source: src/ResolvExpr/ConversionCost.cc@ 50f0ba9

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 50f0ba9 was b0837e4, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Minor cleanup in conversion code
  • Property mode set to 100644
File size: 17.7 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->get_name(); )
47 if ( env.lookup( destAsTypeInst->get_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->get_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->get_base() ) {
59 return conversionCost( src, type->get_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 TypeEnvironment & env, const SymTab::Indexer &){
80 return ptrsAssignable( t1, t2, env );
81 });
82 } else {
83 ConversionCost converter( dest, indexer, env );
84 src->accept( converter );
85 if ( converter.get_cost() == Cost::infinity ) {
86 return Cost::infinity;
87 } else {
88 return converter.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 << std::endl; )
95 if ( diff > 0 ) {
96 // TODO: document this
97 Cost cost = convertToReferenceCost( strict_dynamic_cast< ReferenceType * >( src )->get_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 )->get_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 if ( srcAsRef->get_base()->get_qualifiers() <= destAsRef->get_base()->get_qualifiers() && typesCompatibleIgnoreQualifiers( srcAsRef->get_base(), destAsRef->get_base(), indexer, env ) ) {
111 return Cost::safe;
112 } else { // xxx - this discards reference qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
113 int assignResult = func( srcAsRef->get_base(), destAsRef->get_base(), env, indexer );
114 PRINT( std::cerr << "comparing references: " << assignResult << " " << srcAsRef << " " << destAsRef << std::endl; )
115 if ( assignResult > 0 ) {
116 return Cost::safe;
117 } else if ( assignResult < 0 ) {
118 return Cost::unsafe;
119 } // if
120 } // if
121 } else {
122 PRINT( std::cerr << "reference to rvalue conversion" << std::endl; )
123 ConversionCost converter( dest, indexer, env );
124 src->accept( converter );
125 return converter.get_cost();
126 } // if
127 } else {
128 ReferenceType * destAsRef = dynamic_cast< ReferenceType * >( dest );
129 assert( diff == -1 && destAsRef );
130 PRINT( std::cerr << "dest is: " << dest << " / src is: " << src << std::endl; )
131 if ( typesCompatibleIgnoreQualifiers( src, destAsRef->get_base(), indexer, env ) ) {
132 PRINT( std::cerr << "converting compatible base type" << std::endl; )
133 if ( src->get_lvalue() ) {
134 PRINT(
135 std::cerr << "lvalue to reference conversion" << std::endl;
136 std::cerr << src << " => " << destAsRef << std::endl;
137 )
138 // lvalue-to-reference conversion: cv lvalue T => cv T &
139 if ( src->get_qualifiers() == destAsRef->get_base()->get_qualifiers() ) {
140 return Cost::reference; // cost needs to be non-zero to add cast
141 } if ( src->get_qualifiers() < destAsRef->get_base()->get_qualifiers() ) {
142 return Cost::safe; // cost needs to be higher than previous cast to differentiate adding qualifiers vs. keeping same
143 } else {
144 return Cost::unsafe;
145 } // if
146 } else if ( destAsRef->get_base()->get_const() ) {
147 PRINT( std::cerr << "rvalue to const ref conversion" << std::endl; )
148 // rvalue-to-const-reference conversion: T => const T &
