source: src/ControlStruct/MultiLevelExit.cpp@ 0fba0d4

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since 0fba0d4 was cb921d4, checked in by Andrew Beach <ajbeach@…>, 4 years ago

Changed some of the new ast code so they no longer pass around the empty LabelGenerator.
  • Property mode set to 100644
File size: 21.0 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// MultiLevelExit.cpp -- Replaces CFA's local control flow with C's versions.
8//
9// Author : Andrew Beach
10// Created On : Mon Nov 1 13:48:00 2021
11// Last Modified By : Andrew Beach
12// Last Modified On : Mon Nov 8 10:56:00 2021
13// Update Count : 2
14//
15
16#include "MultiLevelExit.hpp"
17
18#include "AST/Pass.hpp"
19#include "AST/Stmt.hpp"
20#include "ControlStruct/LabelGenerator.h"
21
22#include <set>
23
24namespace ControlStruct {
25
26namespace {
27
28class Entry {
29public:
30 const ast::Stmt * stmt;
31private:
32 // Organized like a manual ADT. Avoids creating a bunch of dead data.
33 struct Target {
34 ast::Label label;
35 bool used = false;
36 Target( const ast::Label & label ) : label( label ) {}
37 Target() : label( CodeLocation() ) {}
38 };
39 Target firstTarget;
40 Target secondTarget;
41
42 enum Kind {
43 ForStmt, WhileStmt, CompoundStmt, IfStmt, CaseStmt, SwitchStmt, TryStmt
44 } kind;
45
46 bool fallDefaultValid = true;
47
48 static ast::Label & useTarget( Target & target ) {
49 target.used = true;
50 return target.label;
51 }
52
53public:
54 Entry( const ast::ForStmt * stmt, ast::Label breakExit, ast::Label contExit ) :
55 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( ForStmt ) {}
56 Entry( const ast::WhileStmt * stmt, ast::Label breakExit, ast::Label contExit ) :
57 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( WhileStmt ) {}
58 Entry( const ast::CompoundStmt *stmt, ast::Label breakExit ) :
59 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( CompoundStmt ) {}
60 Entry( const ast::IfStmt *stmt, ast::Label breakExit ) :
61 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( IfStmt ) {}
62 Entry( const ast::CaseStmt *stmt, ast::Label fallExit ) :
63 stmt( stmt ), firstTarget( fallExit ), secondTarget(), kind( CaseStmt ) {}
64 Entry( const ast::SwitchStmt *stmt, ast::Label breakExit, ast::Label fallDefaultExit ) :
65 stmt( stmt ), firstTarget( breakExit ), secondTarget( fallDefaultExit ), kind( SwitchStmt ) {}
66 Entry( const ast::TryStmt *stmt, ast::Label breakExit ) :
67 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( TryStmt ) {}
68
69 bool isContTarget() const { return kind <= WhileStmt; }
70 bool isBreakTarget() const { return CaseStmt != kind; }
71 bool isFallTarget() const { return CaseStmt == kind; }
72 bool isFallDefaultTarget() const { return SwitchStmt == kind; }
73
74 ast::Label useContExit() { assert( kind <= WhileStmt ); return useTarget(secondTarget); }
75 ast::Label useBreakExit() { assert( CaseStmt != kind ); return useTarget(firstTarget); }
76 ast::Label useFallExit() { assert( CaseStmt == kind ); return useTarget(firstTarget); }
77 ast::Label useFallDefaultExit() { assert( SwitchStmt == kind ); return useTarget(secondTarget); }
78
79 bool isContUsed() const { assert( kind <= WhileStmt ); return secondTarget.used; }
80 bool isBreakUsed() const { assert( CaseStmt != kind ); return firstTarget.used; }
81 bool isFallUsed() const { assert( CaseStmt == kind ); return firstTarget.used; }
82 bool isFallDefaultUsed() const { assert( SwitchStmt == kind ); return secondTarget.used; }
83 void seenDefault() { fallDefaultValid = false; }
84 bool isFallDefaultValid() const { return fallDefaultValid; }
85};
86
87// Helper predicates used in std::find_if calls (it doesn't take methods):
88bool isBreakTarget( const Entry & entry ) {
89 return entry.isBreakTarget();
