source: src/GenPoly/Lvalue.cc@ b1ccdfd

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 stuck-waitfor-destruct with_gc
Last change on this file since b1ccdfd was b1ccdfd, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Code cleanup
  • Property mode set to 100644
File size: 19.5 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->returnVals.empty() ? nullptr : ftype->returnVals.front()->get_type();
153 return func->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->result;
163 appExpr->result = result->stripReferences()->clone();
164 appExpr->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 std::swap( ret->env, appExpr->env );
170 return ret;
171 }
172 delete result;
173 }
174 return appExpr;
175 }
176
177 void FixIntrinsicResult::premutate( FunctionDecl * funcDecl ) {
178 GuardValue( inIntrinsic );
179 inIntrinsic = funcDecl->linkage == LinkageSpec::Intrinsic;
180 }
181
182 Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
183 // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
184 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
185 FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
186 assertf( ftype, "Function declaration does not have function type." );
187 // can be of differing lengths only when function is variadic
188 assertf( ftype->parameters.size() == appExpr->args.size() || ftype->isVarArgs, "ApplicationExpr args do not match formal parameter type." );
189
190
191 unsigned int i = 0;
192 const unsigned int end = ftype->parameters.size();
193 for ( auto p : unsafe_group_iterate( appExpr->args, ftype->parameters ) ) {
194 if (i == end) break;
195 Expression *& arg = std::get<0>( p );
196 Type * formal = std::get<1>( p )->get_type();
197 PRINT(
198 std::cerr << "pair<0>: " << arg << std::endl;
199 std::cerr << "pair<1>: " << formal << std::endl;
200 )
201 if ( dynamic_cast<ReferenceType*>( formal ) ) {
202 if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
203 if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
204 // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
205 PRINT(
206 std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
207 )
208 arg = new AddressExpr( arg );
209 }
210 } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
211 // std::cerr << "===adding deref to arg" << std::endl;
212 // if the parameter is a reference, add a dereference to the reference-typed argument.
213 Type * baseType = InitTweak::getPointerBase( arg->result );
214 assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->result ).c_str() );
215 PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
216 delete arg->result;
217 arg->set_result( ptrType );
218 arg = mkDeref( arg );
219 }
220 }
221 ++i;
222 }
223 }
224 return appExpr;
225 }
226
227 // idea: &&&E: get outer &, inner &
228 // at inner &, record depth D of reference type
229 // at outer &, add D derefs.
230 void AddrRef::premutate( Expression * ) {
231 GuardValue( current );
232 GuardValue( first );
233 current = false;
234 first = true;
235 }
236
237 void AddrRef::premutate( AddressExpr * ) {
238 GuardValue( current );
239 GuardValue( first );
240 current = first;
241 first = false;
242 if ( current ) {
243 GuardValue( refDepth );
244 refDepth = 0;
245 }
246 }
247
248 Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
249 if ( refDepth == 0 ) {
250 if ( ! isIntrinsicReference( addrExpr->arg ) ) {
251 // try to avoid ?[?]
252 refDepth = addrExpr->arg->result->referenceDepth();
253 }
254 }
255 if ( current ) {
256 Expression * ret = addrExpr;
257 while ( refDepth ) {
258 ret = mkDeref( ret );
259 refDepth--;
260 }
261 return ret;
262 }
263 return addrExpr;
264 }
265
266 Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
267 // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
268 // In this case, remove the outer address expression and return the argument.
269 // TODO: It's possible that this might catch too much and require a more sophisticated check.
270 return addrExpr;
271 }
272
273 Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
274 // xxx - is it possible to convert directly between reference types with a different base? E.g.,
275 // int x;
276 // (double&)x;
277 // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
278 // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
279 // pointer casts in the right places.
280
281 // conversion to reference type
282 if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->result ) ) {
283 (void)refType;
284 if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->arg->result ) ) {
285 // nothing to do if casting from reference to reference.
