1 //===-- lib/Semantics/semantics.cpp ---------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "flang/Semantics/semantics.h"
10 #include "assignment.h"
11 #include "canonicalize-acc.h"
12 #include "canonicalize-do.h"
13 #include "canonicalize-omp.h"
14 #include "check-acc-structure.h"
15 #include "check-allocate.h"
16 #include "check-arithmeticif.h"
17 #include "check-case.h"
18 #include "check-coarray.h"
19 #include "check-data.h"
20 #include "check-deallocate.h"
21 #include "check-declarations.h"
22 #include "check-do-forall.h"
23 #include "check-if-stmt.h"
24 #include "check-io.h"
25 #include "check-namelist.h"
26 #include "check-nullify.h"
27 #include "check-omp-structure.h"
28 #include "check-purity.h"
29 #include "check-return.h"
30 #include "check-select-rank.h"
31 #include "check-select-type.h"
32 #include "check-stop.h"
33 #include "compute-offsets.h"
34 #include "mod-file.h"
35 #include "resolve-labels.h"
36 #include "resolve-names.h"
37 #include "rewrite-parse-tree.h"
38 #include "flang/Common/default-kinds.h"
39 #include "flang/Parser/parse-tree-visitor.h"
40 #include "flang/Parser/tools.h"
41 #include "flang/Semantics/expression.h"
42 #include "flang/Semantics/scope.h"
43 #include "flang/Semantics/symbol.h"
44 #include "llvm/Support/raw_ostream.h"
45 
46 namespace Fortran::semantics {
47 
48 using NameToSymbolMap = std::multimap<parser::CharBlock, SymbolRef>;
49 static void DoDumpSymbols(llvm::raw_ostream &, const Scope &, int indent = 0);
50 static void PutIndent(llvm::raw_ostream &, int indent);
51 
52 static void GetSymbolNames(const Scope &scope, NameToSymbolMap &symbols) {
53   // Finds all symbol names in the scope without collecting duplicates.
54   for (const auto &pair : scope) {
55     symbols.emplace(pair.second->name(), *pair.second);
56   }
57   for (const auto &pair : scope.commonBlocks()) {
58     symbols.emplace(pair.second->name(), *pair.second);
59   }
60   for (const auto &child : scope.children()) {
61     GetSymbolNames(child, symbols);
62   }
63 }
64 
65 // A parse tree visitor that calls Enter/Leave functions from each checker
66 // class C supplied as template parameters. Enter is called before the node's
67 // children are visited, Leave is called after. No two checkers may have the
68 // same Enter or Leave function. Each checker must be constructible from
69 // SemanticsContext and have BaseChecker as a virtual base class.
70 template <typename... C> class SemanticsVisitor : public virtual C... {
71 public:
72   using C::Enter...;
73   using C::Leave...;
74   using BaseChecker::Enter;
75   using BaseChecker::Leave;
76   SemanticsVisitor(SemanticsContext &context)
77       : C{context}..., context_{context} {}
78 
79   template <typename N> bool Pre(const N &node) {
80     if constexpr (common::HasMember<const N *, ConstructNode>) {
81       context_.PushConstruct(node);
82     }
83     Enter(node);
84     return true;
85   }
86   template <typename N> void Post(const N &node) {
87     Leave(node);
88     if constexpr (common::HasMember<const N *, ConstructNode>) {
89       context_.PopConstruct();
90     }
91   }
92 
93   template <typename T> bool Pre(const parser::Statement<T> &node) {
94     context_.set_location(node.source);
95     Enter(node);
96     return true;
97   }
98   template <typename T> bool Pre(const parser::UnlabeledStatement<T> &node) {
99     context_.set_location(node.source);
100     Enter(node);
101     return true;
102   }
103   template <typename T> void Post(const parser::Statement<T> &node) {
104     Leave(node);
105     context_.set_location(std::nullopt);
106   }
107   template <typename T> void Post(const parser::UnlabeledStatement<T> &node) {
108     Leave(node);
109     context_.set_location(std::nullopt);
110   }
111 
112   bool Walk(const parser::Program &program) {
113     parser::Walk(program, *this);
114     return !context_.AnyFatalError();
115   }
116 
117 private:
118   SemanticsContext &context_;
119 };
120 
121 class MiscChecker : public virtual BaseChecker {
122 public:
123   explicit MiscChecker(SemanticsContext &context) : context_{context} {}
124   void Leave(const parser::EntryStmt &) {
125     if (!context_.constructStack().empty()) { // C1571
126       context_.Say("ENTRY may not appear in an executable construct"_err_en_US);
127     }
128   }
129   void Leave(const parser::AssignStmt &stmt) {