90}
91
92bool isContinueTarget( const Entry & entry ) {
93 return entry.isContTarget();
94}
95
96bool isFallthroughTarget( const Entry & entry ) {
97 return entry.isFallTarget();
98}
99
100bool isFallthroughDefaultTarget( const Entry & entry ) {
101 return entry.isFallDefaultTarget();
102}
103
104struct MultiLevelExitCore final :
105 public ast::WithVisitorRef<MultiLevelExitCore>,
106 public ast::WithShortCircuiting, public ast::WithGuards {
107 MultiLevelExitCore( const LabelToStmt & lt );
108
109 void previsit( const ast::FunctionDecl * );
110
111 const ast::CompoundStmt * previsit( const ast::CompoundStmt * );
112 const ast::BranchStmt * postvisit( const ast::BranchStmt * );
113 void previsit( const ast::WhileStmt * );
114 const ast::WhileStmt * postvisit( const ast::WhileStmt * );
115 void previsit( const ast::ForStmt * );
116 const ast::ForStmt * postvisit( const ast::ForStmt * );
117 const ast::CaseStmt * previsit( const ast::CaseStmt * );
118 void previsit( const ast::IfStmt * );
119 const ast::IfStmt * postvisit( const ast::IfStmt * );
120 void previsit( const ast::SwitchStmt * );
121 const ast::SwitchStmt * postvisit( const ast::SwitchStmt * );
122 void previsit( const ast::ReturnStmt * );
123 void previsit( const ast::TryStmt * );
124 void postvisit( const ast::TryStmt * );
125 void previsit( const ast::FinallyStmt * );
126
127 const ast::Stmt * mutateLoop( const ast::Stmt * body, Entry& );
128
129 const LabelToStmt & target_table;
130 std::set<ast::Label> fallthrough_labels;
131 std::vector<Entry> enclosing_control_structures;
132 ast::Label break_label;
133 bool inFinally;
134
135 template<typename LoopNode>
136 void prehandleLoopStmt( const LoopNode * loopStmt );
137 template<typename LoopNode>
138 const LoopNode * posthandleLoopStmt( const LoopNode * loopStmt );
139
140 std::list<ast::ptr<ast::Stmt>> fixBlock(
141 const std::list<ast::ptr<ast::Stmt>> & kids, bool caseClause );
142
143 template<typename UnaryPredicate>
144 auto findEnclosingControlStructure( UnaryPredicate pred ) {
145 return std::find_if( enclosing_control_structures.rbegin(),
146 enclosing_control_structures.rend(), pred );
147 }
148};
149
150ast::NullStmt * labelledNullStmt(
151 const CodeLocation & cl, const ast::Label & label ) {
152 return new ast::NullStmt( cl, std::vector<ast::Label>{ label } );
153}
154
155MultiLevelExitCore::MultiLevelExitCore( const LabelToStmt & lt ) :
156 target_table( lt ), break_label( CodeLocation(), "" ),
157 inFinally( false )
158{}
159
160void MultiLevelExitCore::previsit( const ast::FunctionDecl * ) {
161 visit_children = false;
162}
163
164const ast::CompoundStmt * MultiLevelExitCore::previsit(
165 const ast::CompoundStmt * stmt ) {
166 visit_children = false;
167 bool isLabeled = !stmt->labels.empty();
168 if ( isLabeled ) {
169 ast::Label breakLabel = LabelGenerator::newLabel( "blockBreak", stmt );
170 enclosing_control_structures.emplace_back( stmt, breakLabel );
171 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
172 }
173
174 auto mutStmt = ast::mutate( stmt );
175 // A child statement may set the break label.
176 mutStmt->kids = std::move( fixBlock( stmt->kids, false ) );
177
178 if ( isLabeled ) {
179 assert( !enclosing_control_structures.empty() );
180 Entry & entry = enclosing_control_structures.back();
181 if ( !entry.useBreakExit().empty() ) {
182 break_label = entry.useBreakExit();
183 }
184 }
185 return mutStmt;
186}
187
188size_t getUnusedIndex(
189 const ast::Stmt * stmt, const ast::Label & originalTarget ) {
190 const size_t size = stmt->labels.size();
191
192 // If the label is empty, we can skip adding the unused attribute:
193 if ( originalTarget.empty() ) return size;
194
195 // Search for a label that matches the originalTarget.
