source: src/ResolvExpr/ConversionCost.cc@ 538334a

ADT aaron-thesis arm-eh ast-experimental cleanup-dtors deferred_resn demangler enum forall-pointer-decay jacob/cs343-translation jenkins-sandbox new-ast new-ast-unique-expr new-env no_list persistent-indexer pthread-emulation qualifiedEnum resolv-new with_gc
Last change on this file since 538334a was bd0b6b62, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Convert ConversionCost and CastCost to PassVisitor
  • Property mode set to 100644
File size: 18.1 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// ConversionCost.cc --
8//
9// Author : Richard C. Bilson
10// Created On : Sun May 17 07:06:19 2015
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Sep 25 15:43:34 2017
13// Update Count : 10
14//
15
16#include "ConversionCost.h"
17
18#include <cassert> // for assert
19#include <list> // for list, list<>::const_iterator
20#include <string> // for operator==, string
21
22#include "ResolvExpr/Cost.h" // for Cost
23#include "ResolvExpr/TypeEnvironment.h" // for EqvClass, TypeEnvironment
24#include "SymTab/Indexer.h" // for Indexer
25#include "SynTree/Declaration.h" // for TypeDecl, NamedTypeDecl
26#include "SynTree/Type.h" // for Type, BasicType, TypeInstType
27#include "typeops.h" // for typesCompatibleIgnoreQualifiers
28
29namespace ResolvExpr {
30 const Cost Cost::zero = Cost( 0, 0, 0, 0 );
31 const Cost Cost::infinity = Cost( -1, -1, -1, -1 );
32 const Cost Cost::unsafe = Cost( 1, 0, 0, 0 );
33 const Cost Cost::poly = Cost( 0, 1, 0, 0 );
34 const Cost Cost::safe = Cost( 0, 0, 1, 0 );
35 const Cost Cost::reference = Cost( 0, 0, 0, 1 );
36
37#if 0
38#define PRINT(x) x
39#else
40#define PRINT(x)
41#endif
42 Cost conversionCost( Type *src, Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
43 if ( TypeInstType *destAsTypeInst = dynamic_cast< TypeInstType* >( dest ) ) {
44 EqvClass eqvClass;
45 NamedTypeDecl *namedType;
46 PRINT( std::cerr << "type inst " << destAsTypeInst->name; )
47 if ( env.lookup( destAsTypeInst->name, eqvClass ) ) {
48 if ( eqvClass.type ) {
49 return conversionCost( src, eqvClass.type, indexer, env );
50 } else {
51 return Cost::infinity;
52 }
53 } else if ( ( namedType = indexer.lookupType( destAsTypeInst->name ) ) ) {
54 PRINT( std::cerr << " found" << std::endl; )
55 TypeDecl *type = dynamic_cast< TypeDecl* >( namedType );
56 // all typedefs should be gone by this point
57 assert( type );
58 if ( type->base ) {
59 return conversionCost( src, type->base, indexer, env ) + Cost::safe;
60 } // if
61 } // if
62 PRINT( std::cerr << " not found" << std::endl; )
63 } // if
64 PRINT(
65 std::cerr << "src is ";
66 src->print( std::cerr );
67 std::cerr << std::endl << "dest is ";
68 dest->print( std::cerr );
69 std::cerr << std::endl << "env is" << std::endl;
70 env.print( std::cerr, 8 );
71 )
72 if ( typesCompatibleIgnoreQualifiers( src, dest, indexer, env ) ) {
73 PRINT( std::cerr << "compatible!" << std::endl; )
74 return Cost::zero;
75 } else if ( dynamic_cast< VoidType* >( dest ) ) {
76 return Cost::safe;
77 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * > ( dest ) ) {
78 PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
79 return convertToReferenceCost( src, refType, indexer, env, [](Type * t1, Type * t2, const SymTab::Indexer &, const TypeEnvironment & env ){
80 return ptrsAssignable( t1, t2, env );
81 });
