[NewPM] Fix wrong perfect forwardings

[vhscampos]

Summary

Some template functions were missing '&&' in function arguments,
therefore these were always taken by value after template instantiation.

This patch adds the double ampersand to introduce proper perfect
forwarding.

[aeubanks]

there are a couple more adaptors in CGSCCPassManager.h and LoopPassManager.h, should those be udpated too?

[vhscampos]

Fixes in other places of the new pass manager.

[vhscampos]

@aeubanks Yes, thank you. Just did that.

[aeubanks]

llvm/include/llvm/Transforms/Scalar/LoopPassManager.h

136 ↗

(On Diff #359743)

forward?

148 ↗

(On Diff #359743)

forward?

490 ↗

(On Diff #359743)

forward?

[vhscampos]

llvm/include/llvm/Transforms/Scalar/LoopPassManager.h

136 ↗

(On Diff #359743)

Pass is an rvalue reference.

Note that the type of 'Pass' is RepeatedPass<PassT>, not PassT, i.e. it does not have the type of the template. Which means that perfect forwarding doesn't work here. Therefore we'd need one implementation for lvalue ref and another for rvalue ref. Since this function is called only passing rvalues, it is safe to have only the rvalue reference version.

148 ↗

(On Diff #359743)

Same reason as above.

490 ↗

(On Diff #359743)

In this case here, LPM is fixed as an rvalue reference, so no need for forwarding. That means that it accepts only calls that pass an rvalue. This is true for all call sites.

[aeubanks]

lgtm

[vhscampos]

Thanks for your review

llvm/include/llvm/IR/PassManager.h

 private:
   std::unique_ptr<PassConceptT> Pass;
 };
 
 /// A function to deduce a function pass type and wrap it in the
 /// templated adaptor.
 template <typename FunctionPassT>
 ModuleToFunctionPassAdaptor
-createModuleToFunctionPassAdaptor(FunctionPassT Pass) {
+createModuleToFunctionPassAdaptor(FunctionPassT &&Pass) {
   using PassModelT =
       detail::PassModel<Function, FunctionPassT, PreservedAnalyses,
                         FunctionAnalysisManager>;
 
   return ModuleToFunctionPassAdaptor(
-      std::make_unique<PassModelT>(std::move(Pass)));
+      std::make_unique<PassModelT>(std::forward<FunctionPassT>(Pass)));
 }
 
 /// A utility pass template to force an analysis result to be available.
 ///
 /// If there are extra arguments at the pass's run level there may also be
 /// extra arguments to the analysis manager's \c getResult routine. We can't
 /// guess how to effectively map the arguments from one to the other, and so
 /// this specialization just ignores them.