196 for ( size_t i = 0 ; i < size ; ++i ) {
197 const ast::Label & label = stmt->labels[i];
198 if ( label == originalTarget ) {
199 for ( const ast::Attribute * attr : label.attributes ) {
200 if ( attr->name == "unused" ) return size;
201 }
202 return i;
203 }
204 }
205 assertf( false, "Could not find label '%s' on statement %s",
206 originalTarget.name.c_str(), toString( stmt ).c_str() );
207}
208
209const ast::Stmt * addUnused(
210 const ast::Stmt * stmt, const ast::Label & originalTarget ) {
211 size_t i = getUnusedIndex( stmt, originalTarget );
212 if ( i == stmt->labels.size() ) {
213 return stmt;
214 }
215 ast::Stmt * mutStmt = ast::mutate( stmt );
216 mutStmt->labels[i].attributes.push_back( new ast::Attribute( "unused" ) );
217 return mutStmt;
218}
219
220const ast::BranchStmt * MultiLevelExitCore::postvisit( const ast::BranchStmt * stmt ) {
221 std::vector<Entry>::reverse_iterator targetEntry =
222 enclosing_control_structures.rend();
223 switch ( stmt->kind ) {
224 case ast::BranchStmt::Goto:
225 return stmt;
226 case ast::BranchStmt::Continue:
227 case ast::BranchStmt::Break: {
228 bool isContinue = stmt->kind == ast::BranchStmt::Continue;
229 // Handle unlabeled break and continue.
230 if ( stmt->target.empty() ) {
231 if ( isContinue ) {
232 targetEntry = findEnclosingControlStructure( isContinueTarget );
233 } else {
234 if ( enclosing_control_structures.empty() ) {
235 SemanticError( stmt->location,
236 "'break' outside a loop, 'switch', or labelled block" );
237 }
238 targetEntry = findEnclosingControlStructure( isBreakTarget );
239 }
240 // Handle labeled break and continue.
241 } else {
242 // Lookup label in table to find attached control structure.
243 targetEntry = findEnclosingControlStructure(
244 [ targetStmt = target_table.at(stmt->target) ](auto entry){
245 return entry.stmt == targetStmt;
246 } );
247 }
248 // Ensure that selected target is valid.
249 if ( targetEntry == enclosing_control_structures.rend() || ( isContinue && !isContinueTarget( *targetEntry ) ) ) {
250 SemanticError(
251 stmt->location,
252 toString( (isContinue ? "'continue'" : "'break'"),
253 " target must be an enclosing ",
254 (isContinue ? "loop: " : "control structure: "),
255 stmt->originalTarget ) );
256 }
257 break;
258 }
259 case ast::BranchStmt::FallThrough: {
260 targetEntry = findEnclosingControlStructure( isFallthroughTarget );
261 // Check that target is valid.
262 if ( targetEntry == enclosing_control_structures.rend() ) {
263 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
264 }
265 if ( !stmt->target.empty() ) {
266 // Labelled fallthrough: target must be a valid fallthough label.
267 if ( !fallthrough_labels.count( stmt->target ) ) {
268 SemanticError( stmt->location, toString( "'fallthrough' target must be a later case statement: ", stmt->originalTarget ) );
269 }
270 return new ast::BranchStmt(
271 stmt->location, ast::BranchStmt::Goto, stmt->originalTarget );
272 }
273 break;
274 }
275 case ast::BranchStmt::FallThroughDefault: {
276 targetEntry = findEnclosingControlStructure( isFallthroughDefaultTarget );
277
278 // Check that this is in a switch or choose statement.
279 if ( targetEntry == enclosing_control_structures.rend() ) {
280 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
281 }
282
283 // Check that the switch or choose has a default clause.
284 auto switchStmt = strict_dynamic_cast< const ast::SwitchStmt * >(
285 targetEntry->stmt );
286 bool foundDefault = false;
287 for ( auto subStmt : switchStmt->stmts ) {
288 const ast::CaseStmt * caseStmt = subStmt.strict_as<ast::CaseStmt>();
289 if ( caseStmt->isDefault() ) {
290 foundDefault = true;
291 break;
292 }
293 }
294 if ( !foundDefault ) {
295 SemanticError( stmt->location, "'fallthrough default' must be enclosed in a 'switch' or 'choose' control structure with a 'default' clause" );
296 }
297 break;
298 }
299 default:
300 assert( false );
301 }
302
303 // Branch error checks: get the appropriate label name:
304 // (This label will always be replaced.)
