Build the Hopfield network incrementally when splitting global live ranges.

It is common for large live ranges to have few basic blocks with register uses
and many live-through blocks without any uses. This approach grows the Hopfield
network incrementally around the use blocks, completely avoiding checking
interference for some through blocks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129188 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 4 deletions

diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index 20ac8a1fdc..f1ff501fbd 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -89,7 +89,10 @@ private:
   SmallVector<BlockInfo, 8> UseBlocks;
 
   /// ThroughBlocks - Block numbers where CurLI is live through without uses.
-  SmallVector<unsigned, 8> ThroughBlocks;
+  BitVector ThroughBlocks;
+
+  /// NumThroughBlocks - Number of live-through blocks.
+  unsigned NumThroughBlocks;
 
   SlotIndex computeLastSplitPoint(unsigned Num);
 
@@ -135,9 +138,11 @@ public:
   /// where CurLI has uses.
   ArrayRef<BlockInfo> getUseBlocks() { return UseBlocks; }
 
-  /// getThroughBlocks - Return an array of block numbers where CurLI is live
-  /// through without uses.
-  ArrayRef<unsigned> getThroughBlocks() { return ThroughBlocks; }
+  /// getNumThroughBlocks - Return the number of through blocks.
+  unsigned getNumThroughBlocks() const { return NumThroughBlocks; }
+
+  /// isThroughBlock - Return true if CurLI is live through MBB without uses.
+  bool isThroughBlock(unsigned MBB) const { return ThroughBlocks.test(MBB); }
 
   typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet;