source: src/ControlStruct/MultiLevelExit.cpp@ f69fac7

ADT ast-experimental enum pthread-emulation qualifiedEnum
Last change on this file since f69fac7 was 891f707, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Removed move in MLE as it prevents copy-ellision.
  • Property mode set to 100644
File size: 21.2 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 : Peter A. Buhr
12// Last Modified On : Wed Feb 2 23:07:54 2022
13// Update Count : 33
14//
15
16#include "MultiLevelExit.hpp"
17
18#include "AST/Pass.hpp"
19#include "AST/Stmt.hpp"
20#include "LabelGeneratorNew.hpp"
21
22#include <set>
23using namespace std;
24using namespace ast;
25
26namespace ControlStruct {
27class Entry {
28 public:
29 const Stmt * stmt;
30 private:
31 // Organized like a manual ADT. Avoids creating a bunch of dead data.
32 struct Target {
33 Label label;
34 bool used = false;
35 Target( const Label & label ) : label( label ) {}
36 Target() : label( CodeLocation() ) {}
37 };
38 Target firstTarget;
39 Target secondTarget;
40
41 enum Kind {
42 ForStmtK, WhileDoStmtK, CompoundStmtK, IfStmtK, CaseStmtK, SwitchStmtK, TryStmtK
43 } kind;
44
45 bool fallDefaultValid = true;
46
47 static Label & useTarget( Target & target ) {
48 target.used = true;
49 return target.label;
50 }
51 public:
52 Entry( const ForStmt * stmt, Label breakExit, Label contExit ) :
53 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( ForStmtK ) {}
54 Entry( const WhileDoStmt * stmt, Label breakExit, Label contExit ) :
55 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( WhileDoStmtK ) {}
56 Entry( const CompoundStmt *stmt, Label breakExit ) :
57 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( CompoundStmtK ) {}
58 Entry( const IfStmt *stmt, Label breakExit ) :
59 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( IfStmtK ) {}
60 Entry( const CaseStmt *stmt, Label fallExit ) :
61 stmt( stmt ), firstTarget( fallExit ), secondTarget(), kind( CaseStmtK ) {}
62 Entry( const SwitchStmt *stmt, Label breakExit, Label fallDefaultExit ) :
63 stmt( stmt ), firstTarget( breakExit ), secondTarget( fallDefaultExit ), kind( SwitchStmtK ) {}
64 Entry( const TryStmt *stmt, Label breakExit ) :
65 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( TryStmtK ) {}
66
67 bool isContTarget() const { return kind <= WhileDoStmtK; }
68 bool isBreakTarget() const { return kind != CaseStmtK; }
69 bool isFallTarget() const { return kind == CaseStmtK; }
70 bool isFallDefaultTarget() const { return kind == SwitchStmtK; }
71
72 // These routines set a target as being "used" by a BranchStmt
73 Label useContExit() { assert( kind <= WhileDoStmtK ); return useTarget(secondTarget); }
74 Label useBreakExit() { assert( kind != CaseStmtK ); return useTarget(firstTarget); }
75 Label useFallExit() { assert( kind == CaseStmtK ); return useTarget(firstTarget); }
76 Label useFallDefaultExit() { assert( kind == SwitchStmtK ); return useTarget(secondTarget); }
77
78 // These routines check if a specific label for a statement is used by a BranchStmt
79 bool isContUsed() const { assert( kind <= WhileDoStmtK ); return secondTarget.used; }
80 bool isBreakUsed() const { assert( kind != CaseStmtK ); return firstTarget.used; }
81 bool isFallUsed() const { assert( kind == CaseStmtK ); return firstTarget.used; }
82 bool isFallDefaultUsed() const { assert( kind == SwitchStmtK ); return secondTarget.used; }
83 void seenDefault() { fallDefaultValid = false; }
84 bool isFallDefaultValid() const { return fallDefaultValid; }
85};
86
87// Helper predicates used in 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 WithVisitorRef<MultiLevelExitCore>,
106 public WithShortCircuiting, public WithGuards {
107 MultiLevelExitCore( const LabelToStmt & lt );
108
109 void previsit( const FunctionDecl * );
110
111 const CompoundStmt * previsit( const CompoundStmt * );
112 const BranchStmt * postvisit( const BranchStmt * );
