source: src/ResolvExpr/ConversionCost.cc@ 6ccfb7f

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 6ccfb7f was 8135d4c, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Merge branch 'master' into references
  • Property mode set to 100644
File size: 17.2 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// 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 : Wed Mar 2 17:35:46 2016
13// Update Count : 6
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
43 Cost conversionCost( Type *src, Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env ) {
44 if ( TypeInstType *destAsTypeInst = dynamic_cast< TypeInstType* >( dest ) ) {
45 EqvClass eqvClass;
46 NamedTypeDecl *namedType;
47 PRINT( std::cerr << "type inst " << destAsTypeInst->get_name(); )
48 if ( env.lookup( destAsTypeInst->get_name(), eqvClass ) ) {
49 if ( eqvClass.type ) {
50 return conversionCost( src, eqvClass.type, indexer, env );
51 } else {
52 return Cost::infinity;
53 }
54 } else if ( ( namedType = indexer.lookupType( destAsTypeInst->get_name() ) ) ) {
55 PRINT( std::cerr << " found" << std::endl; )
56 TypeDecl *type = dynamic_cast< TypeDecl* >( namedType );
57 // all typedefs should be gone by this point
58 assert( type );
59 if ( type->get_base() ) {
60 return conversionCost( src, type->get_base(), indexer, env ) + Cost::safe;
61 } // if
62 } // if
63 PRINT( std::cerr << " not found" << std::endl; )
64 } // if
65 PRINT(
66 std::cerr << "src is ";
67 src->print( std::cerr );
68 std::cerr << std::endl << "dest is ";
69 dest->print( std::cerr );
70 std::cerr << std::endl << "env is" << std::endl;
71 env.print( std::cerr, 8 );
72 )
73 if ( typesCompatibleIgnoreQualifiers( src, dest, indexer, env ) ) {
74 PRINT( std::cerr << "compatible!" << std::endl; )
75 return Cost::zero;
76 } else if ( dynamic_cast< VoidType* >( dest ) ) {
77 return Cost::safe;
78 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * > ( dest ) ) {
79 PRINT( std::cerr << "conversionCost: dest is reference" << std::endl; )
80 return convertToReferenceCost( src, refType, indexer, env );
81 } else {
82 ConversionCost converter( dest, indexer, env );
83 src->accept( converter );
84 if ( converter.get_cost() == Cost::infinity ) {
85 return Cost::infinity;
86 } else {
87 return converter.get_cost() + Cost::zero;
88 } // if
89 } // if
90 }
91
92 Cost convertToReferenceCost( Type * src, Type * dest, int diff, const SymTab::Indexer & indexer, const TypeEnvironment & env ) {
93 PRINT( std::cerr << "convert to reference cost..." << std::endl; )
94 if ( diff > 0 ) {
95 // TODO: document this
96 Cost cost = convertToReferenceCost( safe_dynamic_cast< ReferenceType * >( src )->get_base(), dest, diff-1, indexer, env );
97 cost.incReference();
98 return cost;
99 } else if ( diff < -1 ) {
100 // TODO: document this
101 Cost cost = convertToReferenceCost( src, safe_dynamic_cast< ReferenceType * >( dest )->get_base(), diff+1, indexer, env );
102 cost.incReference();
103 return cost;
104 } else if ( diff == 0 ) {
105 ReferenceType * srcAsRef = dynamic_cast< ReferenceType * >( src );
106 ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
107 if ( srcAsRef && destAsRef ) { // pointer-like conversions between references
108 PRINT( std::cerr << "converting between references" << std::endl; )
109 if ( srcAsRef->get_base()->get_qualifiers() <= destAsRef->get_base()->get_qualifiers() && typesCompatibleIgnoreQualifiers( srcAsRef->get_base(), destAsRef->get_base(), indexer, env ) ) {
110 return Cost::safe;
111 } else { // xxx - this discards reference qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
112 int assignResult = ptrsAssignable( srcAsRef->get_base(), destAsRef->get_base(), env );
113 PRINT( std::cerr << "comparing references: " << assignResult << " " << srcAsRef << " " << destAsRef << std::endl; )
