[Flang] Fix ASSIGN statement

[ceseo]

Handle the case where the assigned variable also has a pointer attribute.

Fixes #121721

[llvmbot]

@llvm/pr-subscribers-flang-fir-hlfir

Author: Carlos Seo (ceseo)

Changes

Handle the case where the assigned variable also has a pointer attribute.

Fixes #121721

---

Full diff: https://github.com/llvm/llvm-project/pull/149941.diff

1 Files Affected:

• (modified) flang/lib/Lower/Bridge.cpp (+27-2)

diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 7ce397a11861b..243fda63d5e29 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -5506,10 +5506,35 @@ class FirConverter : public Fortran::lower::AbstractConverter {
   void genFIR(const Fortran::parser::AssignStmt &stmt) {
     const Fortran::semantics::Symbol &symbol =
         *std::get<Fortran::parser::Name>(stmt.t).symbol;
+
     mlir::Location loc = toLocation();
+    mlir::Type symbolType = genType(symbol);
+    mlir::Value addr = getSymbolAddress(symbol);
+
+    // Handle the case where the assigned variable is declared as a pointer
+    if (auto eleTy = fir::dyn_cast_ptrOrBoxEleTy(symbolType)) {
+      if (auto ptrType = mlir::dyn_cast<fir::PointerType>(eleTy)) {
+        symbolType = ptrType.getEleTy();
+      } else {
+        symbolType = eleTy;
+      }
+    }
+    else if (auto ptrType = mlir::dyn_cast<fir::PointerType>(symbolType)) {
+      symbolType = ptrType.getEleTy();
+    }
+
     mlir::Value labelValue = builder->createIntegerConstant(
-        loc, genType(symbol), std::get<Fortran::parser::Label>(stmt.t));
-    builder->create<fir::StoreOp>(loc, labelValue, getSymbolAddress(symbol));
+        loc, symbolType, std::get<Fortran::parser::Label>(stmt.t));
+
+    // If the address points to a boxed pointer, we need to dereference it
+    if (auto refType = mlir::dyn_cast<fir::ReferenceType>(addr.getType())) {
+      if (auto boxType = mlir::dyn_cast<fir::BoxType>(refType.getEleTy())) {
+        mlir::Value boxValue = builder->create<fir::LoadOp>(loc, addr);
+        addr = builder->create<fir::BoxAddrOp>(loc, boxValue);
+      }
+    }
+
+    builder->create<fir::StoreOp>(loc, labelValue, addr);
   }
 
   void genFIR(const Fortran::parser::FormatStmt &) {

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[tblah]

Thanks for the bugfix. Please could you add a lit test for this.

[tblah]

LGTM. Thanks for the fix

Edit: please could this be backported to the LLVM 21 release branch. There are instructions here