source: src/GenPoly/Lvalue.cc@ f6582243

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 f6582243 was 9236060, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Merge branch 'master' into references
  • Property mode set to 100644
File size: 17.3 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>
17
18#include "Lvalue.h"
19
20#include "GenPoly.h"
21
22#include "SynTree/Declaration.h"
23#include "SynTree/Type.h"
24#include "SynTree/Expression.h"
25#include "SynTree/Statement.h"
26#include "SynTree/Visitor.h"
27#include "SynTree/Mutator.h"
28#include "SymTab/Indexer.h"
29#include "SymTab/Autogen.h"
30
31#include "ResolvExpr/Resolver.h"
32#include "ResolvExpr/TypeEnvironment.h"
33#include "ResolvExpr/typeops.h"
34#include "ResolvExpr/Unify.h"
35
36#include "Common/UniqueName.h"
37#include "Common/utility.h"
38#include "Common/PassVisitor.h"
39
40#include "InitTweak/InitTweak.h"
41
42#if 0
43#define PRINT(x) x
44#else
45#define PRINT(x)
46#endif
47
48namespace GenPoly {
49 namespace {
50 // TODO: fold this into the general createDeref function??
51 Expression * mkDeref( Expression * arg ) {
52 if ( SymTab::dereferenceOperator ) {
53 VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
54 deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
55 Type * base = InitTweak::getPointerBase( arg->get_result() );
56 assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
57 ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
58 delete ret->get_result();
59 ret->set_result( base->clone() );
60 ret->get_result()->set_lvalue( true );
61 return ret;
62 } else {
63 return UntypedExpr::createDeref( arg );
64 }
65 }
66
67 struct ReferenceConversions final {
68 Expression * postmutate( CastExpr * castExpr );
69 Expression * postmutate( AddressExpr * addrExpr );
70 };
71
72 /// Intrinsic functions that take reference parameters don't REALLY take reference parameters -- their reference arguments must always be implicitly dereferenced.
73 struct FixIntrinsicArgs final {
74 Expression * postmutate( ApplicationExpr * appExpr );
75 };
76
77 struct FixIntrinsicResult final {
78 Expression * postmutate( ApplicationExpr * appExpr );
79 };
80
81 /// Replace reference types with pointer types
82 struct ReferenceTypeElimination final {
83 Type * postmutate( ReferenceType * refType );
84 };
85
86 /// GCC-like Generalized Lvalues (which have since been removed from GCC)
87 /// https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Lvalues.html#Lvalues
88 /// Replaces &(a,b) with (a, &b), &(a ? b : c) with (a ? &b : &c)
89 struct GeneralizedLvalue final : public WithVisitorRef<GeneralizedLvalue> {
90 Expression * postmutate( AddressExpr * addressExpr );
91 Expression * postmutate( MemberExpr * memExpr );
92
93 template<typename Func>
94 Expression * applyTransformation( Expression * expr, Expression * arg, Func mkExpr );
95 };
96
97 /// Removes redundant &*/*& pattern that this pass can generate
98 struct CollapseAddrDeref final {
99 Expression * postmutate( AddressExpr * addressExpr );
100 Expression * postmutate( ApplicationExpr * appExpr );
101 };
102
103 struct AddrRef final : public WithGuards {
104 void premutate( AddressExpr * addrExpr );
105 Expression * postmutate( AddressExpr * addrExpr );
106 void premutate( Expression * expr );
107
108 bool first = true;
109 bool current = false;
110 int refDepth = 0;
111 };
112 } // namespace
113
114 static bool referencesEliminated = false;
115 // used by UntypedExpr::createDeref to determine whether result type of dereference should be ReferenceType or value type.
116 bool referencesPermissable() {
117 return ! referencesEliminated;
118 }
119
120 void convertLvalue( std::list< Declaration* >& translationUnit ) {
121 std::cerr << "convertLvalue" << std::endl;
122 PassVisitor<ReferenceConversions> refCvt;
123 PassVisitor<ReferenceTypeElimination> elim;
124 PassVisitor<GeneralizedLvalue> genLval;
125 PassVisitor<FixIntrinsicArgs> fixer;
126 PassVisitor<CollapseAddrDeref> collapser;
127 PassVisitor<AddrRef> addrRef;
128 PassVisitor<FixIntrinsicResult> intrinsicResults;
129 mutateAll( translationUnit, intrinsicResults );
130 mutateAll( translationUnit, addrRef );
131 mutateAll( translationUnit, refCvt );
132 mutateAll( translationUnit, fixer );
133 mutateAll( translationUnit, collapser );
134 mutateAll( translationUnit, genLval );
135 mutateAll( translationUnit, elim ); // last because other passes need reference types to work
136
137 // from this point forward, no other pass should create reference types.
