gcc/
2014-01-08 Florian Weimer <fweimer@redhat.com>
* cfgexpand.c (stack_protect_decl_p): New function, extracted from
expand_used_vars.
(stack_protect_return_slot_p): New function.
(expand_used_vars): Call stack_protect_decl_p and
stack_protect_return_slot_p for -fstack-protector-strong.
gcc/testsuite/
2014-01-08 Florian Weimer <fweimer@redhat.com>
* gcc.dg/fstack-protector-strong.c: Add coverage for return slots.
* g++.dg/fstack-protector-strong.C: Likewise.
* gcc.target/i386/ssp-strong-reg.c: New file.
===================================================================
@@ -1599,6 +1599,52 @@
return 0;
}
+/* Check if the current function has local referenced variables that
+ have their addresses taken, contain an array, or are arrays. */
+
+static bool
+stack_protect_decl_p ()
+{
+ unsigned i;
+ tree var;
+
+ FOR_EACH_LOCAL_DECL (cfun, i, var)
+ if (!is_global_var (var))
+ {
+ tree var_type = TREE_TYPE (var);
+ if (TREE_CODE (var) == VAR_DECL
+ && (TREE_CODE (var_type) == ARRAY_TYPE
+ || TREE_ADDRESSABLE (var)
+ || (RECORD_OR_UNION_TYPE_P (var_type)
+ && record_or_union_type_has_array_p (var_type))))
+ return true;
+ }
+ return false;
+}
+
+/* Check if the current function has calls that use a return slot. */
+
+static bool
+stack_protect_return_slot_p ()
+{
+ basic_block bb;
+
+ FOR_ALL_BB_FN (bb, cfun)
+ for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
+ !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple stmt = gsi_stmt (gsi);
+ /* This assumes that calls to internal-only functions never
+ use a return slot. */
+ if (is_gimple_call (stmt)
+ && !gimple_call_internal_p (stmt)
+ && aggregate_value_p (TREE_TYPE (gimple_call_fntype (stmt)),
+ gimple_call_fndecl (stmt)))
+ return true;
+ }
+ return false;
+}
+
/* Expand all variables used in the function. */
static rtx
@@ -1669,22 +1715,8 @@
pointer_map_destroy (ssa_name_decls);
if (flag_stack_protect == SPCT_FLAG_STRONG)
- FOR_EACH_LOCAL_DECL (cfun, i, var)
- if (!is_global_var (var))
- {
- tree var_type = TREE_TYPE (var);
- /* Examine local referenced variables that have their addresses taken,
- contain an array, or are arrays. */
- if (TREE_CODE (var) == VAR_DECL
- && (TREE_CODE (var_type) == ARRAY_TYPE
- || TREE_ADDRESSABLE (var)
- || (RECORD_OR_UNION_TYPE_P (var_type)
- && record_or_union_type_has_array_p (var_type))))
- {
- gen_stack_protect_signal = true;
- break;
- }
- }
+ gen_stack_protect_signal
+ = stack_protect_decl_p () || stack_protect_return_slot_p ();
/* At this point all variables on the local_decls with TREE_USED
set are not associated with any block scope. Lay them out. */
===================================================================
@@ -32,4 +32,52 @@
return global_func (a);
}
-/* { dg-final { scan-assembler-times "stack_chk_fail" 2 } } */
+/* Frame addressed exposed through return slot. */
+
+struct B
+{
+ /* Discourage passing this struct in registers. */
+ int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10;
+ int method ();
+ B return_slot();
+};
+
+B global_func ();
+void noop ();
+
+int foo3 ()
+{
+ return global_func ().a1;
+}
+
+int foo4 ()
+{
+ try {
+ noop ();
+ return 0;
+ } catch (...) {
+ return global_func ().a1;
+ }
+}
+
+int foo5 ()
+{
+ try {
+ return global_func ().a1;
+ } catch (...) {
+ return 0;
+ }
+}
+
+int foo6 ()
+{
+ B b;
+ return b.method ();
+}
+
+int foo7 (B *p)
+{
+ return p->return_slot ().a1;
+}
+
+/* { dg-final { scan-assembler-times "stack_chk_fail" 7 } } */
===================================================================
@@ -131,4 +131,22 @@
return bb.three;
}
-/* { dg-final { scan-assembler-times "stack_chk_fail" 10 } } */
+struct B
+{
+ /* Discourage passing this struct in registers. */
+ int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10;
+};
+
+struct B global3 (void);
+
+int foo11 ()
+{
+ return global3 ().a1;
+}
+
+void foo12 ()
+{
+ global3 ();
+}
+
+/* { dg-final { scan-assembler-times "stack_chk_fail" 12 } } */
===================================================================
@@ -0,0 +1,19 @@
+/* Test that structs returned in registers do not lead to
+ instrumentation with -fstack-protector-strong. */
+
+/* { dg-do compile { target { ! { ia32 } } } } */
+/* { dg-options "-O2 -fstack-protector-strong" } */
+
+struct S {
+ int a;
+ int b;
+};
+
+struct S f (void);
+
+int g (void)
+{
+ return f ().a;
+}
+
+/* { dg-final { scan-assembler-times "stack_chk_fail" 0 } } */