[pushed] c++: allocator temps in list of arrays [PR108773]
Checks
Commit Message
Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
The optimization to reuse the same allocator temporary for all string
constructor calls was breaking on this testcase, because the temps were
already in the argument to build_vec_init, and replacing them with
references to one slot got confused with calls at multiple levels (for the
initializer_list backing array, and then again for the array member of the
std::array). Fixed by reusing the whole TARGET_EXPR instead of pulling out
the slot; gimplification ensures that it's only initialized once.
I also moved the check for initializing a std:: class down into the tree
walk, and handle multiple temps within a single array element
initialization.
PR c++/108773
gcc/cp/ChangeLog:
* init.cc (find_allocator_temps_r): New.
(combine_allocator_temps): Replace find_allocator_temp.
(build_vec_init): Adjust.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/initlist-array18.C: New test.
* g++.dg/cpp0x/initlist-array19.C: New test.
---
gcc/cp/init.cc | 78 ++++++++++++++-----
gcc/testsuite/g++.dg/cpp0x/initlist-array18.C | 30 +++++++
gcc/testsuite/g++.dg/cpp0x/initlist-array19.C | 23 ++++++
3 files changed, 110 insertions(+), 21 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/initlist-array18.C
create mode 100644 gcc/testsuite/g++.dg/cpp0x/initlist-array19.C
base-commit: afe1f0c251d0429069c2414d4f3f14042efc174f
@@ -4330,8 +4330,54 @@ find_temps_r (tree *tp, int *walk_subtrees, void *data)
return NULL_TREE;
}
+/* walk_tree callback to collect temporaries in an expression that
+ are allocator arguments to standard library classes. */
+
+static tree
+find_allocator_temps_r (tree *tp, int *walk_subtrees, void *data)
+{
+ vec<tree*> &temps = *static_cast<auto_vec<tree*> *>(data);
+ tree t = *tp;
+ if (TYPE_P (t))
+ {
+ *walk_subtrees = 0;
+ return NULL_TREE;
+ }
+
+ /* If this is a call to a constructor for a std:: class, look for
+ a reference-to-allocator argument. */
+ tree fn = cp_get_callee_fndecl_nofold (t);
+ if (fn && DECL_CONSTRUCTOR_P (fn)
+ && decl_in_std_namespace_p (TYPE_NAME (DECL_CONTEXT (fn))))
+ {
+ int nargs = call_expr_nargs (t);
+ for (int i = 1; i < nargs; ++i)
+ {
+ tree arg = get_nth_callarg (t, i);
+ tree atype = TREE_TYPE (arg);
+ if (TREE_CODE (atype) == REFERENCE_TYPE
+ && is_std_allocator (TREE_TYPE (atype)))
+ {
+ STRIP_NOPS (arg);
+ if (TREE_CODE (arg) == ADDR_EXPR)
+ {
+ tree *ap = &TREE_OPERAND (arg, 0);
+ if (TREE_CODE (*ap) == TARGET_EXPR)
+ temps.safe_push (ap);
+ }
+ }
+ }
+ }
+
+ return NULL_TREE;
+}
+
/* If INIT initializes a standard library class, and involves a temporary
- std::allocator<T>, return a pointer to the temp.
+ std::allocator<T>, use ALLOC_OBJ for all such temporaries.
+
+ Note that this can clobber the input to build_vec_init; no unsharing is
+ done. To make this safe we use the TARGET_EXPR in all places rather than
+ pulling out the TARGET_EXPR_SLOT.
Used by build_vec_init when initializing an array of e.g. strings to reuse
the same temporary allocator for all of the strings. We can do this because
@@ -4341,22 +4387,18 @@ find_temps_r (tree *tp, int *walk_subtrees, void *data)
??? Add an attribute to allow users to assert the same property for other
classes, i.e. one object of the type is interchangeable with any other? */
-static tree*
-find_allocator_temp (tree init)
+static void
+combine_allocator_temps (tree &init, tree &alloc_obj)
{
- if (TREE_CODE (init) == EXPR_STMT)
- init = EXPR_STMT_EXPR (init);
- if (TREE_CODE (init) == CONVERT_EXPR)
- init = TREE_OPERAND (init, 0);
- tree type = TREE_TYPE (init);
- if (!CLASS_TYPE_P (type) || !decl_in_std_namespace_p (TYPE_NAME (type)))
- return NULL;
auto_vec<tree*> temps;
- cp_walk_tree_without_duplicates (&init, find_temps_r, &temps);
+ cp_walk_tree_without_duplicates (&init, find_allocator_temps_r, &temps);
for (tree *p : temps)
- if (is_std_allocator (TREE_TYPE (*p)))
- return p;
- return NULL;
+ {
+ if (!alloc_obj)
+ alloc_obj = *p;
+ else
+ *p = alloc_obj;
+ }
}
/* `build_vec_init' returns tree structure that performs
@@ -4694,13 +4736,7 @@ build_vec_init (tree base, tree maxindex, tree init,
if (one_init)
{
/* Only create one std::allocator temporary. */
- if (tree *this_alloc = find_allocator_temp (one_init))
- {
- if (alloc_obj)
- *this_alloc = alloc_obj;
- else
- alloc_obj = TARGET_EXPR_SLOT (*this_alloc);
- }
+ combine_allocator_temps (one_init, alloc_obj);
finish_expr_stmt (one_init);
}
new file mode 100644
@@ -0,0 +1,30 @@
+// PR c++/108773
+// { dg-do compile { target c++11 } }
+
+#include <initializer_list>
+
+namespace std {
+struct __new_allocator {};
+struct allocator : __new_allocator {};
+template <typename T>
+struct basic_string {
+ basic_string(const T *, allocator = allocator());
+ ~basic_string();
+};
+using string = basic_string<char>;
+template <typename T>
+struct array {
+ T _M_elems;
+};
+template <typename T>
+struct list {
+ list &operator=(initializer_list<T>);
+};
+}
+struct RGWSyncTraceManager {
+ std::list<std::array<std::string>> admin_commands;
+ void hook_to_admin_command();
+};
+void RGWSyncTraceManager::hook_to_admin_command() {
+ admin_commands = {{""}, {""}};
+}
new file mode 100644
@@ -0,0 +1,23 @@
+// PR c++/108773
+// { dg-do compile { target c++20 } }
+
+#include <initializer_list>
+
+namespace std {
+template <typename _Tp, int _Nm> struct array {
+ _Tp _M_elems[_Nm];
+};
+template <typename _Tp> struct list { void operator=(initializer_list<_Tp>); };
+struct allocator {};
+struct basic_string {
+ int _M_p;
+ constexpr basic_string() {}
+ basic_string(const char *, const allocator & = allocator());
+ ~basic_string();
+};
+} // namespace std
+
+std::list<std::array<std::basic_string, 3>> stuff;
+void foo() {
+ stuff = {{"", ""}, {"", ""}};
+}