source: src/Virtual/ExpandCasts.cc@ 056bee8

ADT ast-experimental
Last change on this file since 056bee8 was 0026d67, checked in by Andrew Beach <ajbeach@…>, 3 years ago

Replaced Mangle::typeMode() with Mangle::mangleType(...), as it is how typeMode() was always used and it is shorter. Various other clean-up in the Mangler files.
  • Property mode set to 100644
File size: 15.8 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// ExpandCasts.cc --
8//
9// Author : Andrew Beach
10// Created On : Mon Jul 24 13:59:00 2017
11// Last Modified By : Andrew Beach
12// Last Modified On : Thu Aug 11 12:06:00 2022
13// Update Count : 5
14//
15
16#include "ExpandCasts.h"
17
18#include <cassert> // for assert, assertf
19#include <iterator> // for back_inserter, inserter
20#include <string> // for string, allocator, operator==, ope...
21
22#include "AST/Decl.hpp"
23#include "AST/Expr.hpp"
24#include "AST/Pass.hpp"
25#include "Common/PassVisitor.h" // for PassVisitor
26#include "Common/ScopedMap.h" // for ScopedMap
27#include "Common/SemanticError.h" // for SemanticError
28#include "SymTab/Mangler.h" // for mangleType
29#include "SynTree/Declaration.h" // for ObjectDecl, StructDecl, FunctionDecl
30#include "SynTree/Expression.h" // for VirtualCastExpr, CastExpr, Address...
31#include "SynTree/Mutator.h" // for mutateAll
32#include "SynTree/Type.h" // for Type, PointerType, StructInstType
33#include "SynTree/Visitor.h" // for acceptAll
34
35namespace Virtual {
36
37namespace {
38
39bool is_prefix( const std::string & prefix, const std::string& entire ) {
40 size_t const p_size = prefix.size();
41 return (p_size < entire.size() && prefix == entire.substr(0, p_size));
42}
43
44bool is_type_id_object( const ObjectDecl * objectDecl ) {
45 const std::string & objectName = objectDecl->name;
46 return is_prefix( "__cfatid_", objectName );
47}
48
49bool is_type_id_object( const ast::ObjectDecl * decl ) {
50 return is_prefix( "__cfatid_", decl->name );
51}
52
53 // Indented until the new ast code gets added.
54
55 /// Maps virtual table types the instance for that type.
56 class VirtualTableMap final {
57 ScopedMap<std::string, ObjectDecl *> vtable_instances;
58 public:
59 void enterScope() {
60 vtable_instances.beginScope();
61 }
62 void leaveScope() {
63 vtable_instances.endScope();
64 }
65
66 ObjectDecl * insert( ObjectDecl * vtableDecl ) {
67 std::string const & mangledName = SymTab::Mangler::mangleType( vtableDecl->type );
68 ObjectDecl *& value = vtable_instances[ mangledName ];
69 if ( value ) {
70 if ( vtableDecl->storageClasses.is_extern ) {
71 return nullptr;
72 } else if ( ! value->storageClasses.is_extern ) {
73 return value;
74 }
75 }
76 value = vtableDecl;
77 return nullptr;
78 }
79
80 ObjectDecl * lookup( const Type * vtableType ) {
81 std::string const & mangledName = SymTab::Mangler::mangleType( vtableType );
82 const auto it = vtable_instances.find( mangledName );
83 return ( vtable_instances.end() == it ) ? nullptr : it->second;
84 }
85 };
86
87 class VirtualCastCore {
88 CastExpr * cast_to_type_id( Expression * expr, int level_of_indirection ) {
89 Type * type = new StructInstType(
90 Type::Qualifiers( Type::Const ), pvt_decl );
91 for (int i = 0 ; i < level_of_indirection ; ++i) {
92 type = new PointerType( noQualifiers, type );
93 }
94 return new CastExpr( expr, type );
95 }
96
97 public:
98 VirtualCastCore() :
99 indexer(), vcast_decl( nullptr ), pvt_decl( nullptr )
100 {}
101
102 void premutate( FunctionDecl * functionDecl );
103 void premutate( StructDecl * structDecl );
104 void premutate( ObjectDecl * objectDecl );
105
