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llvm-project/flang/lib/Evaluate/check-expression.cpp

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//===-- lib/Evaluate/check-expression.cpp ---------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "flang/Evaluate/check-expression.h"
#include "flang/Evaluate/characteristics.h"
#include "flang/Evaluate/intrinsics.h"
#include "flang/Evaluate/traverse.h"
#include "flang/Evaluate/type.h"
#include "flang/Semantics/symbol.h"
#include "flang/Semantics/tools.h"
#include <set>
#include <string>
namespace Fortran::evaluate {
// Constant expression predicates IsConstantExpr() & IsScopeInvariantExpr().
// This code determines whether an expression is a "constant expression"
// in the sense of section 10.1.12. This is not the same thing as being
// able to fold it (yet) into a known constant value; specifically,
// the expression may reference derived type kind parameters whose values
// are not yet known.
//
// The variant form (IsScopeInvariantExpr()) also accepts symbols that are
// INTENT(IN) dummy arguments without the VALUE attribute.
template <bool INVARIANT>
class IsConstantExprHelper
: public AllTraverse<IsConstantExprHelper<INVARIANT>, true> {
public:
using Base = AllTraverse<IsConstantExprHelper, true>;
IsConstantExprHelper() : Base{*this} {}
using Base::operator();
// A missing expression is not considered to be constant.
template <typename A> bool operator()(const std::optional<A> &x) const {
return x && (*this)(*x);
}
bool operator()(const TypeParamInquiry &inq) const {
return INVARIANT || semantics::IsKindTypeParameter(inq.parameter());
}
bool operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{GetAssociationRoot(symbol)};
return IsNamedConstant(ultimate) || IsImpliedDoIndex(ultimate) ||
IsInitialProcedureTarget(ultimate) ||
ultimate.has<semantics::TypeParamDetails>() ||
(INVARIANT && IsIntentIn(symbol) &&
!symbol.attrs().test(semantics::Attr::VALUE));
}
bool operator()(const CoarrayRef &) const { return false; }
bool operator()(const semantics::ParamValue &param) const {
return param.isExplicit() && (*this)(param.GetExplicit());
}
bool operator()(const ProcedureRef &) const;
bool operator()(const StructureConstructor &constructor) const {
for (const auto &[symRef, expr] : constructor) {
if (!IsConstantStructureConstructorComponent(*symRef, expr.value())) {
return false;
}
}
return true;
}
bool operator()(const Component &component) const {
return (*this)(component.base());
}
// Forbid integer division by zero in constants.
template <int KIND>
bool operator()(
const Divide<Type<TypeCategory::Integer, KIND>> &division) const {
using T = Type<TypeCategory::Integer, KIND>;
if (const auto divisor{GetScalarConstantValue<T>(division.right())}) {
return !divisor->IsZero() && (*this)(division.left());
} else {
return false;
}
}
bool operator()(const Constant<SomeDerived> &) const { return true; }
bool operator()(const DescriptorInquiry &x) const {
const Symbol &sym{x.base().GetLastSymbol()};
return INVARIANT && !IsAllocatable(sym) &&
(!IsDummy(sym) ||
(IsIntentIn(sym) && !sym.attrs().test(semantics::Attr::VALUE)));
}
private:
bool IsConstantStructureConstructorComponent(
const Symbol &, const Expr<SomeType> &) const;
bool IsConstantExprShape(const Shape &) const;
};
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::IsConstantStructureConstructorComponent(
const Symbol &component, const Expr<SomeType> &expr) const {
if (IsAllocatable(component)) {
return IsNullPointer(expr);
} else if (IsPointer(component)) {
return IsNullPointer(expr) || IsInitialDataTarget(expr) ||
IsInitialProcedureTarget(expr);
} else {
return (*this)(expr);
}
}
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::operator()(
const ProcedureRef &call) const {
// LBOUND, UBOUND, and SIZE with DIM= arguments will have been rewritten
// into DescriptorInquiry operations.
