[flang-commits] [flang] [Flang] Implement RENAME intrinsic (code-gen + runtime entry point) (PR #98359)

[Tom Eccles via flang-commits]

================
@@ -5911,6 +5917,37 @@ IntrinsicLibrary::genReduce(mlir::Type resultType,
   return readAndAddCleanUp(resultMutableBox, resultType, "REDUCE");
 }
 
+// RENAME
+fir::ExtendedValue
+IntrinsicLibrary::genRename(std::optional<mlir::Type> resultType,
+                            mlir::ArrayRef<fir::ExtendedValue> args) {
+  assert((args.size() == 3 && !resultType.has_value()) ||
+         (args.size() == 2 && resultType.has_value()));
+
+  mlir::Value path1 = fir::getBase(args[0]);
+  mlir::Value path2 = fir::getBase(args[1]);
+  if (!path1 || !path2)
+    fir::emitFatalError(loc, "Expected at least two dummy arguments");
+
+  if (resultType.has_value()) {
+    // code-gen for the function form of RENAME
+    auto statusAddr = builder.createTemporary(loc, *resultType);
+    auto statusBox = builder.createBox(loc, statusAddr);
+    fir::runtime::genRename(builder, loc, path1, path2, statusBox);
+    return builder.create<fir::LoadOp>(loc, statusAddr);
+  } else {
+    // code-gen for the procedure form of RENAME
+    mlir::Type boxNoneTy = fir::BoxType::get(builder.getNoneType());
+    auto status = args[2];
+    mlir::Value statusBox =
+        isStaticallyPresent(status)
+            ? fir::getBase(status)
+            : builder.create<fir::AbsentOp>(loc, boxNoneTy).getResult();
----------------
tblah wrote:

Earlier you defined the intrinsic as supporting a dynamically optional argument. To support this you will also need a runtime check for something like this

```
subroutine doRename(status)
  integer, optional :: status
  call rename("old", "new", status)
end subroutine
```

Here we cannot determine statically whether `status` is present, but if it is present it should be used. I think the current code would treat it as absent. For example, see the implementation of C_ASSOCIATED in this file.

https://github.com/llvm/llvm-project/pull/98359