Changes in src/Tuples/TupleExpansionNew.cpp [d249e0b:bb9924c]

File:

• src/Tuples/TupleExpansionNew.cpp (modified) (2 diffs)

src/Tuples/TupleExpansionNew.cpp

@@ -8 +8 @@
 //
 // Author           : Henry Xue
-// Created On       : Mon Aug 23 15:36:09 2021
+// Created On       : Wed Aug 18 12:54:02 2021
 // Last Modified By : Henry Xue
-// Last Modified On : Mon Aug 23 15:36:09 2021
+// Last Modified On : Wed Aug 18 12:54:02 2021
 // Update Count     : 1
 //
+
+// Currently not working due to unresolved issues with UniqueExpr
 
 #include "Tuples.h"
@@ -18 +20 @@
 namespace Tuples {
 namespace {
-        struct MemberTupleExpander final : public ast::WithShortCircuiting, public ast::WithVisitorRef< MemberTupleExpander > {
-                void previsit( const ast::UntypedMemberExpr * ) { visit_children = false; }
-        const ast::Expr * postvisit( const ast::UntypedMemberExpr * memberExpr );
+        struct UniqueExprExpander final : public ast::WithDeclsToAdd<> {
+                const ast::Expr * postvisit( const ast::UniqueExpr * unqExpr );
+                std::map< int, ast::ptr<ast::Expr> > decls; // not vector, because order added may not be increasing order
         };
 } // namespace
 
-void expandMemberTuples( ast::TranslationUnit & translationUnit ) {
-        ast::Pass< MemberTupleExpander >::run( translationUnit );
+void expandUniqueExpr( ast::TranslationUnit & translationUnit ) {
+        ast::Pass< UniqueExprExpander >::run( translationUnit );
 }
 
 namespace {
-        namespace {
-                /// given a expression representing the member and an expression representing the aggregate,
-                /// reconstructs a flattened UntypedMemberExpr with the right precedence
-                const ast::Expr * reconstructMemberExpr( const ast::Expr * member, const ast::Expr * aggr, const CodeLocation & loc ) {
-                        if ( auto memberExpr = dynamic_cast< const ast::UntypedMemberExpr * >( member ) ) {
-                                // construct a new UntypedMemberExpr with the correct structure , and recursively
-                                // expand that member expression.
-                                ast::Pass< MemberTupleExpander > expander;
-                                auto inner = new ast::UntypedMemberExpr( loc, memberExpr->aggregate, aggr );
-                                auto newMemberExpr = new ast::UntypedMemberExpr( loc, memberExpr->member, inner );
-                                //delete memberExpr;
-                                return newMemberExpr->accept( expander );
+        const ast::Expr * UniqueExprExpander::postvisit( const ast::UniqueExpr * unqExpr ) {
+                const CodeLocation loc = unqExpr->location;
+                const int id = unqExpr->id;
+
+                // on first time visiting a unique expr with a particular ID, generate the expression that replaces all UniqueExprs with that ID,
+                // and lookup on subsequent hits. This ensures that all unique exprs with the same ID reference the same variable.
+                if ( ! decls.count( id ) ) {
+                        ast::ptr< ast::Expr > assignUnq;
+                        const ast::VariableExpr * var = unqExpr->var;
+                        if ( unqExpr->object ) {
+                                // an object was generated to represent this unique expression -- it should be added to the list of declarations now
+                                declsToAddBefore.push_back( unqExpr->object.as< ast::Decl >() );
+                                // deep copy required due to unresolved issues with UniqueExpr
+                                assignUnq = ast::UntypedExpr::createAssign( loc, var, unqExpr->expr );
                         } else {
-                                // not a member expression, so there is nothing to do but attach and return
-                                return new ast::UntypedMemberExpr( loc, member, aggr );
+                                const auto commaExpr = unqExpr->expr.strict_as< ast::CommaExpr >();
+                                assignUnq = commaExpr->arg1;
                         }
+                        auto finished = new ast::ObjectDecl( loc, toString( "_unq", id, "_finished_" ), new ast::BasicType( ast::BasicType::Kind::Bool ),
+                                new ast::SingleInit( loc, ast::ConstantExpr::from_int( loc, 0 ) ), {}, ast::Linkage::Cforall );
+                        declsToAddBefore.push_back( finished );
+                        // (finished ? _unq_expr_N : (_unq_expr_N = <unqExpr->get_expr()>, finished = 1, _unq_expr_N))
+                        // This pattern ensures that each unique expression is evaluated once, regardless of evaluation order of the generated C code.
+                        auto assignFinished = ast::UntypedExpr::createAssign( loc, new ast::VariableExpr( loc, finished ),
+                                ast::ConstantExpr::from_int( loc, 1 ) );
+                        auto condExpr = new ast::ConditionalExpr( loc, new ast::VariableExpr( loc, finished ), var,
+                                new ast::CommaExpr( loc, new ast::CommaExpr( loc, assignUnq, assignFinished ), var ) );
+                        condExpr->result = var->result;
+                        condExpr->env = unqExpr->env;
+                        decls[id] = condExpr;
                 }
-        }
-
-        const ast::Expr * MemberTupleExpander::postvisit( const ast::UntypedMemberExpr * memberExpr ) {
-                const CodeLocation loc = memberExpr->location;
-        if ( auto tupleExpr = memberExpr->member.as< ast::UntypedTupleExpr >() ) {
-                        auto mutExpr = mutate( tupleExpr );
-                        ast::ptr< ast::Expr > aggr = memberExpr->aggregate->accept( *visitor );
-                        // aggregate expressions which might be impure must be wrapped in unique expressions
-                        if ( Tuples::maybeImpureIgnoreUnique( memberExpr->aggregate ) ) aggr = new ast::UniqueExpr( loc, aggr );
-                        for ( auto & expr : mutExpr->exprs ) {
-                                expr = reconstructMemberExpr( expr, aggr, loc );
-                        }
-                        //delete aggr;
-                        return mutExpr;
-                } else {
-                        // there may be a tuple expr buried in the aggregate
-                        return new ast::UntypedMemberExpr( loc, memberExpr->member, memberExpr->aggregate->accept( *visitor ) );
-                }
+                //delete unqExpr;
+                return ast::deepCopy(decls[id].get());
         }
 } // namespace