114 if ( assignResult < 0 ) {
115 return Cost::safe;
116 } else if ( assignResult > 0 ) {
117 return Cost::unsafe;
118 } // if
119 } // if
120 } else {
121 PRINT( std::cerr << "reference to rvalue conversion" << std::endl; )
122 ConversionCost converter( dest, indexer, env );
123 src->accept( converter );
124 return converter.get_cost();
125 } // if
126 } else {
127 ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
128 assert( diff == -1 && destAsRef );
129 if ( typesCompatibleIgnoreQualifiers( src, destAsRef->get_base(), indexer, env ) ) {
130 PRINT( std::cerr << "converting compatible base type" << std::endl; )
131 if ( src->get_lvalue() ) {
132 PRINT(
133 std::cerr << "lvalue to reference conversion" << std::endl;
134 std::cerr << src << " => " << destAsRef << std::endl;
135 )
136 // lvalue-to-reference conversion: cv lvalue T => cv T &
137 if ( src->get_qualifiers() == destAsRef->get_base()->get_qualifiers() ) {
138 return Cost::reference; // cost needs to be non-zero to add cast
139 } if ( src->get_qualifiers() < destAsRef->get_base()->get_qualifiers() ) {
140 return Cost::safe; // cost needs to be higher than previous cast to differentiate adding qualifiers vs. keeping same
141 } else {
142 return Cost::unsafe;
143 } // if
144 } else if ( destAsRef->get_base()->get_const() ) {
145 PRINT( std::cerr << "rvalue to const ref conversion" << std::endl; )
146 // rvalue-to-const-reference conversion: T => const T &
147 return Cost::safe;
148 } else {
149 PRINT( std::cerr << "rvalue to non-const reference conversion" << std::endl; )
150 // rvalue-to-reference conversion: T => T &
151 return Cost::unsafe;
152 } // if
153 } // if
154 PRINT( std::cerr << "attempting to convert from incompatible base type -- fail" << std::endl; )
155 }
156 return Cost::infinity;
157 }
158
159 Cost convertToReferenceCost( Type * src, ReferenceType * dest, const SymTab::Indexer & indexer, const TypeEnvironment & env ) {
160 int sdepth = src->referenceDepth(), ddepth = dest->referenceDepth();
161 return convertToReferenceCost( src, dest, sdepth-ddepth, indexer, env );
162 }
163
164 ConversionCost::ConversionCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env )
165 : dest( dest ), indexer( indexer ), cost( Cost::infinity ), env( env ) {
166 }
167
168/*
169 Old
170 ===
171 Double
172 |
173 Float
174 |
175 ULong
176 / \
177 UInt Long
178 \ /
179 Int
180 |
181 Ushort
182 |
183 Short
184 |
185 Uchar
186 / \
187 Schar Char
188
189 New
190 ===
191 +-----LongDoubleComplex--+
192 LongDouble--+ | +-LongDoubleImag
193 | +---DoubleComplex---+ |
194 Double------+ | +----DoubleImag
195 | +-FloatComplex-+ |
196 Float---------+ +-------FloatImag
197 |
198 ULongLong
199 |
200 LongLong
201 |
202 ULong
203 / \
204 UInt Long
205 \ /
206 Int
207 |
208 Ushort
209 |
210 Short
211 |
212 Uchar
213 / \
214 Schar Char
215 \ /
216 Bool
217*/
218
219 static const int costMatrix[ BasicType::NUMBER_OF_BASIC_TYPES ][ BasicType::NUMBER_OF_BASIC_TYPES ] =
220 {
221 /* Src \ Dest: Bool Char SChar UChar Short UShort Int UInt Long ULong LLong ULLong Float Double LDbl FCplex DCplex LDCplex FImag DImag LDImag */
222 /* Bool */ { 0, 1, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 11, 12, 11, 12, 13, -1, -1, -1 },
223 /* Char */ { -1, 0, -1, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 10, 11, 10, 11, 12, -1, -1, -1 },
224 /* SChar */ { -1, -1, 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 10, 11, 10, 11, 12, -1, -1, -1 },
225 /* UChar */ { -1, -1, -1, 0, 1, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 9, 10, 11, -1, -1, -1 },
226 /* Short */ { -1, -1, -1, -1, 0, 1, 2, 3, 3, 4, 5, 6, 7, 8, 9, 8, 9, 10, -1, -1, -1 },
227 /* UShort */{ -1, -1, -1, -1, -1, 0, 1, 2, 2, 3, 4, 5, 6, 7, 8, 7, 8, 9, -1, -1, -1 },
228 /* Int */ { -1, -1, -1, -1, -1, -1, 0, 1, 1, 2, 3, 4, 5, 6, 7, 6, 7, 8, -1, -1, -1 },
