source: src/ResolvExpr/CandidateFinder.cpp@ 34ed17b

ADT ast-experimental
Last change on this file since 34ed17b was 5bf3976, checked in by Andrew Beach <ajbeach@…>, 3 years ago

Header Clean-Up: Created new headers for new AST typeops and moved declarations.
  • Property mode set to 100644
File size: 68.9 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// CandidateFinder.cpp --
8//
9// Author : Aaron B. Moss
10// Created On : Wed Jun 5 14:30:00 2019
11// Last Modified By : Andrew Beach
12// Last Modified On : Wed Mar 16 11:58:00 2022
13// Update Count : 3
14//
15
16#include "CandidateFinder.hpp"
17
18#include <deque>
19#include <iterator> // for back_inserter
20#include <sstream>
21#include <string>
22#include <unordered_map>
23#include <vector>
24
25#include "AdjustExprType.hpp"
26#include "Candidate.hpp"
27#include "CastCost.hpp" // for castCost
28#include "CompilationState.h"
29#include "ConversionCost.h" // for conversionCast
30#include "Cost.h"
31#include "ExplodedArg.hpp"
32#include "PolyCost.hpp"
33#include "RenameVars.h" // for renameTyVars
34#include "Resolver.h"
35#include "ResolveTypeof.h"
36#include "SatisfyAssertions.hpp"
37#include "SpecCost.hpp"
38#include "typeops.h" // for combos
39#include "Unify.h"
40#include "AST/Expr.hpp"
41#include "AST/Node.hpp"
42#include "AST/Pass.hpp"
43#include "AST/Print.hpp"
44#include "AST/SymbolTable.hpp"
45#include "AST/Type.hpp"
46#include "Common/utility.h" // for move, copy
47#include "SymTab/Mangler.h"
48#include "Tuples/Tuples.h" // for handleTupleAssignment
49#include "InitTweak/InitTweak.h" // for getPointerBase
50
51#include "Common/Stats/Counter.h"
52
53#define PRINT( text ) if ( resolvep ) { text }
54
55namespace ResolvExpr {
56
57const ast::Expr * referenceToRvalueConversion( const ast::Expr * expr, Cost & cost ) {
58 if ( expr->result.as< ast::ReferenceType >() ) {
59 // cast away reference from expr
60 cost.incReference();
61 return new ast::CastExpr{ expr, expr->result->stripReferences() };
62 }
63
64 return expr;
65}
66
67/// Unique identifier for matching expression resolutions to their requesting expression
68UniqueId globalResnSlot = 0;
69
70Cost computeConversionCost(
71 const ast::Type * argType, const ast::Type * paramType, bool argIsLvalue,
72 const ast::SymbolTable & symtab, const ast::TypeEnvironment & env
73) {
74 PRINT(
75 std::cerr << std::endl << "converting ";
76 ast::print( std::cerr, argType, 2 );
77 std::cerr << std::endl << " to ";
78 ast::print( std::cerr, paramType, 2 );
79 std::cerr << std::endl << "environment is: ";
80 ast::print( std::cerr, env, 2 );
81 std::cerr << std::endl;
82 )
83 Cost convCost = conversionCost( argType, paramType, argIsLvalue, symtab, env );
84 PRINT(
85 std::cerr << std::endl << "cost is " << convCost << std::endl;
86 )
87 if ( convCost == Cost::infinity ) return convCost;
88 convCost.incPoly( polyCost( paramType, symtab, env ) + polyCost( argType, symtab, env ) );
89 PRINT(
90 std::cerr << "cost with polycost is " << convCost << std::endl;
91 )
92 return convCost;
93}
94
95namespace {
96 /// First index is which argument, second is which alternative, third is which exploded element
97 using ExplodedArgs_new = std::deque< std::vector< ExplodedArg > >;
98
99 /// Returns a list of alternatives with the minimum cost in the given list
100 CandidateList findMinCost( const CandidateList & candidates ) {
101 CandidateList out;
102 Cost minCost = Cost::infinity;
103 for ( const CandidateRef & r : candidates ) {
104 if ( r->cost < minCost ) {
105 minCost = r->cost;
106 out.clear();
107 out.emplace_back( r );
108 } else if ( r->cost == minCost ) {
109 out.emplace_back( r );
110 }
111 }
112 return out;
113 }
114
115 /// Computes conversion cost for a given expression to a given type
116 const ast::Expr * computeExpressionConversionCost(
117 const ast::Expr * arg, const ast::Type * paramType, const ast::SymbolTable & symtab, const ast::TypeEnvironment & env, Cost & outCost
118 ) {
119 Cost convCost = computeConversionCost(
120 arg->result, paramType, arg->get_lvalue(), symtab, env );
121 outCost += convCost;
122
123 // If there is a non-zero conversion cost, ignoring poly cost, then the expression requires
124 // conversion. Ignore poly cost for now, since this requires resolution of the cast to
125 // infer parameters and this does not currently work for the reason stated below
126 Cost tmpCost = convCost;
127 tmpCost.incPoly( -tmpCost.get_polyCost() );
128 if ( tmpCost != Cost::zero ) {
129 ast::ptr< ast::Type > newType = paramType;
130 env.apply( newType );
131 return new ast::CastExpr{ arg, newType };
132
133 // xxx - *should* be able to resolve this cast, but at the moment pointers are not
134 // castable to zero_t, but are implicitly convertible. This is clearly inconsistent,
135 // once this is fixed it should be possible to resolve the cast.
136 // xxx - this isn't working, it appears because type1 (parameter) is seen as widenable,
137 // but it shouldn't be because this makes the conversion from DT* to DT* since
138 // commontype(zero_t, DT*) is DT*, rather than nothing
139
140 // CandidateFinder finder{ symtab, env };
141 // finder.find( arg, ResolvMode::withAdjustment() );
142 // assertf( finder.candidates.size() > 0,
143 // "Somehow castable expression failed to find alternatives." );
144 // assertf( finder.candidates.size() == 1,
145 // "Somehow got multiple alternatives for known cast expression." );
146 // return finder.candidates.front()->expr;
147 }
148
149 return arg;
150 }
151
152 /// Computes conversion cost for a given candidate
153 Cost computeApplicationConversionCost(
154 CandidateRef cand, const ast::SymbolTable & symtab
155 ) {
156 auto appExpr = cand->expr.strict_as< ast::ApplicationExpr >();
157 auto pointer = appExpr->func->result.strict_as< ast::PointerType >();
158 auto function = pointer->base.strict_as< ast::FunctionType >();
159
160 Cost convCost = Cost::zero;
161 const auto & params = function->params;
162 auto param = params.begin();
163 auto & args = appExpr->args;
164
165 for ( unsigned i = 0; i < args.size(); ++i ) {
166 const ast::Type * argType = args[i]->result;
167 PRINT(
168 std::cerr << "arg expression:" << std::endl;
169 ast::print( std::cerr, args[i], 2 );
170 std::cerr << "--- results are" << std::endl;
171 ast::print( std::cerr, argType, 2 );
172 )
173
174 if ( param == params.end() ) {
175 if ( function->isVarArgs ) {
176 convCost.incUnsafe();
177 PRINT( std::cerr << "end of params with varargs function: inc unsafe: "
178 << convCost << std::endl; ; )
179 // convert reference-typed expressions into value-typed expressions
180 cand->expr = ast::mutate_field_index(
181 appExpr, &ast::ApplicationExpr::args, i,
182 referenceToRvalueConversion( args[i], convCost ) );
183 continue;
184 } else return Cost::infinity;
185 }
186
187 if ( auto def = args[i].as< ast::DefaultArgExpr >() ) {
188 // Default arguments should be free - don't include conversion cost.
