Changeset a0ad7dc for src

Timestamp:

Apr 7, 2017, 6:12:50 PM (8 years ago)

Author:

Aaron Moss <a3moss@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

d919f47

Parents:

3a48e283

git-author:

Aaron Moss <a3moss@…> (04/07/17 18:12:21)

git-committer:

Aaron Moss <a3moss@…> (04/07/17 18:12:50)

Message:

Switch alloca's to VLA's for safe in-loop use

File:

• src/GenPoly/Box.cc (modified) (5 diffs)

src/GenPoly/Box.cc

@@ -34 +34 @@
 #include "Parser/ParseNode.h"
 
+#include "SynTree/Attribute.h"
 #include "SynTree/Constant.h"
 #include "SynTree/Declaration.h"
@@ -165 +166 @@
                         using Parent::mutate;
 
+                        PolyGenericCalculator();
+
                         template< typename DeclClass >
                         DeclClass *handleDecl( DeclClass *decl, Type *type );
@@ -198 +201 @@
                         ScopedSet< std::string > knownLayouts;          ///< Set of generic type layouts known in the current scope, indexed by sizeofName
                         ScopedSet< std::string > knownOffsets;          ///< Set of non-generic types for which the offset array exists in the current scope, indexed by offsetofName
+                        UniqueName bufNamer;                           ///< Namer for VLA buffers
                 };
 
@@ -1452 +1456 @@
 ////////////////////////////////////////// PolyGenericCalculator ////////////////////////////////////////////////////
 
+                PolyGenericCalculator::PolyGenericCalculator()
+                        : Parent(), knownLayouts(), knownOffsets(), bufNamer( "_buf" ) {}
+
                 void PolyGenericCalculator::beginTypeScope( Type *ty ) {
                         scopeTyVars.beginScope();
@@ -1528 +1535 @@
                         if ( ObjectDecl *objectDecl = dynamic_cast< ObjectDecl *>( declStmt->get_decl() ) ) {
                                 if ( findGeneric( objectDecl->get_type() ) ) {
-                                        // change initialization of a polymorphic value object
-                                        // to allocate storage with alloca
+                                        // change initialization of a polymorphic value object to allocate via a VLA
+                                        // (alloca was previously used, but can't be safely used in loops)
                                         Type *declType = objectDecl->get_type();
-                                        UntypedExpr *alloc = new UntypedExpr( new NameExpr( "__builtin_alloca" ) );
-                                        alloc->get_args().push_back( new NameExpr( sizeofName( mangleType( declType ) ) ) );
+                                        std::string bufName = bufNamer.newName();
+                                        ObjectDecl *newBuf = new ObjectDecl( bufName, Type::StorageClasses(), LinkageSpec::C, 0, 
+                                                new ArrayType( Type::Qualifiers(), new BasicType( Type::Qualifiers(), BasicType::Kind::Char), new NameExpr( sizeofName( mangleType(declType) ) ), 
+                                                true, false, std::list<Attribute*>{ new Attribute( std::string{"aligned"}, std::list<Expression*>{ new ConstantExpr( Constant::from_int(8) ) } ) } ), 0 );
+                                        stmtsToAdd.push_back( new DeclStmt( noLabels, newBuf ) );
 
                                         delete objectDecl->get_init();
 
-                                        std::list<Expression*> designators;
-                                        objectDecl->set_init( new SingleInit( alloc, designators, false ) ); // not constructed
+                                        objectDecl->set_init( new SingleInit( new NameExpr( bufName ) ) );
                                 }
                         }