netdev - [PATCH bpf-next 0/4] nfp: bpf: optimize negative sums

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Date:   Tue, 24 Apr 2018 21:22:35 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH bpf-next 0/4] nfp: bpf: optimize negative sums

Hi!

This set adds an optimization run to the NFP jit to turn ADD and SUB
instructions with negative immediate into the opposite operation with
a positive immediate.  NFP can fit small immediates into the instructions
but it can't ever fit negative immediates.  Addition of small negative
immediates is quite common in BPF programs for stack address calculations,
therefore this optimization gives us non-negligible savings in instruction
count (up to 4%).

Jakub Kicinski (4):
  nfp: bpf: remove double space
  nfp: bpf: optimize add/sub of a negative constant
  nfp: bpf: tabularize generations of compare operations
  nfp: bpf: optimize comparisons to negative constants

 drivers/net/ethernet/netronome/nfp/bpf/jit.c  | 231 +++++++++++++-------------
 drivers/net/ethernet/netronome/nfp/bpf/main.h |   6 +-
 2 files changed, 124 insertions(+), 113 deletions(-)

-- 
2.16.2