189 // Unwrap them here because they are not relevant to the rest of the system
190 cand->expr = ast::mutate_field_index(
191 appExpr, &ast::ApplicationExpr::args, i, def->expr );
192 ++param;
193 continue;
194 }
195
196 // mark conversion cost and also specialization cost of param type
197 // const ast::Type * paramType = (*param)->get_type();
198 cand->expr = ast::mutate_field_index(
199 appExpr, &ast::ApplicationExpr::args, i,
200 computeExpressionConversionCost(
201 args[i], *param, symtab, cand->env, convCost ) );
202 convCost.decSpec( specCost( *param ) );
203 ++param; // can't be in for-loop update because of the continue
204 }
205
206 if ( param != params.end() ) return Cost::infinity;
207
208 // specialization cost of return types can't be accounted for directly, it disables
209 // otherwise-identical calls, like this example based on auto-newline in the I/O lib:
210 //
211 // forall(otype OS) {
212 // void ?|?(OS&, int); // with newline
213 // OS& ?|?(OS&, int); // no newline, always chosen due to more specialization
214 // }
215
216 // mark type variable and specialization cost of forall clause
217 convCost.incVar( function->forall.size() );
218 convCost.decSpec( function->assertions.size() );
219
220 return convCost;
221 }
222
223 void makeUnifiableVars(
224 const ast::FunctionType * type, ast::OpenVarSet & unifiableVars,
225 ast::AssertionSet & need
226 ) {
227 for ( auto & tyvar : type->forall ) {
228 unifiableVars[ *tyvar ] = ast::TypeData{ tyvar->base };
229 }
230 for ( auto & assn : type->assertions ) {
231 need[ assn ].isUsed = true;
232 }
233 }
234
235 /// Gets a default value from an initializer, nullptr if not present
236 const ast::ConstantExpr * getDefaultValue( const ast::Init * init ) {
237 if ( auto si = dynamic_cast< const ast::SingleInit * >( init ) ) {
238 if ( auto ce = si->value.as< ast::CastExpr >() ) {
239 return ce->arg.as< ast::ConstantExpr >();
240 } else {
241 return si->value.as< ast::ConstantExpr >();
242 }
243 }
244 return nullptr;
245 }
246
247 /// State to iteratively build a match of parameter expressions to arguments
248 struct ArgPack {
249 std::size_t parent; ///< Index of parent pack
250 ast::ptr< ast::Expr > expr; ///< The argument stored here
251 Cost cost; ///< The cost of this argument
252 ast::TypeEnvironment env; ///< Environment for this pack
253 ast::AssertionSet need; ///< Assertions outstanding for this pack
254 ast::AssertionSet have; ///< Assertions found for this pack
255 ast::OpenVarSet open; ///< Open variables for this pack
256 unsigned nextArg; ///< Index of next argument in arguments list
257 unsigned tupleStart; ///< Number of tuples that start at this index
258 unsigned nextExpl; ///< Index of next exploded element
259 unsigned explAlt; ///< Index of alternative for nextExpl > 0
260
261 ArgPack()
262 : parent( 0 ), expr(), cost( Cost::zero ), env(), need(), have(), open(), nextArg( 0 ),
263 tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {}
264
265 ArgPack(
266 const ast::TypeEnvironment & env, const ast::AssertionSet & need,
267 const ast::AssertionSet & have, const ast::OpenVarSet & open )
268 : parent( 0 ), expr(), cost( Cost::zero ), env( env ), need( need ), have( have ),
269 open( open ), nextArg( 0 ), tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {}
270
271 ArgPack(
272 std::size_t parent, const ast::Expr * expr, ast::TypeEnvironment && env,
273 ast::AssertionSet && need, ast::AssertionSet && have, ast::OpenVarSet && open,
274 unsigned nextArg, unsigned tupleStart = 0, Cost cost = Cost::zero,
275 unsigned nextExpl = 0, unsigned explAlt = 0 )
276 : parent(parent), expr( expr ), cost( cost ), env( std::move( env ) ), need( std::move( need ) ),
277 have( std::move( have ) ), open( std::move( open ) ), nextArg( nextArg ), tupleStart( tupleStart ),
278 nextExpl( nextExpl ), explAlt( explAlt ) {}
279
280 ArgPack(
281 const ArgPack & o, ast::TypeEnvironment && env, ast::AssertionSet && need,
282 ast::AssertionSet && have, ast::OpenVarSet && open, unsigned nextArg, Cost added )
283 : parent( o.parent ), expr( o.expr ), cost( o.cost + added ), env( std::move( env ) ),
284 need( std::move( need ) ), have( std::move( have ) ), open( std::move( open ) ), nextArg( nextArg ),
285 tupleStart( o.tupleStart ), nextExpl( 0 ), explAlt( 0 ) {}
286
287 /// true if this pack is in the middle of an exploded argument
288 bool hasExpl() const { return nextExpl > 0; }
289
290 /// Gets the list of exploded candidates for this pack
291 const ExplodedArg & getExpl( const ExplodedArgs_new & args ) const {
292 return args[ nextArg-1 ][ explAlt ];
293 }
294
295 /// Ends a tuple expression, consolidating the appropriate args
296 void endTuple( const std::vector< ArgPack > & packs ) {
297 // add all expressions in tuple to list, summing cost
298 std::deque< const ast::Expr * > exprs;
299 const ArgPack * pack = this;
300 if ( expr ) { exprs.emplace_front( expr ); }
301 while ( pack->tupleStart == 0 ) {
302 pack = &packs[pack->parent];
303 exprs.emplace_front( pack->expr );
304 cost += pack->cost;
305 }
306 // reset pack to appropriate tuple
307 std::vector< ast::ptr< ast::Expr > > exprv( exprs.begin(), exprs.end() );
308 expr = new ast::TupleExpr{ expr->location, std::move( exprv ) };
309 tupleStart = pack->tupleStart - 1;
310 parent = pack->parent;
311 }
312 };
313
314 /// Instantiates an argument to match a parameter, returns false if no matching results left
315 bool instantiateArgument(
316 const ast::Type * paramType, const ast::Init * init, const ExplodedArgs_new & args,
317 std::vector< ArgPack > & results, std::size_t & genStart, const ast::SymbolTable & symtab,
318 unsigned nTuples = 0
319 ) {
320 if ( auto tupleType = dynamic_cast< const ast::TupleType * >( paramType ) ) {
321 // paramType is a TupleType -- group args into a TupleExpr
322 ++nTuples;
323 for ( const ast::Type * type : *tupleType ) {
324 // xxx - dropping initializer changes behaviour from previous, but seems correct
325 // ^^^ need to handle the case where a tuple has a default argument
326 if ( ! instantiateArgument(
327 type, nullptr, args, results, genStart, symtab, nTuples ) ) return false;
328 nTuples = 0;
329 }
330 // re-constitute tuples for final generation
331 for ( auto i = genStart; i < results.size(); ++i ) {
332 results[i].endTuple( results );
333 }
334 return true;
335 } else if ( const ast::TypeInstType * ttype = Tuples::isTtype( paramType ) ) {
336 // paramType is a ttype, consumes all remaining arguments
337
338 // completed tuples; will be spliced to end of results to finish
339 std::vector< ArgPack > finalResults{};
340
341 // iterate until all results completed
342 std::size_t genEnd;
343 ++nTuples;
344 do {
345 genEnd = results.size();
346
347 // add another argument to results
348 for ( std::size_t i = genStart; i < genEnd; ++i ) {
349 unsigned nextArg = results[i].nextArg;
350
351 // use next element of exploded tuple if present
352 if ( results[i].hasExpl() ) {
353 const ExplodedArg & expl = results[i].getExpl( args );
354
355 unsigned nextExpl = results[i].nextExpl + 1;
356 if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
357
358 results.emplace_back(
359 i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ),
360 copy( results[i].need ), copy( results[i].have ),
361 copy( results[i].open ), nextArg, nTuples, Cost::zero, nextExpl,
362 results[i].explAlt );
363
364 continue;
365 }
366
367 // finish result when out of arguments
368 if ( nextArg >= args.size() ) {
369 ArgPack newResult{
370 results[i].env, results[i].need, results[i].have, results[i].open };
371 newResult.nextArg = nextArg;
372 const ast::Type * argType = nullptr;
373
374 if ( nTuples > 0 || ! results[i].expr ) {
375 // first iteration or no expression to clone,
376 // push empty tuple expression
377 newResult.parent = i;
378 newResult.expr = new ast::TupleExpr{ CodeLocation{}, {} };
379 argType = newResult.expr->result;
380 } else {
381 // clone result to collect tuple
382 newResult.parent = results[i].parent;
383 newResult.cost = results[i].cost;
384 newResult.tupleStart = results[i].tupleStart;
385 newResult.expr = results[i].expr;
386 argType = newResult.expr->result;
387
388 if ( results[i].tupleStart > 0 && Tuples::isTtype( argType ) ) {
389 // the case where a ttype value is passed directly is special,
390 // e.g. for argument forwarding purposes
391 // xxx - what if passing multiple arguments, last of which is
392 // ttype?
393 // xxx - what would happen if unify was changed so that unifying
394 // tuple
395 // types flattened both before unifying lists? then pass in
396 // TupleType (ttype) below.
397 --newResult.tupleStart;
398 } else {
399 // collapse leftover arguments into tuple
400 newResult.endTuple( results );
401 argType = newResult.expr->result;
402 }
403 }
404
405 // check unification for ttype before adding to final
406 if (
407 unify(
408 ttype, argType, newResult.env, newResult.need, newResult.have,
409 newResult.open, symtab )
410 ) {
411 finalResults.emplace_back( std::move( newResult ) );
412 }
413
414 continue;
415 }
416
417 // add each possible next argument
418 for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
419 const ExplodedArg & expl = args[nextArg][j];
420
421 // fresh copies of parent parameters for this iteration
422 ast::TypeEnvironment env = results[i].env;
423 ast::OpenVarSet open = results[i].open;
424
425 env.addActual( expl.env, open );
426
427 // skip empty tuple arguments by (nearly) cloning parent into next gen
428 if ( expl.exprs.empty() ) {
429 results.emplace_back(
430 results[i], std::move( env ), copy( results[i].need ),
431 copy( results[i].have ), std::move( open ), nextArg + 1, expl.cost );
432
433 continue;
434 }
435
436 // add new result
437 results.emplace_back(
438 i, expl.exprs.front(), std::move( env ), copy( results[i].need ),
439 copy( results[i].have ), std::move( open ), nextArg + 1, nTuples,
440 expl.cost, expl.exprs.size() == 1 ? 0 : 1, j );
441 }
442 }
443
444 // reset for next round
445 genStart = genEnd;
446 nTuples = 0;
447 } while ( genEnd != results.size() );
448
449 // splice final results onto results
450 for ( std::size_t i = 0; i < finalResults.size(); ++i ) {
451 results.emplace_back( std::move( finalResults[i] ) );
452 }
453 return ! finalResults.empty();
454 }
455
456 // iterate each current subresult
457 std::size_t genEnd = results.size();
458 for ( std::size_t i = genStart; i < genEnd; ++i ) {
459 unsigned nextArg = results[i].nextArg;
460
461 // use remainder of exploded tuple if present
462 if ( results[i].hasExpl() ) {
463 const ExplodedArg & expl = results[i].getExpl( args );
464 const ast::Expr * expr = expl.exprs[ results[i].nextExpl ];
465
466 ast::TypeEnvironment env = results[i].env;
467 ast::AssertionSet need = results[i].need, have = results[i].have;
468 ast::OpenVarSet open = results[i].open;
469
470 const ast::Type * argType = expr->result;
471
472 PRINT(
473 std::cerr << "param type is ";
474 ast::print( std::cerr, paramType );
475 std::cerr << std::endl << "arg type is ";
476 ast::print( std::cerr, argType );
477 std::cerr << std::endl;
478 )
479
480 if ( unify( paramType, argType, env, need, have, open, symtab ) ) {
481 unsigned nextExpl = results[i].nextExpl + 1;
482 if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
483
484 results.emplace_back(
485 i, expr, std::move( env ), std::move( need ), std::move( have ), std::move( open ), nextArg,
486 nTuples, Cost::zero, nextExpl, results[i].explAlt );
487 }
488
489 continue;
490 }
491
492 // use default initializers if out of arguments
493 if ( nextArg >= args.size() ) {
494 if ( const ast::ConstantExpr * cnst = getDefaultValue( init ) ) {
495 ast::TypeEnvironment env = results[i].env;
496 ast::AssertionSet need = results[i].need, have = results[i].have;
497 ast::OpenVarSet open = results[i].open;
498
499 if ( unify( paramType, cnst->result, env, need, have, open, symtab ) ) {
500 results.emplace_back(
501 i, new ast::DefaultArgExpr{ cnst->location, cnst }, std::move( env ),
502 std::move( need ), std::move( have ), std::move( open ), nextArg, nTuples );
503 }
504 }
505
506 continue;
507 }
508
509 // Check each possible next argument
510 for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
511 const ExplodedArg & expl = args[nextArg][j];
512
513 // fresh copies of parent parameters for this iteration
514 ast::TypeEnvironment env = results[i].env;
515 ast::AssertionSet need = results[i].need, have = results[i].have;
516 ast::OpenVarSet open = results[i].open;
517
518 env.addActual( expl.env, open );
519
520 // skip empty tuple arguments by (nearly) cloning parent into next gen
521 if ( expl.exprs.empty() ) {
522 results.emplace_back(
523 results[i], std::move( env ), std::move( need ), std::move( have ), std::move( open ),
524 nextArg + 1, expl.cost );
525
526 continue;
527 }
528
529 // consider only first exploded arg
530 const ast::Expr * expr = expl.exprs.front();
531 const ast::Type * argType = expr->result;
532
533 PRINT(
534 std::cerr << "param type is ";
535 ast::print( std::cerr, paramType );
536 std::cerr << std::endl << "arg type is ";
537 ast::print( std::cerr, argType );
538 std::cerr << std::endl;
539 )
540
541 // attempt to unify types
542 if ( unify( paramType, argType, env, need, have, open, symtab ) ) {
543 // add new result
544 results.emplace_back(
545 i, expr, std::move( env ), std::move( need ), std::move( have ), std::move( open ),
546 nextArg + 1, nTuples, expl.cost, expl.exprs.size() == 1 ? 0 : 1, j );
547 }
548 }
549 }
550
551 // reset for next parameter
552 genStart = genEnd;
553
554 return genEnd != results.size(); // were any new results added?
