Not for instrumented FDO (not as I know of). But for AutoFDO, this
could be a potential risk because some callee is marked unlikely
executed simply because they are inlined and eliminated in the O2
binary. But in ipa-inline it will not get inlined because the edge is
not hot from cgraph_maybe_hot_edge_p (because callee is
UNLIKELY_EXECUTED), while the edge->count is actually hot.
Dehao
On Mon, Oct 14, 2013 at 9:13 AM, Xinliang David Li <davi...@google.com> wrote:
> Looks like there is some inconsistency between edge hotness and callee
> frequency?
>
> David
>
> On Mon, Oct 14, 2013 at 9:08 AM, Dehao Chen <de...@google.com> wrote:
>> This patch forces to use profile info to check if an edge is hot when
>> profile is available.
>>
>> Bootstrapped and passed regression tests.
>>
>> OK for trunk?
>>
>> Thanks,
>> Dehao
>>
>> gcc/ChangeLog:
>> 2013-10-14 Dehao Chen <de...@google.com>
>> * predict.c(cgraph_maybe_hot_edge_p): Decide edge's hotness from profile.
>>
>> Index: gcc/predict.c
>> ===================================================================
>> --- gcc/predict.c (revision 203568)
>> +++ gcc/predict.c (working copy)
>> @@ -185,10 +185,8 @@ maybe_hot_bb_p (struct function *fun, const_basic_
>> bool
>> cgraph_maybe_hot_edge_p (struct cgraph_edge *edge)
>> {
>> - if (profile_info && flag_branch_probabilities
>> - && !maybe_hot_count_p (NULL,
>> - edge->count))
>> - return false;
>> + if (profile_info && flag_branch_probabilities)
>> + return maybe_hot_count_p (NULL, edge->count);
>> if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED
>> || (edge->callee
>> && edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED))
