Abstract merging of ranges away from number of slots per instruction.

Also make it less aggressive as the current implementation breaks in
some cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11696 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.h b/lib/CodeGen/LiveIntervalAnalysis.h
index 3769f07..24bc895 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.h
+++ b/lib/CodeGen/LiveIntervalAnalysis.h
@@ -126,7 +126,10 @@
         };
 
         static unsigned getBaseIndex(unsigned index) {
-            return index - (index % 4);
+            return index - (index % InstrSlots::NUM);
+        }
+        static unsigned getBoundaryIndex(unsigned index) {
+            return getBaseIndex(index + InstrSlots::NUM - 1);
         }
         static unsigned getLoadIndex(unsigned index) {
             return getBaseIndex(index) + InstrSlots::LOAD;