555 }
556
557 /// Generate a cast expression from `arg` to `toType`
558 const ast::Expr * restructureCast(
559 ast::ptr< ast::Expr > & arg, const ast::Type * toType, ast::GeneratedFlag isGenerated = ast::GeneratedCast
560 ) {
561 if (
562 arg->result->size() > 1
563 && ! toType->isVoid()
564 && ! dynamic_cast< const ast::ReferenceType * >( toType )
565 ) {
566 // Argument is a tuple and the target type is neither void nor a reference. Cast each
567 // member of the tuple to its corresponding target type, producing the tuple of those
568 // cast expressions. If there are more components of the tuple than components in the
569 // target type, then excess components do not come out in the result expression (but
570 // UniqueExpr ensures that the side effects will still be produced)
571 if ( Tuples::maybeImpureIgnoreUnique( arg ) ) {
572 // expressions which may contain side effects require a single unique instance of
573 // the expression
574 arg = new ast::UniqueExpr{ arg->location, arg };
575 }
576 std::vector< ast::ptr< ast::Expr > > components;
577 for ( unsigned i = 0; i < toType->size(); ++i ) {
578 // cast each component
579 ast::ptr< ast::Expr > idx = new ast::TupleIndexExpr{ arg->location, arg, i };
580 components.emplace_back(
581 restructureCast( idx, toType->getComponent( i ), isGenerated ) );
582 }
583 return new ast::TupleExpr{ arg->location, std::move( components ) };
584 } else {
585 // handle normally
586 return new ast::CastExpr{ arg->location, arg, toType, isGenerated };
587 }
588 }
589
590 /// Gets the name from an untyped member expression (must be NameExpr)
591 const std::string & getMemberName( const ast::UntypedMemberExpr * memberExpr ) {
592 if ( memberExpr->member.as< ast::ConstantExpr >() ) {
593 SemanticError( memberExpr, "Indexed access to struct fields unsupported: " );
594 }
595
596 return memberExpr->member.strict_as< ast::NameExpr >()->name;
597 }
598
599 /// Actually visits expressions to find their candidate interpretations
600 class Finder final : public ast::WithShortCircuiting {
601 const ResolveContext & context;
602 const ast::SymbolTable & symtab;
603 public:
604 // static size_t traceId;
605 CandidateFinder & selfFinder;
606 CandidateList & candidates;
607 const ast::TypeEnvironment & tenv;
608 ast::ptr< ast::Type > & targetType;
609
610 enum Errors {
611 NotFound,
612 NoMatch,
613 ArgsToFew,
614 ArgsToMany,
615 RetsToFew,
616 RetsToMany,
617 NoReason
618 };
619
620 struct {
621 Errors code = NotFound;
622 } reason;
623
624 Finder( CandidateFinder & f )
625 : context( f.context ), symtab( context.symtab ), selfFinder( f ),
626 candidates( f.candidates ), tenv( f.env ), targetType( f.targetType ) {}
627
628 void previsit( const ast::Node * ) { visit_children = false; }
629
630 /// Convenience to add candidate to list
631 template<typename... Args>
632 void addCandidate( Args &&... args ) {
633 candidates.emplace_back( new Candidate{ std::forward<Args>( args )... } );
634 reason.code = NoReason;
635 }
636
637 void postvisit( const ast::ApplicationExpr * applicationExpr ) {
638 addCandidate( applicationExpr, tenv );
639 }
640
641 /// Set up candidate assertions for inference
642 void inferParameters( CandidateRef & newCand, CandidateList & out ) {
643 // Set need bindings for any unbound assertions
644 UniqueId crntResnSlot = 0; // matching ID for this expression's assertions
645 for ( auto & assn : newCand->need ) {
646 // skip already-matched assertions
647 if ( assn.second.resnSlot != 0 ) continue;
648 // assign slot for expression if needed
649 if ( crntResnSlot == 0 ) { crntResnSlot = ++globalResnSlot; }
650 // fix slot to assertion
651 assn.second.resnSlot = crntResnSlot;
652 }
653 // pair slot to expression
654 if ( crntResnSlot != 0 ) {
655 newCand->expr.get_and_mutate()->inferred.resnSlots().emplace_back( crntResnSlot );
656 }
657
658 // add to output list; assertion satisfaction will occur later
659 out.emplace_back( newCand );
660 }
661
662 /// Completes a function candidate with arguments located
663 void validateFunctionCandidate(
664 const CandidateRef & func, ArgPack & result, const std::vector< ArgPack > & results,
665 CandidateList & out
666 ) {
667 ast::ApplicationExpr * appExpr =
668 new ast::ApplicationExpr{ func->expr->location, func->expr };
669 // sum cost and accumulate arguments
670 std::deque< const ast::Expr * > args;
671 Cost cost = func->cost;
672 const ArgPack * pack = &result;
673 while ( pack->expr ) {
674 args.emplace_front( pack->expr );
675 cost += pack->cost;
676 pack = &results[pack->parent];
677 }
678 std::vector< ast::ptr< ast::Expr > > vargs( args.begin(), args.end() );
679 appExpr->args = std::move( vargs );
680 // build and validate new candidate
681 auto newCand =
682 std::make_shared<Candidate>( appExpr, result.env, result.open, result.need, cost );
683 PRINT(
684 std::cerr << "instantiate function success: " << appExpr << std::endl;
685 std::cerr << "need assertions:" << std::endl;
686 ast::print( std::cerr, result.need, 2 );
687 )
688 inferParameters( newCand, out );
689 }
690
691 /// Builds a list of candidates for a function, storing them in out
692 void makeFunctionCandidates(
693 const CandidateRef & func, const ast::FunctionType * funcType,
694 const ExplodedArgs_new & args, CandidateList & out
695 ) {
696 ast::OpenVarSet funcOpen;
697 ast::AssertionSet funcNeed, funcHave;
698 ast::TypeEnvironment funcEnv{ func->env };
699 makeUnifiableVars( funcType, funcOpen, funcNeed );
700 // add all type variables as open variables now so that those not used in the
701 // parameter list are still considered open
702 funcEnv.add( funcType->forall );
703
704 if ( targetType && ! targetType->isVoid() && ! funcType->returns.empty() ) {
705 // attempt to narrow based on expected target type
706 const ast::Type * returnType = funcType->returns.front();
707 if ( ! unify(
708 returnType, targetType, funcEnv, funcNeed, funcHave, funcOpen, symtab )
709 ) {
710 // unification failed, do not pursue this candidate
711 return;
712 }
713 }
714
715 // iteratively build matches, one parameter at a time
716 std::vector< ArgPack > results;
717 results.emplace_back( funcEnv, funcNeed, funcHave, funcOpen );
718 std::size_t genStart = 0;
719
720 // xxx - how to handle default arg after change to ftype representation?