if (const auto *intrinsic{std::get_if<SpecificIntrinsic>(&call.proc().u)}) {
if (intrinsic->name == "kind" ||
intrinsic->name == IntrinsicProcTable::InvalidName) {
// kind is always a constant, and we avoid cascading errors by considering
// invalid calls to intrinsics to be constant
return true;
} else if (intrinsic->name == "lbound" && call.arguments().size() == 1) {
// LBOUND(x) without DIM=
auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
return base && IsConstantExprShape(GetLBOUNDs(*base));
} else if (intrinsic->name == "ubound" && call.arguments().size() == 1) {
// UBOUND(x) without DIM=
auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
return base && IsConstantExprShape(GetUBOUNDs(*base));
} else if (intrinsic->name == "shape") {
auto shape{GetShape(call.arguments()[0]->UnwrapExpr())};
return shape && IsConstantExprShape(*shape);
} else if (intrinsic->name == "size" && call.arguments().size() == 1) {
// SIZE(x) without DIM
auto shape{GetShape(call.arguments()[0]->UnwrapExpr())};
return shape && IsConstantExprShape(*shape);
}
// TODO: STORAGE_SIZE
}
return false;
}
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::IsConstantExprShape(
const Shape &shape) const {
for (const auto &extent : shape) {
if (!(*this)(extent)) {
return false;
}
}
return true;
}
template <typename A> bool IsConstantExpr(const A &x) {
return IsConstantExprHelper<false>{}(x);
}
template bool IsConstantExpr(const Expr<SomeType> &);
template bool IsConstantExpr(const Expr<SomeInteger> &);
template bool IsConstantExpr(const Expr<SubscriptInteger> &);
template bool IsConstantExpr(const StructureConstructor &);
// IsScopeInvariantExpr()
template <typename A> bool IsScopeInvariantExpr(const A &x) {
return IsConstantExprHelper<true>{}(x);
}
template bool IsScopeInvariantExpr(const Expr<SomeType> &);
template bool IsScopeInvariantExpr(const Expr<SomeInteger> &);
template bool IsScopeInvariantExpr(const Expr<SubscriptInteger> &);
// IsActuallyConstant()
struct IsActuallyConstantHelper {
template <typename A> bool operator()(const A &) { return false; }
template <typename T> bool operator()(const Constant<T> &) { return true; }
template <typename T> bool operator()(const Parentheses<T> &x) {
return (*this)(x.left());
}
template <typename T> bool operator()(const Expr<T> &x) {
return common::visit([=](const auto &y) { return (*this)(y); }, x.u);
}
bool operator()(const Expr<SomeType> &x) {
if (IsNullPointer(x)) {
return true;
}
return common::visit([this](const auto &y) { return (*this)(y); }, x.u);
}
template <typename A> bool operator()(const A *x) { return x && (*this)(*x); }
template <typename A> bool operator()(const std::optional<A> &x) {
return x && (*this)(*x);
}
};
template <typename A> bool IsActuallyConstant(const A &x) {
return IsActuallyConstantHelper{}(x);
}
template bool IsActuallyConstant(const Expr<SomeType> &);
template bool IsActuallyConstant(const Expr<SomeInteger> &);
template bool IsActuallyConstant(const Expr<SubscriptInteger> &);
// Object pointer initialization checking predicate IsInitialDataTarget().
