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Subject[PATCH 3/3] MIPS,bpf: Cache value of BPF_OP(insn->code) in eBPF JIT.
Date
The code looks a little cleaner if we replace BPF_OP(insn->code) with
the local variable bpf_op. Caching the value this way also saves 300
bytes (about 1%) in the code size of the JIT.

Signed-off-by: David Daney <david.daney@cavium.com>
---
arch/mips/net/ebpf_jit.c | 67 ++++++++++++++++++++++++------------------------
1 file changed, 34 insertions(+), 33 deletions(-)

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index c1e21cb..44ddc12 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -670,6 +670,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
unsigned int target;
u64 t64;
s64 t64s;
+ int bpf_op = BPF_OP(insn->code);

switch (insn->code) {
case BPF_ALU64 | BPF_ADD | BPF_K: /* ALU64_IMM */
@@ -758,13 +759,13 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, sll, dst, dst, 0);
if (insn->imm == 1) {
/* div by 1 is a nop, mod by 1 is zero */
- if (BPF_OP(insn->code) == BPF_MOD)
+ if (bpf_op == BPF_MOD)
emit_instr(ctx, addu, dst, MIPS_R_ZERO, MIPS_R_ZERO);
break;
}
gen_imm_to_reg(insn, MIPS_R_AT, ctx);
emit_instr(ctx, divu, dst, MIPS_R_AT);
- if (BPF_OP(insn->code) == BPF_DIV)
+ if (bpf_op == BPF_DIV)
emit_instr(ctx, mflo, dst);
else
emit_instr(ctx, mfhi, dst);
@@ -786,13 +787,13 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,

if (insn->imm == 1) {
/* div by 1 is a nop, mod by 1 is zero */
- if (BPF_OP(insn->code) == BPF_MOD)
+ if (bpf_op == BPF_MOD)
emit_instr(ctx, addu, dst, MIPS_R_ZERO, MIPS_R_ZERO);
break;
}
gen_imm_to_reg(insn, MIPS_R_AT, ctx);
emit_instr(ctx, ddivu, dst, MIPS_R_AT);
- if (BPF_OP(insn->code) == BPF_DIV)
+ if (bpf_op == BPF_DIV)
emit_instr(ctx, mflo, dst);
else
emit_instr(ctx, mfhi, dst);
@@ -817,7 +818,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32);
did_move = false;
if (insn->src_reg == BPF_REG_10) {
- if (BPF_OP(insn->code) == BPF_MOV) {
+ if (bpf_op == BPF_MOV) {
emit_instr(ctx, daddiu, dst, MIPS_R_SP, MAX_BPF_STACK);
did_move = true;
} else {
@@ -827,7 +828,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
} else if (get_reg_val_type(ctx, this_idx, insn->src_reg) == REG_32BIT) {
int tmp_reg = MIPS_R_AT;

- if (BPF_OP(insn->code) == BPF_MOV) {
+ if (bpf_op == BPF_MOV) {
tmp_reg = dst;
did_move = true;
}
@@ -835,7 +836,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, dinsu, tmp_reg, MIPS_R_ZERO, 32, 32);
src = MIPS_R_AT;
}
- switch (BPF_OP(insn->code)) {
+ switch (bpf_op) {
case BPF_MOV:
if (!did_move)
emit_instr(ctx, daddu, dst, src, MIPS_R_ZERO);
@@ -867,7 +868,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, beq, src, MIPS_R_ZERO, b_off);
emit_instr(ctx, movz, MIPS_R_V0, MIPS_R_ZERO, src);
emit_instr(ctx, ddivu, dst, src);
- if (BPF_OP(insn->code) == BPF_DIV)
+ if (bpf_op == BPF_DIV)
emit_instr(ctx, mflo, dst);
else
emit_instr(ctx, mfhi, dst);
@@ -911,7 +912,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
if (ts == REG_64BIT || ts == REG_32BIT_ZERO_EX) {
int tmp_reg = MIPS_R_AT;

