https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104067
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at gcc dot gnu.org
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
extern void abort ();
struct S { int x; } a[10];
struct S *b;
int
main ()
{
int i, j = 0;
struct S *q = a;
for (i = 100; --i > 0; )
{
struct S *p;
j++;
if (j >= 10)
j = 0;
p = &a[j];
if (p == q)
abort ();
__atomic_thread_fence (__ATOMIC_SEQ_CST);
q = p;
}
return 0;
}
This goes wrong in threadfull2, strlen1 looks correct to me:
<bb 2> [local count: 10737416]:
<bb 3> [local count: 1063004409]:
# j_17 = PHI <j_2(9), 0(2)>
# q_18 = PHI <prephitmp_16(9), &a(2)>
# ivtmp_4 = PHI <ivtmp_3(9), 99(2)>
j_8 = j_17 + 1;
if (j_8 == 10)
goto <bb 5>; [34.00%]
else
goto <bb 4>; [66.00%]
<bb 4> [local count: 701582906]:
_1 = (sizetype) j_8;
_15 = _1 * 4;
_14 = &a + _15;
<bb 5> [local count: 1063004409]:
# j_2 = PHI <j_8(4), 0(3)>
# prephitmp_16 = PHI <_14(4), &a(3)>
if (prephitmp_16 == q_18)
goto <bb 6>; [0.00%]
else
goto <bb 7>; [100.00%]
<bb 6> [count: 0]:
abort ();
<bb 7> [local count: 1063004409]:
__atomic_thread_fence (5);
ivtmp_3 = ivtmp_4 - 1;
if (ivtmp_3 != 0)
goto <bb 9>; [99.00%]
else
goto <bb 8>; [1.00%]
<bb 9> [local count: 1052374367]:
goto <bb 3>; [100.00%]
<bb 8> [local count: 10737416]:
return 0;
but threadfull2 turns that into something that weirdly starts with:
<bb 2> [local count: 10737416]:
j_8 = 1;
if (j_8 == 10)
goto <bb 4>; [34.00%]
else
goto <bb 3>; [66.00%]
<bb 3> [local count: 701582906]:
# ivtmp_22 = PHI <99(2), ivtmp_12(7)>
# j_24 = PHI <j_8(2), j_20(7)>
# q_25 = PHI <&a(2), q_7(7)>
_1 = (sizetype) j_24;
_15 = _1 * 4;
_14 = &a + _15;
<bb 4> [local count: 705197120]:
# j_2 = PHI <j_24(3), 0(2)>
# prephitmp_16 = PHI <_14(3), &a(2)>
# ivtmp_23 = PHI <ivtmp_22(3), 99(2)>
# q_26 = PHI <q_25(3), &a(2)>
if (prephitmp_16 == q_26)
goto <bb 5>; [0.00%]
else
goto <bb 6>; [100.00%]
<bb 5> [count: 0]:
abort ();
and for j == 10 turns it into unconditional abort:
j_20 = j_21 + 1;
if (j_20 == 10)
goto <bb 8>; [34.00%]
else
goto <bb 3>; [66.00%]
<bb 8> [local count: 357807289]:
# j_5 = PHI <0(7)>
# prephitmp_9 = PHI <&a(7)>
goto <bb 5>; [100.00%]
