[PATCH] Adding _Dependent_ptr type qualifier in C part 1/3

Martin Sebor msebor@gmail.com
Tue Jul 30 20:03:00 GMT 2019


On 7/30/19 1:13 AM, Akshat Garg wrote:
> Hi,
> This patch includes C front-end code for a type qualifier _Dependent_ptr.

Just some very high-level comments/questions.  I only followed
the _Dependent_ptr discussion from a distance and I'm likely
missing some context so the first thing I looked for in this
patch is documentation of the new qualifier.  Unless it's
a proposed C2x feature that I missed I would expect to find it
in section 6 - Extensions to the C Language Family of the manual.
I saw the references to WG21's p0190r4 in the tests but the paper
doesn't mention _Dependent_ptr, and I found no references to a C
paper that does.  If it has been proposed for C2X as well can
you point to it?  (In that case, or if a proposal is planned,
the feature should probably either only be available with
-std=c2x and -std=gnu2x or a pedantic warning should be issued
for its use in earlier modes similarly to how uses of _Atomic
are diagnosed in pre-C11 modes.)

Martin

> The patch has been tested using the following
> make bootstrap -j 4
> make -k check -j 4
> 
> on x86_64-linux-gnu.
> 
> Thanks,
> Akshat
> 
> gcc/ChangeLog:
> 
> 2019-07-30  Akshat Garg <xkspr7@gmail.com>
> 
>          * c-family/c-common.c (struct c_common_resword c_common_reswords):
> Add "_Dependent_ptr".
>          (c_apply_type_quals_to_decl): Set the flag for _Dependent_ptr if
> qualified.
>          (keyword_is_type_qualifier): Add RID_DEPENDENT_PTR.
>          * c-family/c-common.h (enum rid): Add RID_DEPENDENT_PTR.
>          * c-family/c-format.c (check_format_types): Add dependent pointer
> as a qualifier check.
>          * c-family/c-pretty-print.c (pp_c_cv_qualifiers): Handle dependent
> pointer qualifier.
>          * c/c-aux-info.c (gen_type): Handle dependent pointer qualifier.
>          (gen_decl): Handle dependent pointer qualifier.
>          * c/c-decl.c (merge_decls): Set old declaration as having dependent
> pointer qualification if new declaration has one.
>          (shadow_tag_warned): Add dependent_ptr_p to declspecs check.
>          (quals_from_declspecs): Add dependent_ptr_p to declspecs check.
>          (grokdeclarator): Add checks for dependent pointer qualifier and
> warn of duplicate or errors. Allow dependent pointer for pointer types only.
>          * c/c-parser.c (c_keyword_starts_typename, c_token_is_qualifier,
> c_token_starts_declspecs): Add RID_DEPENDENT_PTR.
>          (c_parser_static_assert_declaration_no_semi): Add _Dependent_ptr
> qualifier in comments.
>          (c_parser_declspecs, c_parser_attribute_any_word): Add
> RID_DEPENDENT_PTR.
>          * c/c-tree.h (C_TYPE_FIELDS_DEPENDENT_PTR): New macro to mark
> dependent pointer.
>          (enum c_declspec_word): Add cdw_dependent_ptr.
>          (struct c_declspecs): Add dependent_ptr_p field.
>          * print-tree.c (print_node): Print dependent_ptr qualifier.
>          * tree-core.hi (enum cv_qualifier): Add TYPE_QUAL_DEPENDENT_PTR.
>          (enum tree_index): Add TI_DEPENDENT_PTR_TYPE.
>          (struct tree_base): Add dependent_ptr_flag field.
>          * tree-pretty-print.c (dump_generic_node): Print dependent pointer
> type qualifier.
>          * tree.c (fld_type_variant, set_type_quals): Set TYPE_DEPENDENT_PTR.
>          * tree.h (TREE_THIS_DEPENDENT_PTR): New macro. To access
> dependent_ptr_flag field in tree_base.
>          (TYPE_DEPENDENT_PTR): New accessor macro.
>          (TYPE_QUALS, TYPE_QUALS_NO_ADDR_SPACE): Add TYPE_QUAL_DEPENDENT_PTR.
>          (dependent_ptrTI_type_node): Add new type node.
> 
> gcc/testsuite/ChangeLog:
> 
> 2019-07-30  Akshat Garg <xkspr7@gmail.com>
> 
>          * gcc.dg/c11-dependent_ptr-test-1.c: New test for _Dependent_ptr
> qualifier.
>          * gcc.dg/{p0190r4_fig8, p0190r4_fig9, p0190r4_fig10, p0190r4_fig11,
> p0190r4_fig12, p0190r4_fig13}.c: New tests from document P0190R4 for
> _Dependent_ptr qualifier.
