source: src/GenPoly/Lvalue.cc@ 83a071f9

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 83a071f9 was 8499c707, checked in by Rob Schluntz <rschlunt@…>, 8 years ago

Convert intrinsic expressions to value type, add implicit dereferences to reference-typed address-expressions
  • Property mode set to 100644
File size: 16.1 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/typeops.h"
33
34#include "Common/UniqueName.h"
35#include "Common/utility.h"
36#include "Common/PassVisitor.h"
37
38#include "InitTweak/InitTweak.h"
39
40#if 0
41#define PRINT(x) x
42#else
43#define PRINT(x)
44#endif
45
46namespace GenPoly {
47 namespace {
48 // TODO: fold this into the general createDeref function??
49 Expression * mkDeref( Expression * arg ) {
50 if ( SymTab::dereferenceOperator ) {
51 VariableExpr * deref = new VariableExpr( SymTab::dereferenceOperator );
52 deref->set_result( new PointerType( Type::Qualifiers(), deref->get_result() ) );
53 Type * base = InitTweak::getPointerBase( arg->get_result() );
54 assertf( base, "expected pointer type in dereference (type was %s)", toString( arg->get_result() ).c_str() );
55 ApplicationExpr * ret = new ApplicationExpr( deref, { arg } );
56 delete ret->get_result();
57 ret->set_result( base->clone() );
58 ret->get_result()->set_lvalue( true );
59 return ret;
60 } else {
61 return UntypedExpr::createDeref( arg );
62 }
63 }
64
65 struct ReferenceConversions final {
66 void premutate( AddressExpr * addrExpr );
67
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 };
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 std::cerr << "convertLvalue" << std::endl;
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 namespace {
138 // true for intrinsic function calls that return a reference
139 bool isIntrinsicReference( Expression * expr ) {
140 if ( UntypedExpr * untyped = dynamic_cast< UntypedExpr * >( expr ) ) {
141 std::string fname = InitTweak::getFunctionName( untyped );
142 // known intrinsic-reference prelude functions
143 return fname == "*?" || fname == "?[?]";
144 } else if ( ApplicationExpr * appExpr = dynamic_cast< ApplicationExpr * > ( expr ) ) {
145 if ( DeclarationWithType * func = InitTweak::getFunction( appExpr ) ) {
146 // use type of return variable rather than expr result type, since it may have been changed to a pointer type
147 FunctionType * ftype = GenPoly::getFunctionType( func->get_type() );
148 Type * ret = ftype->get_returnVals().empty() ? nullptr : ftype->get_returnVals().front()->get_type();
149 return func->get_linkage() == LinkageSpec::Intrinsic && dynamic_cast<ReferenceType *>( ret );
150 }
151 }
152 return false;
153 }
154
155 Expression * FixIntrinsicResult::postmutate( ApplicationExpr * appExpr ) {
156 if ( isIntrinsicReference( appExpr ) ) {
157 // eliminate reference types from intrinsic applications - now they return lvalues
158 Type * result = appExpr->get_result();
159 appExpr->set_result( result->stripReferences()->clone() );
160 appExpr->get_result()->set_lvalue( true );
161 Expression * ret = new CastExpr( appExpr, result );
162 ret->set_env( appExpr->get_env() );
163 appExpr->set_env( nullptr );
164 return ret;
165 }
166 return appExpr;
167 }
168
169 Expression * FixIntrinsicArgs::postmutate( ApplicationExpr * appExpr ) {
170 // intrinsic functions don't really take reference-typed parameters, so they require an implicit dereference on their arguments.
171 if ( DeclarationWithType * function = InitTweak::getFunction( appExpr ) ) {
172 FunctionType * ftype = GenPoly::getFunctionType( function->get_type() );
173 assertf( ftype, "Function declaration does not have function type." );
174 // can be of differing lengths only when function is variadic
175 assertf( ftype->get_parameters().size() == appExpr->get_args().size() || ftype->get_isVarArgs(), "ApplicationExpr args do not match formal parameter type." );
176
177
178 unsigned int i = 0;
179 const unsigned int end = ftype->get_parameters().size();
180 for ( auto p : unsafe_group_iterate( appExpr->get_args(), ftype->get_parameters() ) ) {
181 if (i == end) break;
182 Expression *& arg = std::get<0>( p );
183 Type * formal = std::get<1>( p )->get_type();
184 PRINT(
185 std::cerr << "pair<0>: " << arg << std::endl;
186 std::cerr << "pair<1>: " << formal << std::endl;
187 )
188 if ( dynamic_cast<ReferenceType*>( formal ) ) {
189 if ( isIntrinsicReference( arg ) ) { // do not combine conditions, because that changes the meaning of the else if
190 if ( function->get_linkage() != LinkageSpec::Intrinsic ) { // intrinsic functions that turn pointers into references
191 // if argument is dereference or array subscript, the result isn't REALLY a reference, so it's not necessary to fix the argument
192 PRINT(
193 std::cerr << "===is intrinsic arg in non-intrinsic call - adding address" << std::endl;
194 )
195 arg = new AddressExpr( arg );
196 }
197 } else if ( function->get_linkage() == LinkageSpec::Intrinsic ) {
198 // std::cerr << "===adding deref to arg" << std::endl;
199 // if the parameter is a reference, add a dereference to the reference-typed argument.
