//===-- lib/Semantics/check-cuda.cpp ----------------------------*- C++ -*-===//
//
// 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 "check-cuda.h"
#include "flang/Common/template.h"
#include "flang/Evaluate/fold.h"
#include "flang/Evaluate/tools.h"
#include "flang/Evaluate/traverse.h"
#include "flang/Parser/parse-tree-visitor.h"
#include "flang/Parser/parse-tree.h"
#include "flang/Parser/tools.h"
#include "flang/Semantics/expression.h"
#include "flang/Semantics/symbol.h"
#include "flang/Semantics/tools.h"
// Once labeled DO constructs have been canonicalized and their parse subtrees
// transformed into parser::DoConstructs, scan the parser::Blocks of the program
// and merge adjacent CUFKernelDoConstructs and DoConstructs whenever the
// CUFKernelDoConstruct doesn't already have an embedded DoConstruct. Also
// emit errors about improper or missing DoConstructs.
namespace Fortran::parser {
struct Mutator {
template <typename A> bool Pre(A &) { return true; }
template <typename A> void Post(A &) {}
bool Pre(Block &);
};
bool Mutator::Pre(Block &block) {
for (auto iter{block.begin()}; iter != block.end(); ++iter) {
if (auto *kernel{Unwrap<CUFKernelDoConstruct>(*iter)}) {
auto &nested{std::get<std::optional<DoConstruct>>(kernel->t)};
if (!nested) {
if (auto next{iter}; ++next != block.end()) {
if (auto *doConstruct{Unwrap<DoConstruct>(*next)}) {
nested = std::move(*doConstruct);
block.erase(next);
}
}
}
} else {
Walk(*iter, *this);
}
}
return false;
}
} // namespace Fortran::parser
namespace Fortran::semantics {
bool CanonicalizeCUDA(parser::Program &program) {
parser::Mutator mutator;
parser::Walk(program, mutator);
return true;
}
using MaybeMsg = std::optional<parser::MessageFormattedText>;
// Traverses an evaluate::Expr<> in search of unsupported operations
// on the device.
struct DeviceExprChecker
: public evaluate::AnyTraverse<DeviceExprChecker, MaybeMsg> {
using Result = MaybeMsg;
using Base = evaluate::AnyTraverse<DeviceExprChecker, Result>;
DeviceExprChecker() : Base(*this) {}
using Base::operator();
Result operator()(const evaluate::ProcedureDesignator &x) const {
if (const Symbol * sym{x.GetInterfaceSymbol()}) {
const auto *subp{
sym->GetUltimate().detailsIf<semantics::SubprogramDetails>()};
if (subp) {
if (auto attrs{subp->cudaSubprogramAttrs()}) {
if (*attrs == common::CUDASubprogramAttrs::HostDevice ||
*attrs == common::CUDASubprogramAttrs::Device) {
return {};
}
}
}
} else if (x.GetSpecificIntrinsic()) {
// TODO(CUDA): Check for unsupported intrinsics here
return {};
}
return parser::MessageFormattedText(
"'%s' may not be called in device code"_err_en_US, x.GetName());
}
};
template <typename A> static MaybeMsg CheckUnwrappedExpr(const A &x) {
if (const auto *expr{parser::Unwrap<parser::Expr>(x)}) {
return DeviceExprChecker{}(expr->typedExpr);
}
return {};
}
template <typename A>
static void CheckUnwrappedExpr(
SemanticsContext &context, SourceName at, const A &x) {
if (const auto *expr{parser::Unwrap<parser::Expr>(x)}) {
if (auto msg{DeviceExprChecker{}(expr->typedExpr)}) {
context.Say(at, std::move(*msg));
}
}
}
template <bool CUF_KERNEL> struct ActionStmtChecker {
template <typename A> static MaybeMsg WhyNotOk(const A &x) {
if constexpr (ConstraintTrait<A>) {
return WhyNotOk(x.thing);
} else if constexpr (WrapperTrait<A>) {
return WhyNotOk(x.v);
} else if constexpr (UnionTrait<A>) {
return WhyNotOk(x.u);
} else if constexpr (TupleTrait<A>) {
return WhyNotOk(x.t);
} else {
return parser::MessageFormattedText{
"Statement may not appear in device code"_err_en_US};
