source: src/GenPoly/Lvalue.cc@ 9b18044

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 9b18044 was 9aaac6e9, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Fix prelude warnings
  • Property mode set to 100644
File size: 19.3 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 safe_dynamic_cast
17#include <string> // for string
18
19#include "Common/PassVisitor.h"
20#include "Common/SemanticError.h" // for SemanticError
21#include "GenPoly.h" // for isPolyType
22#include "Lvalue.h"
23
24#include "Parser/LinkageSpec.h" // for Spec, isBuiltin, Intrinsic
25#include "ResolvExpr/TypeEnvironment.h" // for AssertionSet, OpenVarSet
26#include "ResolvExpr/Unify.h" // for unify
27#include "ResolvExpr/typeops.h"
28#include "SymTab/Autogen.h"
29#include "SymTab/Indexer.h" // for Indexer
30#include "SynTree/Declaration.h" // for Declaration, FunctionDecl
31#include "SynTree/Expression.h" // for Expression, ConditionalExpr
32#include "SynTree/Mutator.h" // for mutateAll, Mutator
33#include "SynTree/Statement.h" // for ReturnStmt, Statement (ptr o...
34#include "SynTree/Type.h" // for PointerType, Type, FunctionType
35#include "SynTree/Visitor.h" // for Visitor, acceptAll
36
37#if 0
38#define PRINT(x) x
39#else
40#define PRINT(x)
41#endif
42
43namespace GenPoly {
44 namespace {
45 // TODO: fold this into the general createDeref function??
46 Expression * mkDeref( Expression * arg ) {
47 if ( SymTab::dereferenceOperator ) {
48 VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
49 deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
50 Type * base = InitTweak::getPointerBase( arg->get_result() );
51 assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
52 ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
53 delete ret->get_result();
54 ret->set_result( base->clone() );
55 ret->get_result()->set_lvalue( true );
56 return ret;
57 } else {
58 return UntypedExpr::createDeref( arg );
59 }
60 }
61
62 struct ReferenceConversions final {
63 Expression * postmutate( CastExpr * castExpr );
64 Expression * postmutate( AddressExpr * addrExpr );
65 };
66
67 /// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
68 struct FixIntrinsicArgs final {
69 Expression * postmutate( ApplicationExpr * appExpr );
70 };
71
72 struct FixIntrinsicResult final : public WithGuards {
73 Expression * postmutate( ApplicationExpr * appExpr );
74 void premutate( FunctionDecl * funcDecl );
75 bool inIntrinsic = false;
76 };
77
78 /// Replace reference types with pointer types
79 struct ReferenceTypeElimination final {
80 Type * postmutate( ReferenceType * refType );
81 };
82
83 /// GCC-like Generalized Lvalues (which have since been removed from GCC)
84 /// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
85 /// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
86 struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
87 Expression * postmutate( AddressExpr * addressExpr );
88 Expression * postmutate( MemberExpr * memExpr );
89
90 template<typename Func>
91 Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
92 };
93
94 /// Removes redundant &*/*& pattern that this pass can generate
95 struct CollapseAddrDeref final {
96 Expression * postmutate( AddressExpr * addressExpr );
97 Expression * postmutate( ApplicationExpr * appExpr );
98 };
99
100 struct AddrRef final : public WithGuards {
101 void premutate( AddressExpr * addrExpr );
102 Expression * postmutate( AddressExpr * addrExpr );
103 void premutate( Expression * expr );
104
105 bool first = true;
106 bool current = false;
107 int refDepth = 0;
108 };
109 } // namespace
110
111 static bool referencesEliminated = false;
112 // used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
113 bool referencesPermissable() {
114 return ! referencesEliminated;
115 }
116
117 void convertLvalue( std::list< Declaration* >& translationUnit ) {
118 PassVisitor<ReferenceConversions> refCvt;
119 PassVisitor<ReferenceTypeElimination> elim;
120 PassVisitor<GeneralizedLvalue> genLval;
121 PassVisitor<FixIntrinsicArgs> fixer;
122 PassVisitor<CollapseAddrDeref> collapser;
123 PassVisitor<AddrRef> addrRef;
124 PassVisitor<FixIntrinsicResult> intrinsicResults;
125 mutateAll( translationUnit, intrinsicResults );
126 mutateAll( translationUnit, addrRef );
127 mutateAll( translationUnit, refCvt );
128 mutateAll( translationUnit, fixer );
129 mutateAll( translationUnit, collapser );
130 mutateAll( translationUnit, genLval );
131 mutateAll( translationUnit, elim ); // last because other passes need reference types to work
132
133 // from this point forward, no other pass should create reference types.
