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[flang][OpenMP][Semantics] improve semantic checks for array sections #132230

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merged 2 commits into from
Mar 21, 2025
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[flang][OpenMP][Semantics] improve semantic checks for array sections #132230

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666e096
[flang][OpenMP][Semantics] improve semantic checks for array sections
tblah Mar 20, 2025
52c542d
Simplify if statements
tblah Mar 20, 2025
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42 changes: 26 additions & 16 deletions flang/lib/Semantics/check-omp-structure.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5304,27 +5304,37 @@ void OmpStructureChecker::CheckArraySection(
if (const auto *triplet{
std::get_if<parser::SubscriptTriplet>(&subscript.u)}) {
if (std::get<0>(triplet->t) && std::get<1>(triplet->t)) {
std::optional<int64_t> strideVal{std::nullopt};
if (const auto &strideExpr = std::get<2>(triplet->t)) {
// OpenMP 6.0 Section 5.2.5: Array Sections
// Restrictions: if a stride expression is specified it must be
// positive. A stride of 0 doesn't make sense.
strideVal = GetIntValue(strideExpr);
if (strideVal && *strideVal < 1) {
context_.Say(GetContext().clauseSource,
"'%s' in %s clause must have a positive stride"_err_en_US,
name.ToString(),
parser::ToUpperCaseLetters(getClauseName(clause).str()));
}
}
const auto &lower{std::get<0>(triplet->t)};
const auto &upper{std::get<1>(triplet->t)};
if (lower && upper) {
const auto lval{GetIntValue(lower)};
const auto uval{GetIntValue(upper)};
if (lval && uval && *uval < *lval) {
context_.Say(GetContext().clauseSource,
"'%s' in %s clause"
" is a zero size array section"_err_en_US,
name.ToString(),
parser::ToUpperCaseLetters(getClauseName(clause).str()));
break;
} else if (std::get<2>(triplet->t)) {
const auto &strideExpr{std::get<2>(triplet->t)};
if (strideExpr) {
if (clause == llvm::omp::Clause::OMPC_depend) {
context_.Say(GetContext().clauseSource,
"Stride should not be specified for array section in "
"DEPEND "
"clause"_err_en_US);
}
if (lval && uval) {
int64_t sectionLen = *uval - *lval;
if (strideVal) {
sectionLen = sectionLen / *strideVal;
}

if (sectionLen < 1) {
context_.Say(GetContext().clauseSource,
"'%s' in %s clause"
" is a zero size array section"_err_en_US,
name.ToString(),
parser::ToUpperCaseLetters(getClauseName(clause).str()));
break;
}
}
}
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11 changes: 9 additions & 2 deletions flang/test/Semantics/OpenMP/depend01.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,15 @@ program omp_depend
a(2:1) = b(2, 2)
!$omp end task

!ERROR: Stride should not be specified for array section in DEPEND clause
!$omp task shared(x) depend(in: a(5:10:1))
!ERROR: 'a' in DEPEND clause must have a positive stride
!ERROR: 'b' in DEPEND clause must have a positive stride
!ERROR: 'b' in DEPEND clause is a zero size array section
!$omp task shared(x) depend(in: a(10:5:-1)) depend(in: b(5:10:-1))
print *, a(5:10), b
!$omp end task

!ERROR: 'a' in DEPEND clause is a zero size array section
!$omp task shared(x) depend(in: a(1:5:10))
print *, a(5:10), b
!$omp end task

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