Allow allocatable ranges from global live range splitting to be split again.

These intervals are allocatable immediately after splitting, but they may be
evicted because of later splitting. This is rare, but when it happens they
should be split again.

The remainder intervals that cannot be allocated after splitting still move
directly to spilling.

SplitEditor::finish can optionally provide a mapping from new live intervals
back to the original interval indexes returned by openIntv().

Each original interval index can map to multiple new intervals after connected
components have been separated. Dead code elimination may also add existing
intervals to the list.

The reverse mapping allows the SplitEditor client to treat the new intervals
differently depending on the split region they came from.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129925 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index cc41e2e321..a8f59d44f6 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -368,7 +368,10 @@ public:
 
   /// finish - after all the new live ranges have been created, compute the
   /// remaining live range, and rewrite instructions to use the new registers.
-  void finish();
+  /// @param LRMap When not null, this vector will map each live range in Edit
+  ///              back to the indices returned by openIntv.
+  ///              There may be extra indices created by dead code elimination.
+  void finish(SmallVectorImpl<unsigned> *LRMap = 0);
 
   /// dump - print the current interval maping to dbgs().
   void dump() const;