On Thu, 28 Apr 2016, Richard Biener wrote:
> On Thu, 28 Apr 2016, Eric Botcazou wrote:
>
> > > Aww, I was hoping for sth that would not require me to fix all
> > > frontends ...
> >
> > I don't really see how this can work without DECL_EXPR though. You need to
> > define when the variable-sized expressions are evaluated to lay out the
> > type,
> > otherwise it will be laid out on the first use, which may see a different
> > value of the expressions than the definition point. The only way to do
> > that
> > for a locally-defined type is to add a DECL_EXPR in GENERIC, so that the
> > gimplifier evaluates the expressions at the right spot.
>
> Ah, so the C++ FE does this correctly but in addition to that it has
>
> /* When the pointed-to type involves components of variable
> size,
> care must be taken to ensure that the size evaluation code is
> emitted early enough to dominate all the possible later uses
> and late enough for the variables on which it depends to have
> been assigned.
>
> This is expected to happen automatically when the pointed-to
> type has a name/declaration of it's own, but special
> attention
> is required if the type is anonymous.
> ...
> if (!TYPE_NAME (type)
> && (decl_context == NORMAL || decl_context == FIELD)
> && at_function_scope_p ()
> && variably_modified_type_p (type, NULL_TREE))
> /* Force evaluation of the SAVE_EXPR. */
> finish_expr_stmt (TYPE_SIZE (type));
>
> so in this case the type doesn't have an associated TYPE_DECL and thus
> we can't build a DECL_EXPR. To me the correct fix is then to
> always force a TYPE_DECL for variable-modified types.
>
> Jason?
The following works (for the testcase):
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c (revision 235547)
+++ gcc/cp/decl.c (working copy)
@@ -10393,8 +10393,11 @@ grokdeclarator (const cp_declarator *dec
&& (decl_context == NORMAL || decl_context == FIELD)
&& at_function_scope_p ()
&& variably_modified_type_p (type, NULL_TREE))
- /* Force evaluation of the SAVE_EXPR. */
- finish_expr_stmt (TYPE_SIZE (type));
+ {
+ TYPE_NAME (type) = build_decl (UNKNOWN_LOCATION, TYPE_DECL,
+ NULL_TREE, type);
+ add_decl_expr (TYPE_NAME (type));
+ }
if (declarator->kind == cdk_reference)
{
and I have a similar fix for the Fortran FE for one testcase I
reduced to
character(10), dimension (2) :: implicit_result
character(10), dimension (2) :: source
implicit_result = reallocate_hnv (LEN (source))
contains
FUNCTION reallocate_hnv(LEN)
CHARACTER(LEN=LEN), DIMENSION(:), POINTER :: reallocate_hnv
END FUNCTION reallocate_hnv
end
Index: fortran/trans-array.c
===================================================================
--- fortran/trans-array.c (revision 235547)
+++ fortran/trans-array.c (working copy)
@@ -1094,6 +1094,16 @@ gfc_trans_create_temp_array (stmtblock_t
info->descriptor = desc;
size = gfc_index_one_node;
+ /* Emit a DECL_EXPR for the variable sized array type in
+ GFC_TYPE_ARRAY_DATAPTR_TYPE so the gimplification of its type
+ sizes works correctly. */
+ tree arraytype = TREE_TYPE (GFC_TYPE_ARRAY_DATAPTR_TYPE (type));
+ if (! TYPE_NAME (arraytype))
+ TYPE_NAME (arraytype) = build_decl (UNKNOWN_LOCATION, TYPE_DECL,
+ NULL_TREE, arraytype);
+ gfc_add_expr_to_block (pre, build1 (DECL_EXPR,
+ arraytype, TYPE_NAME (arraytype)));
+
/* Fill in the array dtype. */
tmp = gfc_conv_descriptor_dtype (desc);
gfc_add_modify (pre, tmp, gfc_get_dtype (TREE_TYPE (desc)));
I wonder if we can avoid allocating the TYPE_DECL by simply also
allowing TREE_TYPE as operand of a DECL_EXPR (to avoid adding
a 'TYPE_EXPR').
Richard.
