On 7/30/19 10:40 AM, Richard Biener wrote:
> On Tue, Jul 30, 2019 at 10:07 AM Martin Liška <mli...@suse.cz> wrote:
>>
>> On 7/30/19 9:46 AM, Martin Liška wrote:
>>> Anyway that's not a candidate for DCE. I'm testing following patch.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> One alternative approach can be to drop DECL_SET_IS_OPERATOR_DELETE in:
>> cat -n gcc/cp/decl.c | less
>> ...
>> 4410 deltype = cp_build_type_attribute_variant (deltype,
>> extvisattr);
>> 4411 deltype = build_exception_variant (deltype,
>> empty_except_spec);
>> 4412 opdel = push_cp_library_fn (DELETE_EXPR, deltype,
>> ECF_NOTHROW);
>> 4413 DECL_SET_IS_OPERATOR_DELETE (opdel, true);
>> 4414 opdel = push_cp_library_fn (VEC_DELETE_EXPR, deltype,
>> ECF_NOTHROW);
>> 4415 DECL_SET_IS_OPERATOR_DELETE (opdel, true);
>> 4416
>> 4417 if (flag_sized_deallocation)
>> 4418 {
>> 4419 /* operator delete (void *, size_t, align_val_t); */
>> 4420 deltype = build_function_type_list (void_type_node,
>> ptr_type_node,
>> 4421 size_type_node,
>> align_type_node,
>> 4422 NULL_TREE);
>> 4423 deltype = cp_build_type_attribute_variant (deltype,
>> extvisattr);
>> 4424 deltype = build_exception_variant (deltype,
>> empty_except_spec);
>> 4425 opdel = push_cp_library_fn (DELETE_EXPR, deltype,
>> ECF_NOTHROW);
>> 4426 DECL_SET_IS_OPERATOR_DELETE (opdel, true);
>> 4427 opdel = push_cp_library_fn (VEC_DELETE_EXPR, deltype,
>> ECF_NOTHROW);
>> 4428 DECL_SET_IS_OPERATOR_DELETE (opdel, true);
>> 4429 }
>> 4430 }
>>
>> at lines 4426 and 4428.
>>
>> Richi what do you prefer?
>
> I don't understand why a "not simple" delete operator isn't fine to be
> DCEd? Does C++
> somehow allow mismatching size specifications here?
No, they are the same.
> And what's the semantics
> then?
>
> Thus I'd rather go with your earlier patch to mark the op necessary.
Ok, I'm sending tested patch.
Ready for trunk?
Thanks,
Martin
>
> Richard.
>
>> Martin
>From b4645189743b2670f77028933086fff56c46eb75 Mon Sep 17 00:00:00 2001
From: Martin Liska <mli...@suse.cz>
Date: Sun, 28 Jul 2019 13:04:28 +0200
Subject: [PATCH] Mark 2nd argument of delete operator as needed (PR
tree-optimization/91270).
gcc/cp/ChangeLog:
2019-07-30 Martin Liska <mli...@suse.cz>
PR tree-optimization/91270
* tree-ssa-dce.c (propagate_necessity): Mark 2nd argument
of delete operator as needed.
gcc/testsuite/ChangeLog:
2019-07-30 Martin Liska <mli...@suse.cz>
PR tree-optimization/91270
* g++.dg/torture/pr91270.C: New test.
---
gcc/testsuite/g++.dg/torture/pr91270.C | 10 ++++++++++
gcc/tree-ssa-dce.c | 19 +++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/torture/pr91270.C
diff --git a/gcc/testsuite/g++.dg/torture/pr91270.C b/gcc/testsuite/g++.dg/torture/pr91270.C
new file mode 100644
index 00000000000..60d766e9e9f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr91270.C
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+
+struct S {
+ ~S();
+};
+int a = 123;
+void fn1() {
+ S *s = new S[a];
+ delete[] s;
+}
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 763b76f0e53..c816fccceb4 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -804,10 +804,11 @@ propagate_necessity (bool aggressive)
/* If this is a call to free which is directly fed by an
allocation function do not mark that necessary through
processing the argument. */
+ bool is_delete_operator
+ = (is_gimple_call (stmt)
+ && gimple_call_operator_delete_p (as_a <gcall *> (stmt)));
if (gimple_call_builtin_p (stmt, BUILT_IN_FREE)
- || (is_gimple_call (stmt)
- && gimple_call_operator_delete_p (as_a <gcall *> (stmt))))
-
+ || is_delete_operator)
{
tree ptr = gimple_call_arg (stmt, 0);
gimple *def_stmt;
@@ -822,7 +823,17 @@ propagate_necessity (bool aggressive)
|| DECL_FUNCTION_CODE (def_callee) == BUILT_IN_MALLOC
|| DECL_FUNCTION_CODE (def_callee) == BUILT_IN_CALLOC))
|| DECL_IS_REPLACEABLE_OPERATOR_NEW_P (def_callee)))
- continue;
+ {
+ /* Some delete operators have size as 2nd argument. */
+ if (is_delete_operator && gimple_call_num_args (stmt) >= 2)
+ {
+ tree size_argument = gimple_call_arg (stmt, 1);
+ if (TREE_CODE (size_argument) == SSA_NAME)
+ mark_operand_necessary (size_argument);
+ }
+
+ continue;
+ }
}
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
--
2.22.0