113 void previsit( const WhileDoStmt * );
114 const WhileDoStmt * postvisit( const WhileDoStmt * );
115 void previsit( const ForStmt * );
116 const ForStmt * postvisit( const ForStmt * );
117 const CaseStmt * previsit( const CaseStmt * );
118 void previsit( const IfStmt * );
119 const IfStmt * postvisit( const IfStmt * );
120 void previsit( const SwitchStmt * );
121 const SwitchStmt * postvisit( const SwitchStmt * );
122 void previsit( const ReturnStmt * );
123 void previsit( const TryStmt * );
124 void postvisit( const TryStmt * );
125 void previsit( const FinallyStmt * );
126
127 const Stmt * mutateLoop( const Stmt * body, Entry& );
128
129 const LabelToStmt & target_table;
130 set<Label> fallthrough_labels;
131 vector<Entry> enclosing_control_structures;
132 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 list<ptr<Stmt>> fixBlock(
141 const list<ptr<Stmt>> & kids, bool caseClause );
142
143 template<typename UnaryPredicate>
144 auto findEnclosingControlStructure( UnaryPredicate pred ) {
145 return find_if( enclosing_control_structures.rbegin(),
146 enclosing_control_structures.rend(), pred );
147 }
148};
149
150NullStmt * labelledNullStmt(
151 const CodeLocation & cl, const Label & label ) {
152 return new NullStmt( cl, vector<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 FunctionDecl * ) {
161 visit_children = false;
162}
163
164const CompoundStmt * MultiLevelExitCore::previsit(
165 const CompoundStmt * stmt ) {
166 visit_children = false;
167
168 // if the stmt is labelled then generate a label to check in postvisit if the label is used
169 bool isLabeled = ! stmt->labels.empty();
170 if ( isLabeled ) {
171 Label breakLabel = newLabel( "blockBreak", stmt );
172 enclosing_control_structures.emplace_back( stmt, breakLabel );
173 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
174 }
175
176 auto mutStmt = mutate( stmt );
177 // A child statement may set the break label.
178 mutStmt->kids = fixBlock( stmt->kids, false );
179
180 if ( isLabeled ) {
181 assert( ! enclosing_control_structures.empty() );
182 Entry & entry = enclosing_control_structures.back();
183 if ( ! entry.useBreakExit().empty() ) {
184 break_label = entry.useBreakExit();
185 }
186 }
187 return mutStmt;
188}
189
190size_t getUnusedIndex(
191 const Stmt * stmt, const Label & originalTarget ) {
192 const size_t size = stmt->labels.size();
193
194 // If the label is empty, do not add unused attribute.
195 if ( originalTarget.empty() ) return size;
196
197 // Search for a label that matches the originalTarget.
198 for ( size_t i = 0 ; i < size ; ++i ) {
199 const Label & label = stmt->labels[i];
200 if ( label == originalTarget ) {
201 for ( const Attribute * attr : label.attributes ) {
202 if ( attr->name == "unused" ) return size;
203 }
204 return i;
205 }
206 }
207 assertf( false, "CFA internal error: could not find label '%s' on statement %s",
208 originalTarget.name.c_str(), toString( stmt ).c_str() );
209}
210
211const Stmt * addUnused(
212 const Stmt * stmt, const Label & originalTarget ) {
213 size_t i = getUnusedIndex( stmt, originalTarget );
214 if ( i == stmt->labels.size() ) {
215 return stmt;
216 }
217 Stmt * mutStmt = mutate( stmt );
218 mutStmt->labels[i].attributes.push_back( new Attribute( "unused" ) );
219 return mutStmt;
220}
221
222// This routine updates targets on enclosing control structures to indicate which
223// label is used by the BranchStmt that is passed
224const BranchStmt * MultiLevelExitCore::postvisit( const BranchStmt * stmt ) {
225 vector<Entry>::reverse_iterator targetEntry =
226 enclosing_control_structures.rend();
227
228 // Labels on different stmts require different approaches to access
229 switch ( stmt->kind ) {
230 case BranchStmt::Goto:
231 return stmt;
232 case BranchStmt::Continue:
233 case BranchStmt::Break: {
234 bool isContinue = stmt->kind == BranchStmt::Continue;
235 // Handle unlabeled break and continue.