> 
> diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
> index cb92710..4f09037 100644
> --- a/gcc/c-family/c-common.c
> +++ b/gcc/c-family/c-common.c
> @@ -345,6 +345,7 @@ const struct c_common_resword c_common_reswords[] =
>     { "_Alignas", RID_ALIGNAS,   D_CONLY },
>     { "_Alignof", RID_ALIGNOF,   D_CONLY },
>     { "_Atomic", RID_ATOMIC,    D_CONLY },
> + { "_Dependent_ptr",   RID_DEPENDENT_PTR,  0 },
>     { "_Bool", RID_BOOL,      D_CONLY },
>     { "_Complex", RID_COMPLEX, 0 },
>     { "_Imaginary", RID_IMAGINARY, D_CONLY },
> @@ -3546,6 +3547,11 @@ c_apply_type_quals_to_decl (int type_quals, tree
> decl)
>         TREE_SIDE_EFFECTS (decl) = 1;
>         TREE_THIS_VOLATILE (decl) = 1;
>       }
> +  if (type_quals & TYPE_QUAL_DEPENDENT_PTR)
> +    {
> +      TREE_SIDE_EFFECTS (decl) = 1;
> +      TREE_THIS_DEPENDENT_PTR (decl) = 1;
> +    }
>     if (type_quals & TYPE_QUAL_RESTRICT)
>       {
>         while (type && TREE_CODE (type) == ARRAY_TYPE)
> @@ -7851,6 +7857,7 @@ keyword_is_type_qualifier (enum rid keyword)
>       case RID_VOLATILE:
>       case RID_RESTRICT:
>       case RID_ATOMIC:
> +    case RID_DEPENDENT_PTR:
>         return true;
>       default:
>         return false;
> diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
> index 117d729..ab55882 100644
> --- a/gcc/c-family/c-common.h
> +++ b/gcc/c-family/c-common.h
> @@ -68,7 +68,7 @@ enum rid
>     RID_UNSIGNED, RID_LONG,    RID_CONST, RID_EXTERN,
>     RID_REGISTER, RID_TYPEDEF, RID_SHORT, RID_INLINE,
>     RID_VOLATILE, RID_SIGNED,  RID_AUTO,  RID_RESTRICT,
> -  RID_NORETURN, RID_ATOMIC,
> +  RID_NORETURN, RID_ATOMIC, RID_DEPENDENT_PTR,
> 
>     /* C extensions */
>     RID_COMPLEX, RID_THREAD, RID_SAT,
> diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
> index d134116..00769bb 100644
> --- a/gcc/c-family/c-format.c
> +++ b/gcc/c-family/c-format.c
> @@ -4172,6 +4172,7 @@ check_format_types (const substring_loc &fmt_loc,
>     && (TYPE_READONLY (cur_type)
>         || TYPE_VOLATILE (cur_type)
>         || TYPE_ATOMIC (cur_type)
> +      || TYPE_DEPENDENT_PTR (cur_type)
>         || TYPE_RESTRICT (cur_type)))
>    warning (OPT_Wformat_, "extra type qualifiers in format "
>    "argument (argument %d)",
> diff --git a/gcc/c-family/c-pretty-print.c b/gcc/c-family/c-pretty-print.c
> index 3e25624..e034a8f 100644
> --- a/gcc/c-family/c-pretty-print.c
> +++ b/gcc/c-family/c-pretty-print.c
> @@ -181,6 +181,8 @@ pp_c_cv_qualifiers (c_pretty_printer *pp, int
> qualifiers, bool func_type)
> 
>     if (qualifiers & TYPE_QUAL_ATOMIC)
>       pp_c_ws_string (pp, "_Atomic");
> +  if (qualifiers & TYPE_QUAL_DEPENDENT_PTR)
> +    pp_c_ws_string (pp, "_Dependent_ptr");
>     if (qualifiers & TYPE_QUAL_CONST)
>       pp_c_ws_string (pp, func_type ? "__attribute__((const))" : "const");
>     if (qualifiers & TYPE_QUAL_VOLATILE)
> diff --git a/gcc/c/c-aux-info.c b/gcc/c/c-aux-info.c
> index 96bb2e2..514093c 100644
> --- a/gcc/c/c-aux-info.c
> +++ b/gcc/c/c-aux-info.c
> @@ -284,6 +284,8 @@ gen_type (const char *ret_val, tree t, formals_style
> style)
>    case POINTER_TYPE:
>     if (TYPE_ATOMIC (t))
>       ret_val = concat ("_Atomic ", ret_val, NULL);
> +  if (TYPE_DEPENDENT_PTR (t))
> +    ret_val = concat ("_Dependent_ptr ", ret_val, NULL);
>     if (TYPE_READONLY (t))
>       ret_val = concat ("const ", ret_val, NULL);
>     if (TYPE_VOLATILE (t))
> @@ -427,6 +429,8 @@ gen_type (const char *ret_val, tree t, formals_style
> style)
>       }
>     if (TYPE_ATOMIC (t))
>       ret_val = concat ("_Atomic ", ret_val, NULL);
> +  if (TYPE_DEPENDENT_PTR (t))
> +    ret_val = concat ("_Dependent_ptr ", ret_val, NULL);
>     if (TYPE_READONLY (t))
>       ret_val = concat ("const ", ret_val, NULL);
>     if (TYPE_VOLATILE (t))
