On Tue, Dec 1, 2015 at 7:02 AM, Gary Funck <g...@intrepid.com> wrote:
>
> Background
> ----------
>
> An overview email, describing the UPC-related changes is here:
> https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00005.html
>
> The GUPC branch is described here:
> http://gcc.gnu.org/projects/gupc.html
>
> The UPC-related source code differences are summarized here:
> http://gccupc.org/gupc-changes
>
> All languages (c, c++, fortran, go, lto, objc, obj-c++) have been
> bootstrapped; no test suite regressions were introduced,
> relative to the GCC trunk.
>
> If you are on the cc-list, your name was chosen either
> because you are listed as a maintainer for the area that
> applies to the patches described in this email, or you
> were a frequent contributor of patches made to files listed
> in this email.
>
> In the change log entries included in each patch, the directory
> containing the affected files is listed, followed by the files.
> When the patches are applied, the change log entries will be
> distributed to the appropriate ChangeLog file.
>
> Overview
> --------
>
> Given that UPC pointers-to-shared (PTS's) have special arithmetic rules
> and their internal representation is a structure with
> three separate fields, they are not meaningfully convertible to integers
> and pointer arithmetic involving PTS's cannot be optimized in
> the same fashion as normal "C" pointer arithmetic. Further,
> the representation of a NULL pointer-to-shared is different from
> a "C" null pointer. Logic has been added to convert.c and jump.c
> to handle operations involving UPC PTS's. In function.c,
> UPC pointers-to-shared which have an internal representation that
> is a 'struct' are treated as aggregates. Also in function.c
> logic is added that prevents marking them as potential
> pointer register values.
>
> In varasm.c, a check is added for the linker section used by
> UPC to coalesce file scoped UPC shared variables. This section
> is used only to assign offsets into UPC's shared data area for
> the UPC shared variables. When UPC linker scripts are supported,
> this shared section is not loaded and has an origin of 0.
I think this also shows that using a POINTER_TYPE for a non-pointer
is bogus. POINTER_TYPE is not for "semantically a pointer" but
for pointers. Just use RECORD_TYPE here (and of course lower
things earlier).
Richard.
> 2015-11-30 Gary Funck <g...@intrepid.com>
>
> gcc/
> * convert.c (convert_to_pointer): Add check for null
> UPC pointer-to-shared.
> (convert_to_integer): Do not optimize pointer
> subtraction for UPC pointers-to-shared.
> (convert_to_integer): Issue error for an attempt
> to convert a UPC pointer-to-shared to an integer.
> * dojump.c (do_jump): If a UPC pointer-to-shared conversion
> can change representation, it must be compared in the result type.
> * function.c (aggregate_value_p): Handle 'struct' pointer-to-shared
> values as an aggregate when passing them as a return value.
> (assign_parm_setup_reg): Do not target UPC pointers-to-shared that are
> represented as a 'struct' into a pointer register.
> * varasm.c (default_section_type_flags): Handle UPC's shared
> section as BSS, and if a UPC link script is supported,
> make it a non-loadable, read-only section.
