[flang-commits] [flang] [flang][cuda] Compute matching distance in generic resolution (PR #90774)

[Peter Klausler via flang-commits]

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@@ -2492,6 +2492,89 @@ static bool CheckCompatibleArguments(
   return true;
 }
 
+// Compute the matching distance as described in section 3.2.3 of the CUDA
+// Fortran references.
+static int GetMatchingDistance(const characteristics::DummyArgument &dummy,
+    const std::optional<ActualArgument> &actual) {
+  std::optional<common::CUDADataAttr> actualDataAttr, dummyDataAttr;
+  if (actual) {
+    if (auto *expr{actual->UnwrapExpr()}) {
+      const auto *actualLastSymbol{evaluate::GetLastSymbol(*expr)};
+      if (actualLastSymbol) {
+        actualLastSymbol = &semantics::ResolveAssociations(*actualLastSymbol);
+        if (const auto *actualObject{actualLastSymbol
+                    ? actualLastSymbol
+                          ->detailsIf<semantics::ObjectEntityDetails>()
+                    : nullptr}) {
+          actualDataAttr = actualObject->cudaDataAttr();
+        }
+      }
+    }
+  }
+
+  common::visit(common::visitors{
+                    [&](const characteristics::DummyDataObject &object) {
+                      dummyDataAttr = object.cudaDataAttr;
+                    },
+                    [&](const auto &) {},
+                },
+      dummy.u);
+
+  if (!dummyDataAttr) {
+    if (!actualDataAttr) {
+      return 0;
+    } else if (*actualDataAttr == common::CUDADataAttr::Device) {
+      return std::numeric_limits<int>::max();
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klausler wrote:

This magic value might be more understandable as a named constant.

https://github.com/llvm/llvm-project/pull/90774