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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2023-02-01 13:04:29 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2023-02-10 14:17:35 +0300 |
| commit | 8616045fe785229b53a24b8698631826298d1500 (patch) | |
| tree | e1eefbcc1a52c62d72f01318bf955e8034d17b6a | |
| parent | d3921cbb6cd663193cecf04f0b170a30c6d0e390 (diff) | |
| download | linux-8616045fe785229b53a24b8698631826298d1500.tar.xz | |
powerpc/bpf/32: Optimise some particular const operations
Simplify multiplications and divisions with constants when the
constant is 1 or -1.
When the constant is a power of 2, replace them by bit shits.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e53b1f4a4150ec6cabcaeeef82bf9c361b5f9204.1675245773.git.christophe.leroy@csgroup.eu
| -rw-r--r-- | arch/powerpc/net/bpf_jit_comp32.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index c3bc20b91cdc..b1d6ed4d8270 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -391,7 +391,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * EMIT(PPC_RAW_MULW(dst_reg, dst_reg, src_reg)); break; case BPF_ALU | BPF_MUL | BPF_K: /* (u32) dst *= (u32) imm */ - if (imm >= -32768 && imm < 32768) { + if (imm == 1) + break; + if (imm == -1) { + EMIT(PPC_RAW_SUBFIC(dst_reg, dst_reg, 0)); + } else if (is_power_of_2((u32)imm)) { + EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, ilog2(imm))); + } else if (imm >= -32768 && imm < 32768) { EMIT(PPC_RAW_MULI(dst_reg, dst_reg, imm)); } else { PPC_LI32(_R0, imm); @@ -411,6 +417,13 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * EMIT(PPC_RAW_SUBFZE(dst_reg_h, dst_reg_h)); break; } + if (imm > 0 && is_power_of_2(imm)) { + imm = ilog2(imm); + EMIT(PPC_RAW_RLWINM(dst_reg_h, dst_reg_h, imm, 0, 31 - imm)); + EMIT(PPC_RAW_RLWIMI(dst_reg_h, dst_reg, imm, 32 - imm, 31)); + EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, imm)); + break; + } bpf_set_seen_register(ctx, tmp_reg); PPC_LI32(tmp_reg, imm); EMIT(PPC_RAW_MULW(dst_reg_h, dst_reg_h, tmp_reg)); @@ -438,8 +451,12 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * if (imm == 1) break; - PPC_LI32(_R0, imm); - EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0)); + if (is_power_of_2((u32)imm)) { + EMIT(PPC_RAW_SRWI(dst_reg, dst_reg, ilog2(imm))); + } else { + PPC_LI32(_R0, imm); + EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, _R0)); + } break; case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */ if (!imm) |