Use a SparseSet in LiveRegUnits.

Some clients may add block live ins and may track liveness over a
large scope. This guarantees an efficient implementation in all cases
with no memory allocation/deallocation, independent of the number of
target registers. It could be slightly less convenient but is fine in
the expected case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192622 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 7 deletions

diff --git a/include/llvm/CodeGen/LiveRegUnits.h b/include/llvm/CodeGen/LiveRegUnits.h
index 0c6df8838e..1e24e695a1 100644
--- a/include/llvm/CodeGen/LiveRegUnits.h
+++ b/include/llvm/CodeGen/LiveRegUnits.h
@@ -17,9 +17,9 @@
 #ifndef LLVM_CODEGEN_LIVEREGUNITS_H
 #define LLVM_CODEGEN_LIVEREGUNITS_H
 
-#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SparseSet.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
-#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include <cassert>
 
 namespace llvm {
@@ -29,17 +29,23 @@ class MachineInstr;
 /// A set of live register units with functions to track liveness when walking
 /// backward/forward through a basic block.
 class LiveRegUnits {
-  SmallSet<unsigned, 32> LiveUnits;
+  SparseSet<unsigned> LiveUnits;
 
+  LiveRegUnits(const LiveRegUnits&) LLVM_DELETED_FUNCTION;
+  LiveRegUnits &operator=(const LiveRegUnits&) LLVM_DELETED_FUNCTION;
 public:
   /// \brief Constructs a new empty LiveRegUnits set.
   LiveRegUnits() {}
 
-  /// \brief Constructs a new LiveRegUnits set by copying @p Other.
-  LiveRegUnits(const LiveRegUnits &Other)
-    : LiveUnits(Other.LiveUnits) {
+  void init(const TargetRegisterInfo *TRI) {
+    LiveUnits.clear();
+    LiveUnits.setUniverse(TRI->getNumRegs());
   }
 
+  void clear() { LiveUnits.clear(); }
+
+  bool empty() const { return LiveUnits.empty(); }
+
   /// \brief Adds a register to the set.
   void addReg(unsigned Reg, const MCRegisterInfo &MCRI) {
     for (MCRegUnitIterator RUnits(Reg, &MCRI); RUnits.isValid(); ++RUnits)
@@ -73,7 +79,7 @@ public:
   /// instruction(bundle): Remove killed-uses, add defs.
   void stepForward(const MachineInstr &MI, const MCRegisterInfo &MCRI);
 
-  /// Adds all registers in the live-in list of block @p BB.
+  /// \brief Adds all registers in the live-in list of block @p BB.
   void addLiveIns(const MachineBasicBlock &BB, const MCRegisterInfo &MCRI);
 };