82 } else {
83 PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
84 src->accept( converter );
85 if ( converter.pass.get_cost() == Cost::infinity ) {
86 return Cost::infinity;
87 } else {
88 return converter.pass.get_cost() + Cost::zero;
89 } // if
90 } // if
91 }
92
93 Cost convertToReferenceCost( Type * src, Type * dest, int diff, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func ) {
94 PRINT( std::cerr << "convert to reference cost... diff " << diff << " " << src << " / " << dest << std::endl; )
95 if ( diff > 0 ) {
96 // TODO: document this
97 Cost cost = convertToReferenceCost( strict_dynamic_cast< ReferenceType * >( src )->base, dest, diff-1, indexer, env, func );
98 cost.incReference();
99 return cost;
100 } else if ( diff < -1 ) {
101 // TODO: document this
102 Cost cost = convertToReferenceCost( src, strict_dynamic_cast< ReferenceType * >( dest )->base, diff+1, indexer, env, func );
103 cost.incReference();
104 return cost;
105 } else if ( diff == 0 ) {
106 ReferenceType * srcAsRef = dynamic_cast< ReferenceType * >( src );
107 ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
108 if ( srcAsRef && destAsRef ) { // pointer-like conversions between references
109 PRINT( std::cerr << "converting between references" << std::endl; )
110 Type::Qualifiers tq1 = srcAsRef->base->get_qualifiers();
111 Type::Qualifiers tq2 = destAsRef->base->get_qualifiers();
112 if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( srcAsRef->base, destAsRef->base, indexer, env ) ) {
113 PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
114 if ( tq1 == tq2 ) {
115 // types are the same
116 return Cost::zero;
117 } else {
118 // types are the same, except otherPointer has more qualifiers
119 return Cost::safe;
120 }
121 } else { // xxx - this discards reference qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
122 int assignResult = func( srcAsRef->base, destAsRef->base, indexer, env );
123 PRINT( std::cerr << "comparing references: " << assignResult << " " << srcAsRef << " " << destAsRef << std::endl; )
124 if ( assignResult > 0 ) {
125 return Cost::safe;
126 } else if ( assignResult < 0 ) {
127 return Cost::unsafe;
128 } // if
129 } // if
130 } else {
131 PRINT( std::cerr << "reference to rvalue conversion" << std::endl; )
132 PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
133 src->accept( converter );
134 return converter.pass.get_cost();
135 } // if
136 } else {
137 ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
138 assert( diff == -1 && destAsRef );
139 PRINT( std::cerr << "dest is: " << dest << " / src is: " << src << std::endl; )
140 if ( typesCompatibleIgnoreQualifiers( src, destAsRef->base, indexer, env ) ) {
141 PRINT( std::cerr << "converting compatible base type" << std::endl; )
142 if ( src->get_lvalue() ) {
143 PRINT(
144 std::cerr << "lvalue to reference conversion" << std::endl;
145 std::cerr << src << " => " << destAsRef << std::endl;
146 )
147 // lvalue-to-reference conversion: cv lvalue T => cv T &
148 if ( src->get_qualifiers() == destAsRef->base->get_qualifiers() ) {
149 return Cost::reference; // cost needs to be non-zero to add cast
150 } if ( src->get_qualifiers() < destAsRef->base->get_qualifiers() ) {
151 return Cost::safe; // cost needs to be higher than previous cast to differentiate adding qualifiers vs. keeping same
152 } else {
153 return Cost::unsafe;
