On Tue, Oct 29, 2019 at 04:26:14PM -0400, Jason Merrill wrote:
I think type_initializer_zero_p should return false if
CLASSTYPE_NON_AGGREGATE; we can't expect that value-initialization will have
the intended effect in that case.
That indeed works for this testcase and doesn't break anything else in the
testsuite. I've actually used TYPE_NON_AGGREGATE_CLASS because a
RECORD_TYPE might not be always a CLASS_TYPE_P.
Here is what I've bootstrapped/regtested on x86_64-linux and i686-linux, ok
for trunk?
2019-10-30 Jakub Jelinek <ja...@redhat.com>
PR c++/90947
* tree.h (type_initializer_zero_p): Remove.
* tree.c (type_initializer_zero_p): Remove.
cp/
* cp-tree.h (type_initializer_zero_p): Declare.
* decl.c (reshape_init_array_1): Formatting fix.
* tree.c (type_initializer_zero_p): New function. Moved from
../tree.c, use next_initializable_field, formatting fix. Return
false for TYPE_NON_AGGREGATE_CLASS types.
--- gcc/tree.h.jj 2019-10-30 08:13:49.017848260 +0100
+++ gcc/tree.h 2019-10-30 08:57:59.457046198 +0100
@@ -4690,12 +4690,6 @@ extern tree first_field (const_tree);
extern bool initializer_zerop (const_tree, bool * = NULL);
extern bool initializer_each_zero_or_onep (const_tree);
-/* Analogous to initializer_zerop but also examines the type for
- which the initializer is being used. Unlike initializer_zerop,
- considers empty strings to be zero initializers for arrays and
- non-zero for pointers. */
-extern bool type_initializer_zero_p (tree, tree);
-
extern wide_int vector_cst_int_elt (const_tree, unsigned int);
extern tree vector_cst_elt (const_tree, unsigned int);
--- gcc/tree.c.jj 2019-10-30 08:13:48.974848922 +0100
+++ gcc/tree.c 2019-10-30 08:57:59.460046152 +0100
@@ -11396,73 +11396,6 @@ initializer_each_zero_or_onep (const_tre
}
}
-/* Given an initializer INIT for a TYPE, return true if INIT is zero
- so that it can be replaced by value initialization. This function
- distinguishes betwen empty strings as initializers for arrays and
- for pointers (which make it return false). */
-
-bool
-type_initializer_zero_p (tree type, tree init)
-{
- if (type == error_mark_node || init == error_mark_node)
- return false;
-
- STRIP_NOPS (init);
-
- if (POINTER_TYPE_P (type))
- return TREE_CODE (init) != STRING_CST && initializer_zerop (init);
-
- if (TREE_CODE (init) != CONSTRUCTOR)
- return initializer_zerop (init);
-
- if (TREE_CODE (type) == ARRAY_TYPE)
- {
- tree elt_type = TREE_TYPE (type);
- elt_type = TYPE_MAIN_VARIANT (elt_type);
- if (elt_type == char_type_node)
- return initializer_zerop (init);
-
- tree elt_init;
- unsigned HOST_WIDE_INT i;
- FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), i, elt_init)
- if (!type_initializer_zero_p (elt_type, elt_init))
- return false;
- return true;
- }
-
- if (TREE_CODE (type) != RECORD_TYPE)
- return initializer_zerop (init);
-
- tree fld = TYPE_FIELDS (type);
-
- tree fld_init;
- unsigned HOST_WIDE_INT i;
- FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), i, fld_init)
- {
- /* Advance to the next member, skipping over everything that
- canot be initialized (including unnamed bit-fields). */
- while (TREE_CODE (fld) != FIELD_DECL
- || DECL_ARTIFICIAL (fld)
- || (DECL_BIT_FIELD (fld) && !DECL_NAME (fld)))
- {
- fld = DECL_CHAIN (fld);
- if (!fld)
- return true;
- continue;
- }
-
- tree fldtype = TREE_TYPE (fld);
- if (!type_initializer_zero_p (fldtype, fld_init))
- return false;
-
- fld = DECL_CHAIN (fld);
- if (!fld)
- break;
- }
-
- return true;
-}
-
/* Check if vector VEC consists of all the equal elements and
that the number of elements corresponds to the type of VEC.