721 if (const ast::VariableExpr * varExpr = func->expr.as<ast::VariableExpr>()) {
722 if (const ast::FunctionDecl * funcDecl = varExpr->var.as<ast::FunctionDecl>()) {
723 // function may have default args only if directly calling by name
724 // must use types on candidate however, due to RenameVars substitution
725 auto nParams = funcType->params.size();
726
727 for (size_t i=0; i<nParams; ++i) {
728 auto obj = funcDecl->params[i].strict_as<ast::ObjectDecl>();
729 if (!instantiateArgument(
730 funcType->params[i], obj->init, args, results, genStart, symtab)) return;
731 }
732 goto endMatch;
733 }
734 }
735 for ( const auto & param : funcType->params ) {
736 // Try adding the arguments corresponding to the current parameter to the existing
737 // matches
738 // no default args for indirect calls
739 if ( ! instantiateArgument(
740 param, nullptr, args, results, genStart, symtab ) ) return;
741 }
742
743 endMatch:
744 if ( funcType->isVarArgs ) {
745 // append any unused arguments to vararg pack
746 std::size_t genEnd;
747 do {
748 genEnd = results.size();
749
750 // iterate results
751 for ( std::size_t i = genStart; i < genEnd; ++i ) {
752 unsigned nextArg = results[i].nextArg;
753
754 // use remainder of exploded tuple if present
755 if ( results[i].hasExpl() ) {
756 const ExplodedArg & expl = results[i].getExpl( args );
757
758 unsigned nextExpl = results[i].nextExpl + 1;
759 if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
760
761 results.emplace_back(
762 i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ),
763 copy( results[i].need ), copy( results[i].have ),
764 copy( results[i].open ), nextArg, 0, Cost::zero, nextExpl,
765 results[i].explAlt );
766
767 continue;
768 }
769
770 // finish result when out of arguments
771 if ( nextArg >= args.size() ) {
772 validateFunctionCandidate( func, results[i], results, out );
773
774 continue;
775 }
776
777 // add each possible next argument
778 for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
779 const ExplodedArg & expl = args[nextArg][j];
780
781 // fresh copies of parent parameters for this iteration
782 ast::TypeEnvironment env = results[i].env;
783 ast::OpenVarSet open = results[i].open;
784
785 env.addActual( expl.env, open );
786
787 // skip empty tuple arguments by (nearly) cloning parent into next gen
788 if ( expl.exprs.empty() ) {
789 results.emplace_back(
790 results[i], std::move( env ), copy( results[i].need ),
791 copy( results[i].have ), std::move( open ), nextArg + 1,
792 expl.cost );
793
794 continue;
795 }
796
797 // add new result
798 results.emplace_back(
799 i, expl.exprs.front(), std::move( env ), copy( results[i].need ),
800 copy( results[i].have ), std::move( open ), nextArg + 1, 0, expl.cost,
801 expl.exprs.size() == 1 ? 0 : 1, j );
802 }
803 }
804
805 genStart = genEnd;
806 } while( genEnd != results.size() );
807 } else {
808 // filter out the results that don't use all the arguments
809 for ( std::size_t i = genStart; i < results.size(); ++i ) {
810 ArgPack & result = results[i];
811 if ( ! result.hasExpl() && result.nextArg >= args.size() ) {
812 validateFunctionCandidate( func, result, results, out );
813 }
814 }
815 }
816 }
817
818 /// Adds implicit struct-conversions to the alternative list
819 void addAnonConversions( const CandidateRef & cand ) {
820 // adds anonymous member interpretations whenever an aggregate value type is seen.
821 // it's okay for the aggregate expression to have reference type -- cast it to the
822 // base type to treat the aggregate as the referenced value
823 ast::ptr< ast::Expr > aggrExpr( cand->expr );
824 ast::ptr< ast::Type > & aggrType = aggrExpr.get_and_mutate()->result;
825 cand->env.apply( aggrType );
826
827 if ( aggrType.as< ast::ReferenceType >() ) {
828 aggrExpr = new ast::CastExpr{ aggrExpr, aggrType->stripReferences() };
829 }
830
831 if ( auto structInst = aggrExpr->result.as< ast::StructInstType >() ) {
832 addAggMembers( structInst, aggrExpr, *cand, Cost::safe, "" );
833 } else if ( auto unionInst = aggrExpr->result.as< ast::UnionInstType >() ) {
834 addAggMembers( unionInst, aggrExpr, *cand, Cost::safe, "" );
835 }
836 }
837
838 /// Adds aggregate member interpretations
839 void addAggMembers(
840 const ast::BaseInstType * aggrInst, const ast::Expr * expr,
841 const Candidate & cand, const Cost & addedCost, const std::string & name
842 ) {
843 for ( const ast::Decl * decl : aggrInst->lookup( name ) ) {
844 auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( decl );
845 CandidateRef newCand = std::make_shared<Candidate>(
846 cand, new ast::MemberExpr{ expr->location, dwt, expr }, addedCost );
847 // add anonymous member interpretations whenever an aggregate value type is seen
848 // as a member expression
849 addAnonConversions( newCand );
850 candidates.emplace_back( std::move( newCand ) );
851 }
852 }
853
854 /// Adds tuple member interpretations
855 void addTupleMembers(
856 const ast::TupleType * tupleType, const ast::Expr * expr, const Candidate & cand,
857 const Cost & addedCost, const ast::Expr * member
858 ) {
859 if ( auto constantExpr = dynamic_cast< const ast::ConstantExpr * >( member ) ) {
860 // get the value of the constant expression as an int, must be between 0 and the
861 // length of the tuple to have meaning
862 long long val = constantExpr->intValue();
863 if ( val >= 0 && (unsigned long long)val < tupleType->size() ) {
864 addCandidate(
865 cand, new ast::TupleIndexExpr{ expr->location, expr, (unsigned)val },
866 addedCost );
867 }
868 }
869 }
870
871 void postvisit( const ast::UntypedExpr * untypedExpr ) {
872 std::vector< CandidateFinder > argCandidates =
873 selfFinder.findSubExprs( untypedExpr->args );
874
875 // take care of possible tuple assignments
876 // if not tuple assignment, handled as normal function call
877 Tuples::handleTupleAssignment( selfFinder, untypedExpr, argCandidates );
878
879 CandidateFinder funcFinder( context, tenv );
880 if (auto nameExpr = untypedExpr->func.as<ast::NameExpr>()) {
881 auto kind = ast::SymbolTable::getSpecialFunctionKind(nameExpr->name);
882 if (kind != ast::SymbolTable::SpecialFunctionKind::NUMBER_OF_KINDS) {
883 assertf(!argCandidates.empty(), "special function call without argument");
884 for (auto & firstArgCand: argCandidates[0]) {
885 ast::ptr<ast::Type> argType = firstArgCand->expr->result;
886 firstArgCand->env.apply(argType);
887 // strip references
888 // xxx - is this correct?
889 while (argType.as<ast::ReferenceType>()) argType = argType.as<ast::ReferenceType>()->base;
890
891 // convert 1-tuple to plain type
892 if (auto tuple = argType.as<ast::TupleType>()) {
893 if (tuple->size() == 1) {
894 argType = tuple->types[0];
895 }
896 }
897
898 // if argType is an unbound type parameter, all special functions need to be searched.
899 if (isUnboundType(argType)) {
900 funcFinder.otypeKeys.clear();
901 break;
902 }
903
904 if (argType.as<ast::PointerType>()) funcFinder.otypeKeys.insert(Mangle::Encoding::pointer);
905 // else if (const ast::EnumInstType * enumInst = argType.as<ast::EnumInstType>()) {
906 // const ast::EnumDecl * enumDecl = enumInst->base; // Here
907 // if ( const ast::Type* enumType = enumDecl->base ) {
908 // // instance of enum (T) is a instance of type (T)
909 // funcFinder.otypeKeys.insert(Mangle::mangle(enumType, Mangle::NoGenericParams | Mangle::Type));
910 // } else {
911 // // instance of an untyped enum is techically int
912 // funcFinder.otypeKeys.insert(Mangle::mangle(enumDecl, Mangle::NoGenericParams | Mangle::Type));
913 // }
914 // }
915 else funcFinder.otypeKeys.insert(Mangle::mangle(argType, Mangle::NoGenericParams | Mangle::Type));
916 }
917 }
918 }
919 // if candidates are already produced, do not fail
920 // xxx - is it possible that handleTupleAssignment and main finder both produce candidates?
921 // this means there exists ctor/assign functions with a tuple as first parameter.