// This code determines whether an expression is allowable as the static
// data address used to initialize a pointer with "=> x". See C765.
class IsInitialDataTargetHelper
: public AllTraverse<IsInitialDataTargetHelper, true> {
public:
using Base = AllTraverse<IsInitialDataTargetHelper, true>;
using Base::operator();
explicit IsInitialDataTargetHelper(parser::ContextualMessages *m)
: Base{*this}, messages_{m} {}
bool emittedMessage() const { return emittedMessage_; }
bool operator()(const BOZLiteralConstant &) const { return false; }
bool operator()(const NullPointer &) const { return true; }
template <typename T> bool operator()(const Constant<T> &) const {
return false;
}
bool operator()(const semantics::Symbol &symbol) {
// This function checks only base symbols, not components.
const Symbol &ultimate{symbol.GetUltimate()};
if (const auto *assoc{
ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
if (const auto &expr{assoc->expr()}) {
if (IsVariable(*expr)) {
return (*this)(*expr);
} else if (messages_) {
messages_->Say(
"An initial data target may not be an associated expression ('%s')"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
}
return false;
} else if (!ultimate.attrs().test(semantics::Attr::TARGET)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an object '%s' that lacks the TARGET attribute"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else if (!IsSaved(ultimate)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an object '%s' that lacks the SAVE attribute"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else {
return CheckVarOrComponent(ultimate);
}
}
bool operator()(const StaticDataObject &) const { return false; }
bool operator()(const TypeParamInquiry &) const { return false; }
bool operator()(const Triplet &x) const {
return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
IsConstantExpr(x.stride());
}
bool operator()(const Subscript &x) const {
return common::visit(common::visitors{
[&](const Triplet &t) { return (*this)(t); },
[&](const auto &y) {
return y.value().Rank() == 0 &&
IsConstantExpr(y.value());
},
},
x.u);
}
bool operator()(const CoarrayRef &) const { return false; }
bool operator()(const Component &x) {
return CheckVarOrComponent(x.GetLastSymbol()) && (*this)(x.base());
}
bool operator()(const Substring &x) const {
return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
(*this)(x.parent());
}
bool operator()(const DescriptorInquiry &) const { return false; }
template <typename T> bool operator()(const ArrayConstructor<T> &) const {
return false;
}
bool operator()(const StructureConstructor &) const { return false; }
template <typename D, typename R, typename... O>
bool operator()(const Operation<D, R, O...> &) const {
return false;
}
template <typename T> bool operator()(const Parentheses<T> &x) const {
return (*this)(x.left());
}
bool operator()(const ProcedureRef &x) const {
if (const SpecificIntrinsic * intrinsic{x.proc().GetSpecificIntrinsic()}) {
return intrinsic->characteristics.value().attrs.test(
characteristics::Procedure::Attr::NullPointer);
}
return false;
}
bool operator()(const Relational<SomeType> &) const { return false; }
private:
bool CheckVarOrComponent(const semantics::Symbol &symbol) {
const Symbol &ultimate{symbol.GetUltimate()};
if (IsAllocatable(ultimate)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an ALLOCATABLE '%s'"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else if (ultimate.Corank() > 0) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to a coarray '%s'"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
}
return true;
}
parser::ContextualMessages *messages_;
bool emittedMessage_{false};
};
bool IsInitialDataTarget(
const Expr<SomeType> &x, parser::ContextualMessages *messages) {
IsInitialDataTargetHelper helper{messages};
bool result{helper(x)};
if (!result && messages && !helper.emittedMessage()) {
