRegSet.insert(Reg).second;
-      assert((!New || SUnits[Reg].empty()) && "stale SUnits vector");
-      (void)New;
-      return SUnits[Reg];
-    }
-
-    /// Erase an existing element without freeing memory.
-    void erase(unsigned Reg) {
-      PhysRegSet.erase(Reg);
-      SUnits[Reg].clear();
-    }
+    unsigned getSparseSetIndex() const { return Reg; }
   };
 
+  /// Use a SparseMultiSet to track physical registers. Storage is only
+  /// allocated once for the pass. It can be cleared in constant time and reused
+  /// without any frees.
+  typedef SparseMultiSet<PhysRegSUOper, llvm::identity<unsigned>, uint16_t> Reg2SUnitsMap;
+
   /// Use SparseSet as a SparseMap by relying on the fact that it never
   /// compares ValueT's, only unsigned keys. This allows the set to be cleared
   /// between scheduling regions in constant time as long as ValueT does not