922 ResolvMode mode = {
923 true, // adjust
924 !untypedExpr->func.as<ast::NameExpr>(), // prune if not calling by name
925 selfFinder.candidates.empty() // failfast if other options are not found
926 };
927 funcFinder.find( untypedExpr->func, mode );
928 // short-circuit if no candidates
929 // if ( funcFinder.candidates.empty() ) return;
930
931 reason.code = NoMatch;
932
933 // find function operators
934 ast::ptr< ast::Expr > opExpr = new ast::NameExpr{ untypedExpr->location, "?()" }; // ??? why not ?{}
935 CandidateFinder opFinder( context, tenv );
936 // okay if there aren't any function operations
937 opFinder.find( opExpr, ResolvMode::withoutFailFast() );
938 PRINT(
939 std::cerr << "known function ops:" << std::endl;
940 print( std::cerr, opFinder.candidates, 1 );
941 )
942
943 // pre-explode arguments
944 ExplodedArgs_new argExpansions;
945 for ( const CandidateFinder & args : argCandidates ) {
946 argExpansions.emplace_back();
947 auto & argE = argExpansions.back();
948 for ( const CandidateRef & arg : args ) { argE.emplace_back( *arg, symtab ); }
949 }
950
951 // Find function matches
952 CandidateList found;
953 SemanticErrorException errors;
954 for ( CandidateRef & func : funcFinder ) {
955 try {
956 PRINT(
957 std::cerr << "working on alternative:" << std::endl;
958 print( std::cerr, *func, 2 );
959 )
960
961 // check if the type is a pointer to function
962 const ast::Type * funcResult = func->expr->result->stripReferences();
963 if ( auto pointer = dynamic_cast< const ast::PointerType * >( funcResult ) ) {
964 if ( auto function = pointer->base.as< ast::FunctionType >() ) {
965 CandidateRef newFunc{ new Candidate{ *func } };
966 newFunc->expr =
967 referenceToRvalueConversion( newFunc->expr, newFunc->cost );
968 makeFunctionCandidates( newFunc, function, argExpansions, found );
969 }
970 } else if (
971 auto inst = dynamic_cast< const ast::TypeInstType * >( funcResult )
972 ) {
973 if ( const ast::EqvClass * clz = func->env.lookup( *inst ) ) {
974 if ( auto function = clz->bound.as< ast::FunctionType >() ) {
975 CandidateRef newFunc{ new Candidate{ *func } };
976 newFunc->expr =
977 referenceToRvalueConversion( newFunc->expr, newFunc->cost );
978 makeFunctionCandidates( newFunc, function, argExpansions, found );
979 }
980 }
981 }
982 } catch ( SemanticErrorException & e ) { errors.append( e ); }
983 }
984
985 // Find matches on function operators `?()`
986 if ( ! opFinder.candidates.empty() ) {
987 // add exploded function alternatives to front of argument list
988 std::vector< ExplodedArg > funcE;
989 funcE.reserve( funcFinder.candidates.size() );
990 for ( const CandidateRef & func : funcFinder ) {
991 funcE.emplace_back( *func, symtab );
992 }
993 argExpansions.emplace_front( std::move( funcE ) );
994
995 for ( const CandidateRef & op : opFinder ) {
996 try {
997 // check if type is pointer-to-function
998 const ast::Type * opResult = op->expr->result->stripReferences();
999 if ( auto pointer = dynamic_cast< const ast::PointerType * >( opResult ) ) {
1000 if ( auto function = pointer->base.as< ast::FunctionType >() ) {
1001 CandidateRef newOp{ new Candidate{ *op} };
1002 newOp->expr =
1003 referenceToRvalueConversion( newOp->expr, newOp->cost );
1004 makeFunctionCandidates( newOp, function, argExpansions, found );
1005 }
1006 }
1007 } catch ( SemanticErrorException & e ) { errors.append( e ); }
1008 }
1009 }
1010
1011 // Implement SFINAE; resolution errors are only errors if there aren't any non-error
1012 // candidates
1013 if ( found.empty() && ! errors.isEmpty() ) { throw errors; }
1014
1015 // Compute conversion costs
1016 for ( CandidateRef & withFunc : found ) {
1017 Cost cvtCost = computeApplicationConversionCost( withFunc, symtab );
1018
1019 PRINT(
1020 auto appExpr = withFunc->expr.strict_as< ast::ApplicationExpr >();
1021 auto pointer = appExpr->func->result.strict_as< ast::PointerType >();
1022 auto function = pointer->base.strict_as< ast::FunctionType >();
1023
1024 std::cerr << "Case +++++++++++++ " << appExpr->func << std::endl;
1025 std::cerr << "parameters are:" << std::endl;
1026 ast::printAll( std::cerr, function->params, 2 );
1027 std::cerr << "arguments are:" << std::endl;
1028 ast::printAll( std::cerr, appExpr->args, 2 );
1029 std::cerr << "bindings are:" << std::endl;
1030 ast::print( std::cerr, withFunc->env, 2 );
1031 std::cerr << "cost is: " << withFunc->cost << std::endl;
1032 std::cerr << "cost of conversion is:" << cvtCost << std::endl;
1033 )
1034
1035 if ( cvtCost != Cost::infinity ) {
1036 withFunc->cvtCost = cvtCost;
1037 candidates.emplace_back( std::move( withFunc ) );
1038 }
1039 }
1040 found = std::move( candidates );
1041
1042 // use a new list so that candidates are not examined by addAnonConversions twice
1043 CandidateList winners = findMinCost( found );
1044 promoteCvtCost( winners );
1045
1046 // function may return a struct/union value, in which case we need to add candidates
1047 // for implicit conversions to each of the anonymous members, which must happen after
1048 // `findMinCost`, since anon conversions are never the cheapest
1049 for ( const CandidateRef & c : winners ) {
1050 addAnonConversions( c );
1051 }
1052 spliceBegin( candidates, winners );
1053
1054 if ( candidates.empty() && targetType && ! targetType->isVoid() ) {
1055 // If resolution is unsuccessful with a target type, try again without, since it
1056 // will sometimes succeed when it wouldn't with a target type binding.
1057 // For example:
1058 // forall( otype T ) T & ?[]( T *, ptrdiff_t );
1059 // const char * x = "hello world";
1060 // unsigned char ch = x[0];
1061 // Fails with simple return type binding (xxx -- check this!) as follows:
1062 // * T is bound to unsigned char
1063 // * (x: const char *) is unified with unsigned char *, which fails
1064 // xxx -- fix this better
1065 targetType = nullptr;
1066 postvisit( untypedExpr );
1067 }
1068 }
1069
1070 /// true if expression is an lvalue
1071 static bool isLvalue( const ast::Expr * x ) {
1072 return x->result && ( x->get_lvalue() || x->result.as< ast::ReferenceType >() );
1073 }
1074
1075 void postvisit( const ast::AddressExpr * addressExpr ) {
1076 CandidateFinder finder( context, tenv );
1077 finder.find( addressExpr->arg );
1078
1079 if( finder.candidates.empty() ) return;
1080
1081 reason.code = NoMatch;
1082
1083 for ( CandidateRef & r : finder.candidates ) {
1084 if ( ! isLvalue( r->expr ) ) continue;
1085 addCandidate( *r, new ast::AddressExpr{ addressExpr->location, r->expr } );
1086 }
1087 }
1088
1089 void postvisit( const ast::LabelAddressExpr * labelExpr ) {
1090 addCandidate( labelExpr, tenv );
1091 }
1092
1093 void postvisit( const ast::CastExpr * castExpr ) {
1094 ast::ptr< ast::Type > toType = castExpr->result;
1095 assert( toType );
1096 toType = resolveTypeof( toType, context );
1097 toType = adjustExprType( toType, tenv, symtab );
1098
1099 CandidateFinder finder( context, tenv, toType );
1100 finder.find( castExpr->arg, ResolvMode::withAdjustment() );
1101
1102 if( !finder.candidates.empty() ) reason.code = NoMatch;
1103
1104 CandidateList matches;
1105 for ( CandidateRef & cand : finder.candidates ) {
1106 ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have;
1107 ast::OpenVarSet open( cand->open );
1108
1109 cand->env.extractOpenVars( open );
1110
1111 // It is possible that a cast can throw away some values in a multiply-valued
1112 // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of the
1113 // subexpression results that are cast directly. The candidate is invalid if it
1114 // has fewer results than there are types to cast to.
1115 int discardedValues = cand->expr->result->size() - toType->size();
1116 if ( discardedValues < 0 ) continue;
1117
1118 // unification run for side-effects
1119 unify( toType, cand->expr->result, cand->env, need, have, open, symtab );
1120 Cost thisCost =
1121 (castExpr->isGenerated == ast::GeneratedFlag::GeneratedCast)
1122 ? conversionCost( cand->expr->result, toType, cand->expr->get_lvalue(), symtab, cand->env )
1123 : castCost( cand->expr->result, toType, cand->expr->get_lvalue(), symtab, cand->env );
1124
1125 PRINT(
1126 std::cerr << "working on cast with result: " << toType << std::endl;
1127 std::cerr << "and expr type: " << cand->expr->result << std::endl;
1128 std::cerr << "env: " << cand->env << std::endl;
1129 )
1130 if ( thisCost != Cost::infinity ) {
1131 PRINT(
1132 std::cerr << "has finite cost." << std::endl;
1133 )
1134 // count one safe conversion for each value that is thrown away
1135 thisCost.incSafe( discardedValues );
1136 CandidateRef newCand = std::make_shared<Candidate>(
1137 restructureCast( cand->expr, toType, castExpr->isGenerated ),
1138 copy( cand->env ), std::move( open ), std::move( need ), cand->cost,
1139 cand->cost + thisCost );
1140 inferParameters( newCand, matches );
1141 }
1142 }
1143
1144 // select first on argument cost, then conversion cost
1145 CandidateList minArgCost = findMinCost( matches );
1146 promoteCvtCost( minArgCost );
1147 candidates = findMinCost( minArgCost );
1148 }
1149
1150 void postvisit( const ast::VirtualCastExpr * castExpr ) {
1151 assertf( castExpr->result, "Implicit virtual cast targets not yet supported." );
1152 CandidateFinder finder( context, tenv );
1153 // don't prune here, all alternatives guaranteed to have same type
1154 finder.find( castExpr->arg, ResolvMode::withoutPrune() );
1155 for ( CandidateRef & r : finder.candidates ) {
1156 addCandidate(
1157 *r,
1158 new ast::VirtualCastExpr{ castExpr->location, r->expr, castExpr->result } );
1159 }
1160 }
1161
1162 void postvisit( const ast::KeywordCastExpr * castExpr ) {
1163 const auto & loc = castExpr->location;
1164 assertf( castExpr->result, "Cast target should have been set in Validate." );
1165 auto ref = castExpr->result.strict_as<ast::ReferenceType>();
