source: src/ControlStruct/MultiLevelExit.cpp@ 4e7171f

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since 4e7171f was 3b0bc16, checked in by Peter A. Buhr <pabuhr@…>, 4 years ago

change class name WhileStmt to WhileDoStmt, add else clause to WhileDoStmt and ForStmt, change names thenPart/ElsePart to then/else_
  • 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 : Tue Feb 1 18:48:47 2022
13// Update Count : 29
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
52 public:
53 Entry( const ForStmt * stmt, Label breakExit, Label contExit ) :
54 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( ForStmtK ) {}
55 Entry( const WhileDoStmt * stmt, Label breakExit, Label contExit ) :
56 stmt( stmt ), firstTarget( breakExit ), secondTarget( contExit ), kind( WhileDoStmtK ) {}
57 Entry( const CompoundStmt *stmt, Label breakExit ) :
58 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( CompoundStmtK ) {}
59 Entry( const IfStmt *stmt, Label breakExit ) :
60 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( IfStmtK ) {}
61 Entry( const CaseStmt *stmt, Label fallExit ) :
62 stmt( stmt ), firstTarget( fallExit ), secondTarget(), kind( CaseStmtK ) {}
63 Entry( const SwitchStmt *stmt, Label breakExit, Label fallDefaultExit ) :
64 stmt( stmt ), firstTarget( breakExit ), secondTarget( fallDefaultExit ), kind( SwitchStmtK ) {}
65 Entry( const TryStmt *stmt, Label breakExit ) :
66 stmt( stmt ), firstTarget( breakExit ), secondTarget(), kind( TryStmtK ) {}
67
68 bool isContTarget() const { return kind <= WhileDoStmtK; }
69 bool isBreakTarget() const { return kind != CaseStmtK; }
70 bool isFallTarget() const { return kind == CaseStmtK; }
71 bool isFallDefaultTarget() const { return kind == SwitchStmtK; }
72
73 // These routines set a target as being "used" by a BranchStmt
74 Label useContExit() { assert( kind <= WhileDoStmtK ); return useTarget(secondTarget); }
75 Label useBreakExit() { assert( kind != CaseStmtK ); return useTarget(firstTarget); }
76 Label useFallExit() { assert( kind == CaseStmtK ); return useTarget(firstTarget); }
77 Label useFallDefaultExit() { assert( kind == SwitchStmtK ); return useTarget(secondTarget); }
78
79 // These routines check if a specific label for a statement is used by a BranchStmt
80 bool isContUsed() const { assert( kind <= WhileDoStmtK ); return secondTarget.used; }
81 bool isBreakUsed() const { assert( kind != CaseStmtK ); return firstTarget.used; }
82 bool isFallUsed() const { assert( kind == CaseStmtK ); return firstTarget.used; }
83 bool isFallDefaultUsed() const { assert( kind == SwitchStmtK ); return secondTarget.used; }
84 void seenDefault() { fallDefaultValid = false; }
85 bool isFallDefaultValid() const { return fallDefaultValid; }
86};
87
88// Helper predicates used in find_if calls (it doesn't take methods):
89bool isBreakTarget( const Entry & entry ) {
90 return entry.isBreakTarget();
91}
92
93bool isContinueTarget( const Entry & entry ) {
94 return entry.isContTarget();
95}
96
97bool isFallthroughTarget( const Entry & entry ) {
98 return entry.isFallTarget();
99}
100
101bool isFallthroughDefaultTarget( const Entry & entry ) {
102 return entry.isFallDefaultTarget();
103}
104
105struct MultiLevelExitCore final :
106 public WithVisitorRef<MultiLevelExitCore>,
107 public WithShortCircuiting, public WithGuards {
108 MultiLevelExitCore( const LabelToStmt & lt );
109
110 void previsit( const FunctionDecl * );
111
112 const CompoundStmt * previsit( const CompoundStmt * );
113 const BranchStmt * postvisit( const BranchStmt * );
114 void previsit( const WhileDoStmt * );
115 const WhileDoStmt * postvisit( const WhileDoStmt * );
116 void previsit( const ForStmt * );
117 const ForStmt * postvisit( const ForStmt * );
118 const CaseStmt * previsit( const CaseStmt * );
119 void previsit( const IfStmt * );
120 const IfStmt * postvisit( const IfStmt * );
121 void previsit( const SwitchStmt * );