149 return Cost::safe;
150 } else {
151 PRINT( std::cerr << "rvalue to non-const reference conversion" << std::endl; )
152 // rvalue-to-reference conversion: T => T &
153 return Cost::unsafe;
154 } // if
155 } // if
156 PRINT( std::cerr << "attempting to convert from incompatible base type -- fail" << std::endl; )
157 }
158 return Cost::infinity;
159 }
160
161 Cost convertToReferenceCost( Type * src, ReferenceType * dest, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func ) {
162 int sdepth = src->referenceDepth(), ddepth = dest->referenceDepth();
163 return convertToReferenceCost( src, dest, sdepth-ddepth, indexer, env, func );
164 }
165
166 ConversionCost::ConversionCost( Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env )
167 : dest( dest ), indexer( indexer ), cost( Cost::infinity ), env( env ) {
168 }
169
170/*
171 Old
172 ===
173 Double
174 |
175 Float
176 |
177 ULong
178 / \
179 UInt Long
180 \ /
181 Int
182 |
183 Ushort
184 |
185 Short
186 |
187 Uchar
188 / \
189 Schar Char
190
191 New
192 ===
193 +-----LongDoubleComplex--+
194 LongDouble--+ | +-LongDoubleImag
195 | +---DoubleComplex---+ |
196 Double------+ | +----DoubleImag
197 | +-FloatComplex-+ |
198 Float---------+ +-------FloatImag
199 |
200 ULongLong
201 |
202 LongLong
203 |
204 ULong
205 / \
206 UInt Long
207 \ /
208 Int
209 |
210 Ushort
211 |
212 Short
213 |
214 Uchar
215 / \
216 Schar Char
217 \ /
218 Bool
219*/
220
221 static const int costMatrix[ BasicType::NUMBER_OF_BASIC_TYPES ][ BasicType::NUMBER_OF_BASIC_TYPES ] = {
222 /* 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 */
223 /* Bool */ { 0, 1, 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 12, 13, 14, 12, 13, 14, -1, -1, -1, 10, 11, },
224 /* Char */ { -1, 0, -1, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
225 /* SChar */ { -1, -1, 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 11, 12, 13, 11, 12, 13, -1, -1, -1, 9, 10, },
226 /* UChar */ { -1, -1, -1, 0, 1, 2, 3, 4, 4, 5, 6, 7, 10, 11, 12, 10, 11, 12, -1, -1, -1, 8, 9, },
227 /* Short */ { -1, -1, -1, -1, 0, 1, 2, 3, 3, 4, 5, 6, 9, 10, 11, 9, 10, 11, -1, -1, -1, 7, 8, },
228 /* UShort */{ -1, -1, -1, -1, -1, 0, 1, 2, 2, 3, 4, 5, 8, 9, 10, 8, 9, 10, -1, -1, -1, 6, 7, },
229 /* Int */ { -1, -1, -1, -1, -1, -1, 0, 1, 1, 2, 3, 4, 7, 8, 9, 7, 8, 9, -1, -1, -1, 5, 6, },
230 /* UInt */ { -1, -1, -1, -1, -1, -1, -1, 0, -1, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
231 /* Long */ { -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 6, 7, 8, 6, 7, 8, -1, -1, -1, 4, 5, },
232 /* ULong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 5, 6, 7, 5, 6, 7, -1, -1, -1, 3, 4, },
233 /* LLong */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 4, 5, 6, 4, 5, 6, -1, -1, -1, 2, 3, },
234 /* ULLong */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 3, 4, 5, 3, 4, 5, -1, -1, -1, 1, 2, },
235
236 /* Float */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 1, 2, 3, -1, -1, -1, -1, -1, },
237 /* Double */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, 1, 2, -1, -1, -1, -1, -1, },
238 /* LDbl */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, 1, -1, -1, -1, -1, -1, },
239 /* FCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, -1, -1, -1, -1, -1, },
