[flang] Added fir.dummy_scope operation to preserve dummy arguments association. (#90642)

The new operation is just an abstract attribute that is attached to
[hl]fir.declare operations of dummy arguments of a subroutine.
Dummy arguments of the same subroutine refer to the same
fir.dummy_scope, so they can be recognized as such during FIR AliasAnalysis.
Note that the fir.dummy_scope must be specific to the runtime
instantiation of a subroutine, so any MLIR inlining/cloning should duplicate and
unique it vs using the same fir.dummy_scope for different runtime instantiations.
This is why I made it an operation rather than an attribute.
The new operation uses a write effect on DebuggingResource, same as
[hl]fir.declare, to avoid optimizing it away.

1 files changed, 5 insertions, 4 deletions

diff --git a/flang/unittests/Optimizer/FortranVariableTest.cpp b/flang/unittests/Optimizer/FortranVariableTest.cpp
index 790f735..f5f559e 100644
--- a/flang/unittests/Optimizer/FortranVariableTest.cpp
+++ b/flang/unittests/Optimizer/FortranVariableTest.cpp
@@ -48,7 +48,8 @@ TEST_F(FortranVariableTest, SimpleScalar) {
   mlir::Value addr = builder->create<fir::AllocaOp>(loc, eleType);
   auto name = mlir::StringAttr::get(&context, "x");
   auto declare = builder->create<fir::DeclareOp>(loc, addr.getType(), addr,
-      /*shape=*/mlir::Value{}, /*typeParams=*/std::nullopt, name,
+      /*shape=*/mlir::Value{}, /*typeParams=*/std::nullopt,
+      /*dummy_scope=*/nullptr, name,
       /*fortran_attrs=*/fir::FortranVariableFlagsAttr{},
       /*cuda_attr=*/fir::CUDADataAttributeAttr{});
 
@@ -74,7 +75,7 @@ TEST_F(FortranVariableTest, CharacterScalar) {
       loc, eleType, /*pinned=*/false, typeParams);
   auto name = mlir::StringAttr::get(&context, "x");
   auto declare = builder->create<fir::DeclareOp>(loc, addr.getType(), addr,
-      /*shape=*/mlir::Value{}, typeParams, name,
+      /*shape=*/mlir::Value{}, typeParams, /*dummy_scope=*/nullptr, name,
       /*fortran_attrs=*/fir::FortranVariableFlagsAttr{},
       /*cuda_attr=*/fir::CUDADataAttributeAttr{});
 
@@ -105,7 +106,7 @@ TEST_F(FortranVariableTest, SimpleArray) {
   mlir::Value shape = createShape(extents);
   auto name = mlir::StringAttr::get(&context, "x");
   auto declare = builder->create<fir::DeclareOp>(loc, addr.getType(), addr,
-      shape, /*typeParams*/ std::nullopt, name,
+      shape, /*typeParams*/ std::nullopt, /*dummy_scope=*/nullptr, name,
       /*fortran_attrs=*/fir::FortranVariableFlagsAttr{},
       /*cuda_attr=*/fir::CUDADataAttributeAttr{});
 
@@ -136,7 +137,7 @@ TEST_F(FortranVariableTest, CharacterArray) {
   mlir::Value shape = createShape(extents);
   auto name = mlir::StringAttr::get(&context, "x");
   auto declare = builder->create<fir::DeclareOp>(loc, addr.getType(), addr,
-      shape, typeParams, name,
+      shape, typeParams, /*dummy_scope=*/nullptr, name,
       /*fortran_attrs=*/fir::FortranVariableFlagsAttr{},
       /*cuda_attr=*/fir::CUDADataAttributeAttr{});