286 (void)otherRef;
287 PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
288 if ( isIntrinsicReference( castExpr->arg ) ) {
289 Expression * callExpr = castExpr->arg;
290 PRINT(
291 std::cerr << "but arg is deref -- &" << std::endl;
292 std::cerr << callExpr << std::endl;
293 )
294 callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
295 delete callExpr->result;
296 callExpr->set_result( refType->clone() );
297 // move environment out to new top-level
298 callExpr->env = castExpr->env;
299 castExpr->arg = nullptr;
300 castExpr->env = nullptr;
301 delete castExpr;
302 return callExpr;
303 }
304 int depth1 = refType->referenceDepth();
305 int depth2 = otherRef->referenceDepth();
306 int diff = depth1-depth2;
307 if ( diff == 0 ) {
308 // conversion between references of the same depth
309 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
310 PRINT( std::cerr << castExpr << std::endl; )
311 return castExpr;
312 } else if ( diff < 0 ) {
313 // conversion from reference to reference with less depth (e.g. int && -> int &): add dereferences
314 Expression * ret = castExpr->arg;
315 for ( int i = 0; i < diff; ++i ) {
316 ret = mkDeref( ret );
317 }
318 ret->env = castExpr->env;
319 delete ret->result;
320 ret->result = castExpr->result;
321 ret->result->set_lvalue( true ); // ensure result is lvalue
322 castExpr->env = nullptr;
323 castExpr->arg = nullptr;
324 castExpr->result = nullptr;
325 delete castExpr;
326 return ret;
327 } else if ( diff > 0 ) {
328 // conversion from reference to reference with more depth (e.g. int & -> int &&): add address-of
329 Expression * ret = castExpr->arg;
330 for ( int i = 0; i < diff; ++i ) {
331 ret = new AddressExpr( ret );
332 }
333 ret->env = castExpr->env;
334 delete ret->result;
335 ret->result = castExpr->result;
336 castExpr->env = nullptr;
337 castExpr->arg = nullptr;
338 castExpr->result = nullptr;
339 delete castExpr;
340 return ret;
341 }
342
343 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
344 PRINT( std::cerr << castExpr << std::endl; )
345 return castExpr;
346 } else if ( castExpr->arg->result->get_lvalue() ) {
347 // conversion from lvalue to reference
348 // xxx - keep cast, but turn into pointer cast??
349 // xxx - memory
350 PRINT(
351 std::cerr << "convert lvalue to reference -- &" << std::endl;
352 std::cerr << castExpr->arg << std::endl;
353 )
354 AddressExpr * ret = new AddressExpr( castExpr->arg );
355 if ( refType->base->get_qualifiers() != castExpr->arg->result->get_qualifiers() ) {
356 // must keep cast if cast-to type is different from the actual type
357 castExpr->arg = ret;
358 return castExpr;
359 }
360 ret->env = castExpr->env;
361 delete ret->result;
362 ret->result = castExpr->result;
363 castExpr->env = nullptr;
364 castExpr->arg = nullptr;
365 castExpr->result = nullptr;
366 delete castExpr;
367 return ret;
368 } else {
369 // rvalue to reference conversion -- introduce temporary
370 }
371 assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
372 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->arg->result ) ) {
373 (void)refType;
374 // conversion from reference to rvalue
375 PRINT(
376 std::cerr << "convert reference to rvalue -- *" << std::endl;
377 std::cerr << "was = " << castExpr << std::endl;
378 )
379 Expression * ret = castExpr->arg;
380 TypeSubstitution * env = castExpr->env;
381 castExpr->set_env( nullptr );
382 if ( ! isIntrinsicReference( ret ) ) {
383 // dereference if not already dereferenced
384 ret = mkDeref( ret );
385 }
386 if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->result, castExpr->arg->result->stripReferences(), SymTab::Indexer() ) ) {
387 // can remove cast if types are compatible, changing expression type to value type
388 ret->result = castExpr->result->clone();
389 ret->result->set_lvalue( true ); // ensure result is lvalue
390 castExpr->arg = nullptr;
391 delete castExpr;
392 } else {
393 // must keep cast if types are different
394 castExpr->arg = ret;
