[CallSite removal] Migrate ConstantFolding APIs and implementation to
`CallBase`.

Users have been updated. You can see how to update any out-of-tree
usages: pass `cast<CallBase>(CS.getInstruction())`.

llvm-svn: 353661
diff --git a/llvm/lib/Transforms/Utils/Evaluator.cpp b/llvm/lib/Transforms/Utils/Evaluator.cpp
index 4a8ec43..fb8cb3d 100644
--- a/llvm/lib/Transforms/Utils/Evaluator.cpp
+++ b/llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -540,7 +540,8 @@
 
       if (Callee->isDeclaration()) {
         // If this is a function we can constant fold, do it.
-        if (Constant *C = ConstantFoldCall(CS, Callee, Formals, TLI)) {
+        if (Constant *C = ConstantFoldCall(cast<CallBase>(CS.getInstruction()),
+                                           Callee, Formals, TLI)) {
           InstResult = castCallResultIfNeeded(CS.getCalledValue(), C);
           if (!InstResult)
             return false;