[flang] Do not leave length parameters uninitialized in descriptor addendums #81858
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Descriptor addendum have a field to hold length parameters (currently only one). This field is currently never used because flang does not lowered derived types with length parameters. However, leaving it uninitialized is causing bugs in code like gFTK where the code is trying to sort POINTERs [1]. More precisely, it is an issue when two pointers should compare equal (same base address), because the uninitialized values in the addendum may differ depending on the "stack history" and optimization level. Always initialized the fields to zero. [1]: https://github.com/Goddard-Fortran-Ecosystem/gFTL/blob/dc93a5fc2fe2b487590580d9f0a17d77ca3fe5c1/include/v1/templates/set_impl.inc#L312 The type being transferred to an integer array may look like: TYPE :: localwrapper TYPE(T), POINTER :: item END TYPE localwrapper Which in flang case ends-up transferring a descriptor to an integer array.
llvmbot
added
flang
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@llvm/pr-subscribers-flang-fir-hlfir @llvm/pr-subscribers-flang-codegen Author: None (jeanPerier) ChangesDescriptor addendum have a field to hold length parameters (currently only one). This field is currently never used because flang does not lowered derived types with length parameters. However, leaving it uninitialized is causing bugs in code like gFTK where the code is trying to sort POINTERs (see 1). More precisely, it is an issue when two pointers should compare equal (same base address), because the uninitialized values in the addendum may differ depending on the "stack history" and optimization level. Always initialized the length parameters field in the addendum to zero. The type being transferred to an integer array may look like: Which in flang case ends-up transferring a descriptor to an integer array, the code in gFTK later compare the integer arrays. This logic is used when building set data structures in gFTK. Full diff: https://github.com/llvm/llvm-project/pull/81858.diff 7 Files Affected:
diff --git a/flang/include/flang/Runtime/descriptor.h b/flang/include/flang/Runtime/descriptor.h
index 38ab4155735976..7ad548d6c72b44 100644
--- a/flang/include/flang/Runtime/descriptor.h
+++ b/flang/include/flang/Runtime/descriptor.h
@@ -99,7 +99,7 @@ class DescriptorAddendum {
public:
explicit RT_API_ATTRS DescriptorAddendum(
const typeInfo::DerivedType *dt = nullptr)
- : derivedType_{dt} {}
+ : derivedType_{dt}, len_{0} {}
RT_API_ATTRS DescriptorAddendum &operator=(const DescriptorAddendum &);
const RT_API_ATTRS typeInfo::DerivedType *derivedType() const {
diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index f89f28c006dece..7fdf39a1af731c 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -147,6 +147,9 @@ static unsigned getTypeDescFieldId(mlir::Type ty) {
auto isArray = fir::dyn_cast_ptrOrBoxEleTy(ty).isa<fir::SequenceType>();
return isArray ? kOptTypePtrPosInBox : kDimsPosInBox;
}
+static unsigned getLenParamFieldId(mlir::Type ty) {
+ return getTypeDescFieldId(ty) + 1;
+}
namespace {
/// FIR conversion pattern template
@@ -1583,6 +1586,14 @@ struct EmboxCommonConversion : public FIROpConversion<OP> {
descriptor =
insertField(rewriter, loc, descriptor, {typeDescFieldId}, typeDesc,
/*bitCast=*/true);
+ // Always initialize the length parameter field to zero to avoid issues
+ // with uninitialized values in Fortran code trying to compare physical
+ // representation of derived types with pointer/allocatable components.
+ // This has been seen in hashing algorithms using TRANSFER.
