[flang-commits] [flang] [flang] Promote scalar slots reached through fir.convert and fir.declare (PR #219314)

[Vijay Kandiah via flang-commits]

================
@@ -2135,6 +2136,131 @@ llvm::LogicalResult fir::ConvertOp::verify() {
          << getValue().getType() << " / " << getType();
 }
 
+/// Pointee of a reference to a simple scalar, or null. Both fir.ref and rank-0
+/// memref qualify, since the storage of a scalar is cast between those forms.
+static mlir::Type getScalarSlotPointeeType(mlir::Type type) {
+  mlir::Type eleTy;
+  if (auto refTy = mlir::dyn_cast<fir::ReferenceType>(type)) {
+    eleTy = refTy.getEleTy();
+  } else if (auto memrefTy = mlir::dyn_cast<mlir::MemRefType>(type)) {
+    // A rank, layout or memory space lets the cast reinterpret the storage.
+    if (memrefTy.getRank() != 0 || !memrefTy.getLayout().isIdentity() ||
+        memrefTy.getMemorySpace())
+      return {};
+    eleTy = memrefTy.getElementType();
+  } else {
+    return {};
+  }
+  if (!mlir::isa<mlir::IntegerType, mlir::FloatType, mlir::ComplexType,
+                 fir::LogicalType>(eleTy))
+    return {};
+  return eleTy;
+}
+
+/// The value a cast or declare aliases, or null if `value` is not one of those.
+static mlir::Value getAliasedSlotPointer(mlir::Value value) {
+  mlir::Operation *def = value.getDefiningOp();
+  if (auto convert = mlir::dyn_cast_or_null<fir::ConvertOp>(def))
----------------
VijayKandiah wrote:

Done! Both checks now go through `fir::FortranObjectViewOpInterface` with a `getViewOffset(result) == 0` requirement. `fir.volatile_cast` is included and keeps the storage in memory as it does not have either of the promotable interfaces

https://github.com/llvm/llvm-project/pull/219314