https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117239
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
int a, b, j = 1, k;
int l () { return a; }
struct c {
int d;
int e;
int f;
int g;
short h;
int i;
};
void m (int n, struct c o) {
if (o.i == 1)
j = 0;
}
int r (struct c n) { return b; }
int main () {
struct c q = {0, 0, 0, 0, 0, 1};
k = r (q);
m (l (), q);
if (j != 0)
__builtin_abort ();
return 0;
}
Indeed, there is
(insn 14 12 15 2 (set (mem:DI (plus:DI (reg/f:DI 7 sp)
(const_int 16 [0x10])) [0 S8 A64])
(reg:DI 1 dx [orig:105 q+16 ] [105])) "pr117239.c":18:7 95
{*movdi_internal}
(nil))
(call_insn/i 15 14 16 2 (set (reg:SI 0 ax)
(call (mem:QI (symbol_ref:DI ("r") [flags 0x3] <function_decl
0x7ffb2e2bdf00 r>) [0 r S1 A8])
(const_int 24 [0x18]))) "pr117239.c":18:7 1476 {*call_value}
(expr_list:REG_CALL_DECL (symbol_ref:DI ("r") [flags 0x3] <function_decl
0x7ffb2e2bdf00 r>)
(expr_list:REG_EH_REGION (const_int 0 [0])
(nil)))
(nil))
(insn 16 15 18 2 (parallel [
(set (reg/f:DI 7 sp)
(plus:DI (reg/f:DI 7 sp)
(const_int 24 [0x18])))
(clobber (reg:CC 17 flags))
]) "pr117239.c":18:7 285 {*adddi_1}
(expr_list:REG_ARGS_SIZE (const_int 0 [0])
(nil)))
...
(call_insn/i 19 18 21 2 (set (reg:SI 0 ax)
(call (mem:QI (symbol_ref:DI ("l") [flags 0x3] <function_decl
0x7ffb2e2bdb00 l>) [0 l S1 A8])
(const_int 0 [0]))) "pr117239.c":19:3 1476 {*call_value}
(expr_list:REG_CALL_DECL (symbol_ref:DI ("l") [flags 0x3] <function_decl
0x7ffb2e2bdb00 l>)
(expr_list:REG_EH_REGION (const_int 0 [0])
(nil)))
(nil))
(insn 21 19 26 2 (parallel [
(set (reg/f:DI 7 sp)
(plus:DI (reg/f:DI 7 sp)
(const_int -24 [0xffffffffffffffe8])))
(clobber (reg:CC 17 flags))
]) "pr117239.c":19:3 discrim 1 285 {*adddi_1}
(expr_list:REG_ARGS_SIZE (const_int 24 [0x18])
(nil)))
(insn 26 21 24 2 (set (mem:DI (plus:DI (reg/f:DI 7 sp)
(const_int 16 [0x10])) [0 S8 A64])
(reg:DI 1 dx [orig:105 q+16 ] [105])) "pr117239.c":19:3 discrim 1 95
{*movdi_internal}
(nil))
So while %rsp+16 is the same on both stores and %rdx has not changed (IPA-RA?),
the stack deallocation followed by a call has clobbered it (without redzone
even the stack deallocation could have done it if there was an async signal in
between).