messages->Say(
"An initial data target must be a designator with constant subscripts"_err_en_US);
}
return result;
}
bool IsInitialProcedureTarget(const semantics::Symbol &symbol) {
const auto &ultimate{symbol.GetUltimate()};
return common::visit(
common::visitors{
[](const semantics::SubprogramDetails &subp) {
return !subp.isDummy();
},
[](const semantics::SubprogramNameDetails &) { return true; },
[&](const semantics::ProcEntityDetails &proc) {
return !semantics::IsPointer(ultimate) && !proc.isDummy();
},
[](const auto &) { return false; },
},
ultimate.details());
}
bool IsInitialProcedureTarget(const ProcedureDesignator &proc) {
if (const auto *intrin{proc.GetSpecificIntrinsic()}) {
return !intrin->isRestrictedSpecific;
} else if (proc.GetComponent()) {
return false;
} else {
return IsInitialProcedureTarget(DEREF(proc.GetSymbol()));
}
}
bool IsInitialProcedureTarget(const Expr<SomeType> &expr) {
if (const auto *proc{std::get_if<ProcedureDesignator>(&expr.u)}) {
return IsInitialProcedureTarget(*proc);
} else {
return IsNullPointer(expr);
}
}
class ArrayConstantBoundChanger {
public:
ArrayConstantBoundChanger(ConstantSubscripts &&lbounds)
: lbounds_{std::move(lbounds)} {}
template <typename A> A ChangeLbounds(A &&x) const {
return std::move(x); // default case
}
template <typename T> Constant<T> ChangeLbounds(Constant<T> &&x) {
x.set_lbounds(std::move(lbounds_));
return std::move(x);
}
template <typename T> Expr<T> ChangeLbounds(Parentheses<T> &&x) {
return ChangeLbounds(
std::move(x.left())); // Constant<> can be parenthesized
}
template <typename T> Expr<T> ChangeLbounds(Expr<T> &&x) {
return common::visit(
[&](auto &&x) { return Expr<T>{ChangeLbounds(std::move(x))}; },
std::move(x.u)); // recurse until we hit a constant
}
private:
ConstantSubscripts &&lbounds_;
};
// Converts, folds, and then checks type, rank, and shape of an
// initialization expression for a named constant, a non-pointer
// variable static initialization, a component default initializer,
// a type parameter default value, or instantiated type parameter value.
std::optional<Expr<SomeType>> NonPointerInitializationExpr(const Symbol &symbol,
Expr<SomeType> &&x, FoldingContext &context,
const semantics::Scope *instantiation) {
CHECK(!IsPointer(symbol));
if (auto symTS{
characteristics::TypeAndShape::Characterize(symbol, context)}) {
auto xType{x.GetType()};
auto converted{ConvertToType(symTS->type(), Expr<SomeType>{x})};
if (!converted &&
symbol.owner().context().IsEnabled(
common::LanguageFeature::LogicalIntegerAssignment)) {
converted = DataConstantConversionExtension(context, symTS->type(), x);
if (converted &&
symbol.owner().context().ShouldWarn(
common::LanguageFeature::LogicalIntegerAssignment)) {
context.messages().Say(
"nonstandard usage: initialization of %s with %s"_port_en_US,
symTS->type().AsFortran(), x.GetType().value().AsFortran());
}
}
if (converted) {
auto folded{Fold(context, std::move(*converted))};
if (IsActuallyConstant(folded)) {
int symRank{GetRank(symTS->shape())};
if (IsImpliedShape(symbol)) {
if (folded.Rank() == symRank) {
return {std::move(folded)};
} else {
context.messages().Say(
"Implied-shape parameter '%s' has rank %d but its initializer has rank %d"_err_en_US,
symbol.name(), symRank, folded.Rank());
}
} else if (auto extents{AsConstantExtents(context, symTS->shape())}) {
if (folded.Rank() == 0 && symRank == 0) {
// symbol and constant are both scalars
return {std::move(folded)};
} else if (folded.Rank() == 0 && symRank > 0) {
// expand the scalar constant to an array
return ScalarConstantExpander{std::move(*extents),
AsConstantExtents(
context, GetRawLowerBounds(context, NamedEntity{symbol}))}
.Expand(std::move(folded));
} else if (auto resultShape{GetShape(context, folded)}) {
if (CheckConformance(context.messages(), symTS->shape(),
*resultShape, CheckConformanceFlags::None,
