[CallSite removal] Migrate all Alias Analysis APIs to use the newly
minted `CallBase` class instead of the `CallSite` wrapper.

This moves the largest interwoven collection of APIs that traffic in
`CallSite`s. While a handful of these could have been migrated with
a minorly more shallow migration by converting from a `CallSite` to
a `CallBase`, it hardly seemed worth it. Most of the APIs needed to
migrate together because of the complex interplay of AA APIs and the
fact that converting from a `CallBase` to a `CallSite` isn't free in its
current implementation.

Out of tree users of these APIs can fairly reliably migrate with some
combination of `.getInstruction()` on the `CallSite` instance and
casting the resulting pointer. The most generic form will look like `CS`
-> `cast_or_null<CallBase>(CS.getInstruction())` but in most cases there
is a more elegant migration. Hopefully, this migrates enough APIs for
users to fully move from `CallSite` to the base class. All of the
in-tree users were easily migrated in that fashion.

Thanks for the review from Saleem!

Differential Revision: https://reviews.llvm.org/D55641

llvm-svn: 350503
diff --git a/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp b/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
index f48d3cc..83861b9 100644
--- a/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopVersioningLICM.cpp
@@ -360,10 +360,11 @@
 bool LoopVersioningLICM::instructionSafeForVersioning(Instruction *I) {
   assert(I != nullptr && "Null instruction found!");
   // Check function call safety
-  if (isa<CallInst>(I) && !AA->doesNotAccessMemory(CallSite(I))) {
-    LLVM_DEBUG(dbgs() << "    Unsafe call site found.\n");
-    return false;
-  }
+  if (auto *Call = dyn_cast<CallBase>(I))
+    if (!AA->doesNotAccessMemory(Call)) {
+      LLVM_DEBUG(dbgs() << "    Unsafe call site found.\n");
+      return false;
+    }
   // Avoid loops with possiblity of throw
   if (I->mayThrow()) {
     LLVM_DEBUG(dbgs() << "    May throw instruction found in loop body\n");