Module Name: src
Committed By: alnsn
Date: Thu Nov 20 19:18:52 UTC 2014
Modified Files:
src/sys/net: bpfjit.c
Log Message:
Implement BPF_ALU+BPF_MOD-BPF_K when pc->k is a power of 2. Get rid of divt
and divw arguments in emit_moddiv(), they're accessible via the pc argument.
To generate a diff of this commit:
cvs rdiff -u -r1.34 -r1.35 src/sys/net/bpfjit.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/net/bpfjit.c
diff -u src/sys/net/bpfjit.c:1.34 src/sys/net/bpfjit.c:1.35
--- src/sys/net/bpfjit.c:1.34 Thu Nov 20 14:35:01 2014
+++ src/sys/net/bpfjit.c Thu Nov 20 19:18:52 2014
@@ -1,4 +1,4 @@
-/* $NetBSD: bpfjit.c,v 1.34 2014/11/20 14:35:01 alnsn Exp $ */
+/* $NetBSD: bpfjit.c,v 1.35 2014/11/20 19:18:52 alnsn Exp $ */
/*-
* Copyright (c) 2011-2014 Alexander Nasonov.
@@ -31,9 +31,9 @@
#include <sys/cdefs.h>
#ifdef _KERNEL
-__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.34 2014/11/20 14:35:01 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.35 2014/11/20 19:18:52 alnsn Exp $");
#else
-__RCSID("$NetBSD: bpfjit.c,v 1.34 2014/11/20 14:35:01 alnsn Exp $");
+__RCSID("$NetBSD: bpfjit.c,v 1.35 2014/11/20 19:18:52 alnsn Exp $");
#endif
#include <sys/types.h>
@@ -1087,25 +1087,43 @@ emit_msh(struct sljit_compiler *compiler
return SLJIT_SUCCESS;
}
+/*
+ * Emit code for A = A / k or A = A % k when k is a power of 2.
+ * @pc BPF_DIV or BPF_MOD instruction.
+ */
static int
-emit_pow2_division(struct sljit_compiler *compiler, uint32_t k)
+emit_pow2_moddiv(struct sljit_compiler *compiler, const struct bpf_insn *pc)
{
- int shift = 0;
+ uint32_t k = pc->k;
int status = SLJIT_SUCCESS;
- while (k > 1) {
- k >>= 1;
- shift++;
- }
-
- BJ_ASSERT(k == 1 && shift < 32);
+ BJ_ASSERT(k != 0 && (k & (k - 1)) == 0);
- if (shift != 0) {
+ if (BPF_OP(pc->code) == BPF_MOD) {
status = sljit_emit_op2(compiler,
- SLJIT_LSHR|SLJIT_INT_OP,
+ SLJIT_AND,
BJ_AREG, 0,
BJ_AREG, 0,
- SLJIT_IMM, shift);
+ SLJIT_IMM, k - 1);
+ } else {
+ int shift = 0;
+
+ /*
+ * Do shift = __builtin_ctz(k).
+ * The loop is slower, but that's ok.
+ */
+ while (k > 1) {
+ k >>= 1;
+ shift++;
+ }
+
+ if (shift != 0) {
+ status = sljit_emit_op2(compiler,
+ SLJIT_LSHR|SLJIT_INT_OP,
+ BJ_AREG, 0,
+ BJ_AREG, 0,
+ SLJIT_IMM, shift);
+ }
}
return status;
@@ -1128,15 +1146,15 @@ modulus(sljit_uw x, sljit_uw y)
#endif
/*
- * Emit code for A = A / div or A = A % div
- * divt,divw are either SLJIT_IMM,pc->k or BJ_XREG,0.
+ * Emit code for A = A / div or A = A % div.
+ * @pc BPF_DIV or BPF_MOD instruction.
*/
static int
-emit_moddiv(struct sljit_compiler *compiler,
- const struct bpf_insn *pc, int divt, sljit_sw divw)
+emit_moddiv(struct sljit_compiler *compiler, const struct bpf_insn *pc)
{
int status;
const bool div = BPF_OP(pc->code) == BPF_DIV;
+ const bool xreg = BPF_SRC(pc->code) == BPF_X;
#if BJ_XREG == SLJIT_RETURN_REG || \
BJ_XREG == SLJIT_SCRATCH_REG1 || \
@@ -1157,7 +1175,8 @@ emit_moddiv(struct sljit_compiler *compi
status = sljit_emit_op1(compiler,
SLJIT_MOV,
SLJIT_SCRATCH_REG2, 0,
- divt, divw);
+ xreg ? BJ_XREG : SLJIT_IMM,
+ xreg ? 0 : (uint32_t)pc->k);
if (status != SLJIT_SUCCESS)
return status;
@@ -1940,17 +1959,14 @@ generate_insn_code(struct sljit_compiler
}
if (src == BPF_X) {
- status = emit_moddiv(compiler, pc, BJ_XREG, 0);
+ status = emit_moddiv(compiler, pc);
if (status != SLJIT_SUCCESS)
goto fail;
} else if (pc->k != 0) {
- /* XXX: We can do better here for MOD */
- if ((pc->k & (pc->k - 1)) || op == BPF_MOD) {
- status = emit_moddiv(compiler, pc,
- SLJIT_IMM, (uint32_t)pc->k);
+ if (pc->k & (pc->k - 1)) {
+ status = emit_moddiv(compiler, pc);
} else {
- status = emit_pow2_division(compiler,
- (uint32_t)pc->k);
+ status = emit_pow2_moddiv(compiler, pc);
}
if (status != SLJIT_SUCCESS)
goto fail;
