[src/trunk]: src/sys/net For P[X+0] load, don't emit wrap around check and co...

[alnsn <alnsn%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d60fff1d125d
branches:  trunk
changeset: 330888:d60fff1d125d
user:      alnsn <alnsn%NetBSD.org@localhost>
date:      Thu Jul 24 22:54:38 2014 +0000

description:
For P[X+0] load, don't emit wrap around check and copy X intead of emitting X+0.

diffstat:

 sys/net/bpfjit.c |  50 ++++++++++++++++++++++++++++++--------------------
 1 files changed, 30 insertions(+), 20 deletions(-)

diffs (73 lines):

diff -r 6eaa9795fd3a -r d60fff1d125d sys/net/bpfjit.c
--- a/sys/net/bpfjit.c  Thu Jul 24 22:54:10 2014 +0000
+++ b/sys/net/bpfjit.c  Thu Jul 24 22:54:38 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: bpfjit.c,v 1.30 2014/07/22 08:29:51 alnsn Exp $        */
+/*     $NetBSD: bpfjit.c,v 1.31 2014/07/24 22:54:38 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 1.30 2014/07/22 08:29:51 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.31 2014/07/24 22:54:38 alnsn Exp $");
 #else
-__RCSID("$NetBSD: bpfjit.c,v 1.30 2014/07/22 08:29:51 alnsn Exp $");
+__RCSID("$NetBSD: bpfjit.c,v 1.31 2014/07/24 22:54:38 alnsn Exp $");
 #endif
 
 #include <sys/types.h>
@@ -558,24 +558,34 @@
                return status;
 
        if (BPF_CLASS(pc->code) == BPF_LD && BPF_MODE(pc->code) == BPF_IND) {
-               /* if (X > UINT32_MAX - pc->k) return 0; */
-               jump = sljit_emit_cmp(compiler,
-                   SLJIT_C_GREATER,
-                   BJ_XREG, 0,
-                   SLJIT_IMM, UINT32_MAX - pc->k);
-               if (jump == NULL)
-                       return SLJIT_ERR_ALLOC_FAILED;
-               if (!append_jump(jump, ret0, ret0_size, ret0_maxsize))
-                       return SLJIT_ERR_ALLOC_FAILED;
+               if (pc->k == 0) {
+                       /* k = X; */
+                       status = sljit_emit_op1(compiler,
+                           SLJIT_MOV,
+                           SLJIT_SCRATCH_REG2, 0,
+                           BJ_XREG, 0);
+                       if (status != SLJIT_SUCCESS)
+                               return status;
+               } else {
+                       /* if (X > UINT32_MAX - pc->k) return 0; */
+                       jump = sljit_emit_cmp(compiler,
+                           SLJIT_C_GREATER,
+                           BJ_XREG, 0,
+                           SLJIT_IMM, UINT32_MAX - pc->k);
+                       if (jump == NULL)
+                               return SLJIT_ERR_ALLOC_FAILED;
+                       if (!append_jump(jump, ret0, ret0_size, ret0_maxsize))
+                               return SLJIT_ERR_ALLOC_FAILED;
 
-               /* k = X + pc->k; */
-               status = sljit_emit_op2(compiler,
-                   SLJIT_ADD,
-                   SLJIT_SCRATCH_REG2, 0,
-                   BJ_XREG, 0,
-                   SLJIT_IMM, (uint32_t)pc->k);
-               if (status != SLJIT_SUCCESS)
-                       return status;
+                       /* k = X + pc->k; */
+                       status = sljit_emit_op2(compiler,
+                           SLJIT_ADD,
+                           SLJIT_SCRATCH_REG2, 0,
+                           BJ_XREG, 0,
+                           SLJIT_IMM, (uint32_t)pc->k);
+                       if (status != SLJIT_SUCCESS)
+                               return status;
+               }
        } else {
                /* k = pc->k */
                status = sljit_emit_op1(compiler,