"initialized object", "initialization expression")
.value_or(false /*fail if not known now to conform*/)) {
// make a constant array with adjusted lower bounds
return ArrayConstantBoundChanger{
std::move(*AsConstantExtents(context,
GetRawLowerBounds(context, NamedEntity{symbol})))}
.ChangeLbounds(std::move(folded));
}
}
} else if (IsNamedConstant(symbol)) {
if (IsExplicitShape(symbol)) {
context.messages().Say(
"Named constant '%s' array must have constant shape"_err_en_US,
symbol.name());
} else {
// Declaration checking handles other cases
}
} else {
context.messages().Say(
"Shape of initialized object '%s' must be constant"_err_en_US,
symbol.name());
}
} else if (IsErrorExpr(folded)) {
} else if (IsLenTypeParameter(symbol)) {
return {std::move(folded)};
} else if (IsKindTypeParameter(symbol)) {
if (instantiation) {
context.messages().Say(
"Value of kind type parameter '%s' (%s) must be a scalar INTEGER constant"_err_en_US,
symbol.name(), folded.AsFortran());
} else {
return {std::move(folded)};
}
} else if (IsNamedConstant(symbol)) {
context.messages().Say(
"Value of named constant '%s' (%s) cannot be computed as a constant value"_err_en_US,
symbol.name(), folded.AsFortran());
} else {
context.messages().Say(
"Initialization expression for '%s' (%s) cannot be computed as a constant value"_err_en_US,
symbol.name(), folded.AsFortran());
}
} else if (xType) {
context.messages().Say(
"Initialization expression cannot be converted to declared type of '%s' from %s"_err_en_US,
symbol.name(), xType->AsFortran());
} else {
context.messages().Say(
"Initialization expression cannot be converted to declared type of '%s'"_err_en_US,
symbol.name());
}
}
return std::nullopt;
}
// Specification expression validation (10.1.11(2), C1010)
class CheckSpecificationExprHelper
: public AnyTraverse<CheckSpecificationExprHelper,
std::optional<std::string>> {
public:
using Result = std::optional<std::string>;
using Base = AnyTraverse<CheckSpecificationExprHelper, Result>;
explicit CheckSpecificationExprHelper(
const semantics::Scope &s, FoldingContext &context)
: Base{*this}, scope_{s}, context_{context} {}
using Base::operator();
Result operator()(const CoarrayRef &) const { return "coindexed reference"; }
Result operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{symbol.GetUltimate()};
if (const auto *assoc{
ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
return (*this)(assoc->expr());
} else if (semantics::IsNamedConstant(ultimate) ||
ultimate.owner().IsModule() || ultimate.owner().IsSubmodule()) {
return std::nullopt;
} else if (scope_.IsDerivedType() &&
IsVariableName(ultimate)) { // C750, C754
return "derived type component or type parameter value not allowed to "
"reference variable '"s +
ultimate.name().ToString() + "'";
} else if (IsDummy(ultimate)) {
if (ultimate.attrs().test(semantics::Attr::OPTIONAL)) {
return "reference to OPTIONAL dummy argument '"s +
ultimate.name().ToString() + "'";
} else if (ultimate.attrs().test(semantics::Attr::INTENT_OUT)) {
return "reference to INTENT(OUT) dummy argument '"s +
ultimate.name().ToString() + "'";
} else if (ultimate.has<semantics::ObjectEntityDetails>()) {
return std::nullopt;
} else {
return "dummy procedure argument";
}
} else if (&symbol.owner() != &scope_ || &ultimate.owner() != &scope_) {
return std::nullopt; // host association is in play
} else if (const auto *object{
ultimate.detailsIf<semantics::ObjectEntityDetails>()}) {
if (object->commonBlock()) {
return std::nullopt;
}
}
return "reference to local entity '"s + ultimate.name().ToString() + "'";
}
Result operator()(const Component &x) const {
// Don't look at the component symbol.
return (*this)(x.base());
}
Result operator()(const DescriptorInquiry &) const {
// Subtle: Uses of SIZE(), LBOUND(), &c. that are valid in specification
// expressions will have been converted to expressions over descriptor
// inquiries by Fold().