305 ast::Label exitLabel( CodeLocation(), "" );
306 switch ( stmt->kind ) {
307 case ast::BranchStmt::Break:
308 assert( !targetEntry->useBreakExit().empty() );
309 exitLabel = targetEntry->useBreakExit();
310 break;
311 case ast::BranchStmt::Continue:
312 assert( !targetEntry->useContExit().empty() );
313 exitLabel = targetEntry->useContExit();
314 break;
315 case ast::BranchStmt::FallThrough:
316 assert( !targetEntry->useFallExit().empty() );
317 exitLabel = targetEntry->useFallExit();
318 break;
319 case ast::BranchStmt::FallThroughDefault:
320 assert( !targetEntry->useFallDefaultExit().empty() );
321 exitLabel = targetEntry->useFallDefaultExit();
322 // Check that fallthrough default comes before the default clause.
323 if ( !targetEntry->isFallDefaultValid() ) {
324 SemanticError( stmt->location,
325 "'fallthrough default' must precede the 'default' clause" );
326 }
327 break;
328 default:
329 assert(0);
330 }
331
332 // Add unused attribute to silence warnings.
333 targetEntry->stmt = addUnused( targetEntry->stmt, stmt->originalTarget );
334
335 // Replace this with a goto to make later passes more uniform.
336 return new ast::BranchStmt( stmt->location, ast::BranchStmt::Goto, exitLabel );
337}
338
339void MultiLevelExitCore::previsit( const ast::WhileStmt * stmt ) {
340 return prehandleLoopStmt( stmt );
341}
342
343const ast::WhileStmt * MultiLevelExitCore::postvisit( const ast::WhileStmt * stmt ) {
344 return posthandleLoopStmt( stmt );
345}
346
347void MultiLevelExitCore::previsit( const ast::ForStmt * stmt ) {
348 return prehandleLoopStmt( stmt );
349}
350
351const ast::ForStmt * MultiLevelExitCore::postvisit( const ast::ForStmt * stmt ) {
352 return posthandleLoopStmt( stmt );
353}
354
355// Mimic what the built-in push_front would do anyways. It is O(n).
356void push_front(
357 std::vector<ast::ptr<ast::Stmt>> & vec, const ast::Stmt * element ) {
358 vec.emplace_back( nullptr );
359 for ( size_t i = vec.size() - 1 ; 0 < i ; --i ) {
360 vec[ i ] = std::move( vec[ i - 1 ] );
361 }
362 vec[ 0 ] = element;
363}
364
365const ast::CaseStmt * MultiLevelExitCore::previsit( const ast::CaseStmt * stmt ) {
366 visit_children = false;
367
368 // If it is the default, mark the default as seen.
369 if ( stmt->isDefault() ) {
370 assert( !enclosing_control_structures.empty() );
371 enclosing_control_structures.back().seenDefault();
372 }
373
374 // The cond may not exist, but if it does update it now.
375 visitor->maybe_accept( stmt, &ast::CaseStmt::cond );
376
377 // Just save the mutated node for simplicity.
378 ast::CaseStmt * mutStmt = ast::mutate( stmt );
379
380 ast::Label fallLabel = LabelGenerator::newLabel( "fallThrough", stmt );
381 if ( !mutStmt->stmts.empty() ) {
382 // Ensure that the stack isn't corrupted by exceptions in fixBlock.
383 auto guard = makeFuncGuard(
384 [&](){ enclosing_control_structures.emplace_back( mutStmt, fallLabel ); },
385 [this](){ enclosing_control_structures.pop_back(); }
386 );
387
388 // These should already be in a block.
389 auto block = ast::mutate( mutStmt->stmts.front().strict_as<ast::CompoundStmt>() );
390 block->kids = fixBlock( block->kids, true );
391
392 // Add fallthrough label if necessary.
393 assert( !enclosing_control_structures.empty() );
394 Entry & entry = enclosing_control_structures.back();
395 if ( entry.isFallUsed() ) {
396 mutStmt->stmts.push_back(
397 labelledNullStmt( mutStmt->location, entry.useFallExit() ) );
398 }
399 }
400 assert( !enclosing_control_structures.empty() );
401 Entry & entry = enclosing_control_structures.back();
402 assertf( dynamic_cast< const ast::SwitchStmt * >( entry.stmt ),
403 "Control structure enclosing a case clause must be a switch, but is: %s",
404 toString( entry.stmt ).c_str() );
405 if ( mutStmt->isDefault() ) {
406 if ( entry.isFallDefaultUsed() ) {
407 // Add fallthrough default label if necessary.
