This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

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


And please see the following URL for an update:

http://www.rdrop.com/~paulmck/submission/DNNNN%20_Dependent_ptr%20to%20simplify%20carries%20a%20dependency.pdf

This adds a description of conversions, warnings, and patches.

							Thanx, Paul

On Sun, Aug 04, 2019 at 04:11:12PM -0700, Paul E. McKenney wrote:
> Good points!
> 
> On the type-qualifier interactions, here is an initial list.  Thoughts?
> 
> 							Thanx, Paul
> 
> _Alignas: Dependency-breaking optimizations would be avoided, and the
> variable would be aligned as specified.
> 
> _Atomic: Dependency-breaking optimizations would be avoided, and the
> variable would be accessed using C11 atomics.
> 
> const: This is not particularly useful for variables with static storage
> duration because compile-time initialization does not require dependency
> ordering, but then again, use of _Dependent_ptr on such variables is
> suspect to begin with.  Otherwise, the const _Dependent_ptr variable
> would normally be initialized from another _Dependent_ptr variable or
> from a memory_order_consume load.  The variable would disallow further
> stores and avoid breaking dependencies.
> 
> extern: Dependency-breaking optimizations would be avoided, and the
> variable would be usable within other translation units.  This is
> also an unusual addition to a _Dependent_ptr unless also accompanied by
> _Thread_local because there are no known non-suspect multi-threaded-access
> use cases for _Dependent_ptr.
> 
> register: Dependency-breaking optimizations would be avoided, and the
> compiler would be given a hint to keep the variable in a register.
> 
> restrict: Dependency-breaking optimizations would be avoided, and the
> compiler may assume that the pointed-to object is only accessed through
> this pointer and through pointers derived from it.
> 
> static: Dependency-breaking optimizations would be avoided, and the
> variable would be static.  This is also an unusual addition to a
> _Dependent_ptr unless also accompanied by _Thread_local because there are
> no known non-suspect multi-threaded-access use cases for _Dependent_ptr.
> 
> _Thread_local: The dependency-carrying variable is thread-local, and
> avoids dependency-breaking optimizations.
> 
> volatile: All accesses would be executed as per the abstract machine,
> and dependency-breaking optimizations would be avoided.
> 
> On Fri, Aug 02, 2019 at 08:30:49PM -0600, Martin Sebor wrote:
> > On 8/1/19 9:26 AM, Paul McKenney wrote:
> > >Excellent point, this discussion needs to be made official.
> > >Please see attached for an initial draft of a working paper.
> > >
> > >Thoughts?
> > 
> > The draft is a start but it (obviously) needs a lot of work to cover
> > the constraints and semantics so I'll just comment on the patch in
> > a bit more detail.
> > 
> > Since the feature is being (or will be) proposed to WG14 and could
> > change I would expect it to be only available under -std=c2x and
> > disabled otherwise, so that code that makes use of it does so with
> > the understanding that it's only experimental.  (I just noticed
> > Akshat email with a tweak to the patch.  I'm not sure that issuing
> > a pedantic warning and having the name in the implementation namepace
> > is enough but others (the C FE maintainers) will know better.)
> > 
> > Other than that, I would also expect to see more extensive test
> > coverage, at a minimum to exercise error detection (invalid uses,
> > conversions, etc.).  For example, I see the code that rejects it
> > but no tests for declaring, say, a _Dependent_ptr-qualified integer.
> > What I don't think I see is code that rejects _Dependent_ptr-qualified
> > function pointers (AFAIK, POINTER_TYPE_P evaluates to nonzero for both).
> > Is that intended?  (And if so, what does it mean?)    I also see that
> > the new tests look for warnings but it's not clear to me that that's
> > their intent or that the dg-warning directives are being used to
> > "suppress" warnings for issues in the tests.  For instance, this
> > is common:
> > 
> >   rcu_assign_pointer (gp,p);		/* { dg-warning
> > "\\\[-Wincompatible-pointer-types]" } */
> > 
> > but neither gp nor p is a  _Dependent_ptr.  (I may be missing
> > the purpose of the compile-only tests.  E.g., the only thing
> > p0190r4_fig10.c seems to be exercising besides that the _Dependent_ptr
> > qualifier is accepted is a couple of warnings, one of which is the one
> > above.)  I would suggest to look at tests for other qualifiers for
> > examples and model the new ones after those.
> > 
> > I'm also wondering how the new qualifier interacts with others like
> > const.  Should all combinations of qualifiers be accepted and do
> > they affect the semantics in any interesting way?  This is probably
> > something to cover in the proposal.
> > 
> > Martin
> > 
> > >
> > >                                          Thanx, Paul
> > >
> > >On Tue, Jul 30, 2019 at 12:46 PM Martin Sebor <msebor@gmail.com> wrote:
> > >>
> > >>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);
> > >>>+}
> > >>>
> > >>
> > 


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]