106 Expression * postmutate( VirtualCastExpr * castExpr );
107
108 VirtualTableMap indexer;
109 private:
110 FunctionDecl *vcast_decl;
111 StructDecl *pvt_decl;
112 };
113
114 void VirtualCastCore::premutate( FunctionDecl * functionDecl ) {
115 if ( (! vcast_decl) &&
116 functionDecl->get_name() == "__cfavir_virtual_cast" ) {
117 vcast_decl = functionDecl;
118 }
119 }
120
121 void VirtualCastCore::premutate( StructDecl * structDecl ) {
122 if ( pvt_decl || ! structDecl->has_body() ) {
123 return;
124 } else if ( structDecl->get_name() == "__cfavir_type_info" ) {
125 pvt_decl = structDecl;
126 }
127 }
128
129 void VirtualCastCore::premutate( ObjectDecl * objectDecl ) {
130 if ( is_type_id_object( objectDecl ) ) {
131 // Multiple definitions should be fine because of linkonce.
132 indexer.insert( objectDecl );
133 }
134 }
135
136 /// Better error locations for generated casts.
137 CodeLocation castLocation( const VirtualCastExpr * castExpr ) {
138 if ( castExpr->location.isSet() ) {
139 return castExpr->location;
140 } else if ( castExpr->arg->location.isSet() ) {
141 return castExpr->arg->location;
142 } else if ( castExpr->result->location.isSet() ) {
143 return castExpr->result->location;
144 } else {
145 return CodeLocation();
146 }
147 }
148
149 [[noreturn]] void castError( const VirtualCastExpr * castExpr, std::string const & message ) {
150 SemanticError( castLocation( castExpr ), message );
151 }
152
153 /// Get the base type from a pointer or reference.
154 const Type * getBaseType( const Type * type ) {
155 if ( auto target = dynamic_cast<const PointerType *>( type ) ) {
156 return target->base;
157 } else if ( auto target = dynamic_cast<const ReferenceType *>( type ) ) {
158 return target->base;
159 } else {
160 return nullptr;
161 }
162 }
163
164 /* Attempt to follow the "head" field of the structure to get the...
165 * Returns nullptr on error, otherwise owner must free returned node.
166 */
167 StructInstType * followHeadPointerType(
168 const StructInstType * oldType,
169 const std::string& fieldName,
170 const CodeLocation& errorLocation ) {
171
172 // First section of the function is all about trying to fill this variable in.
173 StructInstType * newType = nullptr;
174 {
175 const StructDecl * oldDecl = oldType->baseStruct;
176 assert( oldDecl );
177
178 // Helper function for throwing semantic errors.
179 auto throwError = [&fieldName, &errorLocation, &oldDecl](const std::string& message) {
180 const std::string& context = "While following head pointer of " +
181 oldDecl->name + " named '" + fieldName + "': ";
182 SemanticError( errorLocation, context + message );
183 };
184
185 if ( oldDecl->members.empty() ) {
186 throwError( "Type has no fields." );
187 }
188 const Declaration * memberDecl = oldDecl->members.front();
189 assert( memberDecl );
190 const ObjectDecl * fieldDecl = dynamic_cast<const ObjectDecl *>( memberDecl );
191 assert( fieldDecl );
192 if ( fieldName != fieldDecl->name ) {
193 throwError( "Head field did not have expected name." );
194 }
195
196 const Type * fieldType = fieldDecl->type;
197 if ( nullptr == fieldType ) {
198 throwError( "Could not get head field." );
199 }
200 const PointerType * ptrType = dynamic_cast<const PointerType *>( fieldType );
201 if ( nullptr == ptrType ) {
202 throwError( "First field is not a pointer type." );
203 }
204 assert( ptrType->base );
205 newType = dynamic_cast<StructInstType *>( ptrType->base );
206 if ( nullptr == newType ) {
207 throwError( "First field does not point to a structure type." );
208 }
209 }
210
211 // Now we can look into copying it.
