[Attributor][Fix] Manifest nocapture only in CSArgument or Argument

[uenoku]

Summary

We can query to Attributor whether the value is captured in the scope or not on the following way:

const auto & NoCapAA = A.getAAFor<AANoCapture>(*this, IRPosition::value(V));

And if V is CallSiteReturned then getDeducedAttribute will add nocatpure to the callsite returned value. It is not valid.
This patch checks the position is an argument or call site argument.

[jdoerfert]

Test missing.

[uenoku]

In D67342#1663869, @jdoerfert wrote:

Test missing.

Yes, test is missing but without this patch, D67286 doesn't work well. If we query whether a callsite retured value is captured in the scope and the value has nocapture, this kind of error will be raised.

Attributes 'byval', 'inalloca', 'nest', 'sret', 'nocapture', 'returned', 'swiftself', and 'swifterror' do not apply to return values!
  %B = tail call noalias nocapture i8* @malloc(i64 4)
in function test12_1
LLVM ERROR: Broken function found, compilation aborted!

I think this fix is trivial then a test is not necessary.

[jdoerfert]

Mention that this is tested in D67286 in the commit message.

llvm/trunk/lib/Transforms/IPO/Attributor.cpp

struct AANoCaptureImpl : public AANoCapture {
 
   /// see AbstractAttribute::isAssumedNoCaptureMaybeReturned(...).
   virtual void
   getDeducedAttributes(LLVMContext &Ctx,
                        SmallVectorImpl<Attribute> &Attrs) const override {
     if (!isAssumedNoCaptureMaybeReturned())
       return;
 
+    if (getArgNo() >= 0) {
       if (isAssumedNoCapture())
         Attrs.emplace_back(Attribute::get(Ctx, Attribute::NoCapture));
       else if (ManifestInternal)
         Attrs.emplace_back(Attribute::get(Ctx, "no-capture-maybe-returned"));
     }
+  }
 
   /// Set the NOT_CAPTURED_IN_MEM and NOT_CAPTURED_IN_RET bits in \p Known
   /// depending on the ability of the function associated with \p IRP to capture
   /// state in memory and through "returning/throwing", respectively.
   static void determineFunctionCaptureCapabilities(const Function &F,
                                                    IntegerState &State) {
     // TODO: Once we have memory behavior attributes we should use them here.