240 /* DCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, -1, -1, -1, -1, -1, },
241 /* LDCplex */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1, -1, -1, },
242 /* FImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 0, 1, 2, -1, -1, },
243 /* DImag */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, -1, 0, 1, -1, -1, },
244 /* LDImag */{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 0, -1, -1, },
245
246 /* I128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 2, 3, 4, 3, 4, 5, -1, -1, -1, 0, 1, },
247 /* U128 */ { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 3, 2, 3, 4, -1, -1, -1, -1, 0, },
248 };
249
250 void ConversionCost::visit( __attribute((unused)) VoidType *voidType ) {
251 cost = Cost::infinity;
252 }
253
254 void ConversionCost::visit(BasicType *basicType) {
255 if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
256 int tableResult = costMatrix[ basicType->get_kind() ][ destAsBasic->get_kind() ];
257 if ( tableResult == -1 ) {
258 cost = Cost::unsafe;
259 } else {
260 cost = Cost::zero;
261 cost.incSafe( tableResult );
262 } // if
263 } else if ( dynamic_cast< EnumInstType *>( dest ) ) {
264 // xxx - not positive this is correct, but appears to allow casting int => enum
265 cost = Cost::unsafe;
266 } else if ( dynamic_cast< ZeroType* >( dest ) != nullptr || dynamic_cast< OneType* >( dest ) != nullptr ) {
267 cost = Cost::unsafe;
268 } // if
269 }
270
271 void ConversionCost::visit( PointerType * pointerType ) {
272 if ( PointerType *destAsPtr = dynamic_cast< PointerType* >( dest ) ) {
273 PRINT( std::cerr << pointerType << " ===> " << destAsPtr; )
274 Type::Qualifiers tq1 = pointerType->get_base()->get_qualifiers();
275 Type::Qualifiers tq2 = destAsPtr->get_base()->get_qualifiers();
276 if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers( pointerType->get_base(), destAsPtr->get_base(), indexer, env ) ) {
277 if ( tq1 == tq2 ) {
278 // types are the same
279 cost = Cost::zero;
280 } else {
281 // types are the same, except otherPointer has more qualifiers
282 PRINT( std::cerr << " :: compatible and good qualifiers" << std::endl; )
283 cost = Cost::safe;
284 }
285 } else { // xxx - this discards qualifiers from consideration -- reducing qualifiers is a safe conversion; is this right?
286 int assignResult = ptrsAssignable( pointerType->base, destAsPtr->base, env );
287 PRINT( std::cerr << " :: " << assignResult << std::endl; )
288 if ( assignResult > 0 && pointerType->get_base()->get_qualifiers() <= destAsPtr->get_qualifiers() ) {
289 cost = Cost::safe;
290 } else if ( assignResult < 0 ) {
291 cost = Cost::unsafe;
292 } // if
293 // assignResult == 0 means Cost::Infinity
294 } // if
295 } else if ( dynamic_cast< ZeroType * >( dest ) ) {
296 cost = Cost::unsafe;
297 } // if
298 }
299
300 void ConversionCost::visit( ArrayType * ) {}
301
302 void ConversionCost::visit( ReferenceType * refType ) {
303 // Note: dest can never be a reference, since it would have been caught in an earlier check
304 assert( ! dynamic_cast< ReferenceType * >( dest ) );
305 // convert reference to rvalue: cv T1 & => T2
306 // recursively compute conversion cost from T1 to T2.
307 // cv can be safely dropped because of 'implicit dereference' behavior.