130     CheckAssignGotoName(std::get<parser::Name>(stmt.t));
131   }
132   void Leave(const parser::AssignedGotoStmt &stmt) {
133     CheckAssignGotoName(std::get<parser::Name>(stmt.t));
134   }
135 
136 private:
137   void CheckAssignGotoName(const parser::Name &name) {
138     if (context_.HasError(name.symbol)) {
139       return;
140     }
141     const Symbol &symbol{DEREF(name.symbol)};
142     auto type{evaluate::DynamicType::From(symbol)};
143     if (!IsVariableName(symbol) || symbol.Rank() != 0 || !type ||
144         type->category() != TypeCategory::Integer ||
145         type->kind() !=
146             context_.defaultKinds().GetDefaultKind(TypeCategory::Integer)) {
147       context_
148           .Say(name.source,
149               "'%s' must be a default integer scalar variable"_err_en_US,
150               name.source)
151           .Attach(symbol.name(), "Declaration of '%s'"_en_US, symbol.name());
152     }
153   }
154 
155   SemanticsContext &context_;
156 };
157 
158 using StatementSemanticsPass1 = ExprChecker;
159 using StatementSemanticsPass2 = SemanticsVisitor<AccStructureChecker,
160     AllocateChecker, ArithmeticIfStmtChecker, AssignmentChecker, CaseChecker,
161     CoarrayChecker, DataChecker, DeallocateChecker, DoForallChecker,
162     IfStmtChecker, IoChecker, MiscChecker, NamelistChecker, NullifyChecker,
163     OmpStructureChecker, PurityChecker, ReturnStmtChecker,
164     SelectRankConstructChecker, SelectTypeChecker, StopChecker>;
165 
166 static bool PerformStatementSemantics(
167     SemanticsContext &context, parser::Program &program) {
168   ResolveNames(context, program);
169   RewriteParseTree(context, program);
170   ComputeOffsets(context, context.globalScope());
171   CheckDeclarations(context);
172   StatementSemanticsPass1{context}.Walk(program);
173   StatementSemanticsPass2 pass2{context};
174   pass2.Walk(program);
175   if (!context.AnyFatalError()) {
176     pass2.CompileDataInitializationsIntoInitializers();
177   }
178   return !context.AnyFatalError();
179 }
180 
181 SemanticsContext::SemanticsContext(
182     const common::IntrinsicTypeDefaultKinds &defaultKinds,
183     const common::LanguageFeatureControl &languageFeatures,
184     parser::AllCookedSources &allCookedSources)
185     : defaultKinds_{defaultKinds}, languageFeatures_{languageFeatures},
186       allCookedSources_{allCookedSources},
187       intrinsics_{evaluate::IntrinsicProcTable::Configure(defaultKinds_)},
188       globalScope_{*this}, foldingContext_{
189                                parser::ContextualMessages{&messages_},
190                                defaultKinds_, intrinsics_} {}
191 
192 SemanticsContext::~SemanticsContext() {}
193 
194 int SemanticsContext::GetDefaultKind(TypeCategory category) const {
195   return defaultKinds_.GetDefaultKind(category);
196 }
197 
198 bool SemanticsContext::IsEnabled(common::LanguageFeature feature) const {
199   return languageFeatures_.IsEnabled(feature);
200 }
201 
202 bool SemanticsContext::ShouldWarn(common::LanguageFeature feature) const {
203   return languageFeatures_.ShouldWarn(feature);
204 }
205 
206 const DeclTypeSpec &SemanticsContext::MakeNumericType(
207     TypeCategory category, int kind) {
208   if (kind == 0) {
209     kind = GetDefaultKind(category);
210   }
211   return globalScope_.MakeNumericType(category, KindExpr{kind});
212 }
213 const DeclTypeSpec &SemanticsContext::MakeLogicalType(int kind) {
214   if (kind == 0) {
215     kind = GetDefaultKind(TypeCategory::Logical);
216   }
217   return globalScope_.MakeLogicalType(KindExpr{kind});
218 }
219 
220 bool SemanticsContext::AnyFatalError() const {
221   return !messages_.empty() &&
222       (warningsAreErrors_ || messages_.AnyFatalError());
223 }
224 bool SemanticsContext::HasError(const Symbol &symbol) {
225   return errorSymbols_.count(symbol) > 0;
226 }
227 bool SemanticsContext::HasError(const Symbol *symbol) {
228   return !symbol || HasError(*symbol);
229 }
230 bool SemanticsContext::HasError(const parser::Name &name) {
231   return HasError(name.symbol);
232 }
233 void SemanticsContext::SetError(const Symbol &symbol, bool value) {
234   if (value) {
235     CheckError(symbol);
236     errorSymbols_.emplace(symbol);
237   }
238 }
239 void SemanticsContext::CheckError(const Symbol &symbol) {