}
}
template <typename A>
static MaybeMsg WhyNotOk(const common::Indirection<A> &x) {
return WhyNotOk(x.value());
}
template <typename... As>
static MaybeMsg WhyNotOk(const std::variant<As...> &x) {
return common::visit([](const auto &x) { return WhyNotOk(x); }, x);
}
template <std::size_t J = 0, typename... As>
static MaybeMsg WhyNotOk(const std::tuple<As...> &x) {
if constexpr (J == sizeof...(As)) {
return {};
} else if (auto msg{WhyNotOk(std::get<J>(x))}) {
return msg;
} else {
return WhyNotOk<(J + 1)>(x);
}
}
template <typename A> static MaybeMsg WhyNotOk(const std::list<A> &x) {
for (const auto &y : x) {
if (MaybeMsg result{WhyNotOk(y)}) {
return result;
}
}
return {};
}
template <typename A> static MaybeMsg WhyNotOk(const std::optional<A> &x) {
if (x) {
return WhyNotOk(*x);
} else {
return {};
}
}
template <typename A>
static MaybeMsg WhyNotOk(const parser::UnlabeledStatement<A> &x) {
return WhyNotOk(x.statement);
}
template <typename A>
static MaybeMsg WhyNotOk(const parser::Statement<A> &x) {
return WhyNotOk(x.statement);
}
static MaybeMsg WhyNotOk(const parser::AllocateStmt &) {
return {}; // AllocateObjects are checked elsewhere
}
static MaybeMsg WhyNotOk(const parser::AllocateCoarraySpec &) {
return parser::MessageFormattedText(
"A coarray may not be allocated on the device"_err_en_US);
}
static MaybeMsg WhyNotOk(const parser::DeallocateStmt &) {
return {}; // AllocateObjects are checked elsewhere
}
static MaybeMsg WhyNotOk(const parser::AssignmentStmt &x) {
return DeviceExprChecker{}(x.typedAssignment);
}
static MaybeMsg WhyNotOk(const parser::CallStmt &x) {
return DeviceExprChecker{}(x.typedCall);
}
static MaybeMsg WhyNotOk(const parser::ContinueStmt &) { return {}; }
static MaybeMsg WhyNotOk(const parser::IfStmt &x) {
if (auto result{
CheckUnwrappedExpr(std::get<parser::ScalarLogicalExpr>(x.t))}) {
return result;
}
return WhyNotOk(
std::get<parser::UnlabeledStatement<parser::ActionStmt>>(x.t)
.statement);
}
static MaybeMsg WhyNotOk(const parser::NullifyStmt &x) {
for (const auto &y : x.v) {
if (MaybeMsg result{DeviceExprChecker{}(y.typedExpr)}) {
return result;
}
}
return {};
}
static MaybeMsg WhyNotOk(const parser::PointerAssignmentStmt &x) {
return DeviceExprChecker{}(x.typedAssignment);
}
};
template <bool IsCUFKernelDo> class DeviceContextChecker {
public:
explicit DeviceContextChecker(SemanticsContext &c) : context_{c} {}
void CheckSubprogram(const parser::Name &name, const parser::Block &body) {
if (name.symbol) {
const auto *subp{
name.symbol->GetUltimate().detailsIf<SubprogramDetails>()};
if (subp && subp->moduleInterface()) {
subp = subp->moduleInterface()
->GetUltimate()
.detailsIf<SubprogramDetails>();
}
if (subp &&
subp->cudaSubprogramAttrs().value_or(
common::CUDASubprogramAttrs::Host) !=
common::CUDASubprogramAttrs::Host) {
Check(body);
}
}
}
void Check(const parser::Block &block) {
for (const auto &epc : block) {
Check(epc);
}
}
private:
void Check(const parser::ExecutionPartConstruct &epc) {
common::visit(
common::visitors{
[&](const parser::ExecutableConstruct &x) { Check(x); },
[&](const parser::Statement<common::Indirection<parser::EntryStmt>>
&x) {
context_.Say(x.source,
"Device code may not contain an ENTRY statement"_err_en_US);
},
[](const parser::Statement<common::Indirection<parser::FormatStmt>>
&) {},
[](const parser::Statement<common::Indirection<parser::DataStmt>>
&) {},
[](const parser::Statement<
common::Indirection<parser::NamelistStmt>> &) {},
[](const parser::ErrorRecovery &) {},
},
epc.u);