308 refType->base->accept( *this );
309 if ( refType->base->get_qualifiers() == dest->get_qualifiers() ) {
310 cost.incReference(); // prefer exact qualifiers
311 } else if ( refType->base->get_qualifiers() < dest->get_qualifiers() ) {
312 cost.incSafe(); // then gaining qualifiers
313 } else {
314 cost.incUnsafe(); // lose qualifiers as last resort
315 }
316 PRINT( std::cerr << refType << " ==> " << dest << " " << cost << std::endl; )
317 }
318
319 void ConversionCost::visit( FunctionType * ) {}
320
321 void ConversionCost::visit( StructInstType * inst ) {
322 if ( StructInstType *destAsInst = dynamic_cast< StructInstType* >( dest ) ) {
323 if ( inst->name == destAsInst->name ) {
324 cost = Cost::zero;
325 } // if
326 } // if
327 }
328
329 void ConversionCost::visit( UnionInstType * inst ) {
330 if ( UnionInstType *destAsInst = dynamic_cast< UnionInstType* >( dest ) ) {
331 if ( inst->name == destAsInst->name ) {
332 cost = Cost::zero;
333 } // if
334 } // if
335 }
336
337 void ConversionCost::visit( EnumInstType * ) {
338 static Type::Qualifiers q;
339 static BasicType integer( q, BasicType::SignedInt );
340 integer.accept( *this ); // safe if dest >= int
341 if ( cost < Cost::unsafe ) {
342 cost.incSafe();
343 } // if
344 }
345
346 void ConversionCost::visit( TraitInstType * ) {}
347
348 void ConversionCost::visit( TypeInstType *inst ) {
349 EqvClass eqvClass;
350 NamedTypeDecl *namedType;
351 if ( env.lookup( inst->get_name(), eqvClass ) ) {
352 cost = conversionCost( eqvClass.type, dest, indexer, env );
353 } else if ( TypeInstType *destAsInst = dynamic_cast< TypeInstType* >( dest ) ) {
354 if ( inst->get_name() == destAsInst->get_name() ) {
355 cost = Cost::zero;
356 }
357 } else if ( ( namedType = indexer.lookupType( inst->get_name() ) ) ) {
358 TypeDecl *type = dynamic_cast< TypeDecl* >( namedType );
359 // all typedefs should be gone by this point
360 assert( type );
361 if ( type->get_base() ) {
362 cost = conversionCost( type->get_base(), dest, indexer, env ) + Cost::safe;
363 } // if
364 } // if
365 }
366
367 void ConversionCost::visit( TupleType * tupleType ) {
368 Cost c = Cost::zero;
369 if ( TupleType * destAsTuple = dynamic_cast< TupleType * >( dest ) ) {
370 std::list< Type * >::const_iterator srcIt = tupleType->get_types().begin();
371 std::list< Type * >::const_iterator destIt = destAsTuple->get_types().begin();
372 while ( srcIt != tupleType->get_types().end() && destIt != destAsTuple->get_types().end() ) {
373 Cost newCost = conversionCost( *srcIt++, *destIt++, indexer, env );
374 if ( newCost == Cost::infinity ) {
375 return;
376 } // if
377 c += newCost;
378 } // while
379 if ( destIt != destAsTuple->get_types().end() ) {
380 cost = Cost::infinity;
381 } else {
382 cost = c;
383 } // if
384 } // if
385 }
386
387 void ConversionCost::visit( VarArgsType * ) {
388 if ( dynamic_cast< VarArgsType* >( dest ) ) {
389 cost = Cost::zero;
390 }
391 }
392
393 void ConversionCost::visit( ZeroType * ) {
394 if ( dynamic_cast< ZeroType * >( dest ) ) {
395 cost = Cost::zero;
396 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
397 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
398 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
399 if ( tableResult == -1 ) {
400 cost = Cost::unsafe;
401 } else {
402 cost = Cost::zero;
403 cost.incSafe( tableResult + 1 );
404 }
405 } else if ( dynamic_cast< PointerType* >( dest ) ) {
406 cost = Cost::safe;
407 }
408 }
409
410 void ConversionCost::visit( OneType * ) {
411 if ( dynamic_cast< OneType * >( dest ) ) {
412 cost = Cost::zero;
413 } else if ( BasicType *destAsBasic = dynamic_cast< BasicType* >( dest ) ) {
414 // copied from visit(BasicType*) for signed int, but +1 for safe conversions
415 int tableResult = costMatrix[ BasicType::SignedInt ][ destAsBasic->get_kind() ];
416 if ( tableResult == -1 ) {
417 cost = Cost::unsafe;
418 } else {
419 cost = Cost::zero;
420 cost.incSafe( tableResult + 1 );
421 }
422 }
423 }
424} // namespace ResolvExpr
425
426// Local Variables: //
427// tab-width: 4 //
428// mode: c++ //
429// compile-command: "make install" //
430// End: //
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