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Re: [PATCH GCC]Improve bound information in loop niter analysis

From: Jeff Law <law at redhat dot com>
To: "Bin.Cheng" <amker dot cheng at gmail dot com>
Cc: Bin Cheng <bin dot cheng at arm dot com>, gcc-patches List <gcc-patches at gcc dot gnu dot org>
Date: Fri, 14 Aug 2015 12:28:22 -0600
Subject: Re: [PATCH GCC]Improve bound information in loop niter analysis
Authentication-results: sourceware.org; auth=none
References: <000401d0c918$d7a2e780$86e8b680$ at arm dot com> <55CD156B dot 3030506 at redhat dot com> <CAHFci28-o-htn7TnU4N6bcK5WiusCrcOVB=2r=vqfDHV_PzA9Q at mail dot gmail dot com>

On 08/13/2015 09:06 PM, Bin.Cheng wrote:


Thanks for the comment.
IIUC, the niter information in struct tree_niter_desc means the number
of executions of the latch of the loop, so it's 254, rather than 255.
And same the bound information.  Of course, statements in the loop
body could execute bound+1 times depending on its position in loop.
For example, struct nb_iter_bound is to describe number of iterations
of statements(exit conditions).

Ah, if we go to tree_niter_desc, niter is defined as the # executions ofthe loop latch. That's what I was missing. Now back to the real reviewwork :-)


jeff

References:
- Re: [PATCH GCC]Improve bound information in loop niter analysis
  - From: Jeff Law
- Re: [PATCH GCC]Improve bound information in loop niter analysis
  - From: Bin.Cheng

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