138 referencesEliminated = true;
139 }
140
141 Expression * generalizedLvalue( Expression * expr ) {
142 PassVisitor<GeneralizedLvalue> genLval;
143 return expr->acceptMutator( genLval );
144 }
145
146 namespace {
147 // true for intrinsic function calls that return a reference
148 bool isIntrinsicReference( Expression * expr ) {
149 if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
150 std::string fname = InitTweak::getFunctionName( untyped );
151 // known intrinsic-reference prelude functions
152 return fname == "*?" || fname == "?[?]";
153 } else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
154 if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
155 // use type of return variable rather than expr result type, since it may have been changed to a pointer type
156 FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
157 Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
158 return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
159 }
160 }
161 return false;
162 }
163
164 Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
165 if ( isIntrinsicReference( appExpr ) ) {
166 // eliminate reference types from intrinsic applications - now they return lvalues
167 Type * result = appExpr->get_result();
168 appExpr->set_result( result->stripReferences()->clone() );
169 appExpr->get_result()->set_lvalue( true );
170 Expression * ret = new CastExpr( appExpr, result );
171 ret->set_env( appExpr->get_env() );
172 appExpr->set_env( nullptr );
173 return ret;
174 }
175 return appExpr;
176 }
177
178 Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
179 // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
180 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
181 FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
182 assertf( ftype, "Function declaration does not have function type." );
183 // can be of differing lengths only when function is variadic
184 assertf( ftype->get_parameters().size() == appExpr->get_args().size() || ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
185
186
187 unsigned int i = 0;
188 const unsigned int end = ftype->get_parameters().size();
189 for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
190 if (i == end) break;
191 Expression *& arg = std::get<0>( p );
192 Type * formal = std::get<1>( p )->get_type();
193 PRINT(
194 std::cerr << "pair<0>: " << arg << std::endl;
195 std::cerr << "pair<1>: " << formal << std::endl;
196 )
197 if ( dynamic_cast<ReferenceType*>( formal ) ) {
198 if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
199 if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
200 // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
201 PRINT(
202 std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
203 )
204 arg = new AddressExpr( arg );
205 }
206 } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
207 // std::cerr << "===adding deref to arg" << std::endl;
208 // if the parameter is a reference, add a dereference to the reference-typed argument.
209 Type * baseType = InitTweak::getPointerBase( arg->get_result() );
210 assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
211 PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
212 delete arg->get_result();
213 arg->set_result( ptrType );
214 arg = mkDeref( arg );
215 }
216 }
217 ++i;
218 }
219 }
220 return appExpr;
221 }
222
223 // idea: &&&E: get outer &, inner &
224 // at inner &, record depth D of reference type
225 // at outer &, add D derefs.
226 void AddrRef::premutate( Expression * expr ) {
227 GuardValue( current );
228 GuardValue( first );
229 current = false;
230 first = true;
231 }
232
233 void AddrRef::premutate( AddressExpr * addrExpr ) {
234 GuardValue( current );
235 GuardValue( first );
236 current = first;
237 first = false;
238 if ( current ) {
239 GuardValue( refDepth );
240 refDepth = 0;
241 }
242 }
243
244 Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
245 if ( refDepth == 0 ) {
246 if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
247 // try to avoid ?[?]
248 refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
249 }
250 }
251 if ( current ) {
252 Expression * ret = addrExpr;
253 while ( refDepth ) {
254 ret = mkDeref( ret );
255 refDepth--;
256 }
257 return ret;
258 }
259 return addrExpr;
260 }
261
262 Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
263 // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
264 // In this case, remove the outer address expression and return the argument.
265 // TODO: It's possible that this might catch too much and require a more sophisticated check.
266 return addrExpr;
267 }
268
269 Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
270 // xxx - is it possible to convert directly between reference types with a different base? E.g.,
271 // int x;
272 // (double&)x;
273 // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
274 // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
275 // pointer casts in the right places.
276
277 // conversion to reference type
278 if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
279 (void)refType;
280 if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
281 // nothing to do if casting from reference to reference.
282 (void)otherRef;
283 PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
284 if ( isIntrinsicReference( castExpr->get_arg() ) ) {
285 Expression * callExpr = castExpr->get_arg();
286 PRINT(
287 std::cerr << "but arg is deref -- &" << std::endl;
288 std::cerr << callExpr << std::endl;
289 )
290 callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
291 delete callExpr->get_result();
292 callExpr->set_result( refType->clone() );
293 // move environment out to new top-level
294 callExpr->set_env( castExpr->get_env() );
295 castExpr->set_arg( nullptr );
296 castExpr->set_env( nullptr );
297 delete castExpr;
298 return callExpr;
299 }
300 int depth1 = refType->referenceDepth();
301 int depth2 = otherRef->referenceDepth();
302 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
303 PRINT( std::cerr << castExpr << std::endl; )
304 return castExpr;
305 } else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
306 // conversion from lvalue to reference
307 // xxx - keep cast, but turn into pointer cast??
