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[flang] Deallocate structure constructor allocatable components #83824

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Merged
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Mar 5, 2024
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[flang] Deallocate structure constructor allocatable components #83824

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15 changes: 15 additions & 0 deletions flang/docs/Extensions.md
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Expand Up @@ -706,6 +706,21 @@ end
`INDEX` include an optional `BACK=` argument, but it doesn't actually
work.

* Allocatable components of array and structure constructors are deallocated
after use without calling final subroutines.
The standard does not specify when and how deallocation of array and structure
constructors allocatable components should happen. All compilers free the
memory after use, but the behavior when the allocatable component is a derived
type with finalization differ, especially when dealing with nested array and
structure constructors expressions. Some compilers call final routine for the
allocatable components of each constructor sub-expressions, some call it only
for the allocatable component of the top level constructor, and some only
deallocate the memory. Deallocating only the memory offers the most
flexibility when lowering such expressions, and it is not clear finalization
is desirable in such context (Fortran interop 1.6.2 in F2018 standards require
array and structure constructors not to be finalized, so it also makes sense
not to finalize their allocatable components when releasing their storage).

## De Facto Standard Features

* `EXTENDS_TYPE_OF()` returns `.TRUE.` if both of its arguments have the
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10 changes: 10 additions & 0 deletions flang/lib/Lower/ConvertExprToHLFIR.cpp
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Expand Up @@ -1844,6 +1844,16 @@ class HlfirBuilder {
builder.genIfThen(loc, isAlloc).genThen(genAssign).end();
}

if (fir::isRecordWithAllocatableMember(recTy)) {
// Deallocate allocatable components without calling final subroutines.
// The Fortran 2018 section 9.7.3.2 about deallocation is not ruling
// about the fate of allocatable components of structure constructors,
// and there is no behavior consensus in other compilers.
fir::FirOpBuilder *bldr = &builder;
getStmtCtx().attachCleanup([=]() {
fir::runtime::genDerivedTypeDestroyWithoutFinalization(*bldr, loc, box);
});
}
return varOp;
}

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12 changes: 12 additions & 0 deletions flang/test/Lower/HLFIR/structure-constructor.f90
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Expand Up @@ -161,6 +161,8 @@ end subroutine test4
! CHECK: hlfir.assign %[[VAL_26]] to %[[VAL_20]] realloc keep_lhs_len temporary_lhs : !fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>, !fir.ref<!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>>
! CHECK: }
! CHECK: hlfir.assign %[[VAL_12]]#0 to %[[VAL_3]]#0 : !fir.ref<!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>, !fir.ref<!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>
! CHECK: %[[VAL_27:.*]] = fir.convert %[[VAL_13]] : (!fir.box<!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_27]]
! CHECK: return
! CHECK: }

Expand Down Expand Up @@ -201,6 +203,8 @@ end subroutine test5
! CHECK: hlfir.assign %[[VAL_24]] to %[[VAL_18]] realloc temporary_lhs : !fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>, !fir.ref<!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>>
! CHECK: }
! CHECK: hlfir.assign %[[VAL_11]]#0 to %[[VAL_3]]#0 : !fir.ref<!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>>, !fir.ref<!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>>
! CHECK: %[[VAL_24:.*]] = fir.convert %[[VAL_12]] : (!fir.box<!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_24]]
! CHECK: return
! CHECK: }

Expand Down Expand Up @@ -291,6 +295,10 @@ end subroutine test6
! CHECK: %[[VAL_70:.*]] = hlfir.as_expr %[[VAL_48]]#0 move %[[VAL_69]] : (!fir.heap<!fir.array<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>>, i1) -> !hlfir.expr<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>
! CHECK: hlfir.assign %[[VAL_70]] to %[[VAL_44]] temporary_lhs : !hlfir.expr<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>, !fir.ref<!fir.array<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>>
! CHECK: hlfir.assign %[[VAL_20]]#0 to %[[VAL_12]]#0 : !fir.ref<!fir.type<_QMtypesTt6{t5:!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>,t6m:!fir.array<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>}>>, !fir.ref<!fir.type<_QMtypesTt6{t5:!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>,t6m:!fir.array<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>}>>
! CHECK: %[[VAL_71:.*]] = fir.convert %[[VAL_21]] : (!fir.box<!fir.type<_QMtypesTt6{t5:!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>,t6m:!fir.array<1x!fir.type<_QMtypesTt1{c:!fir.char<1,4>}>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_71]]
! CHECK: %[[VAL_72:.*]] = fir.convert %[[VAL_29]] : (!fir.box<!fir.type<_QMtypesTt5{t5m:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMtypesTt4{c:!fir.box<!fir.heap<!fir.array<?x!fir.char<1,2>>>>}>>>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_72]]
! CHECK: return
! CHECK: }

Expand Down Expand Up @@ -375,6 +383,8 @@ end subroutine test8
! CHECK: hlfir.assign %[[VAL_29]] to %[[VAL_22]] realloc keep_lhs_len temporary_lhs : !fir.heap<!fir.char<1,12>>, !fir.ref<!fir.box<!fir.heap<!fir.char<1,11>>>>
! CHECK: }
! CHECK: hlfir.assign %[[VAL_14]]#0 to %[[VAL_2]]#0 : !fir.ref<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>, !fir.ref<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>
! CHECK: %[[VAL_30:.*]] = fir.convert %[[VAL_15]] : (!fir.box<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_30]]
! CHECK: return
! CHECK: }

Expand Down Expand Up @@ -410,6 +420,8 @@ end subroutine test9
! CHECK: %[[VAL_20:.*]] = hlfir.designate %[[VAL_12]]#0{"c"} typeparams %[[VAL_19]] {fortran_attrs = #fir.var_attrs<allocatable>} : (!fir.ref<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>, index) -> !fir.ref<!fir.box<!fir.heap<!fir.char<1,11>>>>
! CHECK: hlfir.assign %[[VAL_11]]#0 to %[[VAL_20]] realloc keep_lhs_len temporary_lhs : !fir.ref<!fir.char<1,12>>, !fir.ref<!fir.box<!fir.heap<!fir.char<1,11>>>>
! CHECK: hlfir.assign %[[VAL_12]]#0 to %[[VAL_2]]#0 : !fir.ref<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>, !fir.ref<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>
! CHECK: %[[VAL_21:.*]] = fir.convert %[[VAL_13]] : (!fir.box<!fir.type<_QMtypesTt8{c:!fir.box<!fir.heap<!fir.char<1,11>>>}>>) -> !fir.box<none>
! CHECK: fir.call @_FortranADestroyWithoutFinalization(%[[VAL_21]]
! CHECK: return
! CHECK: }

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