- if (BPF_OP(insn->code) == BPF_MOV) {
+ if (bpf_op == BPF_MOV) {
tmp_reg = dst;
did_move = true;
}
@@ -919,7 +920,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, sll, tmp_reg, src, 0);
src = MIPS_R_AT;
}
- switch (BPF_OP(insn->code)) {
+ switch (bpf_op) {
case BPF_MOV:
if (!did_move)
emit_instr(ctx, addu, dst, src, MIPS_R_ZERO);
@@ -950,7 +951,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, beq, src, MIPS_R_ZERO, b_off);
emit_instr(ctx, movz, MIPS_R_V0, MIPS_R_ZERO, src);
emit_instr(ctx, divu, dst, src);
- if (BPF_OP(insn->code) == BPF_DIV)
+ if (bpf_op == BPF_DIV)
emit_instr(ctx, mflo, dst);
else
emit_instr(ctx, mfhi, dst);
@@ -977,7 +978,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
break;
case BPF_JMP | BPF_JEQ | BPF_K: /* JMP_IMM */
case BPF_JMP | BPF_JNE | BPF_K: /* JMP_IMM */
- cmp_eq = (BPF_OP(insn->code) == BPF_JEQ);
+ cmp_eq = (bpf_op == BPF_JEQ);
dst = ebpf_to_mips_reg(ctx, insn, dst_reg_fp_ok);
if (dst < 0)
return dst;
@@ -1012,18 +1013,18 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, sll, MIPS_R_AT, dst, 0);
dst = MIPS_R_AT;
}
- if (BPF_OP(insn->code) == BPF_JSET) {
+ if (bpf_op == BPF_JSET) {
emit_instr(ctx, and, MIPS_R_AT, dst, src);
cmp_eq = false;
dst = MIPS_R_AT;
src = MIPS_R_ZERO;
- } else if (BPF_OP(insn->code) == BPF_JSGT || BPF_OP(insn->code) == BPF_JSLE) {
+ } else if (bpf_op == BPF_JSGT || bpf_op == BPF_JSLE) {
emit_instr(ctx, dsubu, MIPS_R_AT, dst, src);
if ((insn + 1)->code == (BPF_JMP | BPF_EXIT) && insn->off == 1) {
b_off = b_imm(exit_idx, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
- if (BPF_OP(insn->code) == BPF_JSGT)
+ if (bpf_op == BPF_JSGT)
emit_instr(ctx, blez, MIPS_R_AT, b_off);
else
emit_instr(ctx, bgtz, MIPS_R_AT, b_off);
@@ -1033,18 +1034,18 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
b_off = b_imm(this_idx + insn->off + 1, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
- if (BPF_OP(insn->code) == BPF_JSGT)
+ if (bpf_op == BPF_JSGT)
emit_instr(ctx, bgtz, MIPS_R_AT, b_off);
else
emit_instr(ctx, blez, MIPS_R_AT, b_off);
emit_instr(ctx, nop);
break;
- } else if (BPF_OP(insn->code) == BPF_JSGE || BPF_OP(insn->code) == BPF_JSLT) {
+ } else if (bpf_op == BPF_JSGE || bpf_op == BPF_JSLT) {
emit_instr(ctx, slt, MIPS_R_AT, dst, src);
- cmp_eq = BPF_OP(insn->code) == BPF_JSGE;
+ cmp_eq = bpf_op == BPF_JSGE;
dst = MIPS_R_AT;
src = MIPS_R_ZERO;
- } else if (BPF_OP(insn->code) == BPF_JGT || BPF_OP(insn->code) == BPF_JLE) {
+ } else if (bpf_op == BPF_JGT || bpf_op == BPF_JLE) {
/* dst or src could be AT */
emit_instr(ctx, dsubu, MIPS_R_T8, dst, src);
emit_instr(ctx, sltu, MIPS_R_AT, dst, src);
@@ -1052,16 +1053,16 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
emit_instr(ctx, movz, MIPS_R_T9, MIPS_R_SP, MIPS_R_T8);
emit_instr(ctx, movn, MIPS_R_T9, MIPS_R_ZERO, MIPS_R_T8);
emit_instr(ctx, or, MIPS_R_AT, MIPS_R_T9, MIPS_R_AT);
- cmp_eq = BPF_OP(insn->code) == BPF_JGT;
+ cmp_eq = bpf_op == BPF_JGT;
dst = MIPS_R_AT;
src = MIPS_R_ZERO;
- } else if (BPF_OP(insn->code) == BPF_JGE || BPF_OP(insn->code) == BPF_JLT) {
+ } else if (bpf_op == BPF_JGE || bpf_op == BPF_JLT) {
emit_instr(ctx, sltu, MIPS_R_AT, dst, src);
- cmp_eq = BPF_OP(insn->code) == BPF_JGE;
+ cmp_eq = bpf_op == BPF_JGE;
dst = MIPS_R_AT;
src = MIPS_R_ZERO;
} else { /* JNE/JEQ case */
- cmp_eq = (BPF_OP(insn->code) == BPF_JEQ);
+ cmp_eq = (bpf_op == BPF_JEQ);
}
jeq_common:
/*
@@ -1122,7 +1123,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
case BPF_JMP | BPF_JSGE | BPF_K: /* JMP_IMM */
case BPF_JMP | BPF_JSLT | BPF_K: /* JMP_IMM */
case BPF_JMP | BPF_JSLE | BPF_K: /* JMP_IMM */
- cmp_eq = (BPF_OP(insn->code) == BPF_JSGE);
+ cmp_eq = (bpf_op == BPF_JSGE);
dst = ebpf_to_mips_reg(ctx, insn, dst_reg_fp_ok);
if (dst < 0)
return dst;
@@ -1132,7 +1133,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
b_off = b_imm(exit_idx, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
- switch (BPF_OP(insn->code)) {
+ switch (bpf_op) {
case BPF_JSGT:
emit_instr(ctx, blez, dst, b_off);
break;
@@ -1152,7 +1153,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
b_off = b_imm(this_idx + insn->off + 1, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
- switch (BPF_OP(insn->code)) {
+ switch (bpf_op) {
case BPF_JSGT:
emit_instr(ctx, bgtz, dst, b_off);
break;
@@ -1173,14 +1174,14 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
* only "LT" compare available, so we must use imm + 1
* to generate "GT" and imm -1 to generate LE
*/
- if (BPF_OP(insn->code) == BPF_JSGT)
+ if (bpf_op == BPF_JSGT)
t64s = insn->imm + 1;
- else if (BPF_OP(insn->code) == BPF_JSLE)
+ else if (bpf_op == BPF_JSLE)
t64s = insn->imm + 1;
else
t64s = insn->imm;

