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[flang] Allow OpenMP declarations before type declarations #112414

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30 changes: 28 additions & 2 deletions flang/lib/Semantics/resolve-names.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -720,6 +720,7 @@ class ScopeHandler : public ImplicitRulesVisitor {

bool inSpecificationPart_{false};
bool deferImplicitTyping_{false};
bool skipImplicitTyping_{false};
bool inEquivalenceStmt_{false};

// Some information is collected from a specification part for deferred
Expand Down Expand Up @@ -758,6 +759,10 @@ class ScopeHandler : public ImplicitRulesVisitor {
}
}

void SkipImplicitTyping(bool skip) {
deferImplicitTyping_ = skipImplicitTyping_ = skip;
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Why does deferImplicitTyping_ need to be set here? What is the difference between defer and skip?

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When deferImplicitTyping_ is set, checks for explicit types in contexts that require it (e.g. implicit none) are performed later. Not setting it would result in errors, as in the following example:

implicit none
save :: x1
!$omp threadprivate(x1)
integer :: x1

error: No explicit type declared for 'x1'

This happens because there is a data reference to x1, in !$omp threadprivate(x1), which in other cases would require its explicit type to have already been specified.

The skipImplicitTyping_ flag handles another case. The idea is that it skips setting implicit types. Even when deferImplicitTyping_ is set, the implicit type of an entity is set when it is referenced, as in the example above. The problem is that, if the type that is declared after the reference doesn't match the previous implicit type, an error is reported.
In the example above, with skipImplicitTyping_ = false, x1 type is set to real in the threadprivate line, which doesn't match the integer type specified later.

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Thank you for explaining!

}

private:
Scope *currScope_{nullptr};
FuncResultStack funcResultStack_{*this};
Expand Down Expand Up @@ -1506,6 +1511,25 @@ class OmpVisitor : public virtual DeclarationVisitor {
void Post(const parser::OmpEndCriticalDirective &) {
messageHandler().set_currStmtSource(std::nullopt);
}
bool Pre(const parser::OpenMPThreadprivate &) {
SkipImplicitTyping(true);
return true;
}
void Post(const parser::OpenMPThreadprivate &) { SkipImplicitTyping(false); }
bool Pre(const parser::OpenMPDeclareTargetConstruct &) {
SkipImplicitTyping(true);
return true;
}
void Post(const parser::OpenMPDeclareTargetConstruct &) {
SkipImplicitTyping(false);
}
bool Pre(const parser::OpenMPDeclarativeAllocate &) {
SkipImplicitTyping(true);
return true;
}
void Post(const parser::OpenMPDeclarativeAllocate &) {
SkipImplicitTyping(false);
}
};

bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
Expand Down Expand Up @@ -2556,8 +2580,10 @@ void ScopeHandler::ApplyImplicitRules(
return;
}
if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
symbol.set(Symbol::Flag::Implicit);
symbol.SetType(*type);
if (!skipImplicitTyping_) {
symbol.set(Symbol::Flag::Implicit);
symbol.SetType(*type);
}
return;
}
if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
Expand Down
56 changes: 56 additions & 0 deletions flang/test/Semantics/OpenMP/declarative-directive02.f90
Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
! RUN: %flang -fsyntax-only -fopenmp %s 2>&1

! Check that OpenMP declarative directives can be used with objects that have
! an incomplete type.

subroutine test_decl
! OMPv5.2 5.2 threadprivate
! OMPv5.2 6.5 allocate
implicit none
save :: x1, y1
!$omp threadprivate(x1)
!$omp allocate(y1)
integer :: x1, y1

! OMPv5.2 7.7 declare-simd
external :: simd_func
!$omp declare simd(simd_func)
logical :: simd_func

! OMPv5.2 7.8.1 declare-target
allocatable :: j
!$omp declare target(j)
save :: j
real(kind=8) :: j(:)

! OMPv5.2 5.5.11 declare-reduction - crashes
!external :: my_add_red
!!$omp declare reduction(my_add_red : integer : my_add_red(omp_out, omp_in)) &
!!$omp& initializer(omp_priv=0)
!integer :: my_add_red
end subroutine

subroutine test_decl2
save x1, y1
!$omp threadprivate(x1)
!$omp allocate(y1)
integer :: x1, y1

! implicit decl
!$omp threadprivate(x2)
!$omp allocate(y2)
save x2, y2
end subroutine

module m1
! implicit decl
!$omp threadprivate(x, y, z)
integer :: y
real :: z

contains
subroutine sub
!$omp parallel copyin(x, y, z)
!$omp end parallel
end subroutine
end module
5 changes: 0 additions & 5 deletions flang/test/Semantics/OpenMP/declare-target06.f90
Original file line number Diff line number Diff line change
Expand Up @@ -6,21 +6,16 @@

module test_0
implicit none
!ERROR: The given DECLARE TARGET directive clause has an invalid argument
!ERROR: No explicit type declared for 'no_implicit_materialization_1'
!$omp declare target(no_implicit_materialization_1)

!ERROR: The given DECLARE TARGET directive clause has an invalid argument
!ERROR: No explicit type declared for 'no_implicit_materialization_2'
!$omp declare target link(no_implicit_materialization_2)

!ERROR: The given DECLARE TARGET directive clause has an invalid argument
!WARNING: The usage of TO clause on DECLARE TARGET directive has been deprecated. Use ENTER clause instead.
!ERROR: No explicit type declared for 'no_implicit_materialization_3'
!$omp declare target to(no_implicit_materialization_3)

!ERROR: The given DECLARE TARGET directive clause has an invalid argument
!ERROR: No explicit type declared for 'no_implicit_materialization_3'
!$omp declare target enter(no_implicit_materialization_3)

INTEGER :: data_int = 10
Expand Down
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