On Fri, Feb 11, 2022 at 07:55:50PM +0100, Jakub Jelinek via Gcc-patches wrote:
Something like the https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102586#c16
will still be needed with adjusted testcase from
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102586#c15 such that
__builtin_clear_padding is called directly on var addresses rather than
in separate functions.
Here is an updated version of the
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102586#c15
patch which uses FIELD_DECL in the langhook instead of its TREE_TYPE,
and the testcases have been adjusted for the builtin accepting
pointers to non-trivially-copyable types only if it is address of a
declaration.
Bootstrapped/regtested on powerpc64le-linux, ok for trunk?
2022-04-06 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/102586
gcc/
* langhooks.h (struct lang_hooks_for_types): Add classtype_as_base
langhook.
* langhooks-def.h (LANG_HOOKS_CLASSTYPE_AS_BASE): Define.
(LANG_HOOKS_FOR_TYPES_INITIALIZER): Add it.
* gimple-fold.cc (clear_padding_type): Use ftype instead of
TREE_TYPE (field) some more. For artificial FIELD_DECLs without
name try the lang_hooks.types.classtype_as_base langhook and
if it returns non-NULL, use that instead of ftype for recursive call.
gcc/cp/
* cp-objcp-common.h (cp_classtype_as_base): Declare.
(LANG_HOOKS_CLASSTYPE_AS_BASE): Redefine.
* cp-objcp-common.cc (cp_classtype_as_base): New function.
gcc/testsuite/
* g++.dg/torture/builtin-clear-padding-5.C: New test.
* g++.dg/cpp2a/builtin-clear-padding1.C (bar): Uncomment one
call that is now accepted.
--- gcc/langhooks.h.jj 2022-02-11 00:18:54.909437559 +0100
+++ gcc/langhooks.h 2022-04-06 12:34:43.312087323 +0200
@@ -188,6 +188,11 @@ struct lang_hooks_for_types
/* Returns a tree for the unit size of T excluding tail padding that
might be used by objects inheriting from T. */
tree (*unit_size_without_reusable_padding) (tree);
+
+ /* Returns type corresponding to FIELD's type when FIELD is a C++ base class
+ i.e., type without virtual base classes or tail padding. Returns
+ NULL_TREE otherwise. */
+ tree (*classtype_as_base) (const_tree);
};
/* Language hooks related to decls and the symbol table. */
--- gcc/langhooks-def.h.jj 2022-02-11 00:18:54.887437859 +0100
+++ gcc/langhooks-def.h 2022-04-06 12:31:39.149670170 +0200
@@ -216,6 +216,7 @@ extern tree lhd_unit_size_without_reusab
#define LANG_HOOKS_GET_FIXED_POINT_TYPE_INFO NULL
#define LANG_HOOKS_TYPE_DWARF_ATTRIBUTE lhd_type_dwarf_attribute
#define LANG_HOOKS_UNIT_SIZE_WITHOUT_REUSABLE_PADDING
lhd_unit_size_without_reusable_padding
+#define LANG_HOOKS_CLASSTYPE_AS_BASE hook_tree_const_tree_null
#define LANG_HOOKS_FOR_TYPES_INITIALIZER { \
LANG_HOOKS_MAKE_TYPE, \
@@ -243,7 +244,8 @@ extern tree lhd_unit_size_without_reusab
LANG_HOOKS_GET_DEBUG_TYPE, \
LANG_HOOKS_GET_FIXED_POINT_TYPE_INFO, \
LANG_HOOKS_TYPE_DWARF_ATTRIBUTE, \
- LANG_HOOKS_UNIT_SIZE_WITHOUT_REUSABLE_PADDING \
+ LANG_HOOKS_UNIT_SIZE_WITHOUT_REUSABLE_PADDING, \
+ LANG_HOOKS_CLASSTYPE_AS_BASE \
}
/* Declaration hooks. */
--- gcc/gimple-fold.cc.jj 2022-04-06 09:59:32.744654454 +0200
+++ gcc/gimple-fold.cc 2022-04-06 12:35:29.413440758 +0200
@@ -4747,7 +4747,7 @@ clear_padding_type (clear_padding_struct
"have well defined padding bits for %qs",
field, "__builtin_clear_padding");
}
- else if (is_empty_type (TREE_TYPE (field)))
+ else if (is_empty_type (ftype))
continue;
else
{
@@ -4758,8 +4758,9 @@ clear_padding_type (clear_padding_struct
gcc_assert (pos >= 0 && fldsz >= 0 && pos >= cur_pos);
clear_padding_add_padding (buf, pos - cur_pos);
cur_pos = pos;