154 } // if
155 } else if ( destAsRef->base->get_const() ) {
156 PRINT( std::cerr << "rvalue to const ref conversion" << std::endl; )
157 // rvalue-to-const-reference conversion: T => const T &
158 return Cost::safe;
159 } else {
160 PRINT( std::cerr << "rvalue to non-const reference conversion" << std::endl; )
161 // rvalue-to-reference conversion: T => T &
162 return Cost::unsafe;
163 } // if
164 } // if
165 PRINT( std::cerr << "attempting to convert from incompatible base type -- fail" << std::endl; )
166 }
167 return Cost::infinity;
168 }
169
170 Cost convertToReferenceCost( Type * src, ReferenceType * dest, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func ) {
171 int sdepth = src->referenceDepth(), ddepth = dest->referenceDepth();
172 return convertToReferenceCost( src, dest, sdepth-ddepth, indexer, env, func );
173 }
174
175 ConversionCost::ConversionCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env, CostFunction costFunc )
176 : dest( dest ), indexer( indexer ), cost( Cost::infinity ), env( env ), costFunc( costFunc ) {
177 }
178
179/*
180 Old
181 ===
182 Double
183 |
184 Float
185 |
186 ULong
187 / \
188 UInt Long
189 \ /
190 Int
191 |
192 Ushort
193 |
194 Short
195 |
196 Uchar
197 / \
198 Schar Char
199
200 New
201 ===
202 +-----LongDoubleComplex--+
203 LongDouble--+ | +-LongDoubleImag
204 | +---DoubleComplex---+ |
205 Double------+ | +----DoubleImag
206 | +-FloatComplex-+ |
207 Float---------+ +-------FloatImag
208 |
209 ULongLong
210 |
211 LongLong
212 |
213 ULong
214 / \
215 UInt Long
216 \ /
217 Int
218 |
219 Ushort
220 |
221 Short
222 |
223 Uchar
224 / \
225 Schar Char
226 \ /
227 Bool
228*/
229
230 static const int costMatrix[ BasicType::NUMBER_OF_BASIC_TYPES ][ BasicType::NUMBER_OF_BASIC_TYPES ] = {
231 /* Src \ Dest: Bool Char SChar UChar Short UShort Int UInt Long ULong LLong ULLong Float Double LDbl FCplex DCplex LDCplex FImag DImag LDImag I128, U128 */
232 /* Bool */ { 0, 1, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 12, 13, 14, 12, 13, 14, -1, -1, -1, 10, 11, },
233 /* Char */ { -1, 0, -1, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
234 /* SChar */ { -1, -1, 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
235 /* UChar */ { -1, -1, -1, 0, 1, 2, 3, 4, 4, 5, 6, 7, 10, 11, 12, 10, 11, 12, -1, -1, -1, 8, 9, },
236 /* Short */ { -1, -1, -1, -1, 0, 1, 2, 3, 3, 4, 5, 6, 9, 10, 11, 9, 10, 11, -1, -1, -1, 7, 8, },
237 /* UShort */{ -1, -1, -1, -1, -1, 0, 1, 2, 2, 3, 4, 5, 8, 9, 10, 8, 9, 10, -1, -1, -1, 6, 7, },
238 /* Int */ { -1, -1, -1, -1, -1, -1, 0, 1, 1, 2, 3, 4, 7, 8, 9, 7, 8, 9, -1, -1, -1, 5, 6, },
239 /* UInt */ { -1, -1, -1, -1, -1, -1, -1, 0, -1, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
240 /* Long */ { -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
241 /* ULong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 5, 6, 7, 5, 6, 7, -1, -1, -1, 3, 4, },
242 /* LLong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 4, 5, 6, 4, 5, 6, -1, -1, -1, 2, 3, },
243 /* ULLong */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 3, 4, 5, 3, 4, 5, -1, -1, -1, 1, 2, },
244
245 /* Float */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 1, 2, 3, -1, -1, -1, -1, -1, },
246 /* Double */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, 1, 2, -1, -1, -1, -1, -1, },
247 /* LDbl */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 1, -1, -1, -1, -1, -1, },
