https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54742
Sebastian Pop <spop at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |spop at gcc dot gnu.org
--- Comment #37 from Sebastian Pop <spop at gcc dot gnu.org> ---
Hi Jeff, can you fix this bug, or should I give it a try?
I know some folks who would be happy to have this coremark perf bug fixed in
trunk ;-)
Thanks,
Sebastian
(In reply to jgreenhalgh from comment #27)
> Created attachment 31308 [details]
> Dumps for less reduced testcase in comment 27
>
> As of revision 205398, I'm not seeing this optimisation trigger when
> compiling the benchmark in question.
>
> I've attached the dumps from a less agressively reduced version of the
> testcase given in the intial report, which we don't currently thread.
>
> This testcase is more representative of the control structure in the
> benchmark code. In particular, we have the problematic scenario of two
> 'joiner' blocks in the thread path.
>
> Looking at the dumps for this testcase I think that we would need to spot
> threads like:
>
> (17, 23) incoming edge; (23, 4) joiner; (4, 5) joiner; (5, 8) back-edge;
> (8, 15) switch-statement;
>
> The testcase I am using is:
>
> ---
>
> int sum0, sum1, sum2, sum3;
> int foo(char * s, char** ret)
> {
> int state=0;
> char c;
>
> for (; *s && state != 4; s++)
> {
> c = *s;
> if (c == '*')
> {
> s++;
> break;
> }
> switch (state) {
> case 0:
> if (c == '+') state = 1;
> else if (c != '-') sum0+=c;
> break;
> case 1:
> if (c == '+') state = 2;
> else if (c == '-') state = 0;
> else sum1+=c;
> break;
> case 2:
> if (c == '+') state = 3;
> else if (c == '-') state = 1;
> else sum2+=c;
> break;
> case 3:
> if (c == '-') state = 2;
> else if (c == 'x') state = 4;
> break;
> default:
> break;
> }
> }
> *ret = s;
> return state;
> }
