diff options
Diffstat (limited to 'gcc/cp/init.c')
| -rw-r--r-- | gcc/cp/init.c | 171 |
1 files changed, 126 insertions, 45 deletions
diff --git a/gcc/cp/init.c b/gcc/cp/init.c index c2110d1..ec74a25 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -156,70 +156,151 @@ initialize_vtbl_ptrs (addr) dfs_marked_real_bases_queue_p, type); } -/* Types containing pointers to data members cannot be - zero-initialized with zeros, because the NULL value for such - pointers is -1. - - TYPE is a type that requires such zero initialization. The - returned value is the initializer. */ +/* Return an expression for the zero-initialization of an object with + type T. This expression will either be a constant (in the case + that T is a scalar), or a CONSTRUCTOR (in the case that T is an + aggregate). In either case, the value can be used as DECL_INITIAL + for a decl of the indicated TYPE; it is a valid static initializer. + If STATIC_STORAGE_P is TRUE, initializers are only generated for + entities for which zero-initialization does not simply mean filling + the storage with zero bytes. */ tree -build_forced_zero_init (type) - tree type; +build_zero_init (tree type, bool static_storage_p) { - tree init = NULL; + tree init = NULL_TREE; + + /* [dcl.init] + + To zero-initialization storage for an object of type T means: + + -- if T is a scalar type, the storage is set to the value of zero + converted to T. + + -- if T is a non-union class type, the storage for each nonstatic + data member and each base-class subobject is zero-initialized. + + -- if T is a union type, the storage for its first data member is + zero-initialized. + + -- if T is an array type, the storage for each element is + zero-initialized. + + -- if T is a reference type, no initialization is performed. */ - if (AGGREGATE_TYPE_P (type) && !TYPE_PTRMEMFUNC_P (type)) + if (type == error_mark_node) + ; + else if (static_storage_p && zero_init_p (type)) + /* In order to save space, we do not explicitly build initializers + for items that do not need them. GCC's semantics are that + items with static storage duration that are not otherwise + initialized are initialized to zero. */ + ; + else if (SCALAR_TYPE_P (type)) + init = convert (type, integer_zero_node); + else if (CLASS_TYPE_P (type)) + { + tree field; + tree inits; + + /* Build a constructor to contain the initializations. */ + init = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE); + /* Iterate over the fields, building initializations. */ + inits = NULL_TREE; + for (field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field)) + { + if (TREE_CODE (field) != FIELD_DECL) + continue; + + /* Note that for class types there will be FIELD_DECLs + corresponding to base classes as well. Thus, iterating + over TYPE_FIELDs will result in correct initialization of + all of the subobjects. */ + if (static_storage_p && !zero_init_p (TREE_TYPE (field))) + inits = tree_cons (field, + build_zero_init (TREE_TYPE (field), + static_storage_p), + inits); + + /* For unions, only the first field is initialized. */ + if (TREE_CODE (type) == UNION_TYPE) + break; + } + CONSTRUCTOR_ELTS (init) = nreverse (inits); + } + else if (TREE_CODE (type) == ARRAY_TYPE) { - /* This is a default initialization of an aggregate, but not one of - non-POD class type. We cleverly notice that the initialization - rules in such a case are the same as for initialization with an - empty brace-initialization list. */ - init = build (CONSTRUCTOR, NULL_TREE, NULL_TREE, NULL_TREE); + tree index; + tree max_index; + tree inits; + + /* Build a constructor to contain the initializations. */ + init = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE); + /* Iterate over the array elements, building initializations. */ + inits = NULL_TREE; + for (index = size_zero_node, max_index = array_type_nelts (type); + !tree_int_cst_lt (max_index, index); + index = size_binop (PLUS_EXPR, index, size_one_node)) + inits = tree_cons (index, + build_zero_init (TREE_TYPE (type), + static_storage_p), + inits); + CONSTRUCTOR_ELTS (init) = nreverse (inits); } else if (TREE_CODE (type) == REFERENCE_TYPE) - /* --if T is a reference type, no initialization is performed. */ - return NULL_TREE; + ; else - { - init = integer_zero_node; - - if (TREE_CODE (type) == ENUMERAL_TYPE) - /* We must make enumeral types the right type. */ - init = fold (build1 (NOP_EXPR, type, init)); - } + abort (); - init = digest_init (type, init, 0); + /* In all cases, the initializer is a constant. */ + if (init) + TREE_CONSTANT (init) = 1; return init; } -/* [dcl.init]: +/* Build an expression for the default-initialization of an object + with type T. If initialization T requires calling constructors, + this function returns NULL_TREE; the caller is responsible for + arranging for the constructors to be called. */ - To default-initialize an object of type T means: +static tree +build_default_init (type) + tree type; +{ + /* [dcl.init]: - --if T is a non-POD class type (clause _class_), the default construc- - tor for T is called (and the initialization is ill-formed if T has - no accessible default constructor); + To default-initialize an object of type T means: - --if T is an array type, each element is default-initialized; + --if T is a non-POD class type (clause _class_), the default construc- + tor for T is called (and the initialization is ill-formed if T has + no accessible default constructor); - --otherwise, the storage for the object is zero-initialized. + --if T is an array type, each element is default-initialized; - A program that calls for default-initialization of an entity of refer- - ence type is ill-formed. */ + --otherwise, the storage for the object is zero-initialized. -static tree -build_default_init (type) - tree type; -{ + A program that calls for default-initialization of an entity of refer- + ence type is ill-formed. */ + + /* If TYPE_NEEDS_CONSTRUCTING is true, the caller is responsible for + performing the initialization. This is confusing in that some + non-PODs do not have TYPE_NEEDS_CONSTRUCTING set. (For example, + a class with a pointer-to-data member as a non-static data member + does not have TYPE_NEEDS_CONSTRUCTING set.) Therefore, we end up + passing non-PODs to build_zero_init below, which is contrary to + the semantics quoted above from [dcl.init]. + + It happens, however, that the behavior of the constructor the + standard says we should have generated would be precisely the + same as that obtained by calling build_zero_init below, so things + work out OK. */ if (TYPE_NEEDS_CONSTRUCTING (type)) - /* Other code will handle running the default constructor. We can't do - anything with a CONSTRUCTOR for arrays here, as that would imply - copy-initialization. */ return NULL_TREE; - - return build_forced_zero_init (type); + + /* At this point, TYPE is either a POD class type, an array of POD + classes, or something even more inoccuous. */ + return build_zero_init (type, /*static_storage_p=*/false); } /* Subroutine of emit_base_init. */ @@ -335,7 +416,7 @@ build_field_list (t, list, uses_unions_p) for (fields = TYPE_FIELDS (t); fields; fields = TREE_CHAIN (fields)) { /* Skip CONST_DECLs for enumeration constants and so forth. */ - if (TREE_CODE (fields) != FIELD_DECL) + if (TREE_CODE (fields) != FIELD_DECL || DECL_ARTIFICIAL (fields)) continue; /* Keep track of whether or not any fields are unions. */ @@ -3337,7 +3418,7 @@ push_base_cleanups () for (member = TYPE_FIELDS (current_class_type); member; member = TREE_CHAIN (member)) { - if (TREE_CODE (member) != FIELD_DECL) + if (TREE_CODE (member) != FIELD_DECL || DECL_ARTIFICIAL (member)) continue; if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (TREE_TYPE (member))) { |