- clear_padding_type (buf, TREE_TYPE (field),
- fldsz, for_auto_init);
+ if (tree asbase = lang_hooks.types.classtype_as_base (field))
+ ftype = asbase;
+ clear_padding_type (buf, ftype, fldsz, for_auto_init);
cur_pos += fldsz;
}
}
--- gcc/cp/cp-objcp-common.h.jj 2022-02-11 00:18:54.730439994 +0100
+++ gcc/cp/cp-objcp-common.h 2022-04-06 12:31:39.151670141 +0200
@@ -31,6 +31,7 @@ extern int cp_decl_dwarf_attribute (cons
extern int cp_type_dwarf_attribute (const_tree, int);
extern void cp_common_init_ts (void);
extern tree cp_unit_size_without_reusable_padding (tree);
+extern tree cp_classtype_as_base (const_tree);
extern tree cp_get_global_decls ();
extern tree cp_pushdecl (tree);
extern void cp_register_dumps (gcc::dump_manager *);
@@ -167,6 +168,8 @@ extern tree cxx_simulate_record_decl (lo
#define LANG_HOOKS_TYPE_DWARF_ATTRIBUTE cp_type_dwarf_attribute
#undef LANG_HOOKS_UNIT_SIZE_WITHOUT_REUSABLE_PADDING
#define LANG_HOOKS_UNIT_SIZE_WITHOUT_REUSABLE_PADDING
cp_unit_size_without_reusable_padding
+#undef LANG_HOOKS_CLASSTYPE_AS_BASE
+#define LANG_HOOKS_CLASSTYPE_AS_BASE cp_classtype_as_base
#undef LANG_HOOKS_OMP_PREDETERMINED_SHARING
#define LANG_HOOKS_OMP_PREDETERMINED_SHARING cxx_omp_predetermined_sharing
--- gcc/cp/cp-objcp-common.cc.jj 2022-02-11 00:18:54.720440130 +0100
+++ gcc/cp/cp-objcp-common.cc 2022-04-06 13:24:43.543051969 +0200
@@ -280,6 +280,23 @@ cp_unit_size_without_reusable_padding (t
return TYPE_SIZE_UNIT (type);
}
+/* Returns type corresponding to FIELD's type when FIELD is a C++ base class
+ i.e., type without virtual base classes or tail padding. Returns
+ NULL_TREE otherwise. */
+
+tree
+cp_classtype_as_base (const_tree field)
+{
+ tree type = TREE_TYPE (field);
+ if (!DECL_ARTIFICIAL (field)
+ || DECL_NAME (field) != NULL_TREE
+ || TREE_CODE (type) != RECORD_TYPE)
+ return NULL_TREE;
+ if (!TYPE_LANG_SPECIFIC (type))
+ return NULL_TREE;
+ return CLASSTYPE_AS_BASE (type);
+}
+
/* Stubs to keep c-opts.cc happy. */
void
push_file_scope (void)
--- gcc/testsuite/g++.dg/torture/builtin-clear-padding-5.C.jj 2022-04-06
12:31:39.151670141 +0200
+++ gcc/testsuite/g++.dg/torture/builtin-clear-padding-5.C 2022-04-06
13:15:36.674717019 +0200
@@ -0,0 +1,44 @@
+// PR tree-optimization/102586
+// { dg-options "-Wno-inaccessible-base" }
+
+struct C0 {};
+struct C1 {};
+struct C2 : C1, virtual C0 {};
+struct C3 : virtual C2, C1 { virtual int foo () { return 1; } };
+struct C4 : virtual C3, C1 { virtual int foo () { return 2; } };
+struct C5 : C4 { virtual int foo () { return 3; } };
+struct C6 { char c; };
+struct C7 : virtual C6, virtual C3, C1 { virtual int foo () { return 4; } };
+struct C8 : C7 { virtual int foo () { return 5; } };
+
+__attribute__((noipa)) int
+bar (C5 *p)
+{
+ return p->foo ();
+}
+
+__attribute__((noipa)) int
+baz (C3 *p)
+{
+ return p->foo ();
+}
+
+__attribute__((noipa)) int
+qux (C8 *p)
+{
+ return p->foo ();
+}
+
+int
+main ()
+{
+ C5 c5;
+ C8 c8;
+ c8.c = 42;
+ __builtin_clear_padding (&c5);
+ __builtin_clear_padding (&c8);
+ if (bar (&c5) != 3 || baz (&c5) != 3)
+ __builtin_abort ();
+ if (qux (&c8) != 5 || baz (&c8) != 5 || c8.c != 42)
+ __builtin_abort ();
+}
--- gcc/testsuite/g++.dg/cpp2a/builtin-clear-padding1.C.jj 2022-03-14
10:46:42.021766309 +0100
+++ gcc/testsuite/g++.dg/cpp2a/builtin-clear-padding1.C 2022-04-06
13:14:31.614628521 +0200
@@ -43,7 +43,7 @@ bar ()
__builtin_clear_padding (&c2);
__builtin_clear_padding (&c3);
__builtin_clear_padding (&c4);
-// __builtin_clear_padding (&c5);
+ __builtin_clear_padding (&c5);
__builtin_clear_padding (&c6);
__builtin_clear_padding (&c7);
__builtin_clear_padding (&c8);
Jakub
