Insert two blank SlotIndexes between basic blocks instead of just one.

This is the first small step towards using closed intervals for liveness instead
of the half-open intervals we're using now.

We want to be able to distinguish between a SlotIndex that represents a variable
being live-out of a basic block, and an index representing a variable live-in to
its successor.

That requires two separate indexes between blocks. One for live-outs and one for
live-ins.

With this change, getMBBEndIdx(MBB).getPrevSlot() becomes stable so it stays
greater than any instructions inserted at the end of MBB.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118747 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/SlotIndexes.h b/include/llvm/CodeGen/SlotIndexes.h
index d207923099..c8f26544f0 100644
--- a/include/llvm/CodeGen/SlotIndexes.h
+++ b/include/llvm/CodeGen/SlotIndexes.h
@@ -738,6 +738,7 @@ namespace llvm {
       MachineFunction::iterator nextMBB =
         llvm::next(MachineFunction::iterator(mbb));
       IndexListEntry *startEntry = createEntry(0, 0);
+      IndexListEntry *stopEntry = createEntry(0, 0);
       IndexListEntry *nextEntry = 0;
 
       if (nextMBB == mbb->getParent()->end()) {
@@ -747,6 +748,7 @@ namespace llvm {
       }
 
       insert(nextEntry, startEntry);
+      insert(nextEntry, stopEntry);
 
       SlotIndex startIdx(startEntry, SlotIndex::LOAD);
       SlotIndex endIdx(nextEntry, SlotIndex::LOAD);