Fix typos in comments and doc

Committing http://reviews.llvm.org/D4798 for Robin Morisset (morisset@google.com)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214934 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/LoopRotation.cpp

@@ -184,7 +184,7 @@ static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
   }
 }
 
-/// Determine whether the instructions in this range my be safely and cheaply
+/// Determine whether the instructions in this range may be safely and cheaply
 /// speculated. This is not an important enough situation to develop complex
 /// heuristics. We handle a single arithmetic instruction along with any type
 /// conversions.
@@ -232,7 +232,7 @@ static bool shouldSpeculateInstrs(BasicBlock::iterator Begin,
 /// Fold the loop tail into the loop exit by speculating the loop tail
 /// instructions. Typically, this is a single post-increment. In the case of a
 /// simple 2-block loop, hoisting the increment can be much better than
-/// duplicating the entire loop header. In the cast of loops with early exits,
+/// duplicating the entire loop header. In the case of loops with early exits,
 /// rotation will not work anyway, but simplifyLoopLatch will put the loop in
 /// canonical form so downstream passes can handle it.
 ///