}
void Check(const parser::ExecutableConstruct &ec) {
common::visit(
common::visitors{
[&](const parser::Statement<parser::ActionStmt> &stmt) {
Check(stmt.statement, stmt.source);
},
[&](const common::Indirection<parser::DoConstruct> &x) {
if (const std::optional<parser::LoopControl> &control{
x.value().GetLoopControl()}) {
common::visit([&](const auto &y) { Check(y); }, control->u);
}
Check(std::get<parser::Block>(x.value().t));
},
[&](const common::Indirection<parser::BlockConstruct> &x) {
Check(std::get<parser::Block>(x.value().t));
},
[&](const common::Indirection<parser::IfConstruct> &x) {
Check(x.value());
},
[&](const auto &x) {
if (auto source{parser::GetSource(x)}) {
context_.Say(*source,
"Statement may not appear in device code"_err_en_US);
}
},
},
ec.u);
}
template <typename SEEK, typename A>
static const SEEK *GetIOControl(const A &stmt) {
for (const auto &spec : stmt.controls) {
if (const auto *result{std::get_if<SEEK>(&spec.u)}) {
return result;
}
}
return nullptr;
}
template <typename A> static bool IsInternalIO(const A &stmt) {
if (stmt.iounit.has_value()) {
return std::holds_alternative<Fortran::parser::Variable>(stmt.iounit->u);
}
if (auto *unit{GetIOControl<Fortran::parser::IoUnit>(stmt)}) {
return std::holds_alternative<Fortran::parser::Variable>(unit->u);
}
return false;
}
void WarnOnIoStmt(const parser::CharBlock &source) {
context_.Warn(common::UsageWarning::CUDAUsage, source,
"I/O statement might not be supported on device"_warn_en_US);
}
template <typename A>
void WarnIfNotInternal(const A &stmt, const parser::CharBlock &source) {
if (!IsInternalIO(stmt)) {
WarnOnIoStmt(source);
}
}
template <typename A>
void ErrorIfHostSymbol(const A &expr, const parser::CharBlock &source) {
for (const Symbol &sym : CollectCudaSymbols(expr)) {
if (const auto *details =
sym.GetUltimate().detailsIf<semantics::ObjectEntityDetails>()) {
if (details->IsArray() &&
(!details->cudaDataAttr() ||
(details->cudaDataAttr() &&
*details->cudaDataAttr() != common::CUDADataAttr::Device &&
*details->cudaDataAttr() != common::CUDADataAttr::Managed &&
*details->cudaDataAttr() !=
common::CUDADataAttr::Unified))) {
context_.Say(source,
"Host array '%s' cannot be present in CUF kernel"_err_en_US,
sym.name());
}
}
}
}
void Check(const parser::ActionStmt &stmt, const parser::CharBlock &source) {
common::visit(
common::visitors{
[&](const common::Indirection<parser::PrintStmt> &) {},
[&](const common::Indirection<parser::WriteStmt> &x) {
if (x.value().format) { // Formatted write to '*' or '6'
if (std::holds_alternative<Fortran::parser::Star>(
x.value().format->u)) {
if (x.value().iounit) {
if (std::holds_alternative<Fortran::parser::Star>(
x.value().iounit->u)) {
return;
}
}
}
}
WarnIfNotInternal(x.value(), source);
},
[&](const common::Indirection<parser::CloseStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::EndfileStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::OpenStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::ReadStmt> &x) {
WarnIfNotInternal(x.value(), source);
},
[&](const common::Indirection<parser::InquireStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::RewindStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::BackspaceStmt> &x) {
WarnOnIoStmt(source);
},
[&](const common::Indirection<parser::IfStmt> &x) {
Check(x.value());
},
[&](const common::Indirection<parser::AssignmentStmt> &x) {
if (IsCUFKernelDo) {
const evaluate::Assignment *assign{
semantics::GetAssignment(x.value())};
if (assign) {
ErrorIfHostSymbol(assign->lhs, source);