240   if (!AnyFatalError()) {
241     std::string buf;
242     llvm::raw_string_ostream ss{buf};
243     ss << symbol;
244     common::die(
245         "No error was reported but setting error on: %s", ss.str().c_str());
246   }
247 }
248 
249 const Scope &SemanticsContext::FindScope(parser::CharBlock source) const {
250   return const_cast<SemanticsContext *>(this)->FindScope(source);
251 }
252 
253 Scope &SemanticsContext::FindScope(parser::CharBlock source) {
254   if (auto *scope{globalScope_.FindScope(source)}) {
255     return *scope;
256   } else {
257     common::die("SemanticsContext::FindScope(): invalid source location");
258   }
259 }
260 
261 void SemanticsContext::PopConstruct() {
262   CHECK(!constructStack_.empty());
263   constructStack_.pop_back();
264 }
265 
266 void SemanticsContext::CheckIndexVarRedefine(const parser::CharBlock &location,
267     const Symbol &variable, parser::MessageFixedText &&message) {
268   const Symbol &symbol{ResolveAssociations(variable)};
269   auto it{activeIndexVars_.find(symbol)};
270   if (it != activeIndexVars_.end()) {
271     std::string kind{EnumToString(it->second.kind)};
272     Say(location, std::move(message), kind, symbol.name())
273         .Attach(it->second.location, "Enclosing %s construct"_en_US, kind);
274   }
275 }
276 
277 void SemanticsContext::WarnIndexVarRedefine(
278     const parser::CharBlock &location, const Symbol &variable) {
279   CheckIndexVarRedefine(
280       location, variable, "Possible redefinition of %s variable '%s'"_en_US);
281 }
282 
283 void SemanticsContext::CheckIndexVarRedefine(
284     const parser::CharBlock &location, const Symbol &variable) {
285   CheckIndexVarRedefine(
286       location, variable, "Cannot redefine %s variable '%s'"_err_en_US);
287 }
288 
289 void SemanticsContext::CheckIndexVarRedefine(const parser::Variable &variable) {
290   if (const Symbol * entity{GetLastName(variable).symbol}) {
291     CheckIndexVarRedefine(variable.GetSource(), *entity);
292   }
293 }
294 
295 void SemanticsContext::CheckIndexVarRedefine(const parser::Name &name) {
296   if (const Symbol * entity{name.symbol}) {
297     CheckIndexVarRedefine(name.source, *entity);
298   }
299 }
300 
301 void SemanticsContext::ActivateIndexVar(
302     const parser::Name &name, IndexVarKind kind) {
303   CheckIndexVarRedefine(name);
304   if (const Symbol * indexVar{name.symbol}) {
305     activeIndexVars_.emplace(
306         ResolveAssociations(*indexVar), IndexVarInfo{name.source, kind});
307   }
308 }
309 
310 void SemanticsContext::DeactivateIndexVar(const parser::Name &name) {
311   if (Symbol * indexVar{name.symbol}) {
312     auto it{activeIndexVars_.find(ResolveAssociations(*indexVar))};
313     if (it != activeIndexVars_.end() && it->second.location == name.source) {
314       activeIndexVars_.erase(it);
315     }
316   }
317 }
318 
319 SymbolVector SemanticsContext::GetIndexVars(IndexVarKind kind) {
320   SymbolVector result;
321   for (const auto &[symbol, info] : activeIndexVars_) {
322     if (info.kind == kind) {
323       result.push_back(symbol);
324     }
325   }
326   return result;
327 }
328 
329 SourceName SemanticsContext::SaveTempName(std::string &&name) {
330   return {*tempNames_.emplace(std::move(name)).first};
331 }
332 
333 SourceName SemanticsContext::GetTempName(const Scope &scope) {
334   for (const auto &str : tempNames_) {
335     if (str.size() > 5 && str.substr(0, 5) == ".F18.") {
336       SourceName name{str};
337       if (scope.find(name) == scope.end()) {
338         return name;
339       }
340     }
341   }
342   return SaveTempName(".F18."s + std::to_string(tempNames_.size()));
343 }
344 
345 Scope *SemanticsContext::GetBuiltinModule(const char *name) {
346   return ModFileReader{*this}.Read(
347       SourceName{name, std::strlen(name)}, nullptr, true /*silence errors*/);
348 }
349 
350 void SemanticsContext::UseFortranBuiltinsModule() {
351   if (builtinsScope_ == nullptr) {
352     builtinsScope_ = GetBuiltinModule("__fortran_builtins");
353     if (builtinsScope_) {
354       intrinsics_.SupplyBuiltins(*builtinsScope_);
355     }
356   }
357 }
358 
359 bool Semantics::Perform() {
360   // Implicitly USE the __Fortran_builtins module so that special types
361   // (e.g., __builtin_team_type) are available to semantics, esp. for
362   // intrinsic checking.