236 if ( stmt->target.empty() ) {
237 if ( isContinue ) {
238 targetEntry = findEnclosingControlStructure( isContinueTarget );
239 } else {
240 if ( enclosing_control_structures.empty() ) {
241 SemanticError( stmt->location,
242 "'break' outside a loop, 'switch', or labelled block" );
243 }
244 targetEntry = findEnclosingControlStructure( isBreakTarget );
245 }
246 // Handle labeled break and continue.
247 } else {
248 // Lookup label in table to find attached control structure.
249 targetEntry = findEnclosingControlStructure(
250 [ targetStmt = target_table.at(stmt->target) ](auto entry){
251 return entry.stmt == targetStmt;
252 } );
253 }
254 // Ensure that selected target is valid.
255 if ( targetEntry == enclosing_control_structures.rend() || ( isContinue && ! isContinueTarget( *targetEntry ) ) ) {
256 SemanticError( stmt->location, toString( (isContinue ? "'continue'" : "'break'"),
257 " target must be an enclosing ", (isContinue ? "loop: " : "control structure: "),
258 stmt->originalTarget ) );
259 }
260 break;
261 }
262 // handle fallthrough in case/switch stmts
263 case BranchStmt::FallThrough: {
264 targetEntry = findEnclosingControlStructure( isFallthroughTarget );
265 // Check that target is valid.
266 if ( targetEntry == enclosing_control_structures.rend() ) {
267 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
268 }
269 if ( ! stmt->target.empty() ) {
270 // Labelled fallthrough: target must be a valid fallthough label.
271 if ( ! fallthrough_labels.count( stmt->target ) ) {
272 SemanticError( stmt->location, toString( "'fallthrough' target must be a later case statement: ",
273 stmt->originalTarget ) );
274 }
275 return new BranchStmt( stmt->location, BranchStmt::Goto, stmt->originalTarget );
276 }
277 break;
278 }
279 case BranchStmt::FallThroughDefault: {
280 targetEntry = findEnclosingControlStructure( isFallthroughDefaultTarget );
281
282 // Check if in switch or choose statement.
283 if ( targetEntry == enclosing_control_structures.rend() ) {
284 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
285 }
286
287 // Check if switch or choose has default clause.
288 auto switchStmt = strict_dynamic_cast< const SwitchStmt * >( targetEntry->stmt );
289 bool foundDefault = false;
290 for ( auto subStmt : switchStmt->stmts ) {
291 const CaseStmt * caseStmt = subStmt.strict_as<CaseStmt>();
292 if ( caseStmt->isDefault() ) {
293 foundDefault = true;
294 break;
295 }
296 }
297 if ( ! foundDefault ) {
298 SemanticError( stmt->location, "'fallthrough default' must be enclosed in a 'switch' or 'choose'"
299 "control structure with a 'default' clause" );
300 }
301 break;
302 }
303 default:
304 assert( false );
305 }
306
307 // Branch error checks: get the appropriate label name, which is always replaced.
308 Label exitLabel( CodeLocation(), "" );
309 switch ( stmt->kind ) {
310 case BranchStmt::Break:
311 assert( ! targetEntry->useBreakExit().empty() );
312 exitLabel = targetEntry->useBreakExit();
313 break;
314 case BranchStmt::Continue:
315 assert( ! targetEntry->useContExit().empty() );
316 exitLabel = targetEntry->useContExit();
317 break;
318 case BranchStmt::FallThrough:
319 assert( ! targetEntry->useFallExit().empty() );
320 exitLabel = targetEntry->useFallExit();
321 break;
322 case BranchStmt::FallThroughDefault:
323 assert( ! targetEntry->useFallDefaultExit().empty() );
324 exitLabel = targetEntry->useFallDefaultExit();
325 // Check that fallthrough default comes before the default clause.