248 /* FCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, -1, -1, -1, -1, -1, },
249 /* DCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, -1, -1, -1, -1, },
250 /* LDCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, },
251 /* FImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 0, 1, 2, -1, -1, },
252 /* DImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, -1, 0, 1, -1, -1, },
253 /* LDImag */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 0, -1, -1, },
254
255 /* I128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 2, 3, 4, 3, 4, 5, -1, -1, -1, 0, 1, },
256 /* U128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 2, 3, 4, -1, -1, -1, -1, 0, },
257 };
258
259 void ConversionCost::postvisit( VoidType * ) {
260 cost = Cost::infinity;
261 }
262
263 void ConversionCost::postvisit(BasicType *basicType) {
264 if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
265 int tableResult = costMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ];
266 if ( tableResult == -1 ) {
267 cost = Cost::unsafe;
268 } else {
269 cost = Cost::zero;
270 cost.incSafe( tableResult );
271 } // if
272 } else if ( dynamic_cast< EnumInstType *>( dest ) ) {
273 // xxx - not positive this is correct, but appears to allow casting int => enum
274 cost = Cost::unsafe;
275 } else if ( dynamic_cast< ZeroType* >( dest ) != nullptr || dynamic_cast< OneType* >( dest ) != nullptr ) {
276 cost = Cost::unsafe;
277 } // if
278 }
279
280 void ConversionCost::postvisit( PointerType * pointerType ) {
281 if ( PointerType *destAsPtr = dynamic_cast< PointerType* >( dest ) ) {
282 PRINT( std::cerr << pointerType << " ===> " << destAsPtr << std::endl; )
283 Type::Qualifiers tq1 = pointerType->base->get_qualifiers();
284 Type::Qualifiers tq2 = destAsPtr->base->get_qualifiers();
285 if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( pointerType->base, destAsPtr->base, indexer, env ) ) {
286 PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
287 if ( tq1 == tq2 ) {
288 // types are the same
289 cost = Cost::zero;
290 } else {
291 // types are the same, except otherPointer has more qualifiers
292 cost = Cost::safe;
293 }
294 } else {
295 int assignResult = ptrsAssignable( pointerType->base, destAsPtr->base, env );
296 PRINT( std::cerr << " :: " << assignResult << std::endl; )
297 if ( assignResult > 0 && tq1 <= tq2 ) {
298 // xxx - want the case where qualifiers are added to be more expensive than the case where qualifiers are the same. Is 1 safe vs. 2 safe correct?
299 if ( tq1 == tq2 ) {
300 cost = Cost::safe;
301 } else if ( tq1 < tq2 ) {
302 cost = Cost::safe+Cost::safe;
303 }
304 } else if ( assignResult < 0 ) {
305 cost = Cost::unsafe;
306 } // if
307 // assignResult == 0 means Cost::Infinity
308 } // if
309 } else if ( dynamic_cast< ZeroType * >( dest ) ) {
310 cost = Cost::unsafe;
311 } // if
312 }
313
314 void ConversionCost::postvisit( ArrayType * ) {}
315
316 void ConversionCost::postvisit( ReferenceType * refType ) {
317 // Note: dest can never be a reference, since it would have been caught in an earlier check
318 assert( ! dynamic_cast< ReferenceType * >( dest ) );
319 // convert reference to rvalue: cv T1 & => T2
320 // recursively compute conversion cost from T1 to T2.
321 // cv can be safely dropped because of 'implicit dereference' behavior.