1166 auto inst = ref->base.strict_as<ast::StructInstType>();
1167 auto target = inst->base.get();
1168
1169 CandidateFinder finder( context, tenv );
1170
1171 auto pick_alternatives = [target, this](CandidateList & found, bool expect_ref) {
1172 for(auto & cand : found) {
1173 const ast::Type * expr = cand->expr->result.get();
1174 if(expect_ref) {
1175 auto res = dynamic_cast<const ast::ReferenceType*>(expr);
1176 if(!res) { continue; }
1177 expr = res->base.get();
1178 }
1179
1180 if(auto insttype = dynamic_cast<const ast::TypeInstType*>(expr)) {
1181 auto td = cand->env.lookup(*insttype);
1182 if(!td) { continue; }
1183 expr = td->bound.get();
1184 }
1185
1186 if(auto base = dynamic_cast<const ast::StructInstType*>(expr)) {
1187 if(base->base == target) {
1188 candidates.push_back( std::move(cand) );
1189 reason.code = NoReason;
1190 }
1191 }
1192 }
1193 };
1194
1195 try {
1196 // Attempt 1 : turn (thread&)X into (thread$&)X.__thrd
1197 // Clone is purely for memory management
1198 std::unique_ptr<const ast::Expr> tech1 { new ast::UntypedMemberExpr(loc, new ast::NameExpr(loc, castExpr->concrete_target.field), castExpr->arg) };
1199
1200 // don't prune here, since it's guaranteed all alternatives will have the same type
1201 finder.find( tech1.get(), ResolvMode::withoutPrune() );
1202 pick_alternatives(finder.candidates, false);
1203
1204 return;
1205 } catch(SemanticErrorException & ) {}
1206
1207 // Fallback : turn (thread&)X into (thread$&)get_thread(X)
1208 std::unique_ptr<const ast::Expr> fallback { ast::UntypedExpr::createDeref(loc, new ast::UntypedExpr(loc, new ast::NameExpr(loc, castExpr->concrete_target.getter), { castExpr->arg })) };
1209 // don't prune here, since it's guaranteed all alternatives will have the same type
1210 finder.find( fallback.get(), ResolvMode::withoutPrune() );
1211
1212 pick_alternatives(finder.candidates, true);
1213
1214 // Whatever happens here, we have no more fallbacks
1215 }
1216
1217 void postvisit( const ast::UntypedMemberExpr * memberExpr ) {
1218 CandidateFinder aggFinder( context, tenv );
1219 aggFinder.find( memberExpr->aggregate, ResolvMode::withAdjustment() );
1220 for ( CandidateRef & agg : aggFinder.candidates ) {
1221 // it's okay for the aggregate expression to have reference type -- cast it to the
1222 // base type to treat the aggregate as the referenced value
1223 Cost addedCost = Cost::zero;
1224 agg->expr = referenceToRvalueConversion( agg->expr, addedCost );
1225
1226 // find member of the given type
1227 if ( auto structInst = agg->expr->result.as< ast::StructInstType >() ) {
1228 addAggMembers(
1229 structInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) );
1230 } else if ( auto unionInst = agg->expr->result.as< ast::UnionInstType >() ) {
1231 addAggMembers(
1232 unionInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) );
1233 } else if ( auto tupleType = agg->expr->result.as< ast::TupleType >() ) {
1234 addTupleMembers( tupleType, agg->expr, *agg, addedCost, memberExpr->member );
1235 }
1236 }
1237 }
1238
1239 void postvisit( const ast::MemberExpr * memberExpr ) {
1240 addCandidate( memberExpr, tenv );
1241 }
1242
1243 void postvisit( const ast::NameExpr * nameExpr ) {
1244 std::vector< ast::SymbolTable::IdData > declList;
1245 if (!selfFinder.otypeKeys.empty()) {
1246 auto kind = ast::SymbolTable::getSpecialFunctionKind(nameExpr->name);
1247 assertf(kind != ast::SymbolTable::SpecialFunctionKind::NUMBER_OF_KINDS, "special lookup with non-special target: %s", nameExpr->name.c_str());
1248
1249 for (auto & otypeKey: selfFinder.otypeKeys) {
1250 auto result = symtab.specialLookupId(kind, otypeKey);
1251 declList.insert(declList.end(), std::make_move_iterator(result.begin()), std::make_move_iterator(result.end()));
1252 }
1253 }
1254 else {
1255 declList = symtab.lookupId( nameExpr->name );
1256 }
1257 PRINT( std::cerr << "nameExpr is " << nameExpr->name << std::endl; )
1258
1259 if( declList.empty() ) return;
1260
1261 reason.code = NoMatch;
1262
1263 for ( auto & data : declList ) {
1264 Cost cost = Cost::zero;
1265 ast::Expr * newExpr = data.combine( nameExpr->location, cost );
1266
1267 CandidateRef newCand = std::make_shared<Candidate>(
1268 newExpr, copy( tenv ), ast::OpenVarSet{}, ast::AssertionSet{}, Cost::zero,
1269 cost );
1270
1271 if (newCand->expr->env) {
1272 newCand->env.add(*newCand->expr->env);
1273 auto mutExpr = newCand->expr.get_and_mutate();
1274 mutExpr->env = nullptr;
1275 newCand->expr = mutExpr;
1276 }
1277
1278 PRINT(
1279 std::cerr << "decl is ";
1280 ast::print( std::cerr, data.id );
1281 std::cerr << std::endl;
1282 std::cerr << "newExpr is ";
1283 ast::print( std::cerr, newExpr );
1284 std::cerr << std::endl;
1285 )
1286 newCand->expr = ast::mutate_field(
1287 newCand->expr.get(), &ast::Expr::result,
1288 renameTyVars( newCand->expr->result ) );
1289 // add anonymous member interpretations whenever an aggregate value type is seen
1290 // as a name expression
1291 addAnonConversions( newCand );
1292 candidates.emplace_back( std::move( newCand ) );
1293 }
1294 }
1295
1296 void postvisit( const ast::VariableExpr * variableExpr ) {
1297 // not sufficient to just pass `variableExpr` here, type might have changed since
1298 // creation
1299 addCandidate(
1300 new ast::VariableExpr{ variableExpr->location, variableExpr->var }, tenv );
1301 }
1302
1303 void postvisit( const ast::ConstantExpr * constantExpr ) {
1304 addCandidate( constantExpr, tenv );
1305 }
1306
1307 void postvisit( const ast::SizeofExpr * sizeofExpr ) {
1308 if ( sizeofExpr->type ) {
1309 addCandidate(
1310 new ast::SizeofExpr{
1311 sizeofExpr->location, resolveTypeof( sizeofExpr->type, context ) },
1312 tenv );
1313 } else {
1314 // find all candidates for the argument to sizeof
1315 CandidateFinder finder( context, tenv );
1316 finder.find( sizeofExpr->expr );
1317 // find the lowest-cost candidate, otherwise ambiguous
1318 CandidateList winners = findMinCost( finder.candidates );
1319 if ( winners.size() != 1 ) {
1320 SemanticError(
1321 sizeofExpr->expr.get(), "Ambiguous expression in sizeof operand: " );
1322 }
1323 // return the lowest-cost candidate
1324 CandidateRef & choice = winners.front();
1325 choice->expr = referenceToRvalueConversion( choice->expr, choice->cost );
1326 choice->cost = Cost::zero;
1327 addCandidate( *choice, new ast::SizeofExpr{ sizeofExpr->location, choice->expr } );
1328 }
1329 }
1330
1331 void postvisit( const ast::AlignofExpr * alignofExpr ) {
1332 if ( alignofExpr->type ) {
1333 addCandidate(
1334 new ast::AlignofExpr{
1335 alignofExpr->location, resolveTypeof( alignofExpr->type, context ) },
1336 tenv );
1337 } else {
1338 // find all candidates for the argument to alignof
1339 CandidateFinder finder( context, tenv );
1340 finder.find( alignofExpr->expr );
1341 // find the lowest-cost candidate, otherwise ambiguous
1342 CandidateList winners = findMinCost( finder.candidates );
1343 if ( winners.size() != 1 ) {
1344 SemanticError(
1345 alignofExpr->expr.get(), "Ambiguous expression in alignof operand: " );
1346 }
1347 // return the lowest-cost candidate
1348 CandidateRef & choice = winners.front();
1349 choice->expr = referenceToRvalueConversion( choice->expr, choice->cost );
1350 choice->cost = Cost::zero;
1351 addCandidate(
1352 *choice, new ast::AlignofExpr{ alignofExpr->location, choice->expr } );
1353 }
1354 }
1355
1356 void postvisit( const ast::UntypedOffsetofExpr * offsetofExpr ) {
1357 const ast::BaseInstType * aggInst;
1358 if (( aggInst = offsetofExpr->type.as< ast::StructInstType >() )) ;
1359 else if (( aggInst = offsetofExpr->type.as< ast::UnionInstType >() )) ;
1360 else return;
1361
1362 for ( const ast::Decl * member : aggInst->lookup( offsetofExpr->member ) ) {
1363 auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( member );
1364 addCandidate(
1365 new ast::OffsetofExpr{ offsetofExpr->location, aggInst, dwt }, tenv );
1366 }
1367 }
1368
1369 void postvisit( const ast::OffsetofExpr * offsetofExpr ) {
1370 addCandidate( offsetofExpr, tenv );
1371 }
1372
1373 void postvisit( const ast::OffsetPackExpr * offsetPackExpr ) {
1374 addCandidate( offsetPackExpr, tenv );
1375 }
1376
1377 void postvisit( const ast::LogicalExpr * logicalExpr ) {
1378 CandidateFinder finder1( context, tenv );
1379 finder1.find( logicalExpr->arg1, ResolvMode::withAdjustment() );
1380 if ( finder1.candidates.empty() ) return;
1381
1382 CandidateFinder finder2( context, tenv );
1383 finder2.find( logicalExpr->arg2, ResolvMode::withAdjustment() );
1384 if ( finder2.candidates.empty() ) return;
1385
1386 reason.code = NoMatch;
1387
1388 for ( const CandidateRef & r1 : finder1.candidates ) {
1389 for ( const CandidateRef & r2 : finder2.candidates ) {
1390 ast::TypeEnvironment env{ r1->env };
1391 env.simpleCombine( r2->env );
1392 ast::OpenVarSet open{ r1->open };
1393 mergeOpenVars( open, r2->open );
1394 ast::AssertionSet need;
1395 mergeAssertionSet( need, r1->need );
1396 mergeAssertionSet( need, r2->need );
1397
1398 addCandidate(
1399 new ast::LogicalExpr{
1400 logicalExpr->location, r1->expr, r2->expr, logicalExpr->isAnd },
1401 std::move( env ), std::move( open ), std::move( need ), r1->cost + r2->cost );
1402 }
1403 }
1404 }
1405
1406 void postvisit( const ast::ConditionalExpr * conditionalExpr ) {
1407 // candidates for condition
1408 CandidateFinder finder1( context, tenv );
1409 finder1.find( conditionalExpr->arg1, ResolvMode::withAdjustment() );
1410 if ( finder1.candidates.empty() ) return;
1411
1412 // candidates for true result
1413 CandidateFinder finder2( context, tenv );
1414 finder2.find( conditionalExpr->arg2, ResolvMode::withAdjustment() );
1415 if ( finder2.candidates.empty() ) return;
1416
1417 // candidates for false result
1418 CandidateFinder finder3( context, tenv );
1419 finder3.find( conditionalExpr->arg3, ResolvMode::withAdjustment() );