326 if ( ! targetEntry->isFallDefaultValid() ) {
327 SemanticError( stmt->location, "'fallthrough default' must precede the 'default' clause" );
328 }
329 break;
330 default:
331 assert(0);
332 }
333
334 // Add unused attribute to silence warnings.
335 targetEntry->stmt = addUnused( targetEntry->stmt, stmt->originalTarget );
336
337 // Replace with goto to make later passes more uniform.
338 return new BranchStmt( stmt->location, BranchStmt::Goto, exitLabel );
339}
340
341void MultiLevelExitCore::previsit( const WhileDoStmt * stmt ) {
342 return prehandleLoopStmt( stmt );
343}
344
345const WhileDoStmt * MultiLevelExitCore::postvisit( const WhileDoStmt * stmt ) {
346 return posthandleLoopStmt( stmt );
347}
348
349void MultiLevelExitCore::previsit( const ForStmt * stmt ) {
350 return prehandleLoopStmt( stmt );
351}
352
353const ForStmt * MultiLevelExitCore::postvisit( const ForStmt * stmt ) {
354 return posthandleLoopStmt( stmt );
355}
356
357// Mimic what the built-in push_front would do anyways. It is O(n).
358void push_front(
359 vector<ptr<Stmt>> & vec, const Stmt * element ) {
360 vec.emplace_back( nullptr );
361 for ( size_t i = vec.size() - 1 ; 0 < i ; --i ) {
362 vec[ i ] = move( vec[ i - 1 ] );
363 }
364 vec[ 0 ] = element;
365}
366
367const CaseStmt * MultiLevelExitCore::previsit( const CaseStmt * stmt ) {
368 visit_children = false;
369
370 // If default, mark seen.
371 if ( stmt->isDefault() ) {
372 assert( ! enclosing_control_structures.empty() );
373 enclosing_control_structures.back().seenDefault();
374 }
375
376 // The cond may not exist, but if it does update it now.
377 visitor->maybe_accept( stmt, &CaseStmt::cond );
378
379 // Just save the mutated node for simplicity.
380 CaseStmt * mutStmt = mutate( stmt );
381
382 Label fallLabel = newLabel( "fallThrough", stmt );
383 if ( ! mutStmt->stmts.empty() ) {
384 // Ensure that the stack isn't corrupted by exceptions in fixBlock.
385 auto guard = makeFuncGuard(
386 [&](){ enclosing_control_structures.emplace_back( mutStmt, fallLabel ); },
387 [this](){ enclosing_control_structures.pop_back(); }
388 );
389
390 // These should already be in a block.
391 auto block = mutate( mutStmt->stmts.front().strict_as<CompoundStmt>() );
392 block->kids = fixBlock( block->kids, true );
393
394 // Add fallthrough label if necessary.
395 assert( ! enclosing_control_structures.empty() );
396 Entry & entry = enclosing_control_structures.back();
397 if ( entry.isFallUsed() ) {
398 mutStmt->stmts.push_back( labelledNullStmt( mutStmt->location, entry.useFallExit() ) );
399 }
400 }
401 assert( ! enclosing_control_structures.empty() );
402 Entry & entry = enclosing_control_structures.back();
403 assertf( dynamic_cast< const SwitchStmt * >( entry.stmt ),
404 "CFA internal error: control structure enclosing a case clause must be a switch, but is: %s",
405 toString( entry.stmt ).c_str() );
406 if ( mutStmt->isDefault() ) {
407 if ( entry.isFallDefaultUsed() ) {
408 // Add fallthrough default label if necessary.