308 // xxx - memory
309 PRINT(
310 std::cerr << "convert lvalue to reference -- &" << std::endl;
311 std::cerr << castExpr->get_arg() << std::endl;
312 )
313 AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
314 if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
315 // must keep cast if cast-to type is different from the actual type
316 castExpr->set_arg( ret );
317 return castExpr;
318 }
319 ret->set_env( castExpr->get_env() );
320 delete ret->get_result();
321 ret->set_result( castExpr->get_result() );
322 castExpr->set_env( nullptr );
323 castExpr->set_arg( nullptr );
324 castExpr->set_result( nullptr );
325 delete castExpr;
326 return ret;
327 } else {
328 // rvalue to reference conversion -- introduce temporary
329 }
330 assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
331 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
332 (void)refType;
333 // conversion from reference to rvalue
334 PRINT(
335 std::cerr << "convert reference to rvalue -- *" << std::endl;
336 std::cerr << "was = " << castExpr << std::endl;
337 )
338 Expression * ret = castExpr->get_arg();
339 TypeSubstitution * env = castExpr->get_env();
340 castExpr->set_env( nullptr );
341 if ( ! isIntrinsicReference( ret ) ) {
342 // dereference if not already dereferenced
343 ret = mkDeref( ret );
344 }
345 if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
346 // can remove cast if types are compatible, changing expression type to value type
347 ret->set_result( castExpr->get_result()->clone() );
348 castExpr->set_arg( nullptr );
349 delete castExpr;
350 } else {
351 // must keep cast if types are different
352 castExpr->set_arg( ret );
353 ret = castExpr;
354 }
355 ret->set_env( env );
356 PRINT( std::cerr << "now: " << ret << std::endl; )
357 return ret;
358 }
359 return castExpr;
360 }
361
362 Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
363 Type * base = refType->get_base();
364 Type::Qualifiers qualifiers = refType->get_qualifiers();
365 refType->set_base( nullptr );
366 delete refType;
367 return new PointerType( qualifiers, base );
368 }
369
370 template<typename Func>
371 Expression * GeneralizedLvalue::applyTransformation( Expression * expr, Expression * arg, Func mkExpr ) {
372 if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( arg ) ) {
373 Expression * arg1 = commaExpr->get_arg1()->clone();
374 Expression * arg2 = commaExpr->get_arg2()->clone();
375 Expression * ret = new CommaExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ) );
376 ret->set_env( expr->get_env() );
377 expr->set_env( nullptr );
378 delete expr;
379 return ret;
380 } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( arg ) ) {
381 Expression * arg1 = condExpr->get_arg1()->clone();
382 Expression * arg2 = condExpr->get_arg2()->clone();
383 Expression * arg3 = condExpr->get_arg3()->clone();
384 ConditionalExpr * ret = new ConditionalExpr( arg1, mkExpr( arg2 )->acceptMutator( *visitor ), mkExpr( arg3 )->acceptMutator( *visitor ) );
385 ret->set_env( expr->get_env() );
386 expr->set_env( nullptr );
387 delete expr;
388
389 // conditional expr type may not be either of the argument types, need to unify
390 using namespace ResolvExpr;
391 Type* commonType = nullptr;
392 TypeEnvironment newEnv;
393 AssertionSet needAssertions, haveAssertions;
394 OpenVarSet openVars;
395 unify( ret->get_arg2()->get_result(), ret->get_arg3()->get_result(), newEnv, needAssertions, haveAssertions, openVars, SymTab::Indexer(), commonType );
396 ret->set_result( commonType ? commonType : ret->get_arg2()->get_result()->clone() );
397 return ret;
398 }
399 return expr;
400 }
401
402 Expression * GeneralizedLvalue::postmutate( MemberExpr * memExpr ) {
403 return applyTransformation( memExpr, memExpr->get_aggregate(), [=]( Expression * aggr ) { return new MemberExpr( memExpr->get_member(), aggr ); } );
404 }
405
406 Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
407 return applyTransformation( addrExpr, addrExpr->get_arg(), []( Expression * arg ) { return new AddressExpr( arg ); } );
408 }
409
410 Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
411 Expression * arg = addrExpr->get_arg();
412 if ( isIntrinsicReference( arg ) ) {
413 std::string fname = InitTweak::getFunctionName( arg );
414 if ( fname == "*?" ) {
415 Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
416 Expression * ret = arg0;
417 ret->set_env( addrExpr->get_env() );
418 arg0 = nullptr;
419 addrExpr->set_env( nullptr );
420 delete addrExpr;
421 return ret;
422 }
423 }
424 return addrExpr;
425 }
426
427 Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
428 if ( isIntrinsicReference( appExpr ) ) {
429 std::string fname = InitTweak::getFunctionName( appExpr );
430 if ( fname == "*?" ) {
431 Expression * arg = InitTweak::getCallArg( appExpr, 0 );
432 // xxx - this isn't right, because it can remove casts that should be there...
433 // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
434 // arg = castExpr->get_arg();
435 // }
436 if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
437 Expression * ret = addrExpr->get_arg();
438 ret->set_env( appExpr->get_env() );
439 addrExpr->set_arg( nullptr );
440 appExpr->set_env( nullptr );
441 delete appExpr;
442 return ret;
443 }
444 }
445 }
446 return appExpr;
447 }
448 } // namespace
449} // namespace GenPoly
450
451// Local Variables: //
452// tab-width: 4 //
453// mode: c++ //
454// compile-command: "make install" //
455// End: //
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