ErrorIfHostSymbol(assign->rhs, source);
}
}
if (auto msg{ActionStmtChecker<IsCUFKernelDo>::WhyNotOk(x)}) {
context_.Say(source, std::move(*msg));
}
},
[&](const auto &x) {
if (auto msg{ActionStmtChecker<IsCUFKernelDo>::WhyNotOk(x)}) {
context_.Say(source, std::move(*msg));
}
},
},
stmt.u);
}
void Check(const parser::IfConstruct &ic) {
const auto &ifS{std::get<parser::Statement<parser::IfThenStmt>>(ic.t)};
CheckUnwrappedExpr(context_, ifS.source,
std::get<parser::ScalarLogicalExpr>(ifS.statement.t));
Check(std::get<parser::Block>(ic.t));
for (const auto &eib :
std::get<std::list<parser::IfConstruct::ElseIfBlock>>(ic.t)) {
const auto &eIfS{std::get<parser::Statement<parser::ElseIfStmt>>(eib.t)};
CheckUnwrappedExpr(context_, eIfS.source,
std::get<parser::ScalarLogicalExpr>(eIfS.statement.t));
Check(std::get<parser::Block>(eib.t));
}
if (const auto &eb{
std::get<std::optional<parser::IfConstruct::ElseBlock>>(ic.t)}) {
Check(std::get<parser::Block>(eb->t));
}
}
void Check(const parser::IfStmt &is) {
const auto &uS{
std::get<parser::UnlabeledStatement<parser::ActionStmt>>(is.t)};
CheckUnwrappedExpr(
context_, uS.source, std::get<parser::ScalarLogicalExpr>(is.t));
Check(uS.statement, uS.source);
}
void Check(const parser::LoopControl::Bounds &bounds) {
Check(bounds.lower);
Check(bounds.upper);
if (bounds.step) {
Check(*bounds.step);
}
}
void Check(const parser::LoopControl::Concurrent &x) {
const auto &header{std::get<parser::ConcurrentHeader>(x.t)};
for (const auto &cc :
std::get<std::list<parser::ConcurrentControl>>(header.t)) {
Check(std::get<1>(cc.t));
Check(std::get<2>(cc.t));
if (const auto &step{
std::get<std::optional<parser::ScalarIntExpr>>(cc.t)}) {
Check(*step);
}
}
if (const auto &mask{
std::get<std::optional<parser::ScalarLogicalExpr>>(header.t)}) {
Check(*mask);
}
}
void Check(const parser::ScalarLogicalExpr &x) {
Check(DEREF(parser::Unwrap<parser::Expr>(x)));
}
void Check(const parser::ScalarIntExpr &x) {
Check(DEREF(parser::Unwrap<parser::Expr>(x)));
}
void Check(const parser::ScalarExpr &x) {
Check(DEREF(parser::Unwrap<parser::Expr>(x)));
}
void Check(const parser::Expr &expr) {
if (MaybeMsg msg{DeviceExprChecker{}(expr.typedExpr)}) {
context_.Say(expr.source, std::move(*msg));
}
}
SemanticsContext &context_;
};
void CUDAChecker::Enter(const parser::SubroutineSubprogram &x) {
DeviceContextChecker<false>{context_}.CheckSubprogram(
std::get<parser::Name>(
std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t),
std::get<parser::ExecutionPart>(x.t).v);
}
void CUDAChecker::Enter(const parser::FunctionSubprogram &x) {
DeviceContextChecker<false>{context_}.CheckSubprogram(
std::get<parser::Name>(
std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t),
std::get<parser::ExecutionPart>(x.t).v);
}
void CUDAChecker::Enter(const parser::SeparateModuleSubprogram &x) {
DeviceContextChecker<false>{context_}.CheckSubprogram(
std::get<parser::Statement<parser::MpSubprogramStmt>>(x.t).statement.v,
std::get<parser::ExecutionPart>(x.t).v);
}
// !$CUF KERNEL DO semantic checks
static int DoConstructTightNesting(
const parser::DoConstruct *doConstruct, const parser::Block *&innerBlock) {
if (!doConstruct || !doConstruct->IsDoNormal()) {
return 0;
}
innerBlock = &std::get<parser::Block>(doConstruct->t);
if (innerBlock->size() == 1) {
if (const auto *execConstruct{
std::get_if<parser::ExecutableConstruct>(&innerBlock->front().u)}) {
if (const auto *next{
std::get_if<common::Indirection<parser::DoConstruct>>(
&execConstruct->u)}) {
