From: Jerin Jacob
Optimize modulo operation instruction generation by
using single MSUB instruction vs MUL followed by SUB
instruction scheme.
Signed-off-by: Jerin Jacob
---
arch/arm64/net/bpf_jit.h | 3 +++
arch/arm64/net/bpf_jit_comp.c | 6 ++
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index cb7ab50b7657..eb73f9f72c46 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -171,6 +171,9 @@
/* Rd = Ra + Rn * Rm */
#define A64_MADD(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \
A64_VARIANT(sf), AARCH64_INSN_DATA3_MADD)
+/* Rd = Ra - Rn * Rm */
+#define A64_MSUB(sf, Rd, Ra, Rn, Rm) aarch64_insn_gen_data3(Rd, Ra, Rn, Rm, \
+ A64_VARIANT(sf), AARCH64_INSN_DATA3_MSUB)
/* Rd = Rn * Rm */
#define A64_MUL(sf, Rd, Rn, Rm) A64_MADD(sf, Rd, A64_ZR, Rn, Rm)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index f5b437f8a22b..cdc79de0c794 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -409,8 +409,7 @@ static int build_insn(const struct bpf_insn *insn, struct
jit_ctx *ctx,
break;
case BPF_MOD:
emit(A64_UDIV(is64, tmp, dst, src), ctx);
- emit(A64_MUL(is64, tmp, tmp, src), ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ emit(A64_MSUB(is64, dst, dst, tmp, src), ctx);
break;
}
break;
@@ -516,8 +515,7 @@ static int build_insn(const struct bpf_insn *insn, struct
jit_ctx *ctx,
case BPF_ALU64 | BPF_MOD | BPF_K:
emit_a64_mov_i(is64, tmp2, imm, ctx);
emit(A64_UDIV(is64, tmp, dst, tmp2), ctx);
- emit(A64_MUL(is64, tmp, tmp, tmp2), ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ emit(A64_MSUB(is64, dst, dst, tmp, tmp2), ctx);
break;
case BPF_ALU | BPF_LSH | BPF_K:
case BPF_ALU64 | BPF_LSH | BPF_K:
--
2.23.0