200 Type * baseType = InitTweak::getPointerBase( arg->get_result() );
201 assertf( baseType, "parameter is reference, arg must be pointer or reference: %s", toString( arg->get_result() ).c_str() );
202 PointerType * ptrType = new PointerType( Type::Qualifiers(), baseType->clone() );
203 delete arg->get_result();
204 arg->set_result( ptrType );
205 arg = mkDeref( arg );
206 }
207 }
208 ++i;
209 }
210 }
211 return appExpr;
212 }
213
214 // idea: &&&E: get outer &, inner &
215 // at inner &, record depth D of reference type
216 // at outer &, add D derefs.
217 void AddrRef::premutate( Expression * expr ) {
218 GuardValue( current );
219 GuardValue( first );
220 current = false;
221 first = true;
222 }
223
224 void AddrRef::premutate( AddressExpr * addrExpr ) {
225 GuardValue( current );
226 GuardValue( first );
227 current = first;
228 first = false;
229 if ( current ) {
230 GuardValue( refDepth );
231 refDepth = 0;
232 }
233 }
234
235 Expression * AddrRef::postmutate( AddressExpr * addrExpr ) {
236 if ( refDepth == 0 ) {
237 if ( ! isIntrinsicReference( addrExpr->get_arg() ) ) {
238 // try to avoid ?[?]
239 refDepth = addrExpr->get_arg()->get_result()->referenceDepth();
240 }
241 }
242 if ( current ) {
243 Expression * ret = addrExpr;
244 while ( refDepth ) {
245 ret = mkDeref( ret );
246 refDepth--;
247 }
248 return ret;
249 }
250 return addrExpr;
251 }
252
253 Expression * ReferenceConversions::postmutate( AddressExpr * addrExpr ) {
254 // Inner expression may have been lvalue to reference conversion, which becomes an address expression.
255 // In this case, remove the outer address expression and return the argument.
256 // TODO: It's possible that this might catch too much and require a more sophisticated check.
257 return addrExpr;
258 }
259
260 Expression * ReferenceConversions::postmutate( CastExpr * castExpr ) {
261 // xxx - is it possible to convert directly between reference types with a different base? E.g.,
262 // int x;
263 // (double&)x;
264 // At the moment, I am working off of the assumption that this is illegal, thus the cast becomes redundant
265 // after this pass, so trash the cast altogether. If that changes, care must be taken to insert the correct
266 // pointer casts in the right places.
267
268 // conversion to reference type
269 if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_result() ) ) {
270 (void)refType;
271 if ( ReferenceType * otherRef = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
272 // nothing to do if casting from reference to reference.
273 (void)otherRef;
274 PRINT( std::cerr << "convert reference to reference -- nop" << std::endl; )
275 if ( isIntrinsicReference( castExpr->get_arg() ) ) {
276 Expression * callExpr = castExpr->get_arg();
277 PRINT(
278 std::cerr << "but arg is deref -- &" << std::endl;
279 std::cerr << callExpr << std::endl;
280 )
281 callExpr = new AddressExpr( callExpr ); // this doesn't work properly for multiple casts
282 delete callExpr->get_result();
283 callExpr->set_result( refType->clone() );
284 // move environment out to new top-level
285 callExpr->set_env( castExpr->get_env() );
286 castExpr->set_arg( nullptr );
287 castExpr->set_env( nullptr );
288 delete castExpr;
289 return callExpr;
290 }
291 int depth1 = refType->referenceDepth();
292 int depth2 = otherRef->referenceDepth();
293 assertf( depth1 == depth2, "non-intrinsic reference with cast of reference to reference not yet supported: %d %d %s", depth1, depth2, toString( castExpr ).c_str() );
294 PRINT( std::cerr << castExpr << std::endl; )
295 return castExpr;
296 } else if ( castExpr->get_arg()->get_result()->get_lvalue() ) {
297 // conversion from lvalue to reference
298 // xxx - keep cast, but turn into pointer cast??
299 // xxx - memory
300 PRINT(
301 std::cerr << "convert lvalue to reference -- &" << std::endl;
302 std::cerr << castExpr->get_arg() << std::endl;
303 )
304 AddressExpr * ret = new AddressExpr( castExpr->get_arg() );
305 if ( refType->get_base()->get_qualifiers() != castExpr->get_arg()->get_result()->get_qualifiers() ) {
306 // must keep cast if cast-to type is different from the actual type
307 castExpr->set_arg( ret );
308 return castExpr;
309 }
310 ret->set_env( castExpr->get_env() );
311 delete ret->get_result();
312 ret->set_result( castExpr->get_result() );
313 castExpr->set_env( nullptr );
314 castExpr->set_arg( nullptr );
315 castExpr->set_result( nullptr );
316 delete castExpr;
317 return ret;
318 } else {
319 // rvalue to reference conversion -- introduce temporary
320 }
321 assertf( false, "Only conversions to reference from lvalue are currently supported: %s", toString( castExpr ).c_str() );
322 } else if ( ReferenceType * refType = dynamic_cast< ReferenceType * >( castExpr->get_arg()->get_result() ) ) {
323 (void)refType;
324 // conversion from reference to rvalue
325 PRINT(
326 std::cerr << "convert reference to rvalue -- *" << std::endl;
327 std::cerr << "was = " << castExpr << std::endl;
328 )
329 Expression * ret = castExpr->get_arg();
330 TypeSubstitution * env = castExpr->get_env();
331 castExpr->set_env( nullptr );
332 if ( ! isIntrinsicReference( ret ) ) {
333 // dereference if not already dereferenced
334 ret = mkDeref( ret );
335 }
336 if ( ResolvExpr::typesCompatibleIgnoreQualifiers( castExpr->get_result(), castExpr->get_arg()->get_result()->stripReferences(), SymTab::Indexer() ) ) {
337 // can remove cast if types are compatible, changing expression type to value type
338 ret->set_result( castExpr->get_result()->clone() );
339 castExpr->set_arg( nullptr );
340 delete castExpr;
341 } else {
342 // must keep cast if types are different
343 castExpr->set_arg( ret );
344 ret = castExpr;
345 }
346 ret->set_env( env );
347 PRINT( std::cerr << "now: " << ret << std::endl; )
348 return ret;
349 }
350 return castExpr;
351 }
352
353 Type * ReferenceTypeElimination::postmutate( ReferenceType * refType ) {
354 Type * base = refType->get_base();
355 Type::Qualifiers qualifiers = refType->get_qualifiers();
356 refType->set_base( nullptr );
357 delete refType;
358 return new PointerType( qualifiers, base );
359 }
360
361 Expression * GeneralizedLvalue::postmutate( AddressExpr * addrExpr ) {
362 if ( CommaExpr * commaExpr = dynamic_cast< CommaExpr * >( addrExpr->get_arg() ) ) {
363 Expression * arg1 = commaExpr->get_arg1()->clone();
364 Expression * arg2 = commaExpr->get_arg2()->clone();
365 Expression * ret = new CommaExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( *visitor ) );
366 ret->set_env( addrExpr->get_env() );
367 addrExpr->set_env( nullptr );
368 delete addrExpr;
369 return ret;
370 } else if ( ConditionalExpr * condExpr = dynamic_cast< ConditionalExpr * >( addrExpr->get_arg() ) ) {
371 Expression * arg1 = condExpr->get_arg1()->clone();
372 Expression * arg2 = condExpr->get_arg2()->clone();
373 Expression * arg3 = condExpr->get_arg3()->clone();
374 Expression * ret = new ConditionalExpr( arg1, (new AddressExpr( arg2 ))->acceptMutator( *visitor ), (new AddressExpr( arg3 ))->acceptMutator( *visitor ) );
375 ret->set_env( addrExpr->get_env() );
376 addrExpr->set_env( nullptr );
377 delete addrExpr;
378 return ret;
379 }
380 return addrExpr;
381 }
382
383 Expression * CollapseAddrDeref::postmutate( AddressExpr * addrExpr ) {
384 Expression * arg = addrExpr->get_arg();
385 if ( isIntrinsicReference( arg ) ) {
386 std::string fname = InitTweak::getFunctionName( arg );
387 if ( fname == "*?" ) {
388 Expression *& arg0 = InitTweak::getCallArg( arg, 0 );
389 Expression * ret = arg0;
390 ret->set_env( addrExpr->get_env() );
391 arg0 = nullptr;
392 addrExpr->set_env( nullptr );
393 delete addrExpr;
394 return ret;
395 }
396 }
397 return addrExpr;
398 }
399
400 Expression * CollapseAddrDeref::postmutate( ApplicationExpr * appExpr ) {
401 if ( isIntrinsicReference( appExpr ) ) {
402 std::string fname = InitTweak::getFunctionName( appExpr );
403 if ( fname == "*?" ) {
404 Expression * arg = InitTweak::getCallArg( appExpr, 0 );
405 // xxx - this isn't right, because it can remove casts that should be there...
406 // while ( CastExpr * castExpr = dynamic_cast< CastExpr * >( arg ) ) {
407 // arg = castExpr->get_arg();
408 // }
409 if ( AddressExpr * addrExpr = dynamic_cast< AddressExpr * >( arg ) ) {
410 Expression * ret = addrExpr->get_arg();
411 ret->set_env( appExpr->get_env() );
412 addrExpr->set_arg( nullptr );
413 appExpr->set_env( nullptr );
414 delete appExpr;
415 return ret;
416 }
417 }
418 }
419 return appExpr;
420 }
421 } // namespace
422} // namespace GenPoly
423
424// Local Variables: //
425// tab-width: 4 //
426// mode: c++ //
427// compile-command: "make install" //
428// End: //
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