Hi.
Following bug was for me very educative. I learned that we support non-local
gotos that can be combined
with nested functions. Real fun :) Well, the problem is that both
cfun->nonlocal_goto_save_area and
cfun->static_chain_decl (emitted in expand_function_start) are put before
NOTE_INSN_FUNCTION_BEG.
And so result of expand_used_vars is put after these instrumentations. That
causes problems as it uses
stack before we initialize it (use-after-return checking):
expanded cfun->static_chain_decl:
(note 1 0 5 NOTE_INSN_DELETED)
(note 5 1 2 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
(insn 2 5 3 2 (set (reg/f:DI 88 [ CHAIN.1 ])
(reg:DI 39 r10 [ CHAIN.1 ])) "pr81186.c":5 -1
(nil))
(insn 3 2 4 2 (set (mem/c:DI (plus:DI (reg/f:DI 82 virtual-stack-vars)
(const_int -8 [0xfffffffffffffff8])) [0 S8 A64])
(reg:DI 39 r10 [ CHAIN.1 ])) "pr81186.c":5 -1
(nil))
(note 4 3 7 2 NOTE_INSN_FUNCTION_BEG)
(insn 7 4 8 2 (set (reg/f:DI 87 [ _2 ])
(reg/f:DI 88 [ CHAIN.1 ])) "pr81186.c":5 -1
(nil))
(call_insn 8 7 9 2 (call (mem:QI (symbol_ref:DI ("__asan_handle_no_return")
[flags 0x41] <function_decl 0x2ba005ad5d00 __builtin___asan_handle_no_return>)
[0 __builtin___asan_handle_no_return S1 A8])
(const_int 0 [0])) "pr81186.c":5 -1
(expr_list:REG_EH_REGION (const_int 0 [0])
(nil))
(nil))
expanded cfun->nonlocal_goto_save_area:
(note 1 0 34 NOTE_INSN_DELETED)
(note 34 1 31 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
(insn 31 34 32 2 (set (mem/f/c:DI (plus:DI (reg:DI 95)
(const_int -64 [0xffffffffffffffc0])) [4
FRAME.0.__nl_goto_buf+0 S8 A64])
(reg/f:DI 82 virtual-stack-vars)) "pr81186.c":3 -1
(nil))
(insn 32 31 2 2 (set (mem/f/c:DI (plus:DI (reg:DI 95)
(const_int -56 [0xffffffffffffffc8])) [4
FRAME.0.__nl_goto_buf+8 S8 A64])
(reg/f:DI 7 sp)) "pr81186.c":3 -1
(nil))
(insn 2 32 3 2 (parallel [
(set (reg:DI 96)
(plus:DI (reg/f:DI 82 virtual-stack-vars)
(const_int -96 [0xffffffffffffffa0])))
(clobber (reg:CC 17 flags))
]) "pr81186.c":3 -1
(nil))
(insn 3 2 4 2 (set (reg:DI 97)
(reg:DI 96)) "pr81186.c":3 -1
(nil))
(insn 4 3 5 2 (set (reg:CCZ 17 flags)
(compare:CCZ (mem/c:SI (symbol_ref:DI
("__asan_option_detect_stack_use_after_return") [flags 0x40] <var_decl
0x2ba005b5b750 __asan_option_detect_stack_use_after_return>) [5
__asan_option_detect_stack_use_after_return+0 S4 A32])
(const_int 0 [0]))) "pr81186.c":3 -1
(nil))
And thus I suggest to move both these instrumentations after
NOTE_INSN_FUNCTION_BEG.
Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
Ready to be installed?
Martin
gcc/ChangeLog:
2017-06-27 Martin Liska <mli...@suse.cz>
PR sanitize/81186
* function.c (expand_function_start): Move static chain and non-local
goto init after NOTE_INSN_FUNCTION_BEG.
gcc/testsuite/ChangeLog:
2017-06-27 Martin Liska <mli...@suse.cz>
PR sanitize/81186
* gcc.dg/asan/pr81186.c: New test.
---
gcc/function.c | 18 +++++++++---------
gcc/testsuite/gcc.dg/asan/pr81186.c | 13 +++++++++++++
2 files changed, 22 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/asan/pr81186.c
diff --git a/gcc/function.c b/gcc/function.c
index f625489205b..5e8a56099a5 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -5220,6 +5220,14 @@ expand_function_start (tree subr)
In some cases this requires emitting insns. */
assign_parms (subr);
+ /* The following was moved from init_function_start.
+ The move is supposed to make sdb output more accurate. */
+ /* Indicate the beginning of the function body,
+ as opposed to parm setup. */
+ rtx_note *b = emit_note (NOTE_INSN_FUNCTION_BEG);
+
+ gcc_assert (NOTE_P (get_last_insn ()));
+
/* If function gets a static chain arg, store it. */
if (cfun->static_chain_decl)
{
@@ -5284,15 +5292,7 @@ expand_function_start (tree subr)
update_nonlocal_goto_save_area ();
}
- /* The following was moved from init_function_start.
- The move is supposed to make sdb output more accurate. */
- /* Indicate the beginning of the function body,
- as opposed to parm setup. */
- emit_note (NOTE_INSN_FUNCTION_BEG);
-
- gcc_assert (NOTE_P (get_last_insn ()));
-
- parm_birth_insn = get_last_insn ();
+ parm_birth_insn = b;
if (crtl->profile)
{
diff --git a/gcc/testsuite/gcc.dg/asan/pr81186.c b/gcc/testsuite/gcc.dg/asan/pr81186.c
new file mode 100644
index 00000000000..74d3837a482
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/asan/pr81186.c
@@ -0,0 +1,13 @@
+/* PR sanitizer/81186 */
+/* { dg-do run } */
+
+int
+main ()
+{
+ __label__ l;
+ void f () { goto l; }
+
+ f ();
+l:
+ return 0;
+}