134 referencesEliminated = true;
135 }
136
137 Expression * generalizedLvalue( Expression * expr ) {
138 PassVisitor<GeneralizedLvalue> genLval;
139 return expr->acceptMutator( genLval );
140 }
141
142 namespace {
143 // true for intrinsic function calls that return a reference
144 bool isIntrinsicReference( Expression * expr ) {
145 if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
146 std::string fname = InitTweak::getFunctionName( untyped );
147 // known intrinsic-reference prelude functions
148 return fname == "*?" || fname == "?[?]";
149 } else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
150 if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
151 // use type of return variable rather than expr result type, since it may have been changed to a pointer type
152 FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
153 Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
154 return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
155 }
156 }
157 return false;
158 }
159
160 Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
161 if ( isIntrinsicReference( appExpr ) ) {
162 // eliminate reference types from intrinsic applications - now they return lvalues
163 Type * result = appExpr->get_result();
164 appExpr->set_result( result->stripReferences()->clone() );
165 appExpr->get_result()->set_lvalue( true );
166 if ( ! inIntrinsic ) {
167 // when not in an intrinsic function, add a cast to
168 // don't add cast when in an intrinsic function, since they already have the cast
169 Expression * ret = new CastExpr( appExpr, result );
170 ret->set_env( appExpr->get_env() );
171 appExpr->set_env( nullptr );
172 return ret;
173 }
174 delete result;
175 }
176 return appExpr;
177 }
178
179 void FixIntrinsicResult::premutate( FunctionDecl * funcDecl ) {
180 GuardValue( inIntrinsic );
181 inIntrinsic = funcDecl->linkage == LinkageSpec::Intrinsic;
182 }
183
184 Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
185 // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
186 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
187 FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
188 assertf( ftype, "Function declaration does not have function type." );
189 // can be of differing lengths only when function is variadic
190 assertf( ftype->get_parameters().size() == appExpr->get_args().size() || ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
191
192
193 unsigned int i = 0;
194 const unsigned int end = ftype->get_parameters().size();
195 for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
196 if (i == end) break;
197 Expression *& arg = std::get<0>( p );
198 Type * formal = std::get<1>( p )->get_type();
199 PRINT(
200 std::cerr << "pair<0>: " << arg << std::endl;
201 std::cerr << "pair<1>: " << formal << std::endl;
202 )
203 if ( dynamic_cast<ReferenceType*>( formal ) ) {
204 if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
205 if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
206 // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
207 PRINT(
208 std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
209 )
210 arg = new AddressExpr( arg );
211 }
212 } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
213 // std::cerr << "===adding deref to arg" << std::endl;
214 // if the parameter is a reference, add a dereference to the reference-typed argument.
215 Type * baseType = InitTweak::getPointerBase( arg->get_result() );
216 assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
217 PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
218 delete arg->get_result();
219 arg->set_result( ptrType );
220 arg = mkDeref( arg );
221 }
222 }
223 ++i;
224 }
225 }
226 return appExpr;
227 }
228
229 // idea: &&&E: get outer &, inner &
230 // at inner &, record depth D of reference type
231 // at outer &, add D derefs.
