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Re: [PATCH] Disable -fno-reorder-blocks-and-partition if no -fprofile-use to avoid unnecessary overhead
- From: Andi Kleen <andi at firstfloor dot org>
- To: Teresa Johnson <tejohnson at google dot com>
- Cc: "gcc-patches\ at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Jan Hubicka <hubicka at ucw dot cz>, Xinliang David Li <davidxl at google dot com>
- Date: Fri, 25 Sep 2015 09:57:02 -0700
- Subject: Re: [PATCH] Disable -fno-reorder-blocks-and-partition if no -fprofile-use to avoid unnecessary overhead
- Authentication-results: sourceware.org; auth=none
- References: <CAAe5K+WwdWZyp96ODECAxPsu-nf97akiKzremnhPbiYGS2E_bw at mail dot gmail dot com>
Teresa Johnson <tejohnson@google.com> writes:
> This patch unsets -freorder-blocks-and-partition when -fprofile-use
> is not specified. Function splitting was not actually being performed
> in that case, as probably_never_executed_bb_p does not distinguish
> any basic blocks as being cold vs hot when there is no profile data.
Actually I'm experimenting with a patch to fix that by allowing
function splitting even without profile feed back. See PR66890
which has the patch. I would prefer to keep and fix it.
-Andi
--
ak@linux.intel.com -- Speaking for myself only