source: src/GenPoly/Lvalue.cc@ 9bfc9da

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 9bfc9da was a16764a6, checked in by Thierry Delisle <tdelisle@…>, 8 years ago

Changed warning system to prepare for toggling warnings
  • Property mode set to 100644
File size: 19.8 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// Lvalue.cc --
8//
9// Author : Richard C. Bilson
10// Created On : Mon May 18 07:44:20 2015
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Fri Mar 17 09:11:18 2017
13// Update Count : 5
14//
15
16#include <cassert> // for strict_dynamic_cast
17#include <string> // for string
18
19#include "Common/PassVisitor.h"
20#include "GenPoly.h" // for isPolyType
21#include "Lvalue.h"
22
23#include "Parser/LinkageSpec.h" // for Spec, isBuiltin, Intrinsic
24#include "ResolvExpr/TypeEnvironment.h" // for AssertionSet, OpenVarSet
25#include "ResolvExpr/Unify.h" // for unify
26#include "ResolvExpr/typeops.h"
27#include "SymTab/Autogen.h"
28#include "SymTab/Indexer.h" // for Indexer
29#include "SynTree/Declaration.h" // for Declaration, FunctionDecl
30#include "SynTree/Expression.h" // for Expression, ConditionalExpr
31#include "SynTree/Mutator.h" // for mutateAll, Mutator
32#include "SynTree/Statement.h" // for ReturnStmt, Statement (ptr o...
33#include "SynTree/Type.h" // for PointerType, Type, FunctionType
34#include "SynTree/Visitor.h" // for Visitor, acceptAll
35
36#if 0
37#define PRINT(x) x
38#else
39#define PRINT(x)
40#endif
41
42namespace GenPoly {
43 namespace {
44 // TODO: fold this into the general createDeref function??
45 Expression * mkDeref( Expression * arg ) {
46 if ( SymTab::dereferenceOperator ) {
47 VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
48 deref->result = new PointerType( Type::Qualifiers(), deref->result );
49 Type * base = InitTweak::getPointerBase( arg->result );
50 assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->result ).c_str() );
51 ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
52 delete ret->result;
53 ret->result = base->clone();
54 ret->result->set_lvalue( true );
55 return ret;
56 } else {
57 return UntypedExpr::createDeref( arg );
58 }
59 }
60
61 struct ReferenceConversions final {
62 Expression * postmutate( CastExpr * castExpr );
63 Expression * postmutate( AddressExpr * addrExpr );
64 };
65
66 /// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
67 struct FixIntrinsicArgs final {
68 Expression * postmutate( ApplicationExpr * appExpr );
69 };
70
71 struct FixIntrinsicResult final : public WithGuards {
72 Expression * postmutate( ApplicationExpr * appExpr );
73 void premutate( FunctionDecl * funcDecl );
74 bool inIntrinsic = false;
75 };
76
77 /// Replace reference types with pointer types
78 struct ReferenceTypeElimination final {
79 Type * postmutate( ReferenceType * refType );
80 };
81
82 /// GCC-like Generalized Lvalues (which have since been removed from GCC)
83 /// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
84 /// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
85 struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
86 Expression * postmutate( AddressExpr * addressExpr );
87 Expression * postmutate( MemberExpr * memExpr );
88
89 template<typename Func>
90 Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
91 };
92
93 /// Removes redundant &*/*& pattern that this pass can generate
94 struct CollapseAddrDeref final {
95 Expression * postmutate( AddressExpr * addressExpr );
96 Expression * postmutate( ApplicationExpr * appExpr );
97 };
98
99 struct AddrRef final : public WithGuards {
100 void premutate( AddressExpr * addrExpr );
101 Expression * postmutate( AddressExpr * addrExpr );
102 void premutate( Expression * expr );
103
104 bool first = true;
105 bool current = false;
106 int refDepth = 0;
107 };
108 } // namespace
109
110 static bool referencesEliminated = false;
111 // used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
112 bool referencesPermissable() {
113 return ! referencesEliminated;
114 }
115
116 void convertLvalue( std::list< Declaration* >& translationUnit ) {
117 PassVisitor<ReferenceConversions> refCvt;
118 PassVisitor<ReferenceTypeElimination> elim;
119 PassVisitor<GeneralizedLvalue> genLval;
120 PassVisitor<FixIntrinsicArgs> fixer;
121 PassVisitor<CollapseAddrDeref> collapser;
122 PassVisitor<AddrRef> addrRef;
123 PassVisitor<FixIntrinsicResult> intrinsicResults;
124 mutateAll( translationUnit, intrinsicResults );
125 mutateAll( translationUnit, addrRef );
126 mutateAll( translationUnit, refCvt );
127 mutateAll( translationUnit, fixer );
128 mutateAll( translationUnit, collapser );
129 mutateAll( translationUnit, genLval );
130 mutateAll( translationUnit, elim ); // last because other passes need reference types to work
131
132 // from this point forward, no other pass should create reference types.
