Tested x86_64-pc-linux-gnu, ok for trunk?
-- 8< --
Here we hit the MEM_REF case, with its arg an ADDR_EXPR, but had no handling
for that and wrongly assumed it would be a reference to a local variable.
This patch overhauls the logic for deciding whether the target is something
to warn about so that we only warn if we specifically recognize the target
as non-local. None of the existing tests regress as a result.
PR c++/109514
gcc/ChangeLog:
* gimple-ssa-warn-access.cc (pass_waccess::check_dangling_stores):
Overhaul lhs_ref.ref analysis.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wdangling-pointer-6.C: New test.
---
gcc/gimple-ssa-warn-access.cc | 50 ++++++++-----------
.../g++.dg/warn/Wdangling-pointer-6.C | 30 +++++++++++
2 files changed, 50 insertions(+), 30 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Wdangling-pointer-6.C
diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc
index b3de4b77924..d0d2148c872 100644
--- a/gcc/gimple-ssa-warn-access.cc
+++ b/gcc/gimple-ssa-warn-access.cc
@@ -4528,39 +4528,34 @@ pass_waccess::check_dangling_stores (basic_block bb,
if (!m_ptr_qry.get_ref (lhs, stmt, &lhs_ref, 0))
continue;
- if (auto_var_p (lhs_ref.ref))
- continue;
-
- if (DECL_P (lhs_ref.ref))
+ if (TREE_CODE (lhs_ref.ref) == MEM_REF)
{
- if (!POINTER_TYPE_P (TREE_TYPE (lhs_ref.ref))
- || lhs_ref.deref > 0)
- continue;
+ lhs_ref.ref = TREE_OPERAND (lhs_ref.ref, 0);
+ ++lhs_ref.deref;
}
- else if (TREE_CODE (lhs_ref.ref) == SSA_NAME)
+ if (TREE_CODE (lhs_ref.ref) == ADDR_EXPR)
+ {
+ lhs_ref.ref = TREE_OPERAND (lhs_ref.ref, 0);
+ --lhs_ref.deref;
+ }
+ if (TREE_CODE (lhs_ref.ref) == SSA_NAME)
{
gimple *def_stmt = SSA_NAME_DEF_STMT (lhs_ref.ref);
if (!gimple_nop_p (def_stmt))
/* Avoid looking at or before stores into unknown objects. */
return;
- tree var = SSA_NAME_VAR (lhs_ref.ref);
- if (TREE_CODE (var) == PARM_DECL && DECL_BY_REFERENCE (var))
- /* Avoid by-value arguments transformed into by-reference. */
- continue;
+ lhs_ref.ref = SSA_NAME_VAR (lhs_ref.ref);
+ }
- }
- else if (TREE_CODE (lhs_ref.ref) == MEM_REF)
- {
- tree arg = TREE_OPERAND (lhs_ref.ref, 0);
- if (TREE_CODE (arg) == SSA_NAME)
- {
- gimple *def_stmt = SSA_NAME_DEF_STMT (arg);
- if (!gimple_nop_p (def_stmt))
- return;
- }
- }
+ if (TREE_CODE (lhs_ref.ref) == PARM_DECL
+ && (lhs_ref.deref - DECL_BY_REFERENCE (lhs_ref.ref)) > 0)
+ /* Assignment through a (real) pointer/reference parameter. */;
+ else if (TREE_CODE (lhs_ref.ref) == VAR_DECL
+ && !auto_var_p (lhs_ref.ref))
+ /* Assignment to/through a non-local variable. */;
else
+ /* Something else, don't warn. */
continue;
if (stores.add (lhs_ref.ref))
@@ -4587,13 +4582,8 @@ pass_waccess::check_dangling_stores (basic_block bb,
location_t loc = DECL_SOURCE_LOCATION (rhs_ref.ref);
inform (loc, "%qD declared here", rhs_ref.ref);
- if (DECL_P (lhs_ref.ref))
- loc = DECL_SOURCE_LOCATION (lhs_ref.ref);
- else if (EXPR_HAS_LOCATION (lhs_ref.ref))
- loc = EXPR_LOCATION (lhs_ref.ref);
-
- if (loc != UNKNOWN_LOCATION)
- inform (loc, "%qE declared here", lhs_ref.ref);
+ loc = DECL_SOURCE_LOCATION (lhs_ref.ref);
+ inform (loc, "%qD declared here", lhs_ref.ref);
}
}
diff --git a/gcc/testsuite/g++.dg/warn/Wdangling-pointer-6.C
b/gcc/testsuite/g++.dg/warn/Wdangling-pointer-6.C
new file mode 100644
index 00000000000..20d47edecc5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wdangling-pointer-6.C
@@ -0,0 +1,30 @@
+// PR c++/109514
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-O2 -Werror=dangling-pointer" }
+
+struct _Rb_tree_node_base {
+ _Rb_tree_node_base *_M_parent;
+};
+struct _Rb_tree_header {
+ _Rb_tree_node_base _M_header;
+ void _M_move_data() { _M_header._M_parent->_M_parent = &_M_header; }
+};
+struct _Rb_tree {
+ _Rb_tree_header _M_impl;
+ _Rb_tree_node_base *&_M_root() { return _M_impl._M_header._M_parent; }
+ _Rb_tree();
+ _Rb_tree &operator=(_Rb_tree &&);
+};
+_Rb_tree &_Rb_tree::operator=(_Rb_tree &&) {
+ if (_M_root())
+ _M_impl._M_move_data();
+ return *this;
+}
+struct set {
+ _Rb_tree _M_t;
+};
+set FilterRs();
+void f() {
+ set rs;
+ rs = FilterRs();
+};
base-commit: f32f7881fb0db085479525b5a23db5dabd990c3b
--
2.31.1