+ mlir::Value zero =
+ genConstantIndex(loc, rewriter.getI64Type(), rewriter, 0);
+ descriptor = insertField(rewriter, loc, descriptor,
+ {getLenParamFieldId(boxTy), 0}, zero);
}
return descriptor;
}
diff --git a/flang/test/Fir/ignore-missing-type-descriptor.fir b/flang/test/Fir/ignore-missing-type-descriptor.fir
index f55ea1238e47b9..e83c8d684f8910 100644
--- a/flang/test/Fir/ignore-missing-type-descriptor.fir
+++ b/flang/test/Fir/ignore-missing-type-descriptor.fir
@@ -18,5 +18,5 @@ func.func @test_embox(%addr: !fir.ref<!some_freestyle_type>) {
// CHECK-SAME: ptr %[[ADDR:.*]])
// CHECK: insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
// CHECK-SAME: { ptr undef, i64 ptrtoint (ptr getelementptr (%some_not_mangled_type, ptr null, i32 1) to i64),
-// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr null, [1 x i64] undef },
+// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr null, [1 x i64] zeroinitializer },
// CHECK-SAME: ptr %[[ADDR]], 0
diff --git a/flang/test/Fir/polymorphic.fir b/flang/test/Fir/polymorphic.fir
index ecdcdeb5753106..fc891c32acc952 100644
--- a/flang/test/Fir/polymorphic.fir
+++ b/flang/test/Fir/polymorphic.fir
@@ -13,7 +13,7 @@ func.func @_QMpolymorphic_testPtest_allocate_unlimited_polymorphic_non_derived()
// CHECK-LABEL: define void @_QMpolymorphic_testPtest_allocate_unlimited_polymorphic_non_derived(){{.*}}{
// CHECK: %[[MEM:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
// CHECK: %[[DESC:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, i64 1
-// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr null, i64 0, i32 20180515, i8 0, i8 -1, i8 1, i8 1, ptr null, [1 x i64] undef }, ptr %[[MEM]]
+// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr null, i64 0, i32 20180515, i8 0, i8 -1, i8 1, i8 1, ptr null, [1 x i64] zeroinitializer }, ptr %[[MEM]]
// CHECK: %[[LOADED:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %[[MEM]], align 8
// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOADED]], ptr %[[DESC]]
// CHECK: ret void
@@ -100,7 +100,8 @@ func.func @_QMunlimitedPsub1(%arg0: !fir.class<!fir.array<?xnone>> {fir.bindc_na
// CHECK: %[[TYPE_CODE_TRUNC:.*]] = trunc i32 %[[TYPE_CODE]] to i8
// CHECK: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, i8 %[[TYPE_CODE_TRUNC]], 4
// CHECK: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, ptr %[[TYPE_DESC]], 7
-// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %24, ptr %[[BOX]]
+// CHECK: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, i64 0, 8, 0
+// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %{{.*}}, ptr %[[BOX]]
fir.global internal @_QFEx : !fir.class<!fir.ptr<!fir.array<?xnone>>> {
@@ -154,7 +155,7 @@ func.func @_QQmain() {
// CHECK-LABEL: define void @_QQmain(){{.*}}{
// CHECK: %[[CLASS_NONE:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
// CHECK: %[[DESC:.*]] = alloca { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, i64 1
-// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr @_QMmod1Ea, i64 ptrtoint (ptr getelementptr (%_QMmod1TtK2, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 1, i8 1, ptr @_QMmod1E.dt.t.2, [1 x i64] undef }, ptr %[[CLASS_NONE]], align 8
+// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr @_QMmod1Ea, i64 ptrtoint (ptr getelementptr (%_QMmod1TtK2, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 1, i8 1, ptr @_QMmod1E.dt.t.2, [1 x i64] zeroinitializer }, ptr %[[CLASS_NONE]], align 8
// CHECK: %[[LOAD:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %[[CLASS_NONE]]
// CHECK: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOAD]], ptr %[[DESC]]
// CHECK: call void @_QMmod1Psub1(ptr %[[DESC]])
@@ -194,4 +195,4 @@ func.func @_QQembox_input_type(%arg0 : !fir.ref<!fir.type<_QMmod1Tp2{v:!fir.arra
}
// CHECK-LABEL: define void @_QQembox_input_type
-// CHECK: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr undef, i64 ptrtoint (ptr getelementptr (%_QMmod1Tp2, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr @_QMmod1E.dt.p2, [1 x i64] undef }, ptr %{{.*}}, 0
+// CHECK: %{{.*}} = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr undef, i64 ptrtoint (ptr getelementptr (%_QMmod1Tp2, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 0, i8 1, ptr @_QMmod1E.dt.p2, [1 x i64] zeroinitializer }, ptr %{{.*}}, 0