322 cost = costFunc( refType->base, dest, indexer, env );
323 if ( refType->base->get_qualifiers() == dest->get_qualifiers() ) {
324 cost.incReference(); // prefer exact qualifiers
325 } else if ( refType->base->get_qualifiers() < dest->get_qualifiers() ) {
326 cost.incSafe(); // then gaining qualifiers
327 } else {
328 cost.incUnsafe(); // lose qualifiers as last resort
329 }
330 PRINT( std::cerr << refType << " ==> " << dest << " " << cost << std::endl; )
331 }
332
333 void ConversionCost::postvisit( FunctionType * ) {}
334
335 void ConversionCost::postvisit( StructInstType * inst ) {
336 if ( StructInstType *destAsInst = dynamic_cast< StructInstType* >( dest ) ) {
337 if ( inst->name == destAsInst->name ) {
338 cost = Cost::zero;
339 } // if
340 } // if
341 }
342
343 void ConversionCost::postvisit( UnionInstType * inst ) {
344 if ( UnionInstType *destAsInst = dynamic_cast< UnionInstType* >( dest ) ) {
345 if ( inst->name == destAsInst->name ) {
346 cost = Cost::zero;
347 } // if
348 } // if
349 }
350
351 void ConversionCost::postvisit( EnumInstType * ) {
352 static Type::Qualifiers q;
353 static BasicType integer( q, BasicType::SignedInt );
354 cost = costFunc( &integer, dest, indexer, env ); // safe if dest >= int
355 if ( cost < Cost::unsafe ) {
356 cost.incSafe();
357 } // if
358 }
359
360 void ConversionCost::postvisit( TraitInstType * ) {}
361
362 void ConversionCost::postvisit( TypeInstType *inst ) {
363 EqvClass eqvClass;
364 NamedTypeDecl *namedType;
365 if ( env.lookup( inst->name, eqvClass ) ) {
366 cost = costFunc( eqvClass.type, dest, indexer, env );
367 } else if ( TypeInstType *destAsInst = dynamic_cast< TypeInstType* >( dest ) ) {
368 if ( inst->name == destAsInst->name ) {
369 cost = Cost::zero;
370 }
371 } else if ( ( namedType = indexer.lookupType( inst->name ) ) ) {
372 TypeDecl *type = dynamic_cast< TypeDecl* >( namedType );
373 // all typedefs should be gone by this point
374 assert( type );
375 if ( type->base ) {
376 cost = costFunc( type->base, dest, indexer, env ) + Cost::safe;
377 } // if
378 } // if
379 }
380
381 void ConversionCost::postvisit( TupleType * tupleType ) {
382 Cost c = Cost::zero;
383 if ( TupleType * destAsTuple = dynamic_cast< TupleType * >( dest ) ) {
384 std::list< Type * >::const_iterator srcIt = tupleType->types.begin();
385 std::list< Type * >::const_iterator destIt = destAsTuple->types.begin();
386 while ( srcIt != tupleType->types.end() && destIt != destAsTuple->types.end() ) {
387 Cost newCost = costFunc( *srcIt++, *destIt++, indexer, env );
388 if ( newCost == Cost::infinity ) {
389 return;
390 } // if
391 c += newCost;
392 } // while
393 if ( destIt != destAsTuple->types.end() ) {
394 cost = Cost::infinity;
395 } else {
396 cost = c;
397 } // if
398 } // if
399 }
400
401 void ConversionCost::postvisit( VarArgsType * ) {
402 if ( dynamic_cast< VarArgsType* >( dest ) ) {
403 cost = Cost::zero;
404 }
405 }
406
407 void ConversionCost::postvisit( ZeroType * ) {
408 if ( dynamic_cast< ZeroType * >( dest ) ) {
409 cost = Cost::zero;
410 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
411 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
412 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
413 if ( tableResult == -1 ) {
414 cost = Cost::unsafe;
415 } else {
416 cost = Cost::zero;
417 cost.incSafe( tableResult + 1 );
418 }
419 } else if ( dynamic_cast< PointerType* >( dest ) ) {
420 cost = Cost::safe;
421 }
422 }
423
424 void ConversionCost::postvisit( OneType * ) {
425 if ( dynamic_cast< OneType * >( dest ) ) {
426 cost = Cost::zero;
427 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
428 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
429 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
430 if ( tableResult == -1 ) {
431 cost = Cost::unsafe;
432 } else {
433 cost = Cost::zero;
434 cost.incSafe( tableResult + 1 );
435 }
436 }
437 }
438} // namespace ResolvExpr
439
440// Local Variables: //
441// tab-width: 4 //
442// mode: c++ //
443// compile-command: "make install" //
444// End: //
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