> @@ -474,6 +478,8 @@ gen_decl (tree decl, int is_func_definition,
> formals_style style)
>       ret_val = concat ("volatile ", ret_val, NULL);
>     if (TREE_READONLY (decl))
>       ret_val = concat ("const ", ret_val, NULL);
> +  if (TREE_THIS_DEPENDENT_PTR (decl))
> +    ret_val = concat ("dependent_ptr ", ret_val, NULL);
> 
>     data_type = "";
> 
> diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
> index f85f481..2047575 100644
> --- a/gcc/c/c-decl.c
> +++ b/gcc/c/c-decl.c
> @@ -2587,6 +2587,9 @@ merge_decls (tree newdecl, tree olddecl, tree
> newtype, tree oldtype)
>     if (TREE_THIS_VOLATILE (newdecl))
>       TREE_THIS_VOLATILE (olddecl) = 1;
> 
> +  if (TREE_THIS_DEPENDENT_PTR (newdecl))
> +    TREE_THIS_DEPENDENT_PTR (olddecl) = 1;
> +
>     /* Merge deprecatedness.  */
>     if (TREE_DEPRECATED (newdecl))
>       TREE_DEPRECATED (olddecl) = 1;
> @@ -2638,6 +2641,7 @@ merge_decls (tree newdecl, tree olddecl, tree
> newtype, tree oldtype)
>     DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (newdecl)
>       |= DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (olddecl);
>     TREE_THIS_VOLATILE (newdecl) |= TREE_THIS_VOLATILE (olddecl);
> +  TREE_THIS_DEPENDENT_PTR (newdecl) |= TREE_THIS_DEPENDENT_PTR (olddecl);
>     DECL_IS_MALLOC (newdecl) |= DECL_IS_MALLOC (olddecl);
>     if (DECL_IS_OPERATOR_NEW_P (olddecl))
>       DECL_SET_IS_OPERATOR_NEW (newdecl, true);
> @@ -4544,6 +4548,7 @@ shadow_tag_warned (const struct c_declspecs
> *declspecs, int warned)
>      && (declspecs->const_p
>          || declspecs->volatile_p
>          || declspecs->atomic_p
> +       || declspecs->dependent_ptr_p
>          || declspecs->restrict_p
>          || declspecs->address_space))
>       {
> @@ -4672,6 +4677,7 @@ quals_from_declspecs (const struct c_declspecs *specs)
>          | (specs->volatile_p ? TYPE_QUAL_VOLATILE : 0)
>          | (specs->restrict_p ? TYPE_QUAL_RESTRICT : 0)
>          | (specs->atomic_p ? TYPE_QUAL_ATOMIC : 0)
> +       | (specs->dependent_ptr_p ? TYPE_QUAL_DEPENDENT_PTR : 0)
>          | (ENCODE_QUAL_ADDR_SPACE (specs->address_space)));
>     gcc_assert (!specs->type
>         && !specs->decl_attr
> @@ -5837,6 +5843,7 @@ grokdeclarator (const struct c_declarator *declarator,
>     int restrictp;
>     int volatilep;
>     int atomicp;
> +  int dependent_ptrp;
>     int type_quals = TYPE_UNQUALIFIED;
>     tree name = NULL_TREE;
>     bool funcdef_flag = false;
> @@ -6003,6 +6010,7 @@ grokdeclarator (const struct c_declarator *declarator,
>     restrictp = declspecs->restrict_p + TYPE_RESTRICT (element_type);
>     volatilep = declspecs->volatile_p + TYPE_VOLATILE (element_type);
>     atomicp = declspecs->atomic_p + TYPE_ATOMIC (element_type);
> +  dependent_ptrp = declspecs->dependent_ptr_p + TYPE_DEPENDENT_PTR
> (element_type);
>     as1 = declspecs->address_space;
>     as2 = TYPE_ADDR_SPACE (element_type);
>     address_space = ADDR_SPACE_GENERIC_P (as1)? as2 : as1;
> @@ -6015,6 +6023,8 @@ grokdeclarator (const struct c_declarator *declarator,
>       pedwarn_c90 (loc, OPT_Wpedantic, "duplicate %<volatile%>");
>     if (atomicp > 1)
>       pedwarn_c90 (loc, OPT_Wpedantic, "duplicate %<_Atomic%>");
> +  if (dependent_ptrp > 1)
> +    pedwarn_c90 (loc, OPT_Wpedantic, "duplicate %<_Dependent_ptr%>");
> 
>     if (!ADDR_SPACE_GENERIC_P (as1) && !ADDR_SPACE_GENERIC_P (as2) && as1 !=
> as2)
>       error_at (loc, "conflicting named address spaces (%s vs %s)",
> @@ -6031,6 +6041,7 @@ grokdeclarator (const struct c_declarator *declarator,
>    | (restrictp ? TYPE_QUAL_RESTRICT : 0)
>    | (volatilep ? TYPE_QUAL_VOLATILE : 0)
>    | (atomicp ? TYPE_QUAL_ATOMIC : 0)
> + | (dependent_ptrp ? TYPE_QUAL_DEPENDENT_PTR : 0)
>    | ENCODE_QUAL_ADDR_SPACE (address_space));