122 const SwitchStmt * postvisit( const SwitchStmt * );
123 void previsit( const ReturnStmt * );
124 void previsit( const TryStmt * );
125 void postvisit( const TryStmt * );
126 void previsit( const FinallyStmt * );
127
128 const Stmt * mutateLoop( const Stmt * body, Entry& );
129
130 const LabelToStmt & target_table;
131 set<Label> fallthrough_labels;
132 vector<Entry> enclosing_control_structures;
133 Label break_label;
134 bool inFinally;
135
136 template<typename LoopNode>
137 void prehandleLoopStmt( const LoopNode * loopStmt );
138 template<typename LoopNode>
139 const LoopNode * posthandleLoopStmt( const LoopNode * loopStmt );
140
141 list<ptr<Stmt>> fixBlock(
142 const list<ptr<Stmt>> & kids, bool caseClause );
143
144 template<typename UnaryPredicate>
145 auto findEnclosingControlStructure( UnaryPredicate pred ) {
146 return find_if( enclosing_control_structures.rbegin(),
147 enclosing_control_structures.rend(), pred );
148 }
149};
150
151NullStmt * labelledNullStmt(
152 const CodeLocation & cl, const Label & label ) {
153 return new NullStmt( cl, vector<Label>{ label } );
154}
155
156MultiLevelExitCore::MultiLevelExitCore( const LabelToStmt & lt ) :
157 target_table( lt ), break_label( CodeLocation(), "" ),
158 inFinally( false )
159{}
160
161void MultiLevelExitCore::previsit( const FunctionDecl * ) {
162 visit_children = false;
163}
164
165const CompoundStmt * MultiLevelExitCore::previsit(
166 const CompoundStmt * stmt ) {
167 visit_children = false;
168
169 // if the stmt is labelled then generate a label to check in postvisit if the label is used
170 bool isLabeled = !stmt->labels.empty();
171 if ( isLabeled ) {
172 Label breakLabel = newLabel( "blockBreak", stmt );
173 enclosing_control_structures.emplace_back( stmt, breakLabel );
174 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
175 }
176
177 auto mutStmt = mutate( stmt );
178 // A child statement may set the break label.
179 mutStmt->kids = move( fixBlock( stmt->kids, false ) );
180
181 if ( isLabeled ) {
182 assert( !enclosing_control_structures.empty() );
183 Entry & entry = enclosing_control_structures.back();
184 if ( !entry.useBreakExit().empty() ) {
185 break_label = entry.useBreakExit();
186 }
187 }
188 return mutStmt;
189}
190
191size_t getUnusedIndex(
192 const Stmt * stmt, const Label & originalTarget ) {
193 const size_t size = stmt->labels.size();
194
195 // If the label is empty, do not add unused attribute.
196 if ( originalTarget.empty() ) return size;
197
198 // Search for a label that matches the originalTarget.
199 for ( size_t i = 0 ; i < size ; ++i ) {
200 const Label & label = stmt->labels[i];
201 if ( label == originalTarget ) {
202 for ( const Attribute * attr : label.attributes ) {
203 if ( attr->name == "unused" ) return size;
204 }
205 return i;
206 }
207 }
208 assertf( false, "Could not find label '%s' on statement %s",
209 originalTarget.name.c_str(), toString( stmt ).c_str() );
210}
211
212const Stmt * addUnused(
213 const Stmt * stmt, const Label & originalTarget ) {
214 size_t i = getUnusedIndex( stmt, originalTarget );
215 if ( i == stmt->labels.size() ) {
216 return stmt;
217 }
218 Stmt * mutStmt = mutate( stmt );
219 mutStmt->labels[i].attributes.push_back( new Attribute( "unused" ) );
220 return mutStmt;
221}
222
223// This routine updates targets on enclosing control structures to indicate which
224// label is used by the BranchStmt that is passed
225const BranchStmt * MultiLevelExitCore::postvisit( const BranchStmt * stmt ) {
226 vector<Entry>::reverse_iterator targetEntry =
227 enclosing_control_structures.rend();
228
229 // Labels on different stmts require different approaches to access
230 switch ( stmt->kind ) {
231 case BranchStmt::Goto:
232 return stmt;
233 case BranchStmt::Continue:
234 case BranchStmt::Break: {
235 bool isContinue = stmt->kind == BranchStmt::Continue;
236 // Handle unlabeled break and continue.