>
> Index: gcc/convert.c
> ===================================================================
> --- gcc/convert.c (.../trunk) (revision 231059)
> +++ gcc/convert.c (.../branches/gupc) (revision 231080)
> @@ -53,6 +53,14 @@ convert_to_pointer_1 (tree type, tree ex
> if (TREE_TYPE (expr) == type)
> return expr;
>
> + if (integer_zerop (expr) && POINTER_TYPE_P (type)
> + && SHARED_TYPE_P (TREE_TYPE (type)))
> + {
> + expr = copy_node (upc_null_pts_node);
> + TREE_TYPE (expr) = build_unshared_type (type);
> + return expr;
> + }
> +
> switch (TREE_CODE (TREE_TYPE (expr)))
> {
> case POINTER_TYPE:
> @@ -437,6 +445,16 @@ convert_to_integer_1 (tree type, tree ex
> return error_mark_node;
> }
>
> + /* Can't optimize the conversion of UPC shared pointer difference. */
> + if (ex_form == MINUS_EXPR
> + && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))
> + && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
> + && SHARED_TYPE_P (TREE_TYPE (TREE_TYPE (TREE_OPERAND (expr, 0))))
> + && SHARED_TYPE_P (TREE_TYPE (TREE_TYPE (TREE_OPERAND (expr, 1)))))
> + {
> + return build1 (CONVERT_EXPR, type, expr);
> + }
> +
> if (ex_form == COMPOUND_EXPR)
> {
> tree t = convert_to_integer_1 (type, TREE_OPERAND (expr, 1), dofold);
> @@ -581,6 +599,12 @@ convert_to_integer_1 (tree type, tree ex
> {
> case POINTER_TYPE:
> case REFERENCE_TYPE:
> + if (SHARED_TYPE_P (TREE_TYPE (intype)))
> + {
> + error ("invalid conversion from a UPC pointer-to-shared "
> + "to an integer");
> + expr = integer_zero_node;
> + }
> if (integer_zerop (expr))
> return build_int_cst (type, 0);
>
> Index: gcc/dojump.c
> ===================================================================
> --- gcc/dojump.c (.../trunk) (revision 231059)
> +++ gcc/dojump.c (.../branches/gupc) (revision 231080)
> @@ -468,6 +468,10 @@ do_jump (tree exp, rtx_code_label *if_fa
> < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
> goto normal;
> case NON_LVALUE_EXPR:
> + /* if a shared pointer conversion that will change representation,
> + then we have to compare in the result type. */
> + if (PTS_CVT_OP_P (exp))
> + goto normal;
> case ABS_EXPR:
> case NEGATE_EXPR:
> case LROTATE_EXPR:
> Index: gcc/function.c
> ===================================================================
> --- gcc/function.c (.../trunk) (revision 231059)
> +++ gcc/function.c (.../branches/gupc) (revision 231080)
> @@ -2073,6 +2073,17 @@ aggregate_value_p (const_tree exp, const
> if (flag_pcc_struct_return && AGGREGATE_TYPE_P (type))
> return 1;
>
> + /* Pointers-to-shared must be considered as aggregates for
> + the purpose of passing them as return values, but only
> + when the underlying mode of the representation would
> + require that its value be passed on the stack.
> + This occurs when using the 'struct' representation
> + of a shared pointer. */
> + if (flag_pcc_struct_return && POINTER_TYPE_P (type)
> + && SHARED_TYPE_P (TREE_TYPE (type))
> + && AGGREGATE_TYPE_P (upc_pts_rep_type_node))
> + return 1;
> +
> if (targetm.calls.return_in_memory (type, fntype))
> return 1;
>
> @@ -3384,6 +3395,13 @@ assign_parm_setup_reg (struct assign_par
> set_dst_reg_note (linsn, REG_EQUIV, equiv_stack_parm, parmreg);
> }
>
> + /* Do not target UPC pointers-to-shared values into a pointer
> + register if they are represented as struct's. */
> + if (POINTER_TYPE_P (TREE_TYPE (parm))
> + && SHARED_TYPE_P (TREE_TYPE (TREE_TYPE (parm)))
> + && AGGREGATE_TYPE_P (upc_pts_rep_type_node))
> + return;
> +
> /* For pointer data type, suggest pointer register. */
> if (POINTER_TYPE_P (TREE_TYPE (parm)))
> mark_reg_pointer (parmreg,
> Index: gcc/varasm.c
> ===================================================================
> --- gcc/varasm.c (.../trunk) (revision 231059)
> +++ gcc/varasm.c (.../branches/gupc) (revision 231080)
> @@ -6194,6 +6194,21 @@ default_section_type_flags (tree decl, c
> || strcmp (name, ".preinit_array") == 0))
> flags |= SECTION_NOTYPE;
>
> + /* The UPC shared section is not loaded into memory.
> + It is used only to layout shared variables. */
> + if (!(flags & (SECTION_CODE | SECTION_BSS | SECTION_TLS)))
> + {
> + const char *upc_shared_section_name =
> + targetm.upc.shared_section_name ();
> + if (upc_shared_section_name
> + && (strcmp (name, upc_shared_section_name) == 0))
> + {
> + flags |= SECTION_BSS;
> + if (targetm.upc.link_script_p ())
> + flags = SECTION_DEBUG | (flags & ~SECTION_WRITE);
> + }
> + }
> +
> return flags;
> }
>