The function returns first element of the vector
--- gcc/cp/cp-tree.h.jj 2019-10-30 08:13:48.819851308 +0100
+++ gcc/cp/cp-tree.h 2019-10-30 08:57:59.462046121 +0100
@@ -7380,6 +7380,11 @@ extern tree cxx_copy_lang_qualifiers (c
extern void cxx_print_statistics (void);
extern bool maybe_warn_zero_as_null_pointer_constant (tree, location_t);
+/* Analogous to initializer_zerop but also examines the type for
+ which the initializer is being used. Unlike initializer_zerop,
+ considers empty strings to be zero initializers for arrays and
+ non-zero for pointers. */
+extern bool type_initializer_zero_p (tree, tree);
/* in ptree.c */
extern void cxx_print_xnode (FILE *, tree, int);
--- gcc/cp/decl.c.jj 2019-10-30 08:13:48.885850291 +0100
+++ gcc/cp/decl.c 2019-10-30 08:57:59.466046060 +0100
@@ -5972,9 +5972,8 @@ reshape_init_array_1 (tree elt_type, tre
/* Pointers initialized to strings must be treated as non-zero
even if the string is empty. */
tree init_type = TREE_TYPE (elt_init);
- if ((POINTER_TYPE_P (elt_type) != POINTER_TYPE_P (init_type)))
- last_nonzero = index;
- else if (!type_initializer_zero_p (elt_type, elt_init))
+ if (POINTER_TYPE_P (elt_type) != POINTER_TYPE_P (init_type)
+ || !type_initializer_zero_p (elt_type, elt_init))
last_nonzero = index;
/* This can happen with an invalid initializer (c++/54501). */
--- gcc/cp/tree.c.jj 2019-10-30 08:13:48.777851956 +0100
+++ gcc/cp/tree.c 2019-10-30 09:17:23.743135729 +0100
@@ -5541,6 +5541,68 @@ maybe_warn_zero_as_null_pointer_constant
return false;
}
+/* Given an initializer INIT for a TYPE, return true if INIT is zero
+ so that it can be replaced by value initialization. This function
+ distinguishes betwen empty strings as initializers for arrays and
+ for pointers (which make it return false). */
+
+bool
+type_initializer_zero_p (tree type, tree init)
+{
+ if (type == error_mark_node || init == error_mark_node)
+ return false;
+
+ STRIP_NOPS (init);
+
+ if (POINTER_TYPE_P (type))
+ return TREE_CODE (init) != STRING_CST && initializer_zerop (init);
+
+ if (TREE_CODE (init) != CONSTRUCTOR)
+ return initializer_zerop (init);
+
+ if (TREE_CODE (type) == ARRAY_TYPE)
+ {
+ tree elt_type = TREE_TYPE (type);
+ elt_type = TYPE_MAIN_VARIANT (elt_type);
+ if (elt_type == char_type_node)
+ return initializer_zerop (init);
+
+ tree elt_init;
+ unsigned HOST_WIDE_INT i;
+ FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), i, elt_init)
+ if (!type_initializer_zero_p (elt_type, elt_init))
+ return false;
+ return true;
+ }
+
+ if (TREE_CODE (type) != RECORD_TYPE)
+ return initializer_zerop (init);
+
+ if (TYPE_NON_AGGREGATE_CLASS (type))
+ return false;
+
+ tree fld = TYPE_FIELDS (type);
+
+ tree fld_init;
+ unsigned HOST_WIDE_INT i;
+ FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (init), i, fld_init)
+ {
+ fld = next_initializable_field (fld);
+ if (!fld)
+ return true;
+
+ tree fldtype = TREE_TYPE (fld);
+ if (!type_initializer_zero_p (fldtype, fld_init))
+ return false;
+
+ fld = DECL_CHAIN (fld);
+ if (!fld)
+ break;
+ }
+
+ return true;
+}
+
#if defined ENABLE_TREE_CHECKING && (GCC_VERSION >= 2007)
/* Complain that some language-specific thing hanging off a tree
node has been accessed improperly. */
--- gcc/testsuite/g++.dg/init/array54.C.jj 2019-10-30 09:21:12.676608668
+0100
+++ gcc/testsuite/g++.dg/init/array54.C 2019-10-30 09:26:42.813522422 +0100
@@ -0,0 +1,13 @@
+// PR c++/90947
+// { dg-do run { target c++11 } }
+
+#include <atomic>
+
+static std::atomic<int> a[1] { {1} };
+
+int
+main ()
+{
+ if (a[0].load () != 1)
+ __builtin_abort ();
+}
Jakub
