Down-scale slot index distance to save bits.

llvm-svn: 187438

2 files changed, 8 insertions, 1 deletions

diff --git a/llvm/include/llvm/CodeGen/SlotIndexes.h b/llvm/include/llvm/CodeGen/SlotIndexes.h
index 1c7bdb2e586..984796af864 100644
--- a/llvm/include/llvm/CodeGen/SlotIndexes.h
+++ b/llvm/include/llvm/CodeGen/SlotIndexes.h
@@ -218,6 +218,13 @@ namespace llvm {
       return other.getIndex() - getIndex();
     }
 
+    /// Return the scaled distance from this index to the given one, where all
+    /// slots on the same instruction have zero distance.
+    int getInstrDistance(SlotIndex other) const {
+      return (other.listEntry()->getIndex() - listEntry()->getIndex())
+        / Slot_Count;
+    }
+
     /// isBlock - Returns true if this is a block boundary slot.
     bool isBlock() const { return getSlot() == Slot_Block; }
 
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 87b11a5f51c..f9e363b9f3a 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -419,7 +419,7 @@ void RAGreedy::enqueue(LiveInterval *LI) {
       // Allocate original local ranges in linear instruction order. Since they
       // are singly defined, this produces optimal coloring in the absence of
       // global interference and other constraints.
-      Prio = LI->beginIndex().distance(Indexes->getLastIndex());
+      Prio = LI->beginIndex().getInstrDistance(Indexes->getLastIndex());
     }
     else {
       // Allocate global and split ranges in long->short order. Long ranges that