>     if (type_quals != TYPE_QUALS (element_type))
>       orig_qual_type = NULL_TREE;
> @@ -6042,6 +6053,13 @@ grokdeclarator (const struct c_declarator
> *declarator,
>     if (declspecs->atomic_p && TREE_CODE (type) == ARRAY_TYPE)
>       error_at (loc, "%<_Atomic%>-qualified array type");
> 
> +  /* Applying the _Dependent_ptr qualifier to an array type (through
> +     the use of typedefs or typeof) must be detected here.  If the
> +     qualifier is introduced later, any appearance of applying it to
> +     an array is actually applying it to an element of that array.  */
> +  if (declspecs->dependent_ptr_p && TREE_CODE (type) == ARRAY_TYPE)
> +    error_at (loc, "%<_Dependent_ptr%>-qualified array type");
> +
>     /* Warn about storage classes that are invalid for certain
>        kinds of declarations (parameters, typenames, etc.).  */
> 
> @@ -7214,6 +7232,10 @@ grokdeclarator (const struct c_declarator
> *declarator,
>    /* An uninitialized decl with `extern' is a reference.  */
>    int extern_ref = !initialized && storage_class == csc_extern;
> 
> + /* _Dependent_ptr qualifier only reserved for pointer type variable */
> + if ((type_quals & TYPE_QUAL_DEPENDENT_PTR) && (!POINTER_TYPE_P (type)))
> +  error_at (loc, "invalid use of %<_Dependent_ptr%>");
> +
>    type = c_build_qualified_type (type, type_quals, orig_qual_type,
>          orig_qual_indirect);
> 
> @@ -7294,7 +7316,7 @@ grokdeclarator (const struct c_declarator *declarator,
>    DECL_REGISTER (decl) = 1;
>         }
> 
> -    /* Record constancy and volatility.  */
> +    /* Record constancy, data dependency and volatility.  */
>       c_apply_type_quals_to_decl (type_quals, decl);
> 
>       /* Apply _Alignas specifiers.  */
> @@ -8258,6 +8280,11 @@ finish_struct (location_t loc, tree t, tree
> fieldlist, tree attributes,
>         if (TREE_THIS_VOLATILE (x))
>    C_TYPE_FIELDS_VOLATILE (t) = 1;
> 
> +      /* Any field that is a dependent pointer means variables of this
> + type must be treated in some ways as dependent pointer.  */
> +      if (TREE_THIS_DEPENDENT_PTR (x))
> + C_TYPE_FIELDS_DEPENDENT_PTR (t) = 1;
> +
>         /* Any field of nominal variable size implies structure is too.  */
>         if (C_DECL_VARIABLE_SIZE (x))
>    C_TYPE_VARIABLE_SIZE (t) = 1;
> @@ -10177,6 +10204,12 @@ declspecs_add_qual (location_t loc,
>         prev_loc = specs->locations[cdw_atomic];
>         specs->locations[cdw_atomic] = loc;
>         break;
> +    case RID_DEPENDENT_PTR:
> +      dupe = specs->dependent_ptr_p;
> +      specs->dependent_ptr_p = true;
> +      prev_loc = specs->locations[cdw_dependent_ptr];
> +      specs->locations[cdw_dependent_ptr] = loc;
> +      break;
>       default:
>         gcc_unreachable ();
>       }
> diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
> index 6721049..35e25bb 100644
> --- a/gcc/c/c-parser.c
> +++ b/gcc/c/c-parser.c
> @@ -503,6 +503,7 @@ c_keyword_starts_typename (enum rid keyword)
>       case RID_TYPEOF:
>       case RID_CONST:
>       case RID_ATOMIC:
> +    case RID_DEPENDENT_PTR:
>       case RID_VOLATILE:
>       case RID_RESTRICT:
>       case RID_ATTRIBUTE:
> @@ -606,6 +607,7 @@ c_token_is_qualifier (c_token *token)
>    case RID_RESTRICT:
>    case RID_ATTRIBUTE:
>    case RID_ATOMIC:
> + case RID_DEPENDENT_PTR:
>     return true;
>    default:
>     return false;
> @@ -687,6 +689,7 @@ c_token_starts_declspecs (c_token *token)
>    case RID_SAT:
>    case RID_ALIGNAS:
>    case RID_ATOMIC:
> + case RID_DEPENDENT_PTR:
>    case RID_AUTO_TYPE:
>     return true;
>    default:
> @@ -2575,6 +2578,7 @@ c_parser_static_assert_declaration_no_semi (c_parser
> *parser)
>        volatile
>        address-space-qualifier
>        _Atomic
> +     _Dependent_ptr
> 
>      (restrict is new in C99.)
