[LiveRange] Reset the VNIs when splitting subranges

When splitting a subrange we end up with two different subranges covering
two different, non overlapping, lanes.
As part of this splitting the VNIs of the original live-range need
to be dispatched to the subranges according to which lanes they are
actually defining.

Prior to this patch we were assuming that all values were defining
all lanes. This was wrong as demonstrated by llvm.org/PR40835.

Differential Revision: https://reviews.llvm.org/D59731

llvm-svn: 357032

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index 0bdbdce3..5c944fe 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -520,17 +520,18 @@ SlotIndex SplitEditor::buildSingleSubRegCopy(unsigned FromReg, unsigned ToReg,
       .addReg(FromReg, 0, SubIdx);
 
   BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
+  SlotIndexes &Indexes = *LIS.getSlotIndexes();
   if (FirstCopy) {
-    SlotIndexes &Indexes = *LIS.getSlotIndexes();
     Def = Indexes.insertMachineInstrInMaps(*CopyMI, Late).getRegSlot();
   } else {
     CopyMI->bundleWithPred();
   }
   LaneBitmask LaneMask = TRI.getSubRegIndexLaneMask(SubIdx);
   DestLI.refineSubRanges(Allocator, LaneMask,
-                         [Def, &Allocator](LiveInterval::SubRange& SR) {
-    SR.createDeadDef(Def, Allocator);
-  });
+                         [Def, &Allocator](LiveInterval::SubRange &SR) {
+                           SR.createDeadDef(Def, Allocator);
+                         },
+                         Indexes, TRI);
   return Def;
 }