212 newType = newType->clone();
213 if ( ! oldType->parameters.empty() ) {
214 deleteAll( newType->parameters );
215 newType->parameters.clear();
216 cloneAll( oldType->parameters, newType->parameters );
217 }
218 return newType;
219 }
220
221 /// Get the type-id type from a virtual type.
222 StructInstType * getTypeIdType( const Type * type, const CodeLocation& errorLocation ) {
223 const StructInstType * typeInst = dynamic_cast<const StructInstType *>( type );
224 if ( nullptr == typeInst ) {
225 return nullptr;
226 }
227 StructInstType * tableInst =
228 followHeadPointerType( typeInst, "virtual_table", errorLocation );
229 if ( nullptr == tableInst ) {
230 return nullptr;
231 }
232 StructInstType * typeIdInst =
233 followHeadPointerType( tableInst, "__cfavir_typeid", errorLocation );
234 delete tableInst;
235 return typeIdInst;
236 }
237
238 Expression * VirtualCastCore::postmutate( VirtualCastExpr * castExpr ) {
239 assertf( castExpr->result, "Virtual Cast target not found before expansion." );
240
241 assert( vcast_decl );
242 assert( pvt_decl );
243
244 const Type * base_type = getBaseType( castExpr->result );
245 if ( nullptr == base_type ) {
246 castError( castExpr, "Virtual cast target must be a pointer or reference type." );
247 }
248 const Type * type_id_type = getTypeIdType( base_type, castLocation( castExpr ) );
249 if ( nullptr == type_id_type ) {
250 castError( castExpr, "Ill formed virtual cast target type." );
251 }
252 ObjectDecl * type_id = indexer.lookup( type_id_type );
253 delete type_id_type;
254 if ( nullptr == type_id ) {
255 castError( castExpr, "Virtual cast does not target a virtual type." );
256 }
257
258 Expression * result = new CastExpr(
259 new ApplicationExpr( VariableExpr::functionPointer( vcast_decl ), {
260 cast_to_type_id( new AddressExpr( new VariableExpr( type_id ) ), 1 ),
261 cast_to_type_id( castExpr->get_arg(), 2 ),
262 } ),
263 castExpr->get_result()->clone()
264 );
265
266 castExpr->set_arg( nullptr );
267 castExpr->set_result( nullptr );
268 delete castExpr;
269 return result;
270 }
271
272/// Better error locations for generated casts.
273// TODO: Does the improved distribution of code locations make this unneeded?
274CodeLocation castLocation( const ast::VirtualCastExpr * castExpr ) {
275 if ( castExpr->location.isSet() ) {
276 return castExpr->location;
277 } else if ( castExpr->arg->location.isSet() ) {
278 return castExpr->arg->location;
279 } else {
280 return CodeLocation();
281 }
282}
283
284[[noreturn]] void castError( ast::VirtualCastExpr const * castExpr, std::string const & message ) {
285 SemanticError( castLocation( castExpr ), message );
286}
287
288class TypeIdTable final {
289 ScopedMap<std::string, ast::ObjectDecl const *> instances;
290public:
291 void enterScope() { instances.beginScope(); }
292 void leaveScope() { instances.endScope(); }
293
294 // Attempt to insert an instance into the map. If there is a conflict,
295 // returns the previous declaration for error messages.
