diff options
author | guy <guy> | 2003-12-22 00:26:35 +0000 |
---|---|---|
committer | guy <guy> | 2003-12-22 00:26:35 +0000 |
commit | 96623f1a00e941add58e5d051c5b2bb4ee01e158 (patch) | |
tree | d612f9d6ea80e8a9b5f3754924c2bbb8a86d0e92 | |
parent | 8d160ea1e64225359d6d807a1d299d742b0213ec (diff) |
Put some of Takashi Yamamoto's optimizer changes back - those changeslibpcap_0_8rel1
appear not to trigger the other optimizer bug.
Add him to the CREDITS file.
-rw-r--r-- | CREDITS | 1 | ||||
-rw-r--r-- | optimize.c | 78 |
2 files changed, 34 insertions, 45 deletions
@@ -73,6 +73,7 @@ Additional people who have contributed patches: Shaun Clowes <delius@progsoc.uts.edu.au> Solomon Peachy <pizza@shaftnet.org> Stefan Hudson <hudson@mbay.net> + Takashi Yamamoto <yamt@mwd.biglobe.ne.jp> Tony Li <tli@procket.com> Torsten Landschoff <torsten@debian.org> Uns Lider <unslider@miranda.org> @@ -22,7 +22,7 @@ */ #ifndef lint static const char rcsid[] _U_ = - "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.76.2.2 2003-12-22 00:04:06 guy Exp $ (LBL)"; + "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.76.2.3 2003-12-22 00:26:36 guy Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H @@ -760,50 +760,39 @@ opt_peep(b) * is a known constant, we can merge this value into the * comparison. */ - if (last->s.code == (BPF_ALU|BPF_SUB|BPF_X) && - !ATOMELEM(b->out_use, A_ATOM)) { - val = b->val[X_ATOM]; - if (vmap[val].is_const) { - int op; - - b->s.k += vmap[val].const_val; - op = BPF_OP(b->s.code); - if (op == BPF_JGT || op == BPF_JGE) { - struct block *t = JT(b); - JT(b) = JF(b); - JF(b) = t; - b->s.k += 0x80000000; + if (BPF_OP(b->s.code) == BPF_JEQ) { + if (last->s.code == (BPF_ALU|BPF_SUB|BPF_X) && + !ATOMELEM(b->out_use, A_ATOM)) { + val = b->val[X_ATOM]; + if (vmap[val].is_const) { + /* + * sub x -> nop + * jeq #y jeq #(x+y) + */ + b->s.k += vmap[val].const_val; + last->s.code = NOP; + done = 0; + } else if (b->s.k == 0) { + /* + * sub #x -> nop + * jeq #0 jeq #x + */ + last->s.code = NOP; + b->s.code = BPF_CLASS(b->s.code) | + BPF_OP(b->s.code) | BPF_X; + done = 0; } - last->s.code = NOP; - done = 0; - } else if (b->s.k == 0) { - /* - * sub x -> nop - * j #0 j x - */ - last->s.code = NOP; - b->s.code = BPF_CLASS(b->s.code) | BPF_OP(b->s.code) | - BPF_X; - done = 0; } - } - /* - * Likewise, a constant subtract can be simplified. - */ - else if (last->s.code == (BPF_ALU|BPF_SUB|BPF_K) && - !ATOMELEM(b->out_use, A_ATOM)) { - int op; + /* + * Likewise, a constant subtract can be simplified. + */ + else if (last->s.code == (BPF_ALU|BPF_SUB|BPF_K) && + !ATOMELEM(b->out_use, A_ATOM)) { - b->s.k += last->s.k; - last->s.code = NOP; - op = BPF_OP(b->s.code); - if (op == BPF_JGT || op == BPF_JGE) { - struct block *t = JT(b); - JT(b) = JF(b); - JF(b) = t; - b->s.k += 0x80000000; + last->s.code = NOP; + b->s.k += last->s.k; + done = 0; } - done = 0; } /* * and #k nop @@ -996,18 +985,17 @@ opt_stmt(s, val, alter) * that is 0, and simplify. This may not seem like * much of a simplification but it could open up further * optimizations. - * XXX We could also check for mul by 1, and -1, etc. + * XXX We could also check for mul by 1, etc. */ if (alter && vmap[val[A_ATOM]].is_const && vmap[val[A_ATOM]].const_val == 0) { - if (op == BPF_ADD || op == BPF_OR || - op == BPF_LSH || op == BPF_RSH || op == BPF_SUB) { + if (op == BPF_ADD || op == BPF_OR) { s->code = BPF_MISC|BPF_TXA; vstore(s, &val[A_ATOM], val[X_ATOM], alter); break; } else if (op == BPF_MUL || op == BPF_DIV || - op == BPF_AND) { + op == BPF_AND || op == BPF_LSH || op == BPF_RSH) { s->code = BPF_LD|BPF_IMM; s->k = 0; vstore(s, &val[A_ATOM], K(s->k), alter); |