[flang-commits] [flang] 03c3716 - [flang][OpenMP] Reject END DO on construct that crosses label-DO (#169714)
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Fri Dec 5 12:01:28 PST 2025
Author: Krzysztof Parzyszek
Date: 2025-12-05T14:01:24-06:00
New Revision: 03c37160a1735c12e4acbac70a593ff3e68d5ad7
URL: https://github.com/llvm/llvm-project/commit/03c37160a1735c12e4acbac70a593ff3e68d5ad7
DIFF: https://github.com/llvm/llvm-project/commit/03c37160a1735c12e4acbac70a593ff3e68d5ad7.diff
LOG: [flang][OpenMP] Reject END DO on construct that crosses label-DO (#169714)
In a label-DO construct where two or more loops share the same
teminator, an OpenMP construct must enclose all the loops if an
end-directive is present. E.g.
```
do 100 i = 1,10
!$omp do
do 100 j = 1,10
100 continue
!$omp end do ! Error, but ok if this line is removed
```
Fixes https://github.com/llvm/llvm-project/issues/169536.
Added:
Modified:
flang/include/flang/Parser/parse-tree.h
flang/lib/Semantics/canonicalize-do.cpp
flang/lib/Semantics/check-omp-loop.cpp
flang/test/Parser/OpenMP/atomic-label-do.f90
flang/test/Parser/OpenMP/cross-label-do.f90
flang/test/Semantics/OpenMP/loop-association.f90
Removed:
################################################################################
diff --git a/flang/include/flang/Parser/parse-tree.h b/flang/include/flang/Parser/parse-tree.h
index cbfcaafa78dc0..c4ace2d8a2135 100644
--- a/flang/include/flang/Parser/parse-tree.h
+++ b/flang/include/flang/Parser/parse-tree.h
@@ -4982,7 +4982,7 @@ struct OmpClauseList {
// --- Directives and constructs
struct OmpDirectiveSpecification {
- ENUM_CLASS(Flag, DeprecatedSyntax)
+ ENUM_CLASS(Flag, DeprecatedSyntax, CrossesLabelDo)
using Flags = common::EnumSet<Flag, Flag_enumSize>;
TUPLE_CLASS_BOILERPLATE(OmpDirectiveSpecification);
diff --git a/flang/lib/Semantics/canonicalize-do.cpp b/flang/lib/Semantics/canonicalize-do.cpp
index 409195d5960b4..8b23f88c3be90 100644
--- a/flang/lib/Semantics/canonicalize-do.cpp
+++ b/flang/lib/Semantics/canonicalize-do.cpp
@@ -92,8 +92,12 @@ class CanonicalizationOfDoLoops {
[&](common::Indirection<OpenMPConstruct> &construct) {
// If the body of the OpenMP construct ends with a label,
// treat the label as ending the construct itself.
- CanonicalizeIfMatch(
- block, stack, i, omp::GetFinalLabel(construct.value()));
+ OpenMPConstruct &omp{construct.value()};
+ if (CanonicalizeIfMatch(
+ block, stack, i, omp::GetFinalLabel(omp))) {
+ MarkOpenMPConstruct(
+ omp, OmpDirectiveSpecification::Flag::CrossesLabelDo);
+ }
},
},
executableConstruct->u);
@@ -103,12 +107,12 @@ class CanonicalizationOfDoLoops {
private:
template <typename T>
- void CanonicalizeIfMatch(Block &originalBlock, std::vector<LabelInfo> &stack,
+ bool CanonicalizeIfMatch(Block &originalBlock, std::vector<LabelInfo> &stack,
Block::iterator &i, Statement<T> &statement) {
- CanonicalizeIfMatch(originalBlock, stack, i, statement.label);
+ return CanonicalizeIfMatch(originalBlock, stack, i, statement.label);
}
- void CanonicalizeIfMatch(Block &originalBlock, std::vector<LabelInfo> &stack,
+ bool CanonicalizeIfMatch(Block &originalBlock, std::vector<LabelInfo> &stack,
Block::iterator &i, std::optional<Label> label) {
if (!stack.empty() && label && stack.back().label == *label) {
auto currentLabel{stack.back().label};
@@ -141,8 +145,27 @@ class CanonicalizationOfDoLoops {
stack.pop_back();
} while (!stack.empty() && stack.back().label == currentLabel);
i = --next;
+ return true;
+ } else {
+ return false;
}
}
+
+ void MarkOpenMPConstruct(
+ OpenMPConstruct &omp, OmpDirectiveSpecification::Flag flag) {
+ common::visit(
+ [&](const auto &s) {
+ using S = std::decay_t<decltype(s)>;
+ if constexpr (std::is_base_of_v<OmpBlockConstruct, S> ||
+ std::is_same_v<OpenMPLoopConstruct, S>) {
+ const OmpDirectiveSpecification &beginSpec{s.BeginDir()};
+ auto &flags{
+ std::get<OmpDirectiveSpecification::Flags>(beginSpec.t)};
+ const_cast<OmpDirectiveSpecification::Flags &>(flags).set(flag);
+ }
+ },
+ omp.u);
+ }
};
bool CanonicalizeDo(Program &program) {
diff --git a/flang/lib/Semantics/check-omp-loop.cpp b/flang/lib/Semantics/check-omp-loop.cpp
index fc4b9222d91b3..f25cf7eb33817 100644
--- a/flang/lib/Semantics/check-omp-loop.cpp
+++ b/flang/lib/Semantics/check-omp-loop.cpp
@@ -290,6 +290,25 @@ void OmpStructureChecker::CheckNestedConstruct(
const parser::OpenMPLoopConstruct &x) {
size_t nestedCount{0};
+ // End-directive is not allowed in such cases:
+ // do 100 i = ...