296 ast::ObjectDecl const * insert( ast::ObjectDecl const * typeIdDecl ) {
297 std::string mangledName = Mangle::mangleType( typeIdDecl->type );
298 ast::ObjectDecl const *& value = instances[ mangledName ];
299 if ( value ) {
300 if ( typeIdDecl->storage.is_extern ) {
301 return nullptr;
302 } else if ( !value->storage.is_extern ) {
303 return value;
304 }
305 }
306 value = typeIdDecl;
307 return nullptr;
308 }
309
310 ast::ObjectDecl const * lookup( ast::Type const * typeIdType ) {
311 std::string mangledName = Mangle::mangleType( typeIdType );
312 auto const it = instances.find( mangledName );
313 return ( instances.end() == it ) ? nullptr : it->second;
314 }
315};
316
317struct ExpandCastsCore final {
318 void previsit( ast::FunctionDecl const * decl );
319 void previsit( ast::StructDecl const * decl );
320 void previsit( ast::ObjectDecl const * decl );
321 ast::Expr const * postvisit( ast::VirtualCastExpr const * expr );
322
323 ast::CastExpr const * cast_to_type_id(
324 ast::Expr const * expr, unsigned int level_of_indirection );
325
326 ast::FunctionDecl const * vcast_decl = nullptr;
327 ast::StructDecl const * info_decl = nullptr;
328
329 TypeIdTable symtab;
330};
331
332void ExpandCastsCore::previsit( ast::FunctionDecl const * decl ) {
333 if ( !vcast_decl && "__cfavir_virtual_cast" == decl->name ) {
334 vcast_decl = decl;
335 }
336}
337
338void ExpandCastsCore::previsit( ast::StructDecl const * decl ) {
339 if ( !info_decl && decl->body && "__cfavir_type_info" == decl->name ) {
340 info_decl = decl;
341 }
342}
343
344void ExpandCastsCore::previsit( ast::ObjectDecl const * decl ) {
345 if ( is_type_id_object( decl ) ) {
346 // Multiple definitions should be fine because of linkonce.
347 symtab.insert( decl );
348 }
349}
350
351/// Get the base type from a pointer or reference.
352ast::Type const * getBaseType( ast::ptr<ast::Type> const & type ) {
353 if ( auto target = type.as<ast::PointerType>() ) {
354 return target->base.get();
355 } else if ( auto target = type.as<ast::ReferenceType>() ) {
356 return target->base.get();
357 } else {
358 return nullptr;
359 }
360}
361
362/// Copy newType, but give the copy the params of the oldType.
363ast::StructInstType * polyCopy(
364 ast::StructInstType const * oldType,
365 ast::StructInstType const * newType ) {
366 assert( oldType->params.size() == newType->params.size() );
367 ast::StructInstType * retType = ast::deepCopy( newType );
368 if ( ! oldType->params.empty() ) {
369 retType->params.clear();
370 for ( auto oldParams : oldType->params ) {
371 retType->params.push_back( ast::deepCopy( oldParams ) );
372 }
373 }
374 return retType;
375}
376
377/// Follow the "head" field of the structure to get the type that is pointed
378/// to by that field.
379ast::StructInstType const * followHeadPointerType(
380 CodeLocation const & errorLocation,
381 ast::StructInstType const * oldType,
382 std::string const & fieldName ) {
383 ast::StructDecl const * oldDecl = oldType->base;
384 assert( oldDecl );
385
386 // Helper function for throwing semantic errors.
387 auto throwError = [&fieldName, &errorLocation, &oldDecl](
388 std::string const & message ) {
389 std::string const & context = "While following head pointer of " +
390 oldDecl->name + " named '" + fieldName + "': ";
391 SemanticError( errorLocation, context + message );
392 };
393
394 if ( oldDecl->members.empty() ) {
395 throwError( "Type has no fields." );
396 }
397 ast::ptr<ast::Decl> const & memberDecl = oldDecl->members.front();
398 assert( memberDecl );
399 ast::ObjectDecl const * fieldDecl = memberDecl.as<ast::ObjectDecl>();
400 assert( fieldDecl );
401 if ( fieldName != fieldDecl->name ) {
402 throwError( "Head field did not have expected name." );
403 }
404
405 ast::ptr<ast::Type> const & fieldType = fieldDecl->type;
406 if ( nullptr == fieldType ) {
407 throwError( "Could not get head field." );
408 }
409 auto ptrType = fieldType.as<ast::PointerType>();
410 if ( nullptr == ptrType ) {
411 throwError( "First field is not a pointer type." );
412 }
413 assert( ptrType->base );
414 auto newType = ptrType->base.as<ast::StructInstType>();
415 if ( nullptr == newType ) {
416 throwError( "First field does not point to a structure type." );
417 }
418
419 return polyCopy( oldType, newType );
420}
421
422/// Get the type-id type from a virtual type.
