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[flang][debug] Add debug type support for procedure pointers #166764

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Nov 6, 2025
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[flang][debug] Add debug type support for procedure pointers #166764

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[flang][debug] Add debug type support for procedure pointers
abidh Nov 6, 2025
7d757d7
Handle review comments.
abidh Nov 6, 2025
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25 changes: 25 additions & 0 deletions flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
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Expand Up @@ -718,6 +718,31 @@ DebugTypeGenerator::convertType(mlir::Type Ty, mlir::LLVM::DIFileAttr fileAttr,
return convertRecordType(recTy, fileAttr, scope, declOp);
} else if (auto tupleTy = mlir::dyn_cast_if_present<mlir::TupleType>(Ty)) {
return convertTupleType(tupleTy, fileAttr, scope, declOp);
} else if (mlir::isa<mlir::FunctionType>(Ty)) {
// Handle function types - these represent procedure pointers after the
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@jeanPerier jeanPerier Nov 6, 2025

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nit: I think dummy procedures will also fall here now when converting function types with dummy procedure arguments (flang only gives them the () -> () type because they are usually implicitly typed, but with your fix they should at least appear as function address in the debug info now).

All that to say I would just add a mention to dummy procedures to this comment (and maybe a test).

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@abidh abidh Nov 6, 2025

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I have added a comment. I was trying to add a test but noticed that somehow DeclareOp is not being generated for the dummy procedure. I will investigate that separately.

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@jeanPerier jeanPerier Nov 6, 2025

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Yes it is not because as far as lowering is concerned, it is not a variable/entity. But I imagine debug info needs to map the name. I agree this is out of the scope of your PR.

With your change, at least the debug type for the procedure with debug argument should be correct now.

subroutine foo(bar)
  external :: bar
end subroutine

was:

!4 = distinct !DISubprogram(name: "foo", linkageName: "foo_", scope: !1, file: !1, line: 1, type: !5, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0)
!5 = !DISubroutineType(cc: DW_CC_normal, types: !6)
!6 = !{null, !7}
!7 = !DIBasicType(name: "integer", size: 32, encoding: DW_ATE_signed)

and I think your patch is fixing !7

// BoxedProcedure pass has run and unwrapped the fir.boxproc type, as well
// as dummy procedures (which are represented as function types in FIR)
llvm::SmallVector<mlir::LLVM::DITypeAttr> types;

auto funcTy = mlir::cast<mlir::FunctionType>(Ty);
// Add return type (or void if no return type)
if (funcTy.getNumResults() == 0)
types.push_back(mlir::LLVM::DINullTypeAttr::get(context));
else
types.push_back(
convertType(funcTy.getResult(0), fileAttr, scope, declOp));

for (mlir::Type paramTy : funcTy.getInputs())
types.push_back(convertType(paramTy, fileAttr, scope, declOp));

auto subroutineTy = mlir::LLVM::DISubroutineTypeAttr::get(
context, /*callingConvention=*/0, types);

return mlir::LLVM::DIDerivedTypeAttr::get(
context, llvm::dwarf::DW_TAG_pointer_type,
mlir::StringAttr::get(context, ""), subroutineTy,
/*sizeInBits=*/ptrSize * 8, /*alignInBits=*/0, /*offset=*/0,
/*optional<address space>=*/std::nullopt, /*extra data=*/nullptr);
} else if (auto refTy = mlir::dyn_cast_if_present<fir::ReferenceType>(Ty)) {
auto elTy = refTy.getEleTy();
return convertPointerLikeType(elTy, fileAttr, scope, declOp,
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26 changes: 26 additions & 0 deletions flang/test/Integration/debug-proc-ptr-e2e.f90
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@@ -0,0 +1,26 @@
! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck %s
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@jeanPerier jeanPerier Nov 6, 2025

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Please move this test in the test/Integration folder next to the other debug test using -emit-llvm.

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@abidh abidh Nov 6, 2025

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Thanks. I somehow failed to see this. Fixed now.


program test_proc_ptr
implicit none
procedure(fun1), pointer :: fun_ptr

fun_ptr => fun1
print *, fun_ptr(3)

contains
integer function fun1(x)
integer :: x
fun1 = x + 1
end function fun1
end program test_proc_ptr

! Check that fun_ptr is declared with correct type
! CHECK-DAG: ![[INT:.*]] = !DIBasicType(name: "integer", size: 32, encoding: DW_ATE_signed)
! CHECK-DAG: ![[PTR_INT:.*]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[INT]], size: 64)