408 push_front( mutStmt->stmts, labelledNullStmt(
409 stmt->location, entry.useFallDefaultExit()
410 ) );
411 }
412 }
413 return mutStmt;
414}
415
416void MultiLevelExitCore::previsit( const ast::IfStmt * stmt ) {
417 bool labeledBlock = !stmt->labels.empty();
418 if ( labeledBlock ) {
419 ast::Label breakLabel = LabelGenerator::newLabel( "blockBreak", stmt );
420 enclosing_control_structures.emplace_back( stmt, breakLabel );
421 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
422 }
423}
424
425const ast::IfStmt * MultiLevelExitCore::postvisit( const ast::IfStmt * stmt ) {
426 bool labeledBlock = !stmt->labels.empty();
427 if ( labeledBlock ) {
428 auto this_label = enclosing_control_structures.back().useBreakExit();
429 if ( !this_label.empty() ) {
430 break_label = this_label;
431 }
432 }
433 return stmt;
434}
435
436bool isDefaultCase( const ast::ptr<ast::Stmt> & stmt ) {
437 const ast::CaseStmt * caseStmt = stmt.strict_as<ast::CaseStmt>();
438 return caseStmt->isDefault();
439}
440
441void MultiLevelExitCore::previsit( const ast::SwitchStmt * stmt ) {
442 ast::Label label = LabelGenerator::newLabel( "switchBreak", stmt );
443 auto it = std::find_if( stmt->stmts.rbegin(), stmt->stmts.rend(), isDefaultCase );
444
445 const ast::CaseStmt * defaultCase = it != stmt->stmts.rend()
446 ? (it)->strict_as<ast::CaseStmt>() : nullptr;
447 ast::Label defaultLabel = defaultCase
448 ? LabelGenerator::newLabel( "fallThroughDefault", defaultCase )
449 : ast::Label( stmt->location, "" );
450 enclosing_control_structures.emplace_back( stmt, label, defaultLabel );
451 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
452
453 // Collect valid labels for fallthrough. It starts with all labels at
454 // this level, then removed as we see them in traversal.
455 for ( const ast::Stmt * stmt : stmt->stmts ) {
456 auto * caseStmt = strict_dynamic_cast< const ast::CaseStmt * >( stmt );
457 if ( caseStmt->stmts.empty() ) continue;
458 auto block = caseStmt->stmts.front().strict_as<ast::CompoundStmt>();
459 for ( const ast::Stmt * stmt : block->kids ) {
460 for ( const ast::Label & l : stmt->labels ) {
461 fallthrough_labels.insert( l );
462 }
463 }
464 }
465}
466
467const ast::SwitchStmt * MultiLevelExitCore::postvisit( const ast::SwitchStmt * stmt ) {
468 assert( !enclosing_control_structures.empty() );
469 Entry & entry = enclosing_control_structures.back();
470 assert( entry.stmt == stmt );
471
472 // Only run if we need to generate the break label.
473 if ( entry.isBreakUsed() ) {
474 // To keep the switch statements uniform (all direct children of a
475 // SwitchStmt should be CastStmts), append the exit label and break
476 // to the last case, create a default case is there are no cases.
