Add some more comments to the top of this file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72131 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 15b1506700cf0564f993dcf2ffbea28608be8d49..3a71d279772a1124e930053b29e67950ebbb1e0d 100644 (file)
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -7,8 +7,15 @@
 //
 //===----------------------------------------------------------------------===//
 //
+// This transformation analyzes and transforms the induction variables (and
+// computations derived from them) into forms suitable for efficient execution
+// on the target.
+//
 // This pass performs a strength reduction on array references inside loops that
-// have as one or more of their components the loop induction variable.
+// have as one or more of their components the loop induction variable, it
+// rewrites expressions to take advantage of scaled-index addressing modes
+// available on the target, and it performs a variety of other optimizations
+// related to loop induction variables.
 //
 //===----------------------------------------------------------------------===//