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RE: branch probabilities on multiway branches
The calculate branch probabilities algorithm (1) in the Wu Larus paper
also evenly distributes branch probabilities when number of outgoing
edges is > 2, e.g. switch cases implemented as jump tables.
Are they any known heuristics to generate better branch probabilities
in this case?
-----Original Message-----
From: Jan Hubicka [mailto:hubicka@ucw.cz]
Sent: 14 April 2010 00:44
To: Rahul Kharche
Cc: gcc@gcc.gnu.org; sdkteam-gnu
Subject: Re: branch probabilities on multiway branches
> Hi All,
>
> The following bit of code in predict.c implies branch probabilities
> are strictly evenly distributed for multiway branches at present. The
> comment suggests it is possible to generate better estimates for more
> generic cases, apart from being involved. Could anyone point me to
> the reference and/or if an implementation exists already.
There is Wu & Larus paper cited in the comment at the begging of file.
Honza