237 if ( stmt->target.empty() ) {
238 if ( isContinue ) {
239 targetEntry = findEnclosingControlStructure( isContinueTarget );
240 } else {
241 if ( enclosing_control_structures.empty() ) {
242 SemanticError( stmt->location,
243 "'break' outside a loop, 'switch', or labelled block" );
244 }
245 targetEntry = findEnclosingControlStructure( isBreakTarget );
246 }
247 // Handle labeled break and continue.
248 } else {
249 // Lookup label in table to find attached control structure.
250 targetEntry = findEnclosingControlStructure(
251 [ targetStmt = target_table.at(stmt->target) ](auto entry){
252 return entry.stmt == targetStmt;
253 } );
254 }
255 // Ensure that selected target is valid.
256 if ( targetEntry == enclosing_control_structures.rend() || ( isContinue && !isContinueTarget( *targetEntry ) ) ) {
257 SemanticError( stmt->location, toString( (isContinue ? "'continue'" : "'break'"),
258 " target must be an enclosing ", (isContinue ? "loop: " : "control structure: "),
259 stmt->originalTarget ) );
260 }
261 break;
262 }
263 // handle fallthrough in case/switch stmts
264 case BranchStmt::FallThrough: {
265 targetEntry = findEnclosingControlStructure( isFallthroughTarget );
266 // Check that target is valid.
267 if ( targetEntry == enclosing_control_structures.rend() ) {
268 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
269 }
270 if ( !stmt->target.empty() ) {
271 // Labelled fallthrough: target must be a valid fallthough label.
272 if ( !fallthrough_labels.count( stmt->target ) ) {
273 SemanticError( stmt->location, toString( "'fallthrough' target must be a later case statement: ",
274 stmt->originalTarget ) );
275 }
276 return new BranchStmt(
277 stmt->location, BranchStmt::Goto, stmt->originalTarget );
278 }
279 break;
280 }
281 case BranchStmt::FallThroughDefault: {
282 targetEntry = findEnclosingControlStructure( isFallthroughDefaultTarget );
283
284 // Check if in switch or choose statement.
285 if ( targetEntry == enclosing_control_structures.rend() ) {
286 SemanticError( stmt->location, "'fallthrough' must be enclosed in a 'switch' or 'choose'" );
287 }
288
289 // Check if switch or choose has default clause.
290 auto switchStmt = strict_dynamic_cast< const SwitchStmt * >( targetEntry->stmt );
291 bool foundDefault = false;
292 for ( auto subStmt : switchStmt->stmts ) {
293 const CaseStmt * caseStmt = subStmt.strict_as<CaseStmt>();
294 if ( caseStmt->isDefault() ) {
295 foundDefault = true;
296 break;
297 }
298 }
299 if ( ! foundDefault ) {
300 SemanticError( stmt->location, "'fallthrough default' must be enclosed in a 'switch' or 'choose'"
301 "control structure with a 'default' clause" );
302 }
303 break;
304 }
305 default:
306 assert( false );
307 }
308
309 // Branch error checks: get the appropriate label name:
310 // (This label is always replaced.)
311 Label exitLabel( CodeLocation(), "" );
312 switch ( stmt->kind ) {
313 case BranchStmt::Break:
314 assert( !targetEntry->useBreakExit().empty() );
315 exitLabel = targetEntry->useBreakExit();
316 break;
317 case BranchStmt::Continue:
318 assert( !targetEntry->useContExit().empty() );
319 exitLabel = targetEntry->useContExit();
320 break;
321 case BranchStmt::FallThrough:
322 assert( !targetEntry->useFallExit().empty() );
323 exitLabel = targetEntry->useFallExit();
324 break;
325 case BranchStmt::FallThroughDefault:
326 assert( !targetEntry->useFallDefaultExit().empty() );
327 exitLabel = targetEntry->useFallDefaultExit();
328 // Check that fallthrough default comes before the default clause.