>      (_Atomic is new in C11.)
> @@ -2865,6 +2869,11 @@ c_parser_declspecs (c_parser *parser, struct
> c_declspecs *specs,
>     else
>       declspecs_add_qual (loc, specs, value);
>     break;
> + case RID_DEPENDENT_PTR:
> +  attrs_ok = true;
> +  declspecs_add_qual (loc, specs, c_parser_peek_token (parser)->value);
> +  c_parser_consume_token (parser);
> +  break;
>    case RID_CONST:
>    case RID_VOLATILE:
>    case RID_RESTRICT:
> @@ -4275,6 +4284,7 @@ c_parser_attribute_any_word (c_parser *parser)
>    case RID_TRANSACTION_ATOMIC:
>    case RID_TRANSACTION_CANCEL:
>    case RID_ATOMIC:
> + case RID_DEPENDENT_PTR:
>    case RID_AUTO_TYPE:
>    case RID_INT_N_0:
>    case RID_INT_N_1:
> diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
> index dae2979..0e416f2 100644
> --- a/gcc/c/c-tree.h
> +++ b/gcc/c/c-tree.h
> @@ -34,6 +34,9 @@ along with GCC; see the file COPYING3.  If not see
>   /* In a RECORD_TYPE or UNION_TYPE, nonzero if any component is volatile.
>   */
>   #define C_TYPE_FIELDS_VOLATILE(TYPE) TREE_LANG_FLAG_2 (TYPE)
> 
> +/* In a RECORD_TYPE or UNION_TYPE, nonzero if any component is dependent
> pointer.  */
> +#define C_TYPE_FIELDS_DEPENDENT_PTR(TYPE) TREE_LANG_FLAG_3 (TYPE)
> +
>   /* In a RECORD_TYPE or UNION_TYPE or ENUMERAL_TYPE
>      nonzero if the definition of the type has already started.  */
>   #define C_TYPE_BEING_DEFINED(TYPE) TYPE_LANG_FLAG_0 (TYPE)
> @@ -279,6 +282,7 @@ enum c_declspec_word {
>     cdw_volatile,
>     cdw_restrict,
>     cdw_atomic,
> +  cdw_dependent_ptr,
>     cdw_saturating,
>     cdw_alignas,
>     cdw_address_space,
> @@ -387,6 +391,8 @@ struct c_declspecs {
>     BOOL_BITFIELD restrict_p : 1;
>     /* Whether "_Atomic" was specified.  */
>     BOOL_BITFIELD atomic_p : 1;
> +  /* Whether "_Dependent_ptr" was specified.  */
> +  BOOL_BITFIELD dependent_ptr_p : 1;
>     /* Whether "_Sat" was specified.  */
>     BOOL_BITFIELD saturating_p : 1;
>     /* Whether any alignment specifier (even with zero alignment) was
> diff --git a/gcc/print-tree.c b/gcc/print-tree.c
> index debea2b..ec4e3db 100644
> --- a/gcc/print-tree.c
> +++ b/gcc/print-tree.c
> @@ -348,6 +348,8 @@ print_node (FILE *file, const char *prefix, tree node,
> int indent,
>       fputs (" addressable", file);
>     if (TREE_THIS_VOLATILE (node))
>       fputs (" volatile", file);
> +  if (TREE_THIS_DEPENDENT_PTR (node))
> +    fputs (" dependent_ptr", file);
>     if (TREE_ASM_WRITTEN (node))
>       fputs (" asm_written", file);
>     if (TREE_USED (node))
> diff --git a/gcc/tree-core.h b/gcc/tree-core.h
> index 60d8c68..3f3e682 100644
> --- a/gcc/tree-core.h
> +++ b/gcc/tree-core.h
> @@ -567,7 +567,8 @@ enum cv_qualifier {
>     TYPE_QUAL_CONST    = 0x1,
>     TYPE_QUAL_VOLATILE = 0x2,
>     TYPE_QUAL_RESTRICT = 0x4,
> -  TYPE_QUAL_ATOMIC   = 0x8
> +  TYPE_QUAL_ATOMIC   = 0x8,
> +  TYPE_QUAL_DEPENDENT_PTR = 0x10
>   };
> 
>   /* Standard named or nameless data types of the C compiler.  */
> @@ -591,6 +592,8 @@ enum tree_index {
>     TI_ATOMICDI_TYPE,
>     TI_ATOMICTI_TYPE,
> 
> +  TI_DEPENDENT_PTR_TYPE,
> +
>     TI_UINT16_TYPE,
>     TI_UINT32_TYPE,
>     TI_UINT64_TYPE,
> @@ -969,6 +972,7 @@ struct GTY(()) tree_base {
>     unsigned asm_written_flag: 1;
>     unsigned nowarning_flag : 1;
>     unsigned visited : 1;
> +  unsigned dependent_ptr_flag : 1;
> 
>     unsigned used_flag : 1;
>     unsigned nothrow_flag : 1;
> diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
> index 9bea132..ae59cea 100644
> --- a/gcc/tree-pretty-print.c
> +++ b/gcc/tree-pretty-print.c
> @@ -1622,6 +1622,8 @@ dump_generic_node (pretty_printer *pp, tree node, int
> spc, dump_flags_t flags,
>     pp_string (pp, "atomic ");
>    if (quals & TYPE_QUAL_CONST)
>     pp_string (pp, "const ");
> + if (quals & TYPE_QUAL_DEPENDENT_PTR)
> +  pp_string (pp, "dependent_ptr ");
>    else if (quals & TYPE_QUAL_VOLATILE)
>     pp_string (pp, "volatile ");
>    else if (quals & TYPE_QUAL_RESTRICT)
> @@ -1768,6 +1770,8 @@ dump_generic_node (pretty_printer *pp, tree node, int