477 ast::SwitchStmt * mutStmt = ast::mutate( stmt );
478 if ( mutStmt->stmts.empty() ) {
479 mutStmt->stmts.push_back( new ast::CaseStmt(
480 mutStmt->location, nullptr, {} ));
481 }
482
483 auto caseStmt = mutStmt->stmts.back().strict_as<ast::CaseStmt>();
484 auto mutCase = ast::mutate( caseStmt );
485 mutStmt->stmts.back() = mutCase;
486
487 ast::Label label( mutCase->location, "breakLabel" );
488 auto branch = new ast::BranchStmt( mutCase->location, ast::BranchStmt::Break, label );
489 branch->labels.push_back( entry.useBreakExit() );
490 mutCase->stmts.push_back( branch );
491
492 return mutStmt;
493 }
494 return stmt;
495}
496
497void MultiLevelExitCore::previsit( const ast::ReturnStmt * stmt ) {
498 if ( inFinally ) {
499 SemanticError( stmt->location, "'return' may not appear in a finally clause" );
500 }
501}
502
503void MultiLevelExitCore::previsit( const ast::TryStmt * stmt ) {
504 bool isLabeled = !stmt->labels.empty();
505 if ( isLabeled ) {
506 ast::Label breakLabel = LabelGenerator::newLabel( "blockBreak", stmt );
507 enclosing_control_structures.emplace_back( stmt, breakLabel );
508 GuardAction([this](){ enclosing_control_structures.pop_back(); } );
509 }
510}
511
512void MultiLevelExitCore::postvisit( const ast::TryStmt * stmt ) {
513 bool isLabeled = !stmt->labels.empty();
514 if ( isLabeled ) {
515 auto this_label = enclosing_control_structures.back().useBreakExit();
516 if ( !this_label.empty() ) {
517 break_label = this_label;
518 }
519 }
520}
521
522void MultiLevelExitCore::previsit( const ast::FinallyStmt * ) {
523 GuardAction([this, old = std::move(enclosing_control_structures)](){
524 enclosing_control_structures = std::move(old);
525 });
526 enclosing_control_structures = std::vector<Entry>();
527 GuardValue( inFinally ) = true;
528}
529
530const ast::Stmt * MultiLevelExitCore::mutateLoop(
531 const ast::Stmt * body, Entry & entry ) {
532 if ( entry.isBreakUsed() ) {
533 break_label = entry.useBreakExit();
534 }
535
536 if ( entry.isContUsed() ) {
537 ast::CompoundStmt * new_body = new ast::CompoundStmt( body->location );
538 new_body->kids.push_back( body );
539 new_body->kids.push_back(
540 labelledNullStmt( body->location, entry.useContExit() ) );
541 return new_body;
542 }
543
544 return body;
545}
546
547template<typename LoopNode>
548void MultiLevelExitCore::prehandleLoopStmt( const LoopNode * loopStmt ) {
549 // Remember is loop before going onto mutate the body.
550 // The labels will be folded in if they are used.
551 ast::Label breakLabel = LabelGenerator::newLabel( "loopBreak", loopStmt );
552 ast::Label contLabel = LabelGenerator::newLabel( "loopContinue", loopStmt );
553 enclosing_control_structures.emplace_back( loopStmt, breakLabel, contLabel );
554 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
555}
556
557template<typename LoopNode>
558const LoopNode * MultiLevelExitCore::posthandleLoopStmt( const LoopNode * loopStmt ) {
559 assert( !enclosing_control_structures.empty() );
560 Entry & entry = enclosing_control_structures.back();
561 assert( entry.stmt == loopStmt );
562
563 // Now we check if the labels are used and add them if so.
564 return ast::mutate_field(
565 loopStmt, &LoopNode::body, mutateLoop( loopStmt->body, entry ) );
566}
567
568std::list<ast::ptr<ast::Stmt>> MultiLevelExitCore::fixBlock(
569 const std::list<ast::ptr<ast::Stmt>> & kids, bool is_case_clause ) {
570 // Unfortunately we can't use the automatic error collection.
571 SemanticErrorException errors;
572
573 std::list<ast::ptr<ast::Stmt>> ret;
574
575 // Manually visit each child.
576 for ( const ast::ptr<ast::Stmt> & kid : kids ) {
577 if ( is_case_clause ) {
578 // Once a label is seen, it's no longer a valid for fallthrough.
579 for ( const ast::Label & l : kid->labels ) {
580 fallthrough_labels.erase( l );
581 }
582 }
583
584 try {
585 ret.push_back( kid->accept( *visitor ) );
586 } catch ( SemanticErrorException & e ) {
587 errors.append( e );
588 }
589
590 if ( !break_label.empty() ) {
591 ret.push_back(
592 labelledNullStmt( ret.back()->location, break_label ) );
593 break_label = ast::Label( CodeLocation(), "" );
594 }
595 }
596
597 if ( !errors.isEmpty() ) {
598 throw errors;
599 }
600 return ret;
601}
602
603} // namespace
604
605const ast::CompoundStmt * multiLevelExitUpdate(
606 const ast::CompoundStmt * stmt,
607 const LabelToStmt & labelTable ) {
608 // Must start in the body, so FunctionDecls can be a stopping point.
609 ast::Pass<MultiLevelExitCore> visitor( labelTable );
610 const ast::CompoundStmt * ret = stmt->accept( visitor );
611 return ret;
612}
613
614} // namespace ControlStruct
615
616// Local Variables: //
617// tab-width: 4 //
618// mode: c++ //
619// compile-command: "make install" //
620// End: //
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