133 referencesEliminated = true;
134 }
135
136 Expression * generalizedLvalue( Expression * expr ) {
137 PassVisitor<GeneralizedLvalue> genLval;
138 return expr->acceptMutator( genLval );
139 }
140
141 namespace {
142 // true for intrinsic function calls that return a reference
143 bool isIntrinsicReference( Expression * expr ) {
144 if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
145 std::string fname = InitTweak::getFunctionName( untyped );
146 // known intrinsic-reference prelude functions
147 return fname == "*?" || fname == "?[?]";
148 } else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
149 if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
150 // use type of return variable rather than expr result type, since it may have been changed to a pointer type
151 FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
152 Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
153 return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
154 }
155 }
156 return false;
157 }
158
159 Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
160 if ( isIntrinsicReference( appExpr ) ) {
161 // eliminate reference types from intrinsic applications - now they return lvalues
162 Type * result = appExpr->get_result();
163 appExpr->set_result( result->stripReferences()->clone() );
164 appExpr->get_result()->set_lvalue( true );
165 if ( ! inIntrinsic ) {
166 // when not in an intrinsic function, add a cast to
167 // don't add cast when in an intrinsic function, since they already have the cast
168 Expression * ret = new CastExpr( appExpr, result );
169 ret->set_env( appExpr->get_env() );
170 appExpr->set_env( nullptr );
171 return ret;
172 }
173 delete result;
174 }
175 return appExpr;
176 }
177
178 void FixIntrinsicResult::premutate( FunctionDecl * funcDecl ) {
179 GuardValue( inIntrinsic );
180 inIntrinsic = funcDecl->linkage == LinkageSpec::Intrinsic;
181 }
182
183 Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
184 // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
185 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
186 FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
187 assertf( ftype, "Function declaration does not have function type." );
188 // can be of differing lengths only when function is variadic
189 assertf( ftype->get_parameters().size() == appExpr->get_args().size() || ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
190
191
192 unsigned int i = 0;
193 const unsigned int end = ftype->get_parameters().size();
194 for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
195 if (i == end) break;
196 Expression *& arg = std::get<0>( p );
197 Type * formal = std::get<1>( p )->get_type();
198 PRINT(
199 std::cerr << "pair<0>: " << arg << std::endl;
200 std::cerr << "pair<1>: " << formal << std::endl;
201 )
202 if ( dynamic_cast<ReferenceType*>( formal ) ) {
203 if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
204 if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
205 // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
206 PRINT(
207 std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
208 )
209 arg = new AddressExpr( arg );
210 }
211 } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
212 // std::cerr << "===adding deref to arg" << std::endl;
213 // if the parameter is a reference, add a dereference to the reference-typed argument.
214 Type * baseType = InitTweak::getPointerBase( arg->get_result() );
215 assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
216 PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
217 delete arg->get_result();
218 arg->set_result( ptrType );
219 arg = mkDeref( arg );
220 }
221 }
222 ++i;
223 }
224 }
225 return appExpr;
226 }
227
228 // idea: &&&E: get outer &, inner &
229 // at inner &, record depth D of reference type
230 // at outer &, add D derefs.
231 void AddrRef::premutate( Expression * ) {
232 GuardValue( current );
233 GuardValue( first );
234 current = false;
235 first = true;
236 }
237
238 void AddrRef::premutate( AddressExpr * ) {
239 GuardValue( current );
240 GuardValue( first );
241 current = first;
242 first = false;
243 if ( current ) {
244 GuardValue( refDepth );
245 refDepth = 0;
246 }
247 }
248
249 Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
250 if ( refDepth == 0 ) {
251 if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
252 // try to avoid ?[?]