! Check that fun_ptr variable is a pointer to a subroutine type
! The order is: DILocalVariable -> pointer type -> subroutine type -> {return, params}
! CHECK-DAG: ![[FUN_PTR_VAR:.*]] = !DILocalVariable(name: "fun_ptr", {{.*}}type: ![[PROC_PTR:[0-9]+]]
! CHECK-DAG: ![[PROC_PTR]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[SUBR_TYPE:[0-9]+]], size: 64)
! CHECK-DAG: ![[SUBR_TYPE]] = !DISubroutineType(types: ![[SUBR_TYPES:[0-9]+]])
! CHECK-DAG: ![[SUBR_TYPES]] = !{![[INT]], ![[PTR_INT]]}
41 changes: 41 additions & 0 deletions flang/test/Transforms/debug-proc-ptr.fir
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@@ -0,0 +1,41 @@
// RUN: fir-opt --add-debug-info --mlir-print-debuginfo %s | FileCheck %s

module {
func.func @_QQmain() attributes {fir.bindc_name = "test"} {
%0 = fir.alloca (!fir.ref<i32>) -> i32 {bindc_name = "fun_ptr", uniq_name = "_QFEfun_ptr"}
%1 = fircg.ext_declare %0 {uniq_name = "_QFEfun_ptr"} : (!fir.ref<(!fir.ref<i32>) -> i32>) -> !fir.ref<(!fir.ref<i32>) -> i32> loc(#loc1)

// Procedure pointer with no return: procedure(sub1), pointer :: sub_ptr
%2 = fir.alloca () -> () {bindc_name = "sub_ptr", uniq_name = "_QFEsub_ptr"}
%3 = fircg.ext_declare %2 {uniq_name = "_QFEsub_ptr"} : (!fir.ref<() -> ()>) -> !fir.ref<() -> ()> loc(#loc2)

// Procedure pointer with multiple args: procedure(func2), pointer :: func_ptr
%4 = fir.alloca (!fir.ref<i32>, !fir.ref<f64>) -> f32 {bindc_name = "func_ptr", uniq_name = "_QFEfunc_ptr"}
%5 = fircg.ext_declare %4 {uniq_name = "_QFEfunc_ptr"} : (!fir.ref<(!fir.ref<i32>, !fir.ref<f64>) -> f32>) -> !fir.ref<(!fir.ref<i32>, !fir.ref<f64>) -> f32> loc(#loc3)

return
} loc(#loc)
}
#loc = loc("test.f90":1:1)
#loc1 = loc("test.f90":2:30)
#loc2 = loc("test.f90":3:30)
#loc3 = loc("test.f90":4:30)

// CHECK-DAG: #[[INT:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "integer", sizeInBits = 32, encoding = DW_ATE_signed>
// CHECK-DAG: #[[REAL32:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "real", sizeInBits = 32, encoding = DW_ATE_float>
// CHECK-DAG: #[[REAL:.*]] = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "real(kind=8)", sizeInBits = 64, encoding = DW_ATE_float>

// CHECK-DAG: #[[PTR_INT:.*]] = #llvm.di_derived_type<tag = DW_TAG_pointer_type{{.*}}baseType = #[[INT]]{{.*}}>
// CHECK-DAG: #[[PTR_REAL:.*]] = #llvm.di_derived_type<tag = DW_TAG_pointer_type{{.*}}baseType = #[[REAL]]{{.*}}>

// CHECK-DAG: #[[SUB1:.*]] = #llvm.di_subroutine_type<types = #[[INT]], #[[PTR_INT]]>
// CHECK-DAG: #[[PTR_SUB1:.*]] = #llvm.di_derived_type<tag = DW_TAG_pointer_type{{.*}}baseType = #[[SUB1]]{{.*}}>
// CHECK-DAG: #llvm.di_local_variable<{{.*}}name = "fun_ptr"{{.*}}type = #[[PTR_SUB1]]{{.*}}>

// CHECK-DAG: #di_subroutine_type{{.*}} = #llvm.di_subroutine_type<types = #di_null_type>
// CHECK-DAG: #di_local_variable{{.*}} = #llvm.di_local_variable<{{.*}}name = "sub_ptr"{{.*}}type = #di_derived_type{{.*}}>
// CHECK-DAG: #di_derived_type{{.*}} = #llvm.di_derived_type<tag = DW_TAG_pointer_type{{.*}}baseType = #di_subroutine_type{{.*}}{{.*}}>

// CHECK-DAG: #[[SUB3:.*]] = #llvm.di_subroutine_type<types = #[[REAL32]], #[[PTR_INT]], #[[PTR_REAL]]>
// CHECK-DAG: #[[PTR_SUB3:.*]] = #llvm.di_derived_type<tag = DW_TAG_pointer_type{{.*}}baseType = #[[SUB3]]{{.*}}>
// CHECK-DAG: #llvm.di_local_variable<{{.*}}name = "func_ptr"{{.*}}type = #[[PTR_SUB3]]{{.*}}>
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