[CallSite] Make construction from Value* (or Instruction*) explicit.

CallSite roughly behaves as a common base CallInst and InvokeInst. Bring
the behavior closer to that model by making upcasts explicit. Downcasts
remain implicit and work as before.

Following dyn_cast as a mental model checking whether a Value *V isa
CallSite now looks like this: 
  if (auto CS = CallSite(V)) // think dyn_cast
instead of:
  if (CallSite CS = V)

This is an extra token but I think it is slightly clearer. Making the
ctor explicit has the advantage of not accidentally creating nullptr
CallSites, e.g. when you pass a Value * to a function taking a CallSite
argument.

llvm-svn: 234601

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 45442b0..4c79b9f 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -187,7 +187,7 @@ bool AliasSet::aliasesUnknownInst(Instruction *Inst, AliasAnalysis &AA) const {
     return false;
 
   for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
-    CallSite C1 = getUnknownInst(i), C2 = Inst;
+    CallSite C1(getUnknownInst(i)), C2(Inst);
     if (!C1 || !C2 ||
         AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
         AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)