1420 if ( finder3.candidates.empty() ) return;
1421
1422 reason.code = NoMatch;
1423
1424 for ( const CandidateRef & r1 : finder1.candidates ) {
1425 for ( const CandidateRef & r2 : finder2.candidates ) {
1426 for ( const CandidateRef & r3 : finder3.candidates ) {
1427 ast::TypeEnvironment env{ r1->env };
1428 env.simpleCombine( r2->env );
1429 env.simpleCombine( r3->env );
1430 ast::OpenVarSet open{ r1->open };
1431 mergeOpenVars( open, r2->open );
1432 mergeOpenVars( open, r3->open );
1433 ast::AssertionSet need;
1434 mergeAssertionSet( need, r1->need );
1435 mergeAssertionSet( need, r2->need );
1436 mergeAssertionSet( need, r3->need );
1437 ast::AssertionSet have;
1438
1439 // unify true and false results, then infer parameters to produce new
1440 // candidates
1441 ast::ptr< ast::Type > common;
1442 if (
1443 unify(
1444 r2->expr->result, r3->expr->result, env, need, have, open, symtab,
1445 common )
1446 ) {
1447 // generate typed expression
1448 ast::ConditionalExpr * newExpr = new ast::ConditionalExpr{
1449 conditionalExpr->location, r1->expr, r2->expr, r3->expr };
1450 newExpr->result = common ? common : r2->expr->result;
1451 // convert both options to result type
1452 Cost cost = r1->cost + r2->cost + r3->cost;
1453 newExpr->arg2 = computeExpressionConversionCost(
1454 newExpr->arg2, newExpr->result, symtab, env, cost );
1455 newExpr->arg3 = computeExpressionConversionCost(
1456 newExpr->arg3, newExpr->result, symtab, env, cost );
1457 // output candidate
1458 CandidateRef newCand = std::make_shared<Candidate>(
1459 newExpr, std::move( env ), std::move( open ), std::move( need ), cost );
1460 inferParameters( newCand, candidates );
1461 }
1462 }
1463 }
1464 }
1465 }
1466
1467 void postvisit( const ast::CommaExpr * commaExpr ) {
1468 ast::TypeEnvironment env{ tenv };
1469 ast::ptr< ast::Expr > arg1 = resolveInVoidContext( commaExpr->arg1, context, env );
1470
1471 CandidateFinder finder2( context, env );
1472 finder2.find( commaExpr->arg2, ResolvMode::withAdjustment() );
1473
1474 for ( const CandidateRef & r2 : finder2.candidates ) {
1475 addCandidate( *r2, new ast::CommaExpr{ commaExpr->location, arg1, r2->expr } );
1476 }
1477 }
1478
1479 void postvisit( const ast::ImplicitCopyCtorExpr * ctorExpr ) {
1480 addCandidate( ctorExpr, tenv );
1481 }
1482
1483 void postvisit( const ast::ConstructorExpr * ctorExpr ) {
1484 CandidateFinder finder( context, tenv );
1485 finder.find( ctorExpr->callExpr, ResolvMode::withoutPrune() );
1486 for ( CandidateRef & r : finder.candidates ) {
1487 addCandidate( *r, new ast::ConstructorExpr{ ctorExpr->location, r->expr } );
1488 }
1489 }
1490
1491 void postvisit( const ast::RangeExpr * rangeExpr ) {
1492 // resolve low and high, accept candidates where low and high types unify
1493 CandidateFinder finder1( context, tenv );
1494 finder1.find( rangeExpr->low, ResolvMode::withAdjustment() );
1495 if ( finder1.candidates.empty() ) return;
1496
1497 CandidateFinder finder2( context, tenv );
1498 finder2.find( rangeExpr->high, ResolvMode::withAdjustment() );
1499 if ( finder2.candidates.empty() ) return;
1500
1501 reason.code = NoMatch;
1502
1503 for ( const CandidateRef & r1 : finder1.candidates ) {
1504 for ( const CandidateRef & r2 : finder2.candidates ) {
1505 ast::TypeEnvironment env{ r1->env };
1506 env.simpleCombine( r2->env );
1507 ast::OpenVarSet open{ r1->open };
1508 mergeOpenVars( open, r2->open );
1509 ast::AssertionSet need;
1510 mergeAssertionSet( need, r1->need );
1511 mergeAssertionSet( need, r2->need );
1512 ast::AssertionSet have;
1513
1514 ast::ptr< ast::Type > common;
1515 if (
1516 unify(
1517 r1->expr->result, r2->expr->result, env, need, have, open, symtab,
1518 common )
1519 ) {
1520 // generate new expression
1521 ast::RangeExpr * newExpr =
1522 new ast::RangeExpr{ rangeExpr->location, r1->expr, r2->expr };
1523 newExpr->result = common ? common : r1->expr->result;
1524 // add candidate
1525 CandidateRef newCand = std::make_shared<Candidate>(
1526 newExpr, std::move( env ), std::move( open ), std::move( need ),
1527 r1->cost + r2->cost );
1528 inferParameters( newCand, candidates );
1529 }
1530 }
1531 }
1532 }
1533
1534 void postvisit( const ast::UntypedTupleExpr * tupleExpr ) {
1535 std::vector< CandidateFinder > subCandidates =
1536 selfFinder.findSubExprs( tupleExpr->exprs );
1537 std::vector< CandidateList > possibilities;
1538 combos( subCandidates.begin(), subCandidates.end(), back_inserter( possibilities ) );
1539
1540 for ( const CandidateList & subs : possibilities ) {
1541 std::vector< ast::ptr< ast::Expr > > exprs;
1542 exprs.reserve( subs.size() );
1543 for ( const CandidateRef & sub : subs ) { exprs.emplace_back( sub->expr ); }
1544
1545 ast::TypeEnvironment env;
1546 ast::OpenVarSet open;
1547 ast::AssertionSet need;
1548 for ( const CandidateRef & sub : subs ) {
1549 env.simpleCombine( sub->env );
1550 mergeOpenVars( open, sub->open );
1551 mergeAssertionSet( need, sub->need );
1552 }
1553
1554 addCandidate(
1555 new ast::TupleExpr{ tupleExpr->location, std::move( exprs ) },
1556 std::move( env ), std::move( open ), std::move( need ), sumCost( subs ) );
1557 }
1558 }
1559
1560 void postvisit( const ast::TupleExpr * tupleExpr ) {
1561 addCandidate( tupleExpr, tenv );
1562 }
1563
1564 void postvisit( const ast::TupleIndexExpr * tupleExpr ) {
1565 addCandidate( tupleExpr, tenv );
1566 }
1567
1568 void postvisit( const ast::TupleAssignExpr * tupleExpr ) {
1569 addCandidate( tupleExpr, tenv );
1570 }
1571
1572 void postvisit( const ast::UniqueExpr * unqExpr ) {
1573 CandidateFinder finder( context, tenv );
1574 finder.find( unqExpr->expr, ResolvMode::withAdjustment() );
1575 for ( CandidateRef & r : finder.candidates ) {
1576 // ensure that the the id is passed on so that the expressions are "linked"
1577 addCandidate( *r, new ast::UniqueExpr{ unqExpr->location, r->expr, unqExpr->id } );
1578 }
1579 }
1580
1581 void postvisit( const ast::StmtExpr * stmtExpr ) {
1582 addCandidate( resolveStmtExpr( stmtExpr, context ), tenv );
1583 }
1584
1585 void postvisit( const ast::UntypedInitExpr * initExpr ) {
1586 // handle each option like a cast
1587 CandidateList matches;
1588 PRINT(
1589 std::cerr << "untyped init expr: " << initExpr << std::endl;
1590 )
1591 // O(n^2) checks of d-types with e-types
1592 for ( const ast::InitAlternative & initAlt : initExpr->initAlts ) {
1593 // calculate target type
1594 const ast::Type * toType = resolveTypeof( initAlt.type, context );
1595 toType = adjustExprType( toType, tenv, symtab );
1596 // The call to find must occur inside this loop, otherwise polymorphic return
1597 // types are not bound to the initialization type, since return type variables are
1598 // only open for the duration of resolving the UntypedExpr.
1599 CandidateFinder finder( context, tenv, toType );
1600 finder.find( initExpr->expr, ResolvMode::withAdjustment() );
1601 for ( CandidateRef & cand : finder.candidates ) {
1602 if(reason.code == NotFound) reason.code = NoMatch;
1603
1604 ast::TypeEnvironment env{ cand->env };
1605 ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have;
1606 ast::OpenVarSet open{ cand->open };
1607
1608 PRINT(
1609 std::cerr << " @ " << toType << " " << initAlt.designation << std::endl;
1610 )
1611
1612 // It is possible that a cast can throw away some values in a multiply-valued
1613 // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of
1614 // the subexpression results that are cast directly. The candidate is invalid
1615 // if it has fewer results than there are types to cast to.
1616 int discardedValues = cand->expr->result->size() - toType->size();
1617 if ( discardedValues < 0 ) continue;
1618
1619 // unification run for side-effects
1620 bool canUnify = unify( toType, cand->expr->result, env, need, have, open, symtab );
1621 (void) canUnify;
1622 Cost thisCost = computeConversionCost( cand->expr->result, toType, cand->expr->get_lvalue(),
1623 symtab, env );
1624 PRINT(
1625 Cost legacyCost = castCost( cand->expr->result, toType, cand->expr->get_lvalue(),
1626 symtab, env );
1627 std::cerr << "Considering initialization:";
1628 std::cerr << std::endl << " FROM: " << cand->expr->result << std::endl;
1629 std::cerr << std::endl << " TO: " << toType << std::endl;
1630 std::cerr << std::endl << " Unification " << (canUnify ? "succeeded" : "failed");
1631 std::cerr << std::endl << " Legacy cost " << legacyCost;
1632 std::cerr << std::endl << " New cost " << thisCost;
1633 std::cerr << std::endl;
1634 )
1635 if ( thisCost != Cost::infinity ) {
1636 // count one safe conversion for each value that is thrown away
1637 thisCost.incSafe( discardedValues );
1638 CandidateRef newCand = std::make_shared<Candidate>(
1639 new ast::InitExpr{
1640 initExpr->location, restructureCast( cand->expr, toType ),
1641 initAlt.designation },
1642 std::move(env), std::move( open ), std::move( need ), cand->cost, thisCost );
1643 inferParameters( newCand, matches );
1644 }
1645 }
1646
1647 }
1648
1649 // select first on argument cost, then conversion cost
1650 CandidateList minArgCost = findMinCost( matches );
1651 promoteCvtCost( minArgCost );
1652 candidates = findMinCost( minArgCost );
1653 }
1654
1655 void postvisit( const ast::InitExpr * ) {
1656 assertf( false, "CandidateFinder should never see a resolved InitExpr." );
1657 }
1658
1659 void postvisit( const ast::DeletedExpr * ) {
1660 assertf( false, "CandidateFinder should never see a DeletedExpr." );
1661 }
1662
1663 void postvisit( const ast::GenericExpr * ) {
1664 assertf( false, "_Generic is not yet supported." );
1665 }
1666 };
1667
1668 // size_t Finder::traceId = Stats::Heap::new_stacktrace_id("Finder");
1669 /// Prunes a list of candidates down to those that have the minimum conversion cost for a given
1670 /// return type. Skips ambiguous candidates.