> spc, dump_flags_t flags,
>       pp_string (pp, " volatile");
>     if (quals & TYPE_QUAL_RESTRICT)
>       pp_string (pp, " restrict");
> +  if (quals & TYPE_QUAL_DEPENDENT_PTR)
> +    pp_string (pp, " dependent_ptr");
> 
>     if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (node)))
>       {
> @@ -1871,6 +1875,8 @@ dump_generic_node (pretty_printer *pp, tree node, int
> spc, dump_flags_t flags,
> 
>    if (quals & TYPE_QUAL_ATOMIC)
>     pp_string (pp, "atomic ");
> + if (quals & TYPE_QUAL_DEPENDENT_PTR)
> +  pp_string (pp, "dependent_ptr ");
>    if (quals & TYPE_QUAL_CONST)
>     pp_string (pp, "const ");
>    if (quals & TYPE_QUAL_VOLATILE)
> diff --git a/gcc/tree.c b/gcc/tree.c
> index 8cf75f2..b4dff8d 100644
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -5213,6 +5213,7 @@ fld_type_variant (tree first, tree t, class
> free_lang_data_d *fld,
>     TYPE_READONLY (v) = TYPE_READONLY (t);
>     TYPE_VOLATILE (v) = TYPE_VOLATILE (t);
>     TYPE_ATOMIC (v) = TYPE_ATOMIC (t);
> +  TYPE_DEPENDENT_PTR (v) = TYPE_DEPENDENT_PTR (t);
>     TYPE_RESTRICT (v) = TYPE_RESTRICT (t);
>     TYPE_ADDR_SPACE (v) = TYPE_ADDR_SPACE (t);
>     TYPE_NAME (v) = TYPE_NAME (t);
> @@ -6348,6 +6349,7 @@ set_type_quals (tree type, int type_quals)
>     TYPE_VOLATILE (type) = (type_quals & TYPE_QUAL_VOLATILE) != 0;
>     TYPE_RESTRICT (type) = (type_quals & TYPE_QUAL_RESTRICT) != 0;
>     TYPE_ATOMIC (type) = (type_quals & TYPE_QUAL_ATOMIC) != 0;
> +  TYPE_DEPENDENT_PTR (type) = (type_quals & TYPE_QUAL_DEPENDENT_PTR) != 0;
>     TYPE_ADDR_SPACE (type) = DECODE_QUAL_ADDR_SPACE (type_quals);
>   }
> 
> diff --git a/gcc/tree.h b/gcc/tree.h
> index 4aa2c4a..0c2f192 100644
> --- a/gcc/tree.h
> +++ b/gcc/tree.h
> @@ -789,6 +789,9 @@ extern void omp_clause_range_check_failed (const_tree,
> const char *, int,
>      If this bit is set in an expression, so is TREE_SIDE_EFFECTS.  */
>   #define TREE_THIS_VOLATILE(NODE) ((NODE)->base.volatile_flag)
> 
> +/* Nonzero means this expression is involved in some data dependency.  */
> +#define TREE_THIS_DEPENDENT_PTR(NODE) ((NODE)->base.dependent_ptr_flag)
> +
>   /* Nonzero means this node will not trap.  In an INDIRECT_REF, means
>      accessing the memory pointed to won't generate a trap.  However,
>      this only applies to an object when used appropriately: it doesn't
> @@ -2070,6 +2073,9 @@ extern machine_mode vector_type_mode (const_tree);
>   /* Nonzero in a type considered atomic as a whole.  */
>   #define TYPE_ATOMIC(NODE) (TYPE_CHECK (NODE)->base.u.bits.atomic_flag)
> 
> +/* Nonzero in a type considered dependent_ptr as a whole.  */
> +#define TYPE_DEPENDENT_PTR(NODE) (TYPE_CHECK
> (NODE)->base.dependent_ptr_flag)
> +
>   /* Means this type is const-qualified.  */
>   #define TYPE_READONLY(NODE) (TYPE_CHECK (NODE)->base.readonly_flag)
> 
> @@ -2100,6 +2106,7 @@ extern machine_mode vector_type_mode (const_tree);
>     ((int) ((TYPE_READONLY (NODE) * TYPE_QUAL_CONST) \
>     | (TYPE_VOLATILE (NODE) * TYPE_QUAL_VOLATILE) \
>     | (TYPE_ATOMIC (NODE) * TYPE_QUAL_ATOMIC) \
> +  | (TYPE_DEPENDENT_PTR (NODE) * TYPE_QUAL_DEPENDENT_PTR)   \
>     | (TYPE_RESTRICT (NODE) * TYPE_QUAL_RESTRICT) \
>     | (ENCODE_QUAL_ADDR_SPACE (TYPE_ADDR_SPACE (NODE)))))
> 
> @@ -2108,6 +2115,7 @@ extern machine_mode vector_type_mode (const_tree);
>     ((int) ((TYPE_READONLY (NODE) * TYPE_QUAL_CONST) \
>     | (TYPE_VOLATILE (NODE) * TYPE_QUAL_VOLATILE) \
>     | (TYPE_ATOMIC (NODE) * TYPE_QUAL_ATOMIC) \
> +  | (TYPE_DEPENDENT_PTR (NODE) * TYPE_QUAL_DEPENDENT_PTR)   \
>     | (TYPE_RESTRICT (NODE) * TYPE_QUAL_RESTRICT)))
> 
>   /* The same as TYPE_QUALS without the address space and atomic
> @@ -3940,6 +3948,8 @@ tree_strip_any_location_wrapper (tree exp)
>   #define atomicDI_type_node global_trees[TI_ATOMICDI_TYPE]
>   #define atomicTI_type_node global_trees[TI_ATOMICTI_TYPE]
> 
> +#define dependent_ptrTI_type_node global_trees[TI_DEPENDENT_PTR_TYPE]
> +
>   #define uint16_type_node global_trees[TI_UINT16_TYPE]
>   #define uint32_type_node global_trees[TI_UINT32_TYPE]