229 /* UInt */ { -1, -1, -1, -1, -1, -1, -1, 0, -1, 1, 2, 3, 4, 5, 6, 5, 6, 7, -1, -1, -1 },
230 /* Long */ { -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 5, 6, 7, -1, -1, -1 },
231 /* ULong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 4, 5, 6, -1, -1, -1 },
232 /* LLong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 3, 4, 5, -1, -1, -1 },
233 /* ULLong */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 2, 3, 4, -1, -1, -1 },
234 /* Float */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 1, 2, 3, -1, -1, -1 },
235 /* Double */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, 1, 2, -1, -1, -1 },
236 /* LDbl */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 1, -1, -1, -1 },
237 /* FCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, -1, -1, -1 },
238 /* DCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, -1, -1 },
239 /* LDCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1 },
240 /* FImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 0, 1, 2 },
241 /* DImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, -1, 0, 1 },
242 /* LDImag */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 0 }
243 };
244
245 void ConversionCost::visit( __attribute((unused)) VoidType *voidType ) {
246 cost = Cost::infinity;
247 }
248
249 void ConversionCost::visit(BasicType *basicType) {
250 if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
251 int tableResult = costMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ];
252 if ( tableResult == -1 ) {
253 cost = Cost::unsafe;
254 } else {
255 cost = Cost::zero;
256 cost.incSafe( tableResult );
257 } // if
258 } else if ( dynamic_cast< EnumInstType *>( dest ) ) {
259 // xxx - not positive this is correct, but appears to allow casting int => enum
260 cost = Cost::unsafe;
261 } else if ( dynamic_cast< ZeroType* >( dest ) != nullptr || dynamic_cast< OneType* >( dest ) != nullptr ) {
262 cost = Cost::unsafe;
263 } // if
264 }
265
266 void ConversionCost::visit(PointerType *pointerType) {
267 if ( PointerType *destAsPtr = dynamic_cast< PointerType* >( dest ) ) {
268 PRINT( std::cerr << pointerType << " ===> " << destAsPtr; )
269 Type::Qualifiers tq1 = pointerType->get_base()->get_qualifiers();
270 Type::Qualifiers tq2 = destAsPtr->get_base()->get_qualifiers();
271 if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( pointerType->get_base(), destAsPtr->get_base(), indexer, env ) ) {
272 if ( tq1 == tq2 ) {
273 // types are the same
274 cost = Cost::zero;
275 } else {
276 // types are the same, except otherPointer has more qualifiers
277 PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
278 cost = Cost::safe;
279 }
280 } else { // xxx - this discards qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
281 int assignResult = ptrsAssignable( pointerType->get_base(), destAsPtr->get_base(), env );
282 PRINT( std::cerr << " :: " << assignResult << std::endl; )
283 if ( assignResult < 0 && pointerType->get_base()->get_qualifiers() <= destAsPtr->get_qualifiers() ) {
284 cost = Cost::safe;
285 } else if ( assignResult > 0 ) {
286 cost = Cost::unsafe;
287 } // if
288 // assignResult == 0 means Cost::Infinity
289 } // if
290 } else if ( dynamic_cast< ZeroType* >( dest ) != nullptr || dynamic_cast< OneType* >( dest ) != nullptr ) {
291 cost = Cost::unsafe;
292 } // if
293 }
294
295 void ConversionCost::visit(__attribute((unused)) ArrayType *arrayType) {}
296
297 void ConversionCost::visit(ReferenceType *refType) {
298 // Note: dest can never be a reference, since it would have been caught in an earlier check
299 assert( ! dynamic_cast< ReferenceType * >( dest ) );
300 // convert reference to rvalue: cv T1 & => T2
301 // recursively compute conversion cost from T1 to T2.
302 // cv can be safely dropped because of 'implicit dereference' behavior.