329 if ( !targetEntry->isFallDefaultValid() ) {
330 SemanticError( stmt->location, "'fallthrough default' must precede the 'default' clause" );
331 }
332 break;
333 default:
334 assert(0);
335 }
336
337 // Add unused attribute to silence warnings.
338 targetEntry->stmt = addUnused( targetEntry->stmt, stmt->originalTarget );
339
340 // Replace with goto to make later passes more uniform.
341 return new BranchStmt( stmt->location, BranchStmt::Goto, exitLabel );
342}
343
344void MultiLevelExitCore::previsit( const WhileDoStmt * stmt ) {
345 return prehandleLoopStmt( stmt );
346}
347
348const WhileDoStmt * MultiLevelExitCore::postvisit( const WhileDoStmt * stmt ) {
349 return posthandleLoopStmt( stmt );
350}
351
352void MultiLevelExitCore::previsit( const ForStmt * stmt ) {
353 return prehandleLoopStmt( stmt );
354}
355
356const ForStmt * MultiLevelExitCore::postvisit( const ForStmt * stmt ) {
357 return posthandleLoopStmt( stmt );
358}
359
360// Mimic what the built-in push_front would do anyways. It is O(n).
361void push_front(
362 vector<ptr<Stmt>> & vec, const Stmt * element ) {
363 vec.emplace_back( nullptr );
364 for ( size_t i = vec.size() - 1 ; 0 < i ; --i ) {
365 vec[ i ] = move( vec[ i - 1 ] );
366 }
367 vec[ 0 ] = element;
368}
369
370const CaseStmt * MultiLevelExitCore::previsit( const CaseStmt * stmt ) {
371 visit_children = false;
372
373 // If default, mark seen.
374 if ( stmt->isDefault() ) {
375 assert( !enclosing_control_structures.empty() );
376 enclosing_control_structures.back().seenDefault();
377 }
378
379 // The cond may not exist, but if it does update it now.
380 visitor->maybe_accept( stmt, &CaseStmt::cond );
381
382 // Just save the mutated node for simplicity.
383 CaseStmt * mutStmt = mutate( stmt );
384
385 Label fallLabel = newLabel( "fallThrough", stmt );
386 if ( ! mutStmt->stmts.empty() ) {
387 // Ensure that the stack isn't corrupted by exceptions in fixBlock.
388 auto guard = makeFuncGuard(
389 [&](){ enclosing_control_structures.emplace_back( mutStmt, fallLabel ); },
390 [this](){ enclosing_control_structures.pop_back(); }
391 );
392
393 // These should already be in a block.
394 auto block = mutate( mutStmt->stmts.front().strict_as<CompoundStmt>() );
395 block->kids = fixBlock( block->kids, true );
396
397 // Add fallthrough label if necessary.
398 assert( ! enclosing_control_structures.empty() );
399 Entry & entry = enclosing_control_structures.back();
400 if ( entry.isFallUsed() ) {
401 mutStmt->stmts.push_back(
402 labelledNullStmt( mutStmt->location, entry.useFallExit() ) );
403 }
404 }
405 assert( ! enclosing_control_structures.empty() );
406 Entry & entry = enclosing_control_structures.back();
407 assertf( dynamic_cast< const SwitchStmt * >( entry.stmt ),
408 "Control structure enclosing a case clause must be a switch, but is: %s",
409 toString( entry.stmt ).c_str() );
410 if ( mutStmt->isDefault() ) {
411 if ( entry.isFallDefaultUsed() ) {
412 // Add fallthrough default label if necessary.