>   #define uint64_type_node global_trees[TI_UINT64_TYPE]
> diff --git a/gcc/testsuite/gcc.dg/c11-dependent_ptr-test-1.c
> b/gcc/testsuite/gcc.dg/c11-dependent_ptr-test-1.c
> new file mode 100644
> index 0000000..8a70733
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/c11-dependent_ptr-test-1.c
> @@ -0,0 +1,62 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr qualified pointer
> initialization tests. */
> +/* { dg-do run } */
> +/* { dg-options "-std=c11 -pedantic-errors" } */
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +
> +#define TEST_SIMPLE_ASSIGN(TYPE)           \
> +  do                   \
> +    {                 \
> +      static volatile _Atomic (TYPE) * _Dependent_ptr a;     \
> +      static volatile _Atomic (TYPE) b;         \
> +      a = &b;               \
> +      if (a != &b)               \
> +   abort();               \
> +    }                                                             \
> +  while (0)
> +
> +#define TEST_SIMPLE_ASSIGN_POINTER()           \
> +  do                                                               \
> +    {                                                             \
> +      TEST_SIMPLE_ASSIGN (_Bool);         \
> +      TEST_SIMPLE_ASSIGN (char);           \
> +      TEST_SIMPLE_ASSIGN (signed char);         \
> +      TEST_SIMPLE_ASSIGN (unsigned char);       \
> +      TEST_SIMPLE_ASSIGN (signed short);         \
> +      TEST_SIMPLE_ASSIGN (unsigned short);         \
> +      TEST_SIMPLE_ASSIGN (signed int);           \
> +      TEST_SIMPLE_ASSIGN (unsigned int);         \
> +      TEST_SIMPLE_ASSIGN (signed long);         \
> +      TEST_SIMPLE_ASSIGN (unsigned long);       \
> +      TEST_SIMPLE_ASSIGN (signed long long);         \
> +      TEST_SIMPLE_ASSIGN (unsigned long long);         \
> +      TEST_SIMPLE_ASSIGN (float);         \
> +      TEST_SIMPLE_ASSIGN (double);           \
> +      TEST_SIMPLE_ASSIGN (long double);         \
> +      TEST_SIMPLE_ASSIGN (_Complex float);         \
> +      TEST_SIMPLE_ASSIGN (_Complex double);       \
> +      TEST_SIMPLE_ASSIGN (_Complex long double);       \
> +      struct new_struct { struct new_struct * _Dependent_ptr next; };   \
> +      struct new_struct * _Dependent_ptr s;         \
> +      s = malloc (sizeof (struct new_struct));         \
> +      struct new_struct t;             \
> +      s->next = &t;             \
> +      if (s->next != &t)             \
> +        abort();               \
> +    }                 \
> +  while (0)
> +
> +static void
> +test_simple_assign (void)
> +{
> +  TEST_SIMPLE_ASSIGN_POINTER ();
> +}
> +
> +int main (void)
> +{
> +  test_simple_assign ();
> +  exit (0);
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig10.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig10.c
> new file mode 100644
> index 0000000..057c2ba
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig10.c
> @@ -0,0 +1,46 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test for checking dependency
> through non-local storage. Refer figure 10 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +_Atomic struct rcutest *gp;
> +struct rcutest *gslp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest *_Dependent_ptr p = rcu_dereference (gp); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +  gslp = p;
> +  p = gslp;
> +  if (p)
> +    assert (p->a = 42);
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig11.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig11.c
> new file mode 100644
> index 0000000..39c4b61
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig11.c
> @@ -0,0 +1,51 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test in which reload kills
> dependency. Refer figure 11 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +_Atomic struct rcutest *gp;
> +_Atomic struct rcutest *gsgp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest * _Dependent_ptr p = rcu_dereference (gp); /* {
> dg-warning "\\\[-Wincompatible-pointer-types]" } */