return 1 + DoConstructTightNesting(&next->value(), innerBlock);
}
}
}
return 1;
}
static void CheckReduce(
SemanticsContext &context, const parser::CUFReduction &reduce) {
auto op{std::get<parser::CUFReduction::Operator>(reduce.t).v};
for (const auto &var :
std::get<std::list<parser::Scalar<parser::Variable>>>(reduce.t)) {
if (const auto &typedExprPtr{var.thing.typedExpr};
typedExprPtr && typedExprPtr->v) {
const auto &expr{*typedExprPtr->v};
if (auto type{expr.GetType()}) {
auto cat{type->category()};
bool isOk{false};
switch (op) {
case parser::ReductionOperator::Operator::Plus:
case parser::ReductionOperator::Operator::Multiply:
case parser::ReductionOperator::Operator::Max:
case parser::ReductionOperator::Operator::Min:
isOk = cat == TypeCategory::Integer || cat == TypeCategory::Real;
break;
case parser::ReductionOperator::Operator::Iand:
case parser::ReductionOperator::Operator::Ior:
case parser::ReductionOperator::Operator::Ieor:
isOk = cat == TypeCategory::Integer;
break;
case parser::ReductionOperator::Operator::And:
case parser::ReductionOperator::Operator::Or:
case parser::ReductionOperator::Operator::Eqv:
case parser::ReductionOperator::Operator::Neqv:
isOk = cat == TypeCategory::Logical;
break;
}
if (!isOk) {
context.Say(var.thing.GetSource(),
"!$CUF KERNEL DO REDUCE operation is not acceptable for a variable with type %s"_err_en_US,
type->AsFortran());
}
}
}
}
}
void CUDAChecker::Enter(const parser::CUFKernelDoConstruct &x) {
auto source{std::get<parser::CUFKernelDoConstruct::Directive>(x.t).source};
const auto &directive{std::get<parser::CUFKernelDoConstruct::Directive>(x.t)};
std::int64_t depth{1};
if (auto expr{AnalyzeExpr(context_,
std::get<std::optional<parser::ScalarIntConstantExpr>>(
directive.t))}) {
depth = evaluate::ToInt64(expr).value_or(0);
if (depth <= 0) {
context_.Say(source,
"!$CUF KERNEL DO (%jd): loop nesting depth must be positive"_err_en_US,
std::intmax_t{depth});
depth = 1;
}
}
const parser::DoConstruct *doConstruct{common::GetPtrFromOptional(
std::get<std::optional<parser::DoConstruct>>(x.t))};
const parser::Block *innerBlock{nullptr};
if (DoConstructTightNesting(doConstruct, innerBlock) < depth) {
context_.Say(source,
"!$CUF KERNEL DO (%jd) must be followed by a DO construct with tightly nested outer levels of counted DO loops"_err_en_US,
std::intmax_t{depth});
}
if (innerBlock) {
DeviceContextChecker<true>{context_}.Check(*innerBlock);
}
for (const auto &reduce :
std::get<std::list<parser::CUFReduction>>(directive.t)) {
CheckReduce(context_, reduce);
}
inCUFKernelDoConstruct_ = true;
}
void CUDAChecker::Leave(const parser::CUFKernelDoConstruct &) {
inCUFKernelDoConstruct_ = false;
}
void CUDAChecker::Enter(const parser::AssignmentStmt &x) {
auto lhsLoc{std::get<parser::Variable>(x.t).GetSource()};
const auto &scope{context_.FindScope(lhsLoc)};
const Scope &progUnit{GetProgramUnitContaining(scope)};
if (IsCUDADeviceContext(&progUnit) || inCUFKernelDoConstruct_) {
return; // Data transfer with assignment is only perform on host.
}
const evaluate::Assignment *assign{semantics::GetAssignment(x)};
if (!assign) {
return;
}
int nbLhs{evaluate::GetNbOfCUDADeviceSymbols(assign->lhs)};
int nbRhs{evaluate::GetNbOfCUDADeviceSymbols(assign->rhs)};
// device to host transfer with more than one device object on the rhs is not
// legal.
if (nbLhs == 0 && nbRhs > 1) {
context_.Say(lhsLoc,
"More than one reference to a CUDA object on the right hand side of the assigment"_err_en_US);
}
}
} // namespace Fortran::semantics
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