Improve misleading comment.

Patch by Matthias Braun!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188391 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 3680943..c0fc477 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -103,7 +103,7 @@
   VNInfoAllocator.Reset();
 }
 
-/// runOnMachineFunction - Register allocate the whole function
+/// runOnMachineFunction - calculates LiveIntervals
 ///
 bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
   MF = &fn;