413 push_front( mutStmt->stmts, labelledNullStmt(
414 stmt->location, entry.useFallDefaultExit()
415 ) );
416 }
417 }
418 return mutStmt;
419}
420
421void MultiLevelExitCore::previsit( const IfStmt * stmt ) {
422 bool labeledBlock = !stmt->labels.empty();
423 if ( labeledBlock ) {
424 Label breakLabel = newLabel( "blockBreak", stmt );
425 enclosing_control_structures.emplace_back( stmt, breakLabel );
426 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
427 }
428}
429
430const IfStmt * MultiLevelExitCore::postvisit( const IfStmt * stmt ) {
431 bool labeledBlock = !stmt->labels.empty();
432 if ( labeledBlock ) {
433 auto this_label = enclosing_control_structures.back().useBreakExit();
434 if ( !this_label.empty() ) {
435 break_label = this_label;
436 }
437 }
438 return stmt;
439}
440
441bool isDefaultCase( const ptr<Stmt> & stmt ) {
442 const CaseStmt * caseStmt = stmt.strict_as<CaseStmt>();
443 return caseStmt->isDefault();
444}
445
446void MultiLevelExitCore::previsit( const SwitchStmt * stmt ) {
447 Label label = newLabel( "switchBreak", stmt );
448 auto it = find_if( stmt->stmts.rbegin(), stmt->stmts.rend(), isDefaultCase );
449
450 const CaseStmt * defaultCase = it != stmt->stmts.rend()
451 ? (it)->strict_as<CaseStmt>() : nullptr;
452 Label defaultLabel = defaultCase
453 ? newLabel( "fallThroughDefault", defaultCase )
454 : Label( stmt->location, "" );
455 enclosing_control_structures.emplace_back( stmt, label, defaultLabel );
456 GuardAction( [this]() { enclosing_control_structures.pop_back(); } );
457
458 // Collect valid labels for fallthrough. It starts with all labels at
459 // this level, then remove as each is seen during traversal.
460 for ( const Stmt * stmt : stmt->stmts ) {
461 auto * caseStmt = strict_dynamic_cast< const CaseStmt * >( stmt );
462 if ( caseStmt->stmts.empty() ) continue;
463 auto block = caseStmt->stmts.front().strict_as<CompoundStmt>();
464 for ( const Stmt * stmt : block->kids ) {
465 for ( const Label & l : stmt->labels ) {
466 fallthrough_labels.insert( l );
467 }
468 }
469 }
470}
471
472const SwitchStmt * MultiLevelExitCore::postvisit( const SwitchStmt * stmt ) {
473 assert( !enclosing_control_structures.empty() );
474 Entry & entry = enclosing_control_structures.back();
475 assert( entry.stmt == stmt );
476
477 // Only run to generate the break label.
478 if ( entry.isBreakUsed() ) {
479 // To keep the switch statements uniform (all direct children of a
480 // SwitchStmt should be CastStmts), append the exit label and break
481 // to the last case, create a default case is there are no cases.
482 SwitchStmt * mutStmt = mutate( stmt );
483 if ( mutStmt->stmts.empty() ) {
484 mutStmt->stmts.push_back( new CaseStmt(
485 mutStmt->location, nullptr, {} ));
486 }
487
488 auto caseStmt = mutStmt->stmts.back().strict_as<CaseStmt>();
489 auto mutCase = mutate( caseStmt );
490 mutStmt->stmts.back() = mutCase;
491
492 Label label( mutCase->location, "breakLabel" );
493 auto branch = new BranchStmt( mutCase->location, BranchStmt::Break, label );
494 branch->labels.push_back( entry.useBreakExit() );
495 mutCase->stmts.push_back( branch );
496
497 return mutStmt;
498 }
499 return stmt;
500}
501
502void MultiLevelExitCore::previsit( const ReturnStmt * stmt ) {
503 if ( inFinally ) {
504 SemanticError( stmt->location, "'return' may not appear in a finally clause" );
505 }
506}
507
508void MultiLevelExitCore::previsit( const TryStmt * stmt ) {
509 bool isLabeled = !stmt->labels.empty();
510 if ( isLabeled ) {
511 Label breakLabel = newLabel( "blockBreak", stmt );
512 enclosing_control_structures.emplace_back( stmt, breakLabel );
513 GuardAction([this](){ enclosing_control_structures.pop_back(); } );
514 }
515}
516
517void MultiLevelExitCore::postvisit( const TryStmt * stmt ) {
518 bool isLabeled = !stmt->labels.empty();
519 if ( isLabeled ) {
520 auto this_label = enclosing_control_structures.back().useBreakExit();
