On Wed, Mar 27, 2013 at 6:22 PM, Teresa Johnson <tejohn...@google.com> wrote:
> I found that the node weight updates on cloned nodes during ipa-cp were
> leading to incorrect/insane weights. Both the original and new node weight
> computations used truncating divides, leading to a loss of total node weight.
> I have fixed this by making both rounding integer divides.
>
> Bootstrapped and tested on x86-64-unknown-linux-gnu. Ok for trunk?
I'm sure we can outline a rounding integer divide inline function on
gcov_type. To gcov-io.h, I suppose.
Otherwise this looks ok to me.
Thanks,
Richard.
> 2013-03-27 Teresa Johnson <tejohn...@google.com>
>
> * ipa-cp.c (update_profiling_info): Perform rounding integer
> division when updating weights instead of truncating.
> (update_specialized_profile): Ditto.
>
> Index: ipa-cp.c
> ===================================================================
> --- ipa-cp.c (revision 197118)
> +++ ipa-cp.c (working copy)
> @@ -2588,14 +2588,18 @@ update_profiling_info (struct cgraph_node *orig_no
>
> for (cs = new_node->callees; cs ; cs = cs->next_callee)
> if (cs->frequency)
> - cs->count = cs->count * (new_sum * REG_BR_PROB_BASE
> - / orig_node_count) / REG_BR_PROB_BASE;
> + cs->count = (cs->count
> + * ((new_sum * REG_BR_PROB_BASE + orig_node_count/2)
> + / orig_node_count)
> + + REG_BR_PROB_BASE/2) / REG_BR_PROB_BASE;
> else
> cs->count = 0;
>
> for (cs = orig_node->callees; cs ; cs = cs->next_callee)
> - cs->count = cs->count * (remainder * REG_BR_PROB_BASE
> - / orig_node_count) / REG_BR_PROB_BASE;
> + cs->count = (cs->count
> + * ((remainder * REG_BR_PROB_BASE + orig_node_count/2)
> + / orig_node_count)
> + + REG_BR_PROB_BASE/2) / REG_BR_PROB_BASE;
>
> if (dump_file)
> dump_profile_updates (orig_node, new_node);
> @@ -2627,14 +2631,19 @@ update_specialized_profile (struct cgraph_node *ne
>
> for (cs = new_node->callees; cs ; cs = cs->next_callee)
> if (cs->frequency)
> - cs->count += cs->count * redirected_sum / new_node_count;
> + cs->count += (cs->count
> + * ((redirected_sum * REG_BR_PROB_BASE
> + + new_node_count/2) / new_node_count)
> + + REG_BR_PROB_BASE/2) / REG_BR_PROB_BASE;
> else
> cs->count = 0;
>
> for (cs = orig_node->callees; cs ; cs = cs->next_callee)
> {
> - gcov_type dec = cs->count * (redirected_sum * REG_BR_PROB_BASE
> - / orig_node_count) / REG_BR_PROB_BASE;
> + gcov_type dec = (cs->count
> + * ((redirected_sum * REG_BR_PROB_BASE
> + + orig_node_count/2) / orig_node_count)
> + + REG_BR_PROB_BASE/2) / REG_BR_PROB_BASE;
> if (dec < cs->count)
> cs->count -= dec;
> else
>
> --
> This patch is available for review at http://codereview.appspot.com/7812053
