From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: Yonghong Song <yhs@fb.com>
Cc: "alexei.starovoitov@gmail.com" <alexei.starovoitov@gmail.com>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"oss-drivers@netronome.com" <oss-drivers@netronome.com>
Subject: Re: [RFC bpf-next v3 03/12] bpf: verifier: remove dead code
Date: Mon, 31 Dec 2018 14:27:50 -0800 [thread overview]
Message-ID: <20181231142750.0f93d3fa@cakuba.hsd1.ca.comcast.net> (raw)
In-Reply-To: <790ec09d-cdbc-96cc-e7f7-2b0d7bb6dd35@fb.com>
On Mon, 31 Dec 2018 21:41:22 +0000, Yonghong Song wrote:
> > func2 after func adjust will start at off and there is no line info for
> > off + cnt (insn4), so we will preserve line_info2.
>
> Thanks for verification, I missed that
> >>> + /* count lines to be removed */
> >>> + l_off = i;
> >>> + l_cnt = 0;
> >>> + for (; i < nr_linfo; i++)
> >>> + if (linfo[i].insn_off < off + cnt)
> >>> + l_cnt++;
> >>> + else
> >>> + break;
> once you reached linfo[i].insn_off >= off + cnt, no more counting.
> since l_cnt starts from 0, so the last one is actually preserved.
Ah, I see!
> > linfo1:
> > insn1
> > insn2 /* dead */
> > linfo2:
> > insn3 /* dead */
> > insn4
> > linfo3:
> > insn5
> >
> > ||
> > \/
> >
> > linfo1:
> > insn1
> > linfo2:
> > insn4
> > linfo3:
> > insn5
>
> Yes, the above is the desirable output.
Perfect, let me respin.
next prev parent reply other threads:[~2018-12-31 22:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-29 3:09 [RFC bpf-next v3 00/12] bpf: dead code elimination Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 01/12] bpf: change parameters of call/branch offset adjustment Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 02/12] bpf: verifier: hard wire branches to dead code Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 03/12] bpf: verifier: remove " Jakub Kicinski
2018-12-30 22:02 ` Yonghong Song
2018-12-31 20:31 ` Jakub Kicinski
2018-12-31 21:41 ` Yonghong Song
2018-12-31 22:27 ` Jakub Kicinski [this message]
2018-12-29 3:09 ` [RFC bpf-next v3 04/12] bpf: verifier: remove unconditional branches by 0 Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 05/12] selftests: bpf: add tests for dead code removal Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 06/12] bpf: verifier: record original instruction index Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 07/12] bpf: notify offload JITs about optimizations Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 08/12] nfp: bpf: don't use instruction number for jump target Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 09/12] nfp: bpf: split up the skip flag Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 10/12] nfp: bpf: save original program length Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 11/12] nfp: bpf: support optimizing dead branches Jakub Kicinski
2018-12-29 3:09 ` [RFC bpf-next v3 12/12] nfp: bpf: support removing dead code Jakub Kicinski
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