1671
1672} // anonymous namespace
1673
1674bool CandidateFinder::pruneCandidates( CandidateList & candidates, CandidateList & out, std::vector<std::string> & errors ) {
1675 struct PruneStruct {
1676 CandidateRef candidate;
1677 bool ambiguous;
1678
1679 PruneStruct() = default;
1680 PruneStruct( const CandidateRef & c ) : candidate( c ), ambiguous( false ) {}
1681 };
1682
1683 // find lowest-cost candidate for each type
1684 std::unordered_map< std::string, PruneStruct > selected;
1685 // attempt to skip satisfyAssertions on more expensive alternatives if better options have been found
1686 std::sort(candidates.begin(), candidates.end(), [](const CandidateRef & x, const CandidateRef & y){return x->cost < y->cost;});
1687 for ( CandidateRef & candidate : candidates ) {
1688 std::string mangleName;
1689 {
1690 ast::ptr< ast::Type > newType = candidate->expr->result;
1691 assertf(candidate->expr->result, "Result of expression %p for candidate is null", candidate->expr.get());
1692 candidate->env.apply( newType );
1693 mangleName = Mangle::mangle( newType );
1694 }
1695
1696 auto found = selected.find( mangleName );
1697 if (found != selected.end() && found->second.candidate->cost < candidate->cost) {
1698 PRINT(
1699 std::cerr << "cost " << candidate->cost << " loses to "
1700 << found->second.candidate->cost << std::endl;
1701 )
1702 continue;
1703 }
1704
1705 // xxx - when do satisfyAssertions produce more than 1 result?
1706 // this should only happen when initial result type contains
1707 // unbound type parameters, then it should never be pruned by
1708 // the previous step, since renameTyVars guarantees the mangled name
1709 // is unique.
1710 CandidateList satisfied;
1711 bool needRecomputeKey = false;
1712 if (candidate->need.empty()) {
1713 satisfied.emplace_back(candidate);
1714 }
1715 else {
1716 satisfyAssertions(candidate, context.symtab, satisfied, errors);
1717 needRecomputeKey = true;
1718 }
1719
1720 for (auto & newCand : satisfied) {
1721 // recomputes type key, if satisfyAssertions changed it
1722 if (needRecomputeKey)
1723 {
1724 ast::ptr< ast::Type > newType = newCand->expr->result;
1725 assertf(newCand->expr->result, "Result of expression %p for candidate is null", newCand->expr.get());
1726 newCand->env.apply( newType );
1727 mangleName = Mangle::mangle( newType );
1728 }
1729 auto found = selected.find( mangleName );
1730 if ( found != selected.end() ) {
1731 if ( newCand->cost < found->second.candidate->cost ) {
1732 PRINT(
1733 std::cerr << "cost " << newCand->cost << " beats "
1734 << found->second.candidate->cost << std::endl;
1735 )
1736
1737 found->second = PruneStruct{ newCand };
1738 } else if ( newCand->cost == found->second.candidate->cost ) {
1739 // if one of the candidates contains a deleted identifier, can pick the other,
1740 // since deleted expressions should not be ambiguous if there is another option
1741 // that is at least as good
1742 if ( findDeletedExpr( newCand->expr ) ) {
1743 // do nothing
1744 PRINT( std::cerr << "candidate is deleted" << std::endl; )
1745 } else if ( findDeletedExpr( found->second.candidate->expr ) ) {
1746 PRINT( std::cerr << "current is deleted" << std::endl; )
1747 found->second = PruneStruct{ newCand };
1748 } else {
1749 PRINT( std::cerr << "marking ambiguous" << std::endl; )
1750 found->second.ambiguous = true;
1751 }
1752 } else {
1753 // xxx - can satisfyAssertions increase the cost?
1754 PRINT(
1755 std::cerr << "cost " << newCand->cost << " loses to "
1756 << found->second.candidate->cost << std::endl;
1757 )
1758 }
1759 } else {
1760 selected.emplace_hint( found, mangleName, newCand );
1761 }
1762 }
1763 }
1764
1765 // report unambiguous min-cost candidates
1766 // CandidateList out;
1767 for ( auto & target : selected ) {
1768 if ( target.second.ambiguous ) continue;
1769
1770 CandidateRef cand = target.second.candidate;
1771
1772 ast::ptr< ast::Type > newResult = cand->expr->result;
1773 cand->env.applyFree( newResult );
1774 cand->expr = ast::mutate_field(
1775 cand->expr.get(), &ast::Expr::result, std::move( newResult ) );
1776
1777 out.emplace_back( cand );
1778 }
1779 // if everything is lost in satisfyAssertions, report the error
1780 return !selected.empty();
1781}
1782
1783void CandidateFinder::find( const ast::Expr * expr, ResolvMode mode ) {
1784 // Find alternatives for expression
1785 ast::Pass<Finder> finder{ *this };
1786 expr->accept( finder );
1787
1788 if ( mode.failFast && candidates.empty() ) {
1789 switch(finder.core.reason.code) {
1790 case Finder::NotFound:
1791 { SemanticError( expr, "No alternatives for expression " ); break; }
1792 case Finder::NoMatch:
1793 { SemanticError( expr, "Invalid application of existing declaration(s) in expression " ); break; }
1794 case Finder::ArgsToFew:
1795 case Finder::ArgsToMany:
1796 case Finder::RetsToFew:
1797 case Finder::RetsToMany:
1798 case Finder::NoReason:
1799 default:
1800 { SemanticError( expr->location, "No reasonable alternatives for expression : reasons unkown" ); }
1801 }
1802 }
1803
1804 /*
1805 if ( mode.satisfyAssns || mode.prune ) {
1806 // trim candidates to just those where the assertions are satisfiable
1807 // - necessary pre-requisite to pruning
1808 CandidateList satisfied;
1809 std::vector< std::string > errors;
1810 for ( CandidateRef & candidate : candidates ) {
1811 satisfyAssertions( candidate, localSyms, satisfied, errors );
1812 }
1813
1814 // fail early if none such
1815 if ( mode.failFast && satisfied.empty() ) {
1816 std::ostringstream stream;
1817 stream << "No alternatives with satisfiable assertions for " << expr << "\n";
1818 for ( const auto& err : errors ) {
1819 stream << err;
1820 }
1821 SemanticError( expr->location, stream.str() );
1822 }
1823
1824 // reset candidates
1825 candidates = move( satisfied );
1826 }
1827 */
1828
1829 if ( mode.prune ) {
1830 // trim candidates to single best one
1831 PRINT(
1832 std::cerr << "alternatives before prune:" << std::endl;
1833 print( std::cerr, candidates );
1834 )
1835
1836 CandidateList pruned;
1837 std::vector<std::string> errors;
1838 bool found = pruneCandidates( candidates, pruned, errors );
1839
1840 if ( mode.failFast && pruned.empty() ) {
1841 std::ostringstream stream;
1842 if (found) {
1843 CandidateList winners = findMinCost( candidates );
1844 stream << "Cannot choose between " << winners.size() << " alternatives for "
1845 "expression\n";
1846 ast::print( stream, expr );
1847 stream << " Alternatives are:\n";
1848 print( stream, winners, 1 );
1849 SemanticError( expr->location, stream.str() );
1850 }
1851 else {
1852 stream << "No alternatives with satisfiable assertions for " << expr << "\n";
1853 for ( const auto& err : errors ) {
1854 stream << err;
1855 }
1856 SemanticError( expr->location, stream.str() );
1857 }
1858 }
1859
1860 auto oldsize = candidates.size();
1861 candidates = std::move( pruned );
1862
1863 PRINT(
1864 std::cerr << "there are " << oldsize << " alternatives before elimination" << std::endl;
1865 )
1866 PRINT(
1867 std::cerr << "there are " << candidates.size() << " alternatives after elimination"
1868 << std::endl;
1869 )
1870 }
1871
1872 // adjust types after pruning so that types substituted by pruneAlternatives are correctly
1873 // adjusted
1874 if ( mode.adjust ) {
1875 for ( CandidateRef & r : candidates ) {
1876 r->expr = ast::mutate_field(
1877 r->expr.get(), &ast::Expr::result,
1878 adjustExprType( r->expr->result, r->env, context.symtab ) );
1879 }
1880 }
1881
1882 // Central location to handle gcc extension keyword, etc. for all expressions
1883 for ( CandidateRef & r : candidates ) {
1884 if ( r->expr->extension != expr->extension ) {
1885 r->expr.get_and_mutate()->extension = expr->extension;
1886 }
1887 }
1888}
1889
1890std::vector< CandidateFinder > CandidateFinder::findSubExprs(
1891 const std::vector< ast::ptr< ast::Expr > > & xs
1892) {
1893 std::vector< CandidateFinder > out;
1894
1895 for ( const auto & x : xs ) {
1896 out.emplace_back( context, env );
1897 out.back().find( x, ResolvMode::withAdjustment() );
1898
1899 PRINT(
1900 std::cerr << "findSubExprs" << std::endl;
1901 print( std::cerr, out.back().candidates );
1902 )
1903 }
1904
1905 return out;
1906}
1907
1908} // namespace ResolvExpr
1909
1910// Local Variables: //
1911// tab-width: 4 //
1912// mode: c++ //
1913// compile-command: "make install" //
1914// End: //
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