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    SubjectRe: [oss-drivers] [PATCH AUTOSEL 5.0 192/262] nfp: bpf: correct the behavior for shifts by zero
    On Wed, 27 Mar 2019 14:00:47 -0400, Sasha Levin wrote:
    > From: Jiong Wang <jiong.wang@netronome.com>
    >
    > [ Upstream commit db0a4b3b6b83a081a9ec309cc8178e5c9b4706a5 ]
    >
    > Shifts by zero do nothing, and should be treated as nops.
    >
    > Even though compiler is not supposed to generate such instructions and
    > manual written assembly is unlikely to have them, but they are legal
    > instructions and have defined behavior.
    >
    > This patch correct existing shifts code-gen to make sure they do nothing
    > when shift amount is zero except when the instruction is ALU32 for which
    > high bits need to be cleared.
    >
    > For shift amount bigger than type size, already, NFP JIT back-end errors
    > out for immediate shift and only low 5 bits will be taken into account for
    > indirect shift which is the same as x86.
    >
    > Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
    > Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
    > Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    > Signed-off-by: Sasha Levin <sashal@kernel.org>

    Nope.

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