return std::nullopt;
}
Result operator()(const TypeParamInquiry &inq) const {
if (scope_.IsDerivedType() && !IsConstantExpr(inq) &&
inq.base() /* X%T, not local T */) { // C750, C754
return "non-constant reference to a type parameter inquiry not "
"allowed for derived type components or type parameter values";
}
return std::nullopt;
}
Result operator()(const ProcedureRef &x) const {
if (const auto *symbol{x.proc().GetSymbol()}) {
const Symbol &ultimate{symbol->GetUltimate()};
if (!semantics::IsPureProcedure(ultimate)) {
return "reference to impure function '"s + ultimate.name().ToString() +
"'";
}
if (semantics::IsStmtFunction(ultimate)) {
return "reference to statement function '"s +
ultimate.name().ToString() + "'";
}
if (scope_.IsDerivedType()) { // C750, C754
return "reference to function '"s + ultimate.name().ToString() +
"' not allowed for derived type components or type parameter"
" values";
}
if (auto procChars{
characteristics::Procedure::Characterize(x.proc(), context_)}) {
const auto iter{std::find_if(procChars->dummyArguments.begin(),
procChars->dummyArguments.end(),
[](const characteristics::DummyArgument &dummy) {
return std::holds_alternative<characteristics::DummyProcedure>(
dummy.u);
})};
if (iter != procChars->dummyArguments.end()) {
return "reference to function '"s + ultimate.name().ToString() +
"' with dummy procedure argument '" + iter->name + '\'';
}
}
// References to internal functions are caught in expression semantics.
// TODO: other checks for standard module procedures
} else {
const SpecificIntrinsic &intrin{DEREF(x.proc().GetSpecificIntrinsic())};
if (scope_.IsDerivedType()) { // C750, C754
if ((context_.intrinsics().IsIntrinsic(intrin.name) &&
badIntrinsicsForComponents_.find(intrin.name) !=
badIntrinsicsForComponents_.end()) ||
IsProhibitedFunction(intrin.name)) {
return "reference to intrinsic '"s + intrin.name +
"' not allowed for derived type components or type parameter"
" values";
}
if (context_.intrinsics().GetIntrinsicClass(intrin.name) ==
IntrinsicClass::inquiryFunction &&
!IsConstantExpr(x)) {
return "non-constant reference to inquiry intrinsic '"s +
intrin.name +
"' not allowed for derived type components or type"
" parameter values";
}
} else if (intrin.name == "present") {
return std::nullopt; // no need to check argument(s)
}
if (IsConstantExpr(x)) {
// inquiry functions may not need to check argument(s)
return std::nullopt;
}
}
return (*this)(x.arguments());
}
private:
const semantics::Scope &scope_;
FoldingContext &context_;
const std::set<std::string> badIntrinsicsForComponents_{
"allocated", "associated", "extends_type_of", "present", "same_type_as"};
static bool IsProhibitedFunction(std::string name) { return false; }
};
template <typename A>
void CheckSpecificationExpr(
const A &x, const semantics::Scope &scope, FoldingContext &context) {
if (auto why{CheckSpecificationExprHelper{scope, context}(x)}) {
context.messages().Say(
"Invalid specification expression: %s"_err_en_US, *why);
}
}
template void CheckSpecificationExpr(
const Expr<SomeType> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const Expr<SomeInteger> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const Expr<SubscriptInteger> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(const std::optional<Expr<SomeType>> &,
const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(const std::optional<Expr<SomeInteger>> &,
const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const std::optional<Expr<SubscriptInteger>> &, const semantics::Scope &,
FoldingContext &);
// IsSimplyContiguous() -- 9.5.4
class IsSimplyContiguousHelper
: public AnyTraverse<IsSimplyContiguousHelper, std::optional<bool>> {
public:
using Result = std::optional<bool>; // tri-state
using Base = AnyTraverse<IsSimplyContiguousHelper, Result>;
explicit IsSimplyContiguousHelper(FoldingContext &c)
: Base{*this}, context_{c} {}
using Base::operator();
Result operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{symbol.GetUltimate()};
if (ultimate.attrs().test(semantics::Attr::CONTIGUOUS)) {
return true;
} else if (ultimate.Rank() == 0) {
// Extension: accept scalars as a degenerate case of
// simple contiguity to allow their use in contexts like
// data targets in pointer assignments with remapping.