232 void AddrRef::premutate( Expression * ) {
233 GuardValue( current );
234 GuardValue( first );
235 current = false;
236 first = true;
237 }
238
239 void AddrRef::premutate( AddressExpr * ) {
240 GuardValue( current );
241 GuardValue( first );
242 current = first;
243 first = false;
244 if ( current ) {
245 GuardValue( refDepth );
246 refDepth = 0;
247 }
248 }
249
250 Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
251 if ( refDepth == 0 ) {
252 if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
253 // try to avoid ?[?]
254 refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
255 }
256 }
257 if ( current ) {
258 Expression * ret = addrExpr;
259 while ( refDepth ) {
260 ret = mkDeref( ret );
261 refDepth--;
262 }
263 return ret;
264 }
265 return addrExpr;
266 }
267
268 Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
269 // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
270 // In this case, remove the outer address expression and return the argument.
271 // TODO: It's possible that this might catch too much and require a more sophisticated check.
272 return addrExpr;
273 }
274
275 Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
276 // xxx - is it possible to convert directly between reference types with a different base? E.g.,
277 // int x;
278 // (double&)x;
279 // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
280 // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
281 // pointer casts in the right places.
282
283 // conversion to reference type
284 if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
285 (void)refType;
286 if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
287 // nothing to do if casting from reference to reference.
288 (void)otherRef;
289 PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
290 if ( isIntrinsicReference( castExpr->get_arg() ) ) {
291 Expression * callExpr = castExpr->get_arg();
292 PRINT(
293 std::cerr << "but arg is deref -- &" << std::endl;
294 std::cerr << callExpr << std::endl;
295 )
296 callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
297 delete callExpr->get_result();
298 callExpr->set_result( refType->clone() );
299 // move environment out to new top-level
300 callExpr->set_env( castExpr->get_env() );
301 castExpr->set_arg( nullptr );
302 castExpr->set_env( nullptr );
303 delete castExpr;
304 return callExpr;
305 }
306 int depth1 = refType->referenceDepth();
307 int depth2 = otherRef->referenceDepth();
308 int diff = depth1-depth2;
309 if ( diff == 0 ) {
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 Expression * ret = castExpr->get_arg();
315 for ( int i = 0; i < diff; ++i ) {
316 ret = mkDeref( ret );
317 }
318 ret->set_env( castExpr->get_env() );
319 delete ret->get_result();
320 ret->set_result( castExpr->get_result() );
321 castExpr->set_env( nullptr );
322 castExpr->set_arg( nullptr );
323 castExpr->set_result( nullptr );
324 delete castExpr;
325 return ret;
326 } else if ( diff > 0 ) {
327 Expression * ret = castExpr->get_arg();
328 for ( int i = 0; i < diff; ++i ) {
329 ret = new AddressExpr( ret );
330 }
331 ret->set_env( castExpr->get_env() );
332 delete ret->get_result();
333 ret->set_result( castExpr->get_result() );
334 castExpr->set_env( nullptr );
335 castExpr->set_arg( nullptr );
336 castExpr->set_result( nullptr );
337 delete castExpr;
338 return ret;
339 }
340
341 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
342 PRINT( std::cerr << castExpr << std::endl; )
343 return castExpr;
344 } else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
345 // conversion from lvalue to reference
346 // xxx - keep cast, but turn into pointer cast??
