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Re: [PATCH] Ensure count_scale is no larger than REG_BR_PROB_BASE
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Dehao Chen <dehao at google dot com>
- Cc: Jan Hubicka <hubicka at ucw dot cz>, GCC Patches <gcc-patches at gcc dot gnu dot org>, David Li <davidxl at google dot com>
- Date: Sat, 17 May 2014 02:22:08 +0200
- Subject: Re: [PATCH] Ensure count_scale is no larger than REG_BR_PROB_BASE
- Authentication-results: sourceware.org; auth=none
- References: <CAO2gOZVj7vwDDtn1=XjE4PsiB-1B-a-9Ku2gFHViOVOLZUYMrg at mail dot gmail dot com> <20140516234137 dot GC28043 at kam dot mff dot cuni dot cz> <CAO2gOZUx92=GXQ-7ouET5zk+DCZbw=OPFTco=wPYhy-n-TofcQ at mail dot gmail dot com>
> In AutoFDO, a basic block's count can be much larger than it's actual
> count because debug info might be incorrect. In this case, a call edge
> count (calculated from BB count) could be much larger than callee's
> header count, making the count_scale incorrectly large.
In this case I still think we should handle this when producing the clone:
we do not want to have clone's count much larger as well, so i think inliner
and ipa-cp needs to deal with capping here instead....
> > Honza