303 refType->get_base()->accept( *this );
304 if ( refType->get_base()->get_qualifiers() == dest->get_qualifiers() ) {
305 cost.incReference(); // prefer exact qualifiers
306 } else if ( refType->get_base()->get_qualifiers() < dest->get_qualifiers() ) {
307 cost.incSafe(); // then gaining qualifiers
308 } else {
309 cost.incUnsafe(); // lose qualifiers as last resort
310 }
311 PRINT( std::cerr << refType << " ==> " << dest << " " << cost << std::endl; )
312 }
313
314 void ConversionCost::visit(__attribute((unused)) FunctionType *functionType) {}
315
316 void ConversionCost::visit(StructInstType *inst) {
317 if ( StructInstType *destAsInst = dynamic_cast< StructInstType* >( dest ) ) {
318 if ( inst->get_name() == destAsInst->get_name() ) {
319 cost = Cost::zero;
320 } // if
321 } // if
322 }
323
324 void ConversionCost::visit(UnionInstType *inst) {
325 if ( StructInstType *destAsInst = dynamic_cast< StructInstType* >( dest ) ) {
326 if ( inst->get_name() == destAsInst->get_name() ) {
327 cost = Cost::zero;
328 } // if
329 } // if
330 }
331
332 void ConversionCost::visit( __attribute((unused)) EnumInstType *inst ) {
333 static Type::Qualifiers q;
334 static BasicType integer( q, BasicType::SignedInt );
335 integer.accept( *this ); // safe if dest >= int
336 if ( cost < Cost::unsafe ) {
337 cost.incSafe();
338 } // if
339 }
340
341 void ConversionCost::visit( __attribute((unused)) TraitInstType *inst) {
342 }
343
344 void ConversionCost::visit(TypeInstType *inst) {
345 EqvClass eqvClass;
346 NamedTypeDecl *namedType;
347 if ( env.lookup( inst->get_name(), eqvClass ) ) {
348 cost = conversionCost( eqvClass.type, dest, indexer, env );
349 } else if ( TypeInstType *destAsInst = dynamic_cast< TypeInstType* >( dest ) ) {
350 if ( inst->get_name() == destAsInst->get_name() ) {
351 cost = Cost::zero;
352 }
353 } else if ( ( namedType = indexer.lookupType( inst->get_name() ) ) ) {
354 TypeDecl *type = dynamic_cast< TypeDecl* >( namedType );
355 // all typedefs should be gone by this point
356 assert( type );
357 if ( type->get_base() ) {
358 cost = conversionCost( type->get_base(), dest, indexer, env ) + Cost::safe;
359 } // if
360 } // if
361 }
362
363 void ConversionCost::visit( __attribute((unused)) TupleType *tupleType) {
364 Cost c = Cost::zero;
365 if ( TupleType *destAsTuple = dynamic_cast< TupleType* >( dest ) ) {
366 std::list< Type* >::const_iterator srcIt = tupleType->get_types().begin();
367 std::list< Type* >::const_iterator destIt = destAsTuple->get_types().begin();
368 while ( srcIt != tupleType->get_types().end() && destIt != destAsTuple->get_types().end() ) {
369 Cost newCost = conversionCost( *srcIt++, *destIt++, indexer, env );
370 if ( newCost == Cost::infinity ) {
371 return;
372 } // if
373 c += newCost;
374 } // while
375 if ( destIt != destAsTuple->get_types().end() ) {
376 cost = Cost::infinity;
377 } else {
378 cost = c;
379 } // if
380 } // if
381 }
382
383 void ConversionCost::visit( __attribute((unused)) VarArgsType *varArgsType) {
384 if ( dynamic_cast< VarArgsType* >( dest ) ) {
385 cost = Cost::zero;
386 }
387 }
388
389 void ConversionCost::visit( __attribute((unused)) ZeroType *zeroType) {
390 if ( dynamic_cast< ZeroType* >( dest ) ) {
391 cost = Cost::zero;
392 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
393 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
394 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
395 if ( tableResult == -1 ) {
396 cost = Cost::unsafe;
397 } else {
398 cost = Cost::zero;
399 cost.incSafe( tableResult + 1 );
400 }
401 } else if ( dynamic_cast< PointerType* >( dest ) ) {
402 cost = Cost::safe;
403 }
404 }
405
406 void ConversionCost::visit( __attribute((unused)) OneType *oneType) {
407 if ( dynamic_cast< OneType* >( dest ) ) {
408 cost = Cost::zero;
409 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
410 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
411 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
412 if ( tableResult == -1 ) {
413 cost = Cost::unsafe;
414 } else {
415 cost = Cost::zero;
416 cost.incSafe( tableResult + 1 );
417 }
418 }
419 }
420} // namespace ResolvExpr
421
422// Local Variables: //
423// tab-width: 4 //
424// mode: c++ //
425// compile-command: "make install" //
426// End: //
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