Create new intervals for isolated blocks during region splitting.

This merges the behavior of splitSingleBlocks into splitAroundRegion, so the
RS_Region and RS_Block register stages can be coalesced. That means the leftover
intervals after region splitting go directly to spilling instead of a second
pass of per-block splitting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129379 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index fab56f7..a387896 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -347,6 +347,11 @@
 
   // ===--- High level methods ---===
 
+  /// splitSingleBlock - Split CurLI into a separate live interval around the
+  /// uses in a single block. This is intended to be used as part of a larger
+  /// split, and doesn't call finish().
+  void splitSingleBlock(const SplitAnalysis::BlockInfo &BI);
+
   /// splitSingleBlocks - Split CurLI into a separate live interval inside each
   /// basic block in Blocks.
   void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks);