| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
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| 3 | //
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| 4 | // The contents of this file are covered under the licence agreement in the
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| 5 | // file "LICENCE" distributed with Cforall.
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| 6 | //
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| 7 | // Explode.cc --
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| 8 | //
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| 9 | // Author : Rob Schluntz
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| 10 | // Created On : Wed Nov 9 13:12:24 2016
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| 11 | // Last Modified By : Rob Schluntz
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| 12 | // Last Modified On : Wed Nov 9 13:20:24 2016
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| 13 | // Update Count : 2
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| 14 | //
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| 15 |
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| 16 | #include "Explode.h"
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| 17 | #include <list> // for list
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| 18 |
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| 19 | #include "SynTree/Mutator.h" // for Mutator
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| 20 | #include "Common/PassVisitor.h" // for PassVisitor
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| 21 |
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| 22 | namespace Tuples {
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| 23 | namespace {
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| 24 | // remove one level of reference from a reference type -- may be useful elsewhere.
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| 25 | Type * getReferenceBase( Type * t ) {
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| 26 | if ( ReferenceType * refType = dynamic_cast<ReferenceType *>( t ) ) {
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| 27 | return refType->get_base();
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| 28 | } else {
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| 29 | // for the moment, I want to know immediately if a non-reference type is ever passed in here.
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| 30 | assertf( false, "getReferenceBase for non-ref: %s", toString( refType ).c_str() );
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| 31 | return nullptr;
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| 32 | }
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| 33 | }
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| 34 |
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| 35 | struct CastExploder {
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| 36 | bool castAdded = false;
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| 37 | bool foundUniqueExpr = false;
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| 38 | Expression * applyCast( Expression * expr, bool first = true ) {
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| 39 | if ( TupleExpr * tupleExpr = dynamic_cast< TupleExpr * >( expr ) ){
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| 40 | foundUniqueExpr = true;
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| 41 | std::list< Expression * > exprs;
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| 42 | for ( Expression *& expr : tupleExpr->get_exprs() ) {
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| 43 | // move cast into tuple exprs
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| 44 | exprs.push_back( applyCast( expr, false ) );
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| 45 | }
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| 46 | // want the top-level expression to be cast to reference type, but not nested
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| 47 | // tuple expressions
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| 48 | if ( first ) {
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| 49 | castAdded = true;
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| 50 | Expression * tupleExpr = new TupleExpr( exprs );
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| 51 | return new CastExpr( tupleExpr, new ReferenceType( Type::Qualifiers(), tupleExpr->result->clone() ) );
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| 52 | } else {
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| 53 | return new TupleExpr( exprs );
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| 54 | }
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| 55 | }
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| 56 | if ( dynamic_cast<ReferenceType*>( expr->result ) ) {
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| 57 | // don't need to cast reference type to another reference type
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| 58 | return expr->clone();
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| 59 | } else {
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| 60 | // anything else should be cast to reference as normal
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| 61 | castAdded = true;
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| 62 | return new CastExpr( expr->clone(), new ReferenceType( Type::Qualifiers(), expr->result->clone() ) );
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| 63 | }
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| 64 | }
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| 65 |
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| 66 | Expression * postmutate( UniqueExpr * uniqueExpr ) {
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| 67 | // move cast into unique expr so that the unique expr has type T& rather than
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| 68 | // type T. In particular, this transformation helps with generating the
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| 69 | // correct code for reference-cast member tuple expressions, since the result
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| 70 | // should now be a tuple of references rather than a reference to a tuple.
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| 71 | // Still, this code is a bit awkward, and could use some improvement.
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| 72 | UniqueExpr * newUniqueExpr = new UniqueExpr{ applyCast( uniqueExpr->get_expr() ), uniqueExpr->get_id() };
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| 73 | if ( castAdded ) {
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| 74 | // if a cast was added by applyCast, then unique expr now has one more layer of reference
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| 75 | // than it had coming into this function. To ensure types still match correctly, need to cast
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| 76 | // to reference base so that outer expressions are still correct.
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| 77 | castAdded = false;
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| 78 | Type * toType = getReferenceBase( newUniqueExpr->result );
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| 79 | return new CastExpr( newUniqueExpr, toType->clone() );
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| 80 | }
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| 81 | return newUniqueExpr;
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| 82 | }
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| 83 |
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| 84 |
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| 85 | Expression * postmutate( TupleIndexExpr * tupleExpr ) {
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| 86 | // tuple index expr needs to be rebuilt to ensure that the type of the
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| 87 | // field is consistent with the type of the tuple expr, since the field
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| 88 | // may have changed from type T to T&.
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| 89 | return new TupleIndexExpr( tupleExpr->get_tuple(), tupleExpr->get_index() );
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| 90 | }
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| 91 | };
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| 92 | } // namespace
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| 93 |
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| 94 | Expression * distributeReference( Expression * expr ) {
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| 95 | PassVisitor<CastExploder> exploder;
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| 96 | expr = expr->acceptMutator( exploder );
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| 97 | if ( ! exploder.pass.foundUniqueExpr ) {
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| 98 | // if a UniqueExpr was found, then the cast has already been added inside the UniqueExpr as appropriate
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| 99 | expr = new CastExpr( expr, new ReferenceType( Type::Qualifiers(), expr->result->clone() ) );
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| 100 | }
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| 101 | return expr;
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| 102 | }
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| 103 | } // namespace Tuples
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| 104 |
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| 105 | // Local Variables: //
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| 106 | // tab-width: 4 //
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| 107 | // mode: c++ //
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| 108 | // compile-command: "make install" //
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| 109 | // End: //
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