Implement -split-spill-mode=size.

Whenever the complement interval is defined by multiple copies of the
same value, hoist those back-copies to the nearest common dominator.

This ensures that at most one copy is inserted per value in the
complement inteval, and no phi-defs are needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139651 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index 5abdd4c62e..67e80faefa 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -319,6 +319,14 @@ private:
                         MachineBasicBlock &MBB,
                         MachineBasicBlock::iterator I);
 
+  /// removeBackCopies - Remove the copy instructions that defines the values
+  /// in the vector in the complement interval.
+  void removeBackCopies(SmallVectorImpl<VNInfo*> &Copies);
+
+  /// hoistCopiesForSize - Hoist back-copies to the complement interval in a
+  /// way that minimizes code size. This implements the SM_Size spill mode.
+  void hoistCopiesForSize();
+
   /// transferValues - Transfer values to the new ranges.
   /// Return true if any ranges were skipped.
   bool transferValues();