Linux likely() unlikely() for PostgreSQL

Hi Hackers
   When I saw this document:https://en.wikipedia.org/wiki/Branch_predictor, I thought of Linux likely() vs unlikely() and thus thought that there are some code segments in src/backend/executor/execMain.c that can be optimized.
For example :
if (ExecutorStart_hook)
(*ExecutorStart_hook) (queryDesc, eflags);
else
standard_ExecutorStart(queryDesc, eflags);
}
void
ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction, uint64 count,
bool execute_once)
{
if (ExecutorRun_hook)
(*ExecutorRun_hook) (queryDesc, direction, count, execute_once);
else
standard_ExecutorRun(queryDesc, direction, count, execute_once);
}
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