diff --git a/flang/test/Fir/tbaa.fir b/flang/test/Fir/tbaa.fir
index 4474bbbe3dd747..048f53f5c6e47a 100644
--- a/flang/test/Fir/tbaa.fir
+++ b/flang/test/Fir/tbaa.fir
@@ -67,7 +67,8 @@ module {
// CHECK: %[[VAL_36:.*]] = llvm.mlir.constant(1 : i32) : i32
// CHECK: %[[VAL_37:.*]] = llvm.trunc %[[VAL_36]] : i32 to i8
// CHECK: %[[VAL_38:.*]] = llvm.insertvalue %[[VAL_37]], %[[VAL_35]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
-// CHECK: %[[VAL_40:.*]] = llvm.insertvalue %[[VAL_19]], %[[VAL_38]][7] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_40B:.*]] = llvm.insertvalue %[[VAL_19]], %[[VAL_38]][7] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_40:.*]] = llvm.insertvalue %{{.*}}, %[[VAL_40B]][8, 0] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
// CHECK: %[[VAL_42:.*]] = llvm.insertvalue %[[VAL_14]], %[[VAL_40]][0] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
// CHECK: llvm.store %[[VAL_42]], %[[VAL_2]] {tbaa = [#[[$BOXT]]]} : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>, !llvm.ptr
// CHECK: %[[VAL_43:.*]] = llvm.getelementptr %[[VAL_2]][0, 4] : (!llvm.ptr) -> !llvm.ptr, !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, ptr, array<1 x i64>)>
@@ -166,7 +167,8 @@ module {
// CHECK: %[[VAL_40:.*]] = llvm.mlir.constant(1 : i32) : i32
// CHECK: %[[VAL_41:.*]] = llvm.trunc %[[VAL_40]] : i32 to i8
// CHECK: %[[VAL_42:.*]] = llvm.insertvalue %[[VAL_41]], %[[VAL_39]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
-// CHECK: %[[VAL_44:.*]] = llvm.insertvalue %[[VAL_27]], %[[VAL_42]][8] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_44B:.*]] = llvm.insertvalue %[[VAL_27]], %[[VAL_42]][8] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_44:.*]] = llvm.insertvalue %{{.*}}, %[[VAL_44B]][9, 0] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
// CHECK: %[[VAL_45:.*]] = llvm.getelementptr %[[VAL_3]][0, 7, 0, 0] : (!llvm.ptr) -> !llvm.ptr, !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
// CHECK: %[[VAL_46:.*]] = llvm.load %[[VAL_45]] {tbaa = [#[[$BOXT]]]} : !llvm.ptr -> i64
// CHECK: %[[VAL_47:.*]] = llvm.getelementptr %[[VAL_3]][0, 7, 0, 1] : (!llvm.ptr) -> !llvm.ptr, !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
@@ -218,7 +220,8 @@ module {
// CHECK: %[[VAL_17:.*]] = llvm.trunc %[[VAL_16]] : i32 to i8
// CHECK: %[[VAL_18:.*]] = llvm.insertvalue %[[VAL_17]], %[[VAL_15]][6] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
// CHECK: %[[VAL_19:.*]] = llvm.mlir.zero : !llvm.ptr
-// CHECK: %[[VAL_21:.*]] = llvm.insertvalue %[[VAL_19]], %[[VAL_18]][8] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_21B:.*]] = llvm.insertvalue %[[VAL_19]], %[[VAL_18]][8] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
+// CHECK: %[[VAL_21:.*]] = llvm.insertvalue %{{.*}}, %[[VAL_21B]][9, 0] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
// CHECK: %[[VAL_22:.*]] = llvm.mlir.constant(0 : i64) : i64
// CHECK: %[[VAL_23:.*]] = llvm.mlir.constant(1 : i64) : i64
// CHECK: %[[VAL_24:.*]] = llvm.insertvalue %[[VAL_23]], %[[VAL_21]][7, 0, 0] : !llvm.struct<(ptr, i64, i32, i8, i8, i8, i8, array<1 x array<3 x i64>>, ptr, array<1 x i64>)>
diff --git a/flang/test/Fir/type-descriptor.fir b/flang/test/Fir/type-descriptor.fir
index c5362090e659fa..6551efe1a5febc 100644
--- a/flang/test/Fir/type-descriptor.fir
+++ b/flang/test/Fir/type-descriptor.fir
@@ -14,7 +14,7 @@ fir.global internal @_QFfooEx : !fir.box<!fir.heap<!sometype>> {
}
// CHECK: @_QFfooEx = internal global { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
// CHECK-SAME: { ptr null, i64 ptrtoint (ptr getelementptr (%_QFfooTsometype, ptr null, i32 1) to i64),
-// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QFfooE.dt.sometype, [1 x i64] undef }
+// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QFfooE.dt.sometype, [1 x i64] zeroinitializer }
!some_pdt_type = !fir.type<_QFfooTsome_pdt_typeK42K43{num:i32,values:!fir.box<!fir.ptr<!fir.array<?x?xf32>>>}>
fir.global internal @_QFfooE.dt.some_pdt_type.42.43 constant : i8
@@ -26,4 +26,4 @@ fir.global internal @_QFfooEx2 : !fir.box<!fir.heap<!some_pdt_type>> {
}
// CHECK: @_QFfooEx2 = internal global { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }
// CHECK-SAME: { ptr null, i64 ptrtoint (ptr getelementptr (%_QFfooTsome_pdt_typeK42K43, ptr null, i32 1) to i64),
-// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QFfooE.dt.some_pdt_type.42.43, [1 x i64] undef }
+// CHECK-SAME: i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QFfooE.dt.some_pdt_type.42.43, [1 x i64] zeroinitializer }
diff --git a/flang/test/Lower/allocatable-polymorphic.f90 b/flang/test/Lower/allocatable-polymorphic.f90
index f4302144310f74..6ba0b13b24b6c4 100644
--- a/flang/test/Lower/allocatable-polymorphic.f90
+++ b/flang/test/Lower/allocatable-polymorphic.f90
@@ -649,7 +649,8 @@ program test_alloc
! LLVM: %[[BOX3:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX2]], i8 %[[TYPE_CODE_TRUNC]], 4
! LLVM: %[[BOX4:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX3]], i8 0, 5
! LLVM: %[[BOX5:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX4]], i8 1, 6
-! LLVM: %[[BOX6:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX5]], ptr %[[TDESC_C3]], 7
+! LLVM: %[[BOX6A:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX5]], ptr %[[TDESC_C3]], 7
+! LLVM: %[[BOX6:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX6A]], i64 0, 8, 0
! LLVM: %[[BOX7:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX6]], ptr %{{.*}}, 0
! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX7]], ptr %{{.*}}
! LLVM: call void %{{.*}}(ptr %{{.*}})
@@ -669,7 +670,8 @@ program test_alloc
! LLVM: %[[BOX3:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX2]], i8 %[[TYPE_CODE_TRUNC]], 4
! LLVM: %[[BOX4:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX3]], i8 0, 5
! LLVM: %[[BOX5:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX4]], i8 1, 6
-! LLVM: %[[BOX6:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX5]], ptr %[[TDESC_C4]], 7
+! LLVM: %[[BOX6A:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX5]], ptr %[[TDESC_C4]], 7
+! LLVM: %[[BOX6:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX6A]], i64 0, 8, 0
! LLVM: %[[BOX7:.*]] = insertvalue { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX6]], ptr %{{.*}}, 0
! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[BOX7]], ptr %{{.*}}
! LLVM: call void %{{.*}}(ptr %{{.*}})
@@ -679,7 +681,7 @@ program test_alloc
! allocatable.
! LLVM-LABEL: define void @_QMpolyPtest_deallocate()
-! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr null, i64 ptrtoint (ptr getelementptr (%_QMpolyTp1, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QMpolyE.dt.p1, [1 x i64] undef }, ptr %[[ALLOCA1:[0-9]*]]
+! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } { ptr null, i64 ptrtoint (ptr getelementptr (%_QMpolyTp1, ptr null, i32 1) to i64), i32 20180515, i8 0, i8 42, i8 2, i8 1, ptr @_QMpolyE.dt.p1, [1 x i64] zeroinitializer }, ptr %[[ALLOCA1:[0-9]*]]
! LLVM: %[[LOAD:.*]] = load { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] }, ptr %[[ALLOCA1]]
! LLVM: store { ptr, i64, i32, i8, i8, i8, i8, ptr, [1 x i64] } %[[LOAD]], ptr %[[ALLOCA2:[0-9]*]]
! LLVM: %{{.*}} = call {} @_FortranAAllocatableInitDerivedForAllocate(ptr %[[ALLOCA2]], ptr @_QMpolyE.dt.p1, i32 0, i32 0)
|
klausler
reviewed
Feb 20, 2024
| @@ -99,7 +99,7 @@ class DescriptorAddendum { | |||
| public: | |||
| explicit RT_API_ATTRS DescriptorAddendum( | |||
| const typeInfo::DerivedType *dt = nullptr) | |||
| : derivedType_{dt} {} | |||
| : derivedType_{dt}, len_{0} {} | |||
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Can this initializer be placed instead on the component declaration? That's slightly better coding practice.
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Descriptor addendum have a field to hold length parameters (currently only one). This field is currently never used because flang does not lowered derived types with length parameters.
However, leaving it uninitialized is causing bugs in code like gFTL where the code is trying to sort POINTERs (see 1). More precisely, it is an issue when two pointers should compare equal (same base address), because the uninitialized values in the addendum may differ depending on the "stack history" and optimization level.
Always initialized the length parameters field in the addendum to zero.
The type being transferred to an integer array may look like:
Which in flang case ends-up transferring a descriptor to an integer array, the code in gFTL later compare the integer arrays. This logic is used when building set data structures in gFTL.