409 push_front( mutStmt->stmts, labelledNullStmt( stmt->location, entry.useFallDefaultExit() ) );
410 }
411 }
412 return mutStmt;
413}
414
415void MultiLevelExitCore::previsit( const IfStmt * stmt ) {
416 bool labeledBlock = ! stmt->labels.empty();
417 if ( labeledBlock ) {
418 Label breakLabel = newLabel( "blockBreak", stmt );
419 enclosing_control_structures.emplace_back( stmt, breakLabel );
420 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
421 }
422}
423
424const IfStmt * MultiLevelExitCore::postvisit( const IfStmt * stmt ) {
425 bool labeledBlock = ! stmt->labels.empty();
426 if ( labeledBlock ) {
427 auto this_label = enclosing_control_structures.back().useBreakExit();
428 if ( ! this_label.empty() ) {
429 break_label = this_label;
430 }
431 }
432 return stmt;
433}
434
435bool isDefaultCase( const ptr<Stmt> & stmt ) {
436 const CaseStmt * caseStmt = stmt.strict_as<CaseStmt>();
437 return caseStmt->isDefault();
438}
439
440void MultiLevelExitCore::previsit( const SwitchStmt * stmt ) {
441 Label label = newLabel( "switchBreak", stmt );
442 auto it = find_if( stmt->stmts.rbegin(), stmt->stmts.rend(), isDefaultCase );
443
444 const CaseStmt * defaultCase = it != stmt->stmts.rend() ? (it)->strict_as<CaseStmt>() : nullptr;
445 Label defaultLabel = defaultCase ? newLabel( "fallThroughDefault", defaultCase ) : Label( stmt->location, "" );
446 enclosing_control_structures.emplace_back( stmt, label, defaultLabel );
447 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
448
449 // Collect valid labels for fallthrough. It starts with all labels at this level, then remove as each is seen during
450 // traversal.
451 for ( const Stmt * stmt : stmt->stmts ) {
452 auto * caseStmt = strict_dynamic_cast< const CaseStmt * >( stmt );
453 if ( caseStmt->stmts.empty() ) continue;
454 auto block = caseStmt->stmts.front().strict_as<CompoundStmt>();
455 for ( const Stmt * stmt : block->kids ) {
456 for ( const Label & l : stmt->labels ) {
457 fallthrough_labels.insert( l );
458 }
459 }
460 }
461}
462
463const SwitchStmt * MultiLevelExitCore::postvisit( const SwitchStmt * stmt ) {
464 assert( ! enclosing_control_structures.empty() );
465 Entry & entry = enclosing_control_structures.back();
466 assert( entry.stmt == stmt );
467
468 // Only run to generate the break label.
469 if ( entry.isBreakUsed() ) {
470 // To keep the switch statements uniform (all direct children of a SwitchStmt should be CastStmts), append the
471 // exit label and break to the last case, create a default case if no cases.
472 SwitchStmt * mutStmt = mutate( stmt );
473 if ( mutStmt->stmts.empty() ) {
474 mutStmt->stmts.push_back( new CaseStmt( mutStmt->location, nullptr, {} ) );
475 }
476
477 auto caseStmt = mutStmt->stmts.back().strict_as<CaseStmt>();
478 auto mutCase = mutate( caseStmt );
479 mutStmt->stmts.back() = mutCase;
480
481 Label label( mutCase->location, "breakLabel" );
482 auto branch = new BranchStmt( mutCase->location, BranchStmt::Break, label );
483 branch->labels.push_back( entry.useBreakExit() );
484 mutCase->stmts.push_back( branch );
485
486 return mutStmt;
487 }
488 return stmt;
489}
490
491void MultiLevelExitCore::previsit( const ReturnStmt * stmt ) {
492 if ( inFinally ) {
493 SemanticError( stmt->location, "'return' may not appear in a finally clause" );
494 }
495}
496
497void MultiLevelExitCore::previsit( const TryStmt * stmt ) {
498 bool isLabeled = ! stmt->labels.empty();
499 if ( isLabeled ) {
500 Label breakLabel = newLabel( "blockBreak", stmt );
501 enclosing_control_structures.emplace_back( stmt, breakLabel );
502 GuardAction([this](){ enclosing_control_structures.pop_back(); } );
503 }
504}
505
506void MultiLevelExitCore::postvisit( const TryStmt * stmt ) {
507 bool isLabeled = ! stmt->labels.empty();
508 if ( isLabeled ) {
509 auto this_label = enclosing_control_structures.back().useBreakExit();