+ // !$omp do
+ // do 100 j = ...
+ // 100 continue
+ // !$omp end do ! error
+ const parser::OmpDirectiveSpecification &beginSpec{x.BeginDir()};
+ auto &flags{std::get<parser::OmpDirectiveSpecification::Flags>(beginSpec.t)};
+ if (flags.test(parser::OmpDirectiveSpecification::Flag::CrossesLabelDo)) {
+ if (auto &endSpec{x.EndDir()}) {
+ parser::CharBlock beginSource{beginSpec.DirName().source};
+ context_
+ .Say(endSpec->DirName().source,
+ "END %s directive is not allowed when the construct does not contain all loops that share a loop-terminating statement"_err_en_US,
+ parser::ToUpperCaseLetters(beginSource.ToString()))
+ .Attach(beginSource, "The construct starts here"_en_US);
+ }
+ }
+
auto &body{std::get<parser::Block>(x.t)};
if (body.empty()) {
context_.Say(x.source,
diff --git a/flang/test/Parser/OpenMP/atomic-label-do.f90 b/flang/test/Parser/OpenMP/atomic-label-do.f90
index f0c83c01f7a21..1c7037f239191 100644
--- a/flang/test/Parser/OpenMP/atomic-label-do.f90
+++ b/flang/test/Parser/OpenMP/atomic-label-do.f90
@@ -29,7 +29,7 @@ subroutine f
!PARSE-TREE: | | | OmpBeginDirective
!PARSE-TREE: | | | | OmpDirectiveName -> llvm::omp::Directive = atomic
!PARSE-TREE: | | | | OmpClauseList -> OmpClause -> Write
-!PARSE-TREE: | | | | Flags = {}
+!PARSE-TREE: | | | | Flags = {CrossesLabelDo}
!PARSE-TREE: | | | Block
!PARSE-TREE: | | | | ExecutionPartConstruct -> ExecutableConstruct -> ActionStmt -> AssignmentStmt = 'x=i'
!PARSE-TREE: | | | | | Variable = 'x'
diff --git a/flang/test/Parser/OpenMP/cross-label-do.f90 b/flang/test/Parser/OpenMP/cross-label-do.f90
index fd648e0248258..f1a406c334c39 100644
--- a/flang/test/Parser/OpenMP/cross-label-do.f90
+++ b/flang/test/Parser/OpenMP/cross-label-do.f90
@@ -32,7 +32,7 @@ subroutine f00
!PARSE-TREE: | | | OmpBeginLoopDirective
!PARSE-TREE: | | | | OmpDirectiveName -> llvm::omp::Directive = do
!PARSE-TREE: | | | | OmpClauseList ->
-!PARSE-TREE: | | | | Flags = {}
+!PARSE-TREE: | | | | Flags = {CrossesLabelDo}
!PARSE-TREE: | | | Block
!PARSE-TREE: | | | | ExecutionPartConstruct -> ExecutableConstruct -> DoConstruct
!PARSE-TREE: | | | | | NonLabelDoStmt
diff --git a/flang/test/Semantics/OpenMP/loop-association.f90 b/flang/test/Semantics/OpenMP/loop-association.f90
index 4e63cafb3fda1..7070ff5638c72 100644
--- a/flang/test/Semantics/OpenMP/loop-association.f90
+++ b/flang/test/Semantics/OpenMP/loop-association.f90
@@ -64,6 +64,7 @@
do 100 j=1, N
a = 3.14
100 continue
+ !ERROR: END DO directive is not allowed when the construct does not contain all loops that share a loop-terminating statement
!$omp enddo
!ERROR: Non-THREADPRIVATE object 'a' in COPYIN clause
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