Add "const" in GetUnderlyingObjects. NFC

Summary:
Both the input Value pointer and the returned Value
pointers in GetUnderlyingObjects are now declared as
const.

It turned out that all current (in-tree) uses of
GetUnderlyingObjects were trivial to update, being
satisfied with have those Value pointers declared
as const. Actually, in the past several of the users
had to use const_cast, just because of ValueTracking
not providing a version of GetUnderlyingObjects with
"const" Value pointers. With this patch we get rid
of those const casts.

Reviewers: hfinkel, materi, jkorous

Reviewed By: jkorous

Subscribers: dexonsmith, jkorous, jholewinski, sdardis, eraman, hiraditya, jrtc27, atanasyan, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61038

llvm-svn: 359072
diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index 3f166b1..a5776a4 100644
--- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -1190,10 +1190,10 @@
   }
 
   uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8;
-  SmallVector<Value *, 2> Objs;
+  SmallVector<const Value *, 2> Objs;
   GetUnderlyingObjects(Addr, Objs, Pos->getModule()->getDataLayout());
   bool AllConstants = true;
-  for (Value *Obj : Objs) {
+  for (const Value *Obj : Objs) {
     if (isa<Function>(Obj) || isa<BlockAddress>(Obj))
       continue;
     if (isa<GlobalVariable>(Obj) && cast<GlobalVariable>(Obj)->isConstant())