https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88950
Matthew Malcomson <matmal01 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to fail| |5.4.0
--- Comment #5 from Matthew Malcomson <matmal01 at gcc dot gnu.org> ---
This problem has been around for a long time -- I have seen the same
fundamental problem on gcc 5.4 (when looking for a version to put in the "known
to work" field).
With "gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.5) 5.4.0 20160609" on the same
testcase, the stack_protect_test pattern gets reordered to before the second
memory access (the "buf[b] = c" line), and again the stack protection does not
guard this memory access.
(insn:TI 8 126 16 (parallel [
(set (mem/v/f/c:DI (plus:DI (reg/f:DI 29 x29)
(const_int 88 [0x58])) [1 D.2834+0 S8 A64])
(unspec:DI [
(mem/v/f/c:DI (reg/f:DI 3 x3 [100]) [1
__stack_chk_guard+0 S8 A64])
] UNSPEC_SP_SET))
(set (reg:DI 5 x5 [126])
(const_int 0 [0]))
]) stack-reorder.c:1 864 {stack_protect_set_di}
(expr_list:REG_UNUSED (reg:DI 5 x5 [126])
(nil)))
(insn:TI 16 8 71 (set (mem/j:QI (plus:DI (reg:DI 0 x0 [105])
(const_int 4016 [0xfb0])) [0 buf S1 A8])
(reg:QI 4 x4 [106])) stack-reorder.c:3 45 {*movqi_aarch64}
(expr_list:REG_DEAD (reg:QI 4 x4 [106])
(expr_list:REG_DEAD (reg:DI 0 x0 [105])
(nil))))
(insn 71 16 22 (parallel [
(set (reg:DI 3 x3 [125])
(unspec:DI [
(mem/v/f/c:DI (plus:DI (reg/f:DI 29 x29)
(const_int 88 [0x58])) [1 D.2834+0 S8 A64])
(mem/v/f/c:DI (reg/f:DI 3 x3 [100]) [1
__stack_chk_guard+0 S8 A64])
] UNSPEC_SP_TEST))
(clobber (reg:DI 0 x0 [127]))
]) stack-reorder.c:14 866 {stack_protect_test_di}
(expr_list:REG_UNUSED (reg:DI 0 x0 [127])
(nil)))
(insn:TI 22 71 140 (set (mem/j:QI (plus:DI (reg:DI 1 x1 [110])
(const_int 4016 [0xfb0])) [0 buf S1 A8])
(reg:QI 2 x2 [ c ])) stack-reorder.c:4 45 {*movqi_aarch64}
(expr_list:REG_DEAD (reg:QI 2 x2 [ c ])
(expr_list:REG_DEAD (reg:DI 1 x1 [110])
(nil))))
