Improve file comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15069 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocIterativeScan.cpp b/lib/CodeGen/RegAllocIterativeScan.cpp
index 159a005..b92fc74 100644
--- a/lib/CodeGen/RegAllocIterativeScan.cpp
+++ b/lib/CodeGen/RegAllocIterativeScan.cpp
@@ -7,7 +7,13 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements a linear scan register allocator.
+// This file implements an iterative scan register
+// allocator. Iterative scan is a linear scan variant with the
+// following difference:
+//
+// It performs linear scan and keeps a list of the registers it cannot
+// allocate. It then spills all those registers and repeats the
+// process until allocation succeeds.
//
//===----------------------------------------------------------------------===//