363   if (!program_.v.empty()) {
364     const auto *frontModule{std::get_if<common::Indirection<parser::Module>>(
365         &program_.v.front().u)};
366     if (frontModule &&
367         std::get<parser::Statement<parser::ModuleStmt>>(frontModule->value().t)
368                 .statement.v.source == "__fortran_builtins") {
369       // Don't try to read the builtins module when we're actually building it.
370     } else {
371       context_.UseFortranBuiltinsModule();
372     }
373   }
374   return ValidateLabels(context_, program_) &&
375       parser::CanonicalizeDo(program_) && // force line break
376       CanonicalizeAcc(context_.messages(), program_) &&
377       CanonicalizeOmp(context_.messages(), program_) &&
378       PerformStatementSemantics(context_, program_) &&
379       ModFileWriter{context_}.WriteAll();
380 }
381 
382 void Semantics::EmitMessages(llvm::raw_ostream &os) const {
383   context_.messages().Emit(os, context_.allCookedSources());
384 }
385 
386 void Semantics::DumpSymbols(llvm::raw_ostream &os) {
387   DoDumpSymbols(os, context_.globalScope());
388 }
389 
390 void Semantics::DumpSymbolsSources(llvm::raw_ostream &os) const {
391   NameToSymbolMap symbols;
392   GetSymbolNames(context_.globalScope(), symbols);
393   const parser::AllCookedSources &allCooked{context_.allCookedSources()};
394   for (const auto &pair : symbols) {
395     const Symbol &symbol{pair.second};
396     if (auto sourceInfo{allCooked.GetSourcePositionRange(symbol.name())}) {
397       os << symbol.name().ToString() << ": " << sourceInfo->first.file.path()
398          << ", " << sourceInfo->first.line << ", " << sourceInfo->first.column
399          << "-" << sourceInfo->second.column << "\n";
400     } else if (symbol.has<semantics::UseDetails>()) {
401       os << symbol.name().ToString() << ": "
402          << symbol.GetUltimate().owner().symbol()->name().ToString() << "\n";
403     }
404   }
405 }
406 
407 void DoDumpSymbols(llvm::raw_ostream &os, const Scope &scope, int indent) {
408   PutIndent(os, indent);
409   os << Scope::EnumToString(scope.kind()) << " scope:";
410   if (const auto *symbol{scope.symbol()}) {
411     os << ' ' << symbol->name();
412   }
413   if (scope.alignment().has_value()) {
414     os << " size=" << scope.size() << " alignment=" << *scope.alignment();
415   }
416   if (scope.derivedTypeSpec()) {
417     os << " instantiation of " << *scope.derivedTypeSpec();
418   }
419   os << '\n';
420   ++indent;
421   for (const auto &pair : scope) {
422     const auto &symbol{*pair.second};
423     PutIndent(os, indent);
424     os << symbol << '\n';
425     if (const auto *details{symbol.detailsIf<GenericDetails>()}) {
426       if (const auto &type{details->derivedType()}) {
427         PutIndent(os, indent);
428         os << *type << '\n';
429       }
430     }
431   }
432   if (!scope.equivalenceSets().empty()) {
433     PutIndent(os, indent);
434     os << "Equivalence Sets:";
435     for (const auto &set : scope.equivalenceSets()) {
436       os << ' ';
437       char sep = '(';
438       for (const auto &object : set) {
439         os << sep << object.AsFortran();
440         sep = ',';
441       }
442       os << ')';
443     }
444     os << '\n';
445   }
446   if (!scope.crayPointers().empty()) {
447     PutIndent(os, indent);
448     os << "Cray Pointers:";
449     for (const auto &[pointee, pointer] : scope.crayPointers()) {
450       os << " (" << pointer->name() << ',' << pointee << ')';
451     }
452   }
453   for (const auto &pair : scope.commonBlocks()) {
454     const auto &symbol{*pair.second};
455     PutIndent(os, indent);
456     os << symbol << '\n';
457   }
458   for (const auto &child : scope.children()) {
459     DoDumpSymbols(os, child, indent);
460   }
461   --indent;
462 }
463 
464 static void PutIndent(llvm::raw_ostream &os, int indent) {
465   for (int i = 0; i < indent; ++i) {
466     os << "  ";
467   }
468 }
469 } // namespace Fortran::semantics
470