[flang][DRAFT] Copy-in/Copy-out determination

flang/include/flang/Evaluate/call.h

@@ -52,7 +52,7 @@ using SymbolRef = common::Reference<const Symbol>;
 
 class ActualArgument {
 public:
-  ENUM_CLASS(Attr, PassedObject, PercentVal, PercentRef);
+  ENUM_CLASS(Attr, PassedObject, PercentVal, PercentRef, CopyIn, CopyOut);
   using Attrs = common::EnumSet<Attr, Attr_enumSize>;
 
   // Dummy arguments that are TYPE(*) can be forwarded as actual arguments.
@@ -131,7 +131,6 @@ class ActualArgument {
     return *this;
   }
 
-  bool Matches(const characteristics::DummyArgument &) const;
   common::Intent dummyIntent() const { return dummyIntent_; }
   ActualArgument &set_dummyIntent(common::Intent intent) {
     dummyIntent_ = intent;
@@ -161,6 +160,20 @@ class ActualArgument {
     return *this;
   }
 
+  // This actual argument may need copy-in before the procedure call
+  bool mayNeedCopyIn() const { return attrs_.test(Attr::CopyIn); };
+  ActualArgument &set_mayNeedCopyIn() {
+    attrs_ = attrs_ + Attr::CopyIn;
+    return *this;
+  }
+
+  // This actual argument may need copy-out after the procedure call
+  bool mayNeedCopyOut() const { return attrs_.test(Attr::CopyOut); };
+  ActualArgument &set_mayNeedCopyOut() {
+    attrs_ = attrs_ + Attr::CopyOut;
+    return *this;
+  }
+
 private:
   // Subtlety: There is a distinction that must be maintained here between an
   // actual argument expression that is a variable and one that is not,
@@ -235,7 +248,11 @@ class ProcedureRef {
   ProcedureRef(ProcedureDesignator &&p, ActualArguments &&a,
       bool hasAlternateReturns = false)
       : proc_{std::move(p)}, arguments_{std::move(a)},
-        hasAlternateReturns_{hasAlternateReturns} {}
+        hasAlternateReturns_{hasAlternateReturns} {
+    // Gathers necessary information to determine the need for copy-in and
+    // copy-out
+    DetermineCopyInOut();
+  }
   ~ProcedureRef();
   static void Deleter(ProcedureRef *);
 
@@ -273,6 +290,8 @@ class ProcedureRef {
   llvm::raw_ostream &AsFortran(llvm::raw_ostream &) const;
 
 protected:
+  void DetermineCopyInOut();
+
   ProcedureDesignator proc_;
   ActualArguments arguments_;
   Chevrons chevrons_;

flang/lib/Evaluate/call.cpp

@@ -12,6 +12,7 @@
 #include "flang/Evaluate/check-expression.h"
 #include "flang/Evaluate/expression.h"
 #include "flang/Evaluate/tools.h"
+#include "flang/Semantics/semantics.h"
 #include "flang/Semantics/symbol.h"
 #include "flang/Support/Fortran.h"
 
@@ -247,4 +248,19 @@ ProcedureRef::~ProcedureRef() {}
 
 void ProcedureRef::Deleter(ProcedureRef *p) { delete p; }
 
+void ProcedureRef::DetermineCopyInOut() {
+  if (!proc().GetSymbol()) {
+    return;
+  }
+  // Get folding context of the call site owner
+  FoldingContext &fc{proc_.GetSymbol()->owner().context().foldingContext()};
+  auto procInfo{characteristics::Procedure::Characterize(
+      proc_, fc, /*emitError=*/true)};
+  if (!procInfo) {
+    return;
+  }
+  // TODO: at this point have dummy arguments as procInfo->dummyArguments
+  // and have actual arguments via arguments_
+}
+
 } // namespace Fortran::evaluate