510 if ( ! this_label.empty() ) {
511 break_label = this_label;
512 }
513 }
514}
515
516void MultiLevelExitCore::previsit( const FinallyStmt * ) {
517 GuardAction([this, old = move( enclosing_control_structures)](){ enclosing_control_structures = move(old); });
518 enclosing_control_structures = vector<Entry>();
519 GuardValue( inFinally ) = true;
520}
521
522const Stmt * MultiLevelExitCore::mutateLoop(
523 const Stmt * body, Entry & entry ) {
524 if ( entry.isBreakUsed() ) {
525 break_label = entry.useBreakExit();
526 }
527
528 // if continue is used insert a continue label into the back of the body of the loop
529 if ( entry.isContUsed() ) {
530 CompoundStmt * new_body = new CompoundStmt( body->location );
531 // {}
532 new_body->kids.push_back( body );
533 // {
534 // body
535 // }
536 new_body->kids.push_back(
537 labelledNullStmt( body->location, entry.useContExit() ) );
538 // {
539 // body
540 // ContinueLabel: {}
541 // }
542 return new_body;
543 }
544
545 return body;
546}
547
548template<typename LoopNode>
549void MultiLevelExitCore::prehandleLoopStmt( const LoopNode * loopStmt ) {
550 // Remember is loop before going onto mutate the body.
551 // The labels will be folded in if they are used.
552 Label breakLabel = newLabel( "loopBreak", loopStmt );
553 Label contLabel = newLabel( "loopContinue", loopStmt );
554 enclosing_control_structures.emplace_back( loopStmt, breakLabel, contLabel );
555 // labels are added temporarily to see if they are used and then added permanently in postvisit if ther are used
556 // children will tag labels as being used during their traversal which occurs before postvisit
557
558 // GuardAction calls the lambda after the node is done being visited
559 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
560}
561
562template<typename LoopNode>
563const LoopNode * MultiLevelExitCore::posthandleLoopStmt( const LoopNode * loopStmt ) {
564 assert( ! enclosing_control_structures.empty() );
565 Entry & entry = enclosing_control_structures.back();
566 assert( entry.stmt == loopStmt );
567
568 // Now check if the labels are used and add them if so.
569 return mutate_field( loopStmt, &LoopNode::body, mutateLoop( loopStmt->body, entry ) );
570 // this call to mutate_field compares loopStmt->body and the result of mutateLoop
571 // if they are the same the node isn't mutated, if they differ then the new mutated node is returned
572 // the stmts will only differ if a label is used
573}
574
575list<ptr<Stmt>> MultiLevelExitCore::fixBlock(
576 const list<ptr<Stmt>> & kids, bool is_case_clause ) {
577 // Unfortunately cannot use automatic error collection.
578 SemanticErrorException errors;
579
580 list<ptr<Stmt>> ret;
581
582 // Manually visit each child.
583 for ( const ptr<Stmt> & kid : kids ) {
584 if ( is_case_clause ) {
585 // Once a label is seen, it's no longer a valid for fallthrough.
586 for ( const Label & l : kid->labels ) {
587 fallthrough_labels.erase( l );
588 }
589 }
590
591 try {
592 ret.push_back( kid->accept( *visitor ) );
593 } catch ( SemanticErrorException & e ) {
594 errors.append( e );
595 }
596
597 if ( ! break_label.empty() ) {
598 ret.push_back( labelledNullStmt( ret.back()->location, break_label ) );
599 break_label = Label( CodeLocation(), "" );
600 }
601 }
602
603 if ( ! errors.isEmpty() ) {
604 throw errors;
605 }
606 return ret;
607}
608
609const CompoundStmt * multiLevelExitUpdate(
610 const CompoundStmt * stmt,
611 const LabelToStmt & labelTable ) {
612 // Must start in the body, so FunctionDecls can be a stopping point.
613 Pass<MultiLevelExitCore> visitor( labelTable );
614 const CompoundStmt * ret = stmt->accept( visitor );
615 return ret;
616}
617} // namespace ControlStruct
618
619// Local Variables: //
620// tab-width: 4 //
621// mode: c++ //
622// compile-command: "make install" //
623// End: //
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