253 refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
254 }
255 }
256 if ( current ) {
257 Expression * ret = addrExpr;
258 while ( refDepth ) {
259 ret = mkDeref( ret );
260 refDepth--;
261 }
262 return ret;
263 }
264 return addrExpr;
265 }
266
267 Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
268 // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
269 // In this case, remove the outer address expression and return the argument.
270 // TODO: It's possible that this might catch too much and require a more sophisticated check.
271 return addrExpr;
272 }
273
274 Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
275 // xxx - is it possible to convert directly between reference types with a different base? E.g.,
276 // int x;
277 // (double&)x;
278 // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
279 // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
280 // pointer casts in the right places.
281
282 // conversion to reference type
283 if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
284 (void)refType;
285 if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
286 // nothing to do if casting from reference to reference.
287 (void)otherRef;
288 PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
289 if ( isIntrinsicReference( castExpr->get_arg() ) ) {
290 Expression * callExpr = castExpr->get_arg();
291 PRINT(
292 std::cerr << "but arg is deref -- &" << std::endl;
293 std::cerr << callExpr << std::endl;
294 )
295 callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
296 delete callExpr->get_result();
297 callExpr->set_result( refType->clone() );
298 // move environment out to new top-level
299 callExpr->set_env( castExpr->get_env() );
300 castExpr->set_arg( nullptr );
301 castExpr->set_env( nullptr );
302 delete castExpr;
303 return callExpr;
304 }
305 int depth1 = refType->referenceDepth();
306 int depth2 = otherRef->referenceDepth();
307 int diff = depth1-depth2;
308 if ( diff == 0 ) {
309 // conversion between references of the same depth
310 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
311 PRINT( std::cerr << castExpr << std::endl; )
312 return castExpr;
313 } else if ( diff < 0 ) {
314 // conversion from reference to reference with less depth (e.g. int && -> int &): add dereferences
315 Expression * ret = castExpr->arg;
316 for ( int i = 0; i < diff; ++i ) {
317 ret = mkDeref( ret );
318 }
319 ret->env = castExpr->env;
320 delete ret->result;
321 ret->result = castExpr->result;
322 ret->result->set_lvalue( true ); // ensure result is lvalue
323 castExpr->env = nullptr;
324 castExpr->arg = nullptr;
325 castExpr->result = nullptr;
326 delete castExpr;
327 return ret;
328 } else if ( diff > 0 ) {
329 // conversion from reference to reference with more depth (e.g. int & -> int &&): add address-of
330 Expression * ret = castExpr->arg;
331 for ( int i = 0; i < diff; ++i ) {
332 ret = new AddressExpr( ret );
333 }
334 ret->env = castExpr->env;
335 delete ret->result;
336 ret->result = castExpr->result;
337 castExpr->env = nullptr;
338 castExpr->arg = nullptr;
339 castExpr->result = nullptr;
340 delete castExpr;
341 return ret;
342 }
343
344 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
345 PRINT( std::cerr << castExpr << std::endl; )
346 return castExpr;
347 } else if ( castExpr->arg->result->get_lvalue() ) {
348 // conversion from lvalue to reference
349 // xxx - keep cast, but turn into pointer cast??