521 if ( !this_label.empty() ) {
522 break_label = this_label;
523 }
524 }
525}
526
527void MultiLevelExitCore::previsit( const FinallyStmt * ) {
528 GuardAction([this, old = move(enclosing_control_structures)](){
529 enclosing_control_structures = move(old);
530 });
531 enclosing_control_structures = vector<Entry>();
532 GuardValue( inFinally ) = true;
533}
534
535const Stmt * MultiLevelExitCore::mutateLoop(
536 const Stmt * body, Entry & entry ) {
537 if ( entry.isBreakUsed() ) {
538 break_label = entry.useBreakExit();
539 }
540
541 // if continue is used insert a continue label into the back of the body of the loop
542 if ( entry.isContUsed() ) {
543 CompoundStmt * new_body = new CompoundStmt( body->location );
544 // {}
545 new_body->kids.push_back( body );
546 // {
547 // body
548 // }
549 new_body->kids.push_back(
550 labelledNullStmt( body->location, entry.useContExit() ) );
551 // {
552 // body
553 // ContinueLabel: {}
554 // }
555 return new_body;
556 }
557
558 return body;
559}
560
561template<typename LoopNode>
562void MultiLevelExitCore::prehandleLoopStmt( const LoopNode * loopStmt ) {
563 // Remember is loop before going onto mutate the body.
564 // The labels will be folded in if they are used.
565 Label breakLabel = newLabel( "loopBreak", loopStmt );
566 Label contLabel = newLabel( "loopContinue", loopStmt );
567 enclosing_control_structures.emplace_back( loopStmt, breakLabel, contLabel );
568 // labels are added temporarily to see if they are used and then added permanently in postvisit if ther are used
569 // children will tag labels as being used during their traversal which occurs before postvisit
570
571 // GuardAction calls the lambda after the node is done being visited
572 GuardAction( [this](){ enclosing_control_structures.pop_back(); } );
573}
574
575template<typename LoopNode>
576const LoopNode * MultiLevelExitCore::posthandleLoopStmt( const LoopNode * loopStmt ) {
577 assert( !enclosing_control_structures.empty() );
578 Entry & entry = enclosing_control_structures.back();
579 assert( entry.stmt == loopStmt );
580
581 // Now check if the labels are used and add them if so.
582 return mutate_field(
583 loopStmt, &LoopNode::body, mutateLoop( loopStmt->body, entry ) );
584 // this call to mutate_field compares loopStmt->body and the result of mutateLoop
585 // if they are the same the node isn't mutated, if they differ then the new mutated node is returned
586 // the stmts will only differ if a label is used
587}
588
589list<ptr<Stmt>> MultiLevelExitCore::fixBlock(
590 const list<ptr<Stmt>> & kids, bool is_case_clause ) {
591 // Unfortunately cannot use automatic error collection.
592 SemanticErrorException errors;
593
594 list<ptr<Stmt>> ret;
595
596 // Manually visit each child.
597 for ( const ptr<Stmt> & kid : kids ) {
598 if ( is_case_clause ) {
599 // Once a label is seen, it's no longer a valid for fallthrough.
600 for ( const Label & l : kid->labels ) {
601 fallthrough_labels.erase( l );
602 }
603 }
604
605 try {
606 ret.push_back( kid->accept( *visitor ) );
607 } catch ( SemanticErrorException & e ) {
608 errors.append( e );
609 }
610
611 if ( !break_label.empty() ) {
612 ret.push_back(
613 labelledNullStmt( ret.back()->location, break_label ) );
614 break_label = Label( CodeLocation(), "" );
615 }
616 }
617
618 if ( !errors.isEmpty() ) {
619 throw errors;
620 }
621 return ret;
622}
623
624const CompoundStmt * multiLevelExitUpdate(
625 const CompoundStmt * stmt,
626 const LabelToStmt & labelTable ) {
627 // Must start in the body, so FunctionDecls can be a stopping point.
628 Pass<MultiLevelExitCore> visitor( labelTable );
629 const CompoundStmt * ret = stmt->accept( visitor );
630 return ret;
631}
632} // namespace ControlStruct
633
634// Local Variables: //
635// tab-width: 4 //
636// mode: c++ //
637// compile-command: "make install" //
638// End: //
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