- cmp_eq = BPF_OP(insn->code) == BPF_JSGT || BPF_OP(insn->code) == BPF_JSGE;
+ cmp_eq = bpf_op == BPF_JSGT || bpf_op == BPF_JSGE;
if (t64s >= S16_MIN && t64s <= S16_MAX) {
emit_instr(ctx, slti, MIPS_R_AT, dst, (int)t64s);
src = MIPS_R_AT;
@@ -1197,7 +1198,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
case BPF_JMP | BPF_JGE | BPF_K:
case BPF_JMP | BPF_JLT | BPF_K:
case BPF_JMP | BPF_JLE | BPF_K:
- cmp_eq = (BPF_OP(insn->code) == BPF_JGE);
+ cmp_eq = (bpf_op == BPF_JGE);
dst = ebpf_to_mips_reg(ctx, insn, dst_reg_fp_ok);
if (dst < 0)
return dst;
@@ -1205,14 +1206,14 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
* only "LT" compare available, so we must use imm + 1
* to generate "GT" and imm -1 to generate LE
*/
- if (BPF_OP(insn->code) == BPF_JGT)
+ if (bpf_op == BPF_JGT)
t64s = (u64)(u32)(insn->imm) + 1;
- else if (BPF_OP(insn->code) == BPF_JLE)
+ else if (bpf_op == BPF_JLE)
t64s = (u64)(u32)(insn->imm) + 1;
else
t64s = (u64)(u32)(insn->imm);

- cmp_eq = BPF_OP(insn->code) == BPF_JGT || BPF_OP(insn->code) == BPF_JGE;
+ cmp_eq = bpf_op == BPF_JGT || bpf_op == BPF_JGE;

emit_const_to_reg(ctx, MIPS_R_AT, (u64)t64s);
emit_instr(ctx, sltu, MIPS_R_AT, dst, MIPS_R_AT);
--
2.9.5
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