With baseline x64 instruction set, shift count can only be an immediate or in %cl. The implicit dependency on %cl makes it necessary to shuffle registers around and/or add push/pop operations. BMI2 provides shift instructions that can use any general register as the shift count, saving us instructions and bytes in most cases. test_progs: Summary: 267/1340 PASSED, 25 SKIPPED, 0 FAILED test_progs-no_alu32: Summary: 267/1333 PASSED, 26 SKIPPED, 0 FAILED test_verifier: Summary: 1367 PASSED, 636 SKIPPED, 0 FAILED test_maps: OK, 0 SKIPPED lib/test_bpf: test_bpf: Summary: 1026 PASSED, 0 FAILED, [1014/1014 JIT'ed] test_bpf: test_tail_calls: Summary: 10 PASSED, 0 FAILED, [10/10 JIT'ed] test_bpf: test_skb_segment: Summary: 2 PASSED, 0 FAILED Jie Meng (2): bpf,x64: use shrx/sarx/shlx when available bpf: Add selftests for lsh, rsh, arsh with reg operand arch/x86/net/bpf_jit_comp.c | 53 ++++++++++++++++++++++ tools/testing/selftests/bpf/verifier/jit.c | 22 +++++++++ 2 files changed, 75 insertions(+) -- 2.30.2