return true;
} else if (semantics::IsPointer(ultimate) ||
semantics::IsAssumedShape(ultimate)) {
return false;
} else if (const auto *details{
ultimate.detailsIf<semantics::ObjectEntityDetails>()}) {
return !details->IsAssumedRank();
} else if (auto assoc{Base::operator()(ultimate)}) {
return assoc;
} else {
return false;
}
}
Result operator()(const ArrayRef &x) const {
const auto &symbol{x.GetLastSymbol()};
if (!(*this)(symbol).has_value()) {
return false;
} else if (auto rank{CheckSubscripts(x.subscript())}) {
if (x.Rank() == 0) {
return true;
} else if (*rank > 0) {
// a(1)%b(:,:) is contiguous if an only if a(1)%b is contiguous.
return (*this)(x.base());
} else {
// a(:)%b(1,1) is not contiguous.
return false;
}
} else {
return false;
}
}
Result operator()(const CoarrayRef &x) const {
return CheckSubscripts(x.subscript()).has_value();
}
Result operator()(const Component &x) const {
return x.base().Rank() == 0 && (*this)(x.GetLastSymbol()).value_or(false);
}
Result operator()(const ComplexPart &) const { return false; }
Result operator()(const Substring &) const { return false; }
Result operator()(const ProcedureRef &x) const {
if (auto chars{
characteristics::Procedure::Characterize(x.proc(), context_)}) {
if (chars->functionResult) {
const auto &result{*chars->functionResult};
return !result.IsProcedurePointer() &&
result.attrs.test(characteristics::FunctionResult::Attr::Pointer) &&
result.attrs.test(
characteristics::FunctionResult::Attr::Contiguous);
}
}
return false;
}
private:
// If the subscripts can possibly be on a simply-contiguous array reference,
// return the rank.
static std::optional<int> CheckSubscripts(
const std::vector<Subscript> &subscript) {
bool anyTriplet{false};
int rank{0};
for (auto j{subscript.size()}; j-- > 0;) {
if (const auto *triplet{std::get_if<Triplet>(&subscript[j].u)}) {
if (!triplet->IsStrideOne()) {
return std::nullopt;
} else if (anyTriplet) {
if (triplet->lower() || triplet->upper()) {
// all triplets before the last one must be just ":"
return std::nullopt;
}
} else {
anyTriplet = true;
}
++rank;
} else if (anyTriplet || subscript[j].Rank() > 0) {
return std::nullopt;
}
}
return rank;
}
FoldingContext &context_;
};
template <typename A>
bool IsSimplyContiguous(const A &x, FoldingContext &context) {
if (IsVariable(x)) {
auto known{IsSimplyContiguousHelper{context}(x)};
return known && *known;
} else {
return true; // not a variable
}
}
template bool IsSimplyContiguous(const Expr<SomeType> &, FoldingContext &);
// IsErrorExpr()
struct IsErrorExprHelper : public AnyTraverse<IsErrorExprHelper, bool> {
using Result = bool;
using Base = AnyTraverse<IsErrorExprHelper, Result>;
IsErrorExprHelper() : Base{*this} {}
using Base::operator();
bool operator()(const SpecificIntrinsic &x) {
return x.name == IntrinsicProcTable::InvalidName;
}
};
template <typename A> bool IsErrorExpr(const A &x) {
return IsErrorExprHelper{}(x);
}
template bool IsErrorExpr(const Expr<SomeType> &);
} // namespace Fortran::evaluate
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