350 // xxx - memory
351 PRINT(
352 std::cerr << "convert lvalue to reference -- &" << std::endl;
353 std::cerr << castExpr->arg << std::endl;
354 )
355 AddressExpr * ret = new AddressExpr( castExpr->arg );
356 if ( refType->base->get_qualifiers() != castExpr->arg->result->get_qualifiers() ) {
357 // must keep cast if cast-to type is different from the actual type
358 castExpr->arg = ret;
359 return castExpr;
360 }
361 ret->env = castExpr->env;
362 delete ret->result;
363 ret->result = castExpr->result;
364 castExpr->env = nullptr;
365 castExpr->arg = nullptr;
366 castExpr->result = nullptr;
367 delete castExpr;
368 return ret;
369 } else {
370 // rvalue to reference conversion -- introduce temporary
371 }
372 assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
373 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->arg->result ) ) {
374 (void)refType;
375 // conversion from reference to rvalue
376 PRINT(
377 std::cerr << "convert reference to rvalue -- *" << std::endl;
378 std::cerr << "was = " << castExpr << std::endl;
379 )
380 Expression * ret = castExpr->arg;
381 TypeSubstitution * env = castExpr->env;
382 castExpr->set_env( nullptr );
383 if ( ! isIntrinsicReference( ret ) ) {
384 // dereference if not already dereferenced
385 ret = mkDeref( ret );
386 }
387 if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->result, castExpr->arg->result->stripReferences(), SymTab::Indexer() ) ) {
388 // can remove cast if types are compatible, changing expression type to value type
389 ret->result = castExpr->result->clone();
390 ret->result->set_lvalue( true ); // ensure result is lvalue
391 castExpr->arg = nullptr;
392 delete castExpr;
393 } else {
394 // must keep cast if types are different
395 castExpr->arg = ret;
396 ret = castExpr;
397 }
398 ret->set_env( env );
399 PRINT( std::cerr << "now: " << ret << std::endl; )
400 return ret;
401 }
402 return castExpr;
403 }
404
405 Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
406 Type * base = refType->get_base();
407 Type::Qualifiers qualifiers = refType->get_qualifiers();
408 refType->set_base( nullptr );
409 delete refType;
410 return new PointerType( qualifiers, base );
411 }
412
413 template<typename Func>
414 Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
415 if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
416 Expression * arg1 = commaExpr->get_arg1()->clone();
417 Expression * arg2 = commaExpr->get_arg2()->clone();
418 Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
419 ret->set_env( expr->get_env() );
420 expr->set_env( nullptr );
421 delete expr;
422 return ret;
423 } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
424 Expression * arg1 = condExpr->get_arg1()->clone();
425 Expression * arg2 = condExpr->get_arg2()->clone();
426 Expression * arg3 = condExpr->get_arg3()->clone();
427 ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ), mkExpr( arg3 )->acceptMutator( *visitor ) );
428 ret->set_env( expr->get_env() );
429 expr->set_env( nullptr );
430 delete expr;
431
432 // conditional expr type may not be either of the argument types, need to unify
433 using namespace ResolvExpr;
434 Type* commonType = nullptr;
435 TypeEnvironment newEnv;
436 AssertionSet needAssertions, haveAssertions;
437 OpenVarSet openVars;
438 unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
439 ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
440 return ret;
441 }
442 return expr;
443 }
444
445 Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
446 return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
447 }
448
449 Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
450 return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
451 }
452
453 Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
454 Expression * arg = addrExpr->get_arg();
455 if ( isIntrinsicReference( arg ) ) {
456 std::string fname = InitTweak::getFunctionName( arg );
457 if ( fname == "*?" ) {
458 Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
459 Expression * ret = arg0;
460 ret->set_env( addrExpr->get_env() );
461 arg0 = nullptr;
462 addrExpr->set_env( nullptr );
463 delete addrExpr;
464 return ret;
465 }
466 } else if ( CastExpr * castExpr = dynamic_cast< CastExpr * > ( arg ) ) {
467 // need to move cast to pointer type out a level since address of pointer
468 // is not valid C code (can be introduced in prior passes, e.g., InstantiateGeneric)
469 if ( InitTweak::getPointerBase( castExpr->result ) ) {
470 addrExpr->arg = castExpr->arg;
471 castExpr->arg = addrExpr;
472 castExpr->result = new PointerType( Type::Qualifiers(), castExpr->result );
473 return castExpr;
474 }
475 }
476 return addrExpr;
477 }
478
479 Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
480 if ( isIntrinsicReference( appExpr ) ) {
481 std::string fname = InitTweak::getFunctionName( appExpr );
482 if ( fname == "*?" ) {
483 Expression * arg = InitTweak::getCallArg( appExpr, 0 );
484 // xxx - this isn't right, because it can remove casts that should be there...
485 // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
486 // arg = castExpr->get_arg();
487 // }
488 if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
489 Expression * ret = addrExpr->get_arg();
490 ret->set_env( appExpr->get_env() );
491 addrExpr->set_arg( nullptr );
492 appExpr->set_env( nullptr );
493 delete appExpr;
494 return ret;
495 }
496 }
497 }
498 return appExpr;
499 }
500 } // namespace
501} // namespace GenPoly
502
503// Local Variables: //
504// tab-width: 4 //
505// mode: c++ //
506// compile-command: "make install" //
507// End: //
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