395 ret = castExpr;
396 }
397 ret->set_env( env );
398 PRINT( std::cerr << "now: " << ret << std::endl; )
399 return ret;
400 }
401 return castExpr;
402 }
403
404 Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
405 Type * base = refType->base;
406 Type::Qualifiers qualifiers = refType->get_qualifiers();
407 refType->base = nullptr;
408 delete refType;
409 return new PointerType( qualifiers, base );
410 }
411
412 template<typename Func>
413 Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
414 if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
415 Expression * arg1 = commaExpr->arg1->clone();
416 Expression * arg2 = commaExpr->arg2->clone();
417 Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
418 ret->env = expr->env;
419 expr->env = nullptr;
420 delete expr;
421 return ret;
422 } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
423 Expression * arg1 = condExpr->arg1->clone();
424 Expression * arg2 = condExpr->arg2->clone();
425 Expression * arg3 = condExpr->arg3->clone();
426 ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ), mkExpr( arg3 )->acceptMutator( *visitor ) );
427 ret->env = expr->env;
428 expr->env = nullptr;
429 delete expr;
430
431 // conditional expr type may not be either of the argument types, need to unify
432 using namespace ResolvExpr;
433 Type* commonType = nullptr;
434 TypeEnvironment newEnv;
435 AssertionSet needAssertions, haveAssertions;
436 OpenVarSet openVars;
437 unify( ret->arg2->result, ret->arg3->result, newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
438 ret->result = commonType ? commonType : ret->arg2->result->clone();
439 return ret;
440 }
441 return expr;
442 }
443
444 Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
445 return applyTransformation( memExpr, memExpr->aggregate, [=]( Expression * aggr ) { return new MemberExpr( memExpr->member, aggr ); } );
446 }
447
448 Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
449 return applyTransformation( addrExpr, addrExpr->arg, []( Expression * arg ) { return new AddressExpr( arg ); } );
450 }
451
452 Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
453 Expression * arg = addrExpr->arg;
454 if ( isIntrinsicReference( arg ) ) {
455 std::string fname = InitTweak::getFunctionName( arg );
456 if ( fname == "*?" ) {
457 Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
458 Expression * ret = arg0;
459 ret->set_env( addrExpr->env );
460 arg0 = nullptr;
461 addrExpr->env = nullptr;
462 delete addrExpr;
463 return ret;
464 }
465 } else if ( CastExpr * castExpr = dynamic_cast< CastExpr * > ( arg ) ) {
466 // need to move cast to pointer type out a level since address of pointer
467 // is not valid C code (can be introduced in prior passes, e.g., InstantiateGeneric)
468 if ( InitTweak::getPointerBase( castExpr->result ) ) {
469 addrExpr->arg = castExpr->arg;
470 castExpr->arg = addrExpr;
471 castExpr->result = new PointerType( Type::Qualifiers(), castExpr->result );
472 return castExpr;
473 }
474 }
475 return addrExpr;
476 }
477
478 Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
479 if ( isIntrinsicReference( appExpr ) ) {
480 std::string fname = InitTweak::getFunctionName( appExpr );
481 if ( fname == "*?" ) {
482 Expression * arg = InitTweak::getCallArg( appExpr, 0 );
483 // xxx - this isn't right, because it can remove casts that should be there...
484 // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
485 // arg = castExpr->get_arg();
486 // }
487 if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
488 Expression * ret = addrExpr->arg;
489 ret->env = appExpr->env;
490 addrExpr->arg = nullptr;
491 appExpr->env = nullptr;
492 delete appExpr;
493 return ret;
494 }
495 }
496 }
497 return appExpr;
498 }
499 } // namespace
500} // namespace GenPoly
501
502// Local Variables: //
503// tab-width: 4 //
504// mode: c++ //
505// compile-command: "make install" //
506// End: //
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