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Date:   Tue, 07 May 2019 07:05:18 +0200
From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     Jiong Wang <jiong.wang@netronome.com>
Cc:     Jakub Kicinski <jakub.kicinski@netronome.com>,
        "David S. Miller" <davem@davemloft.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        oss-drivers@netronome.com, linux-kernel@vger.kernel.org,
        xdp-newbies@vger.kernel.org, valdis@vt.edu
Subject: Re: [oss-drivers] netronome/nfp/bpf/jit.c cannot be build with -O3
In-Reply-To: <87mujzutsw.fsf@netronome.com>
References: <673b885183fb64f1cbb3ed2387524077@natalenko.name>
 <87mujzutsw.fsf@netronome.com>
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Hi.

On 07.05.2019 00:01, Jiong Wang wrote:
> I guess it's because constant prop. Could you try the following change 
> to
> __emit_shift?
> 
> drivers/net/ethernet/netronome/nfp/bpf/jit.c
> __emit_shift:331
> -       if (sc == SHF_SC_L_SHF)
> +       if (sc == SHF_SC_L_SHF && shift)
>                 shift = 32 - shift;
> 
> emit_shf_indir is passing "0" as shift to __emit_shift which will
> eventually be turned into 32 and it was OK because we truncate to 
> 5-bit,
> but before truncation, it will overflow the shift mask.

Yup, it silences the error for me.

-- 
   Oleksandr Natalenko (post-factum)