[PATCH] IR: Do not canonicalize constant GEPs into an out-of-bounds array access

[Eric Christopher]

================
Comment at: lib/IR/ConstantFold.cpp:1944
@@ +1943,3 @@
+      bool IsSequentialAccessInRange = false;
+      if (LastTy && isa<SequentialType>(LastTy)) {
+        int64_t NumElements = 0;
----------------
Block comment summarizing the following code would be pretty helpful here. 


http://llvm-reviews.chandlerc.com/D2093