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
diff --git a/lib/CodeGen/SlotIndexes.cpp b/lib/CodeGen/SlotIndexes.cpp
index adab9ff..277cce3 100644
--- a/lib/CodeGen/SlotIndexes.cpp
+++ b/lib/CodeGen/SlotIndexes.cpp
@@ -127,8 +127,12 @@
index += (Slots + 1) * SlotIndex::NUM;
}
- // One blank instruction at the end.
- push_back(createEntry(0, index));
+ // We insert two blank instructions between basic blocks.
+ // One to represent live-out registers and one to represent live-ins.
+ push_back(createEntry(0, index));
+ index += SlotIndex::NUM;
+
+ push_back(createEntry(0, index));
SlotIndex blockEndIndex(back(), SlotIndex::LOAD);
mbb2IdxMap.insert(