347 // xxx - memory
348 PRINT(
349 std::cerr << "convert lvalue to reference -- &" << std::endl;
350 std::cerr << castExpr->get_arg() << std::endl;
351 )
352 AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
353 if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
354 // must keep cast if cast-to type is different from the actual type
355 castExpr->set_arg( ret );
356 return castExpr;
357 }
358 ret->set_env( castExpr->get_env() );
359 delete ret->get_result();
360 ret->set_result( castExpr->get_result() );
361 castExpr->set_env( nullptr );
362 castExpr->set_arg( nullptr );
363 castExpr->set_result( nullptr );
364 delete castExpr;
365 return ret;
366 } else {
367 // rvalue to reference conversion -- introduce temporary
368 }
369 assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
370 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
371 (void)refType;
372 // conversion from reference to rvalue
373 PRINT(
374 std::cerr << "convert reference to rvalue -- *" << std::endl;
375 std::cerr << "was = " << castExpr << std::endl;
376 )
377 Expression * ret = castExpr->get_arg();
378 TypeSubstitution * env = castExpr->get_env();
379 castExpr->set_env( nullptr );
380 if ( ! isIntrinsicReference( ret ) ) {
381 // dereference if not already dereferenced
382 ret = mkDeref( ret );
383 }
384 if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
385 // can remove cast if types are compatible, changing expression type to value type
386 ret->set_result( castExpr->get_result()->clone() );
387 castExpr->set_arg( nullptr );
388 delete castExpr;
389 } else {
390 // must keep cast if types are different
391 castExpr->set_arg( ret );
392 ret = castExpr;
393 }
394 ret->set_env( env );
395 PRINT( std::cerr << "now: " << ret << std::endl; )
396 return ret;
397 }
398 return castExpr;
399 }
400
401 Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
402 Type * base = refType->get_base();
403 Type::Qualifiers qualifiers = refType->get_qualifiers();
404 refType->set_base( nullptr );
405 delete refType;
406 return new PointerType( qualifiers, base );
407 }
408
409 template<typename Func>
410 Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
411 if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
412 Expression * arg1 = commaExpr->get_arg1()->clone();
413 Expression * arg2 = commaExpr->get_arg2()->clone();
414 Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
415 ret->set_env( expr->get_env() );
416 expr->set_env( nullptr );
417 delete expr;
418 return ret;
419 } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
420 Expression * arg1 = condExpr->get_arg1()->clone();
421 Expression * arg2 = condExpr->get_arg2()->clone();
422 Expression * arg3 = condExpr->get_arg3()->clone();
423 ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ), mkExpr( arg3 )->acceptMutator( *visitor ) );
424 ret->set_env( expr->get_env() );
425 expr->set_env( nullptr );
426 delete expr;
427
428 // conditional expr type may not be either of the argument types, need to unify
429 using namespace ResolvExpr;
430 Type* commonType = nullptr;
431 TypeEnvironment newEnv;
432 AssertionSet needAssertions, haveAssertions;
433 OpenVarSet openVars;
434 unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
435 ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
436 return ret;
437 }
438 return expr;
439 }
440
441 Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
442 return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
443 }
444
445 Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
446 return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
447 }
448
449 Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
450 Expression * arg = addrExpr->get_arg();
451 if ( isIntrinsicReference( arg ) ) {
452 std::string fname = InitTweak::getFunctionName( arg );
453 if ( fname == "*?" ) {
454 Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
455 Expression * ret = arg0;
456 ret->set_env( addrExpr->get_env() );
457 arg0 = nullptr;
458 addrExpr->set_env( nullptr );
459 delete addrExpr;
460 return ret;
461 }
462 }
463 return addrExpr;
464 }
465
466 Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
467 if ( isIntrinsicReference( appExpr ) ) {
468 std::string fname = InitTweak::getFunctionName( appExpr );
469 if ( fname == "*?" ) {
470 Expression * arg = InitTweak::getCallArg( appExpr, 0 );
471 // xxx - this isn't right, because it can remove casts that should be there...
472 // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
473 // arg = castExpr->get_arg();
474 // }
475 if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
476 Expression * ret = addrExpr->get_arg();
477 ret->set_env( appExpr->get_env() );
478 addrExpr->set_arg( nullptr );
479 appExpr->set_env( nullptr );
480 delete appExpr;
481 return ret;
482 }
483 }
484 }
485 return appExpr;
486 }
487 } // namespace
488} // namespace GenPoly
489
490// Local Variables: //
491// tab-width: 4 //
492// mode: c++ //
493// compile-command: "make install" //
494// End: //
Note: See TracBrowser for help on using the repository browser.