423ast::StructInstType const * getTypeIdType(
424 CodeLocation const & errorLocation,
425 ast::Type const * type ) {
426 auto typeInst = dynamic_cast<ast::StructInstType const *>( type );
427 if ( nullptr == typeInst ) {
428 return nullptr;
429 }
430 ast::ptr<ast::StructInstType> tableInst =
431 followHeadPointerType( errorLocation, typeInst, "virtual_table" );
432 if ( nullptr == tableInst ) {
433 return nullptr;
434 }
435 ast::StructInstType const * typeIdInst =
436 followHeadPointerType( errorLocation, tableInst, "__cfavir_typeid" );
437 return typeIdInst;
438}
439
440ast::Expr const * ExpandCastsCore::postvisit(
441 ast::VirtualCastExpr const * expr ) {
442 assertf( expr->result, "Virtual cast target not found before expansion." );
443
444 assert( vcast_decl );
445 assert( info_decl );
446
447 ast::Type const * base_type = getBaseType( expr->result );
448 if ( nullptr == base_type ) {
449 castError( expr, "Virtual cast target must be a pointer or reference type." );
450 }
451 ast::StructInstType const * type_id_type =
452 getTypeIdType( castLocation( expr ), base_type );
453 if ( nullptr == type_id_type ) {
454 castError( expr, "Ill formed virtual cast target type." );
455 }
456 ast::ObjectDecl const * type_id = symtab.lookup( type_id_type );
457 if ( nullptr == type_id ) {
458 // I'm trying to give a different error for polymorpic types as
459 // different things can go wrong there.
460 if ( type_id_type->params.empty() ) {
461 castError( expr, "Virtual cast does not target a virtual type." );
462 } else {
463 castError( expr, "Virtual cast does not target a type with a "
464 "type id (possible missing virtual table)." );
465 }
466 }
467
468 return new ast::CastExpr( expr->location,
469 new ast::ApplicationExpr( expr->location,
470 ast::VariableExpr::functionPointer( expr->location, vcast_decl ),
471 {
472 cast_to_type_id(
473 new ast::AddressExpr( expr->location,
474 new ast::VariableExpr( expr->location, type_id ) ),
475 1 ),
476 cast_to_type_id( expr->arg, 2 ),
477 }
478 ),
479 ast::deepCopy( expr->result )
480 );
481}
482
483ast::CastExpr const * ExpandCastsCore::cast_to_type_id(
484 ast::Expr const * expr, unsigned int level_of_indirection ) {
485 assert( info_decl );
486 ast::Type * type = new ast::StructInstType( info_decl, ast::CV::Const );
487 for ( unsigned int i = 0 ; i < level_of_indirection ; ++i ) {
488 type = new ast::PointerType( type );
489 }
490 return new ast::CastExpr( expr->location, expr, type );
491}
492
493} // namespace
494
495void expandCasts( std::list< Declaration * > & translationUnit ) {
496 PassVisitor<VirtualCastCore> translator;
497 mutateAll( translationUnit, translator );
498}
499
500void expandCasts( ast::TranslationUnit & translationUnit ) {
501 ast::Pass<ExpandCastsCore>::run( translationUnit );
502}
503
504} // namespace Virtual
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