> +  atomic_store_explicit(&gsgp, p, memory_order_relaxed); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread2 ()
> +{
> +  struct rcutest *p;
> +
> +  p = atomic_load_explicit(&gsgp, memory_order_relaxed); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +  if (p)
> +    assert(p->a == 42);
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig12.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig12.c
> new file mode 100644
> index 0000000..4f7fcd3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig12.c
> @@ -0,0 +1,53 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test when casting a dependency
> pointer to another pointer type which in turn reserves the dependency.
> Refer figure 12 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +struct rcutest1
> +{
> +  int a;
> +  struct rcutest rt;
> +};
> +
> +_Atomic struct rcutest *gp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest * _Dependent_ptr p;
> +  struct rcutest1 *_Dependent_ptr q;
> +
> +  p = rcu_dereference (gp); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +  q = p;                /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +  if (q)
> +    assert(q->a == 42);
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig13.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig13.c
> new file mode 100644
> index 0000000..b4010fc
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig13.c
> @@ -0,0 +1,48 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test: casting to non-pointer
> kills dependency. Refer figure 13 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +_Atomic struct rcutest *gp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest * _Dependent_ptr p;
> +  long int q;
> +
> +  p = rcu_dereference (gp); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +  q = (long int)(p);
> +  p = (_Dependent_ptr struct rcutest *)q;
> +  if (p)
> +    assert(p->a == 42);
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig8.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig8.c
> new file mode 100644
> index 0000000..e706a9b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig8.c
> @@ -0,0 +1,44 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test for checking simple
> left-hand side dependency. Refer figure 8 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +_Atomic struct rcutest *gp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  assert (p->a != 43);
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest * _Dependent_ptr p = rcu_dereference (gp); /* {
> dg-warning "\\\[-Wincompatible-pointer-types]" } */
> +  if (p)
> +    p->a = 43;
> +}
> diff --git a/gcc/testsuite/gcc.dg/p0190r4_fig9.c
> b/gcc/testsuite/gcc.dg/p0190r4_fig9.c
> new file mode 100644
> index 0000000..32f67b3
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/p0190r4_fig9.c
> @@ -0,0 +1,43 @@
> +/* Test for _Dependent_ptr. _Dependent_ptr test for checking simple
> right-hand side dependency. Refer figure 9 in document p0190r4 (
> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0190r4.pdf). */
> +/* { dg-do compile } */
> +/* { dg-options "-std=c11 -pedantic" } */
> +
> +#include <stdatomic.h>
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void abort (void);
> +extern void exit (int);
> +extern void *malloc (size_t);
> +extern int assert ();
> +
> +struct rcutest
> +{
> +  int a;
> +  int b;
> +  int c;
> +};
> +
> +_Atomic struct rcutest *gp;
> +
> +#define rcu_assign_pointer(p,v) \
> +  atomic_store_explicit(&(p), (v), memory_order_release);
> +
> +#define rcu_dereference(p) \
> +  atomic_load_explicit(&(p), memory_order_consume);
> +
> +void thread0 ()
> +{
> +  struct rcutest *p;
> +
> +  p = (struct rcutest *)malloc (sizeof (*p));
> +  assert (p);
> +  p->a = 42;
> +  rcu_assign_pointer (gp,p); /* { dg-warning
> "\\\[-Wincompatible-pointer-types]" } */
> +}
> +
> +void thread1 ()
> +{
> +  struct rcutest * _Dependent_ptr p = rcu_dereference (gp); /* {
> dg-warning "\\\[-Wincompatible-pointer-types]" } */
> +  if (p)
> +    assert (p->a = 42);
> +}
> 



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