sync partly with tcpdump.org. ok'ed by itojun
patches #454 from yamt@mwd.biglobe.ne.jp - avoid optimization involving subtract operations - correct optimization of bitwise operations TODO: re-introduce subtract optimization
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yamt
parent
2ccf86d7da
commit
d3538cc488
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@ -1,4 +1,4 @@
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/* $NetBSD: gencode.c,v 1.30 2002/05/16 19:57:22 wiz Exp $ */
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/* $NetBSD: gencode.c,v 1.31 2002/08/26 11:21:18 yamt Exp $ */
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/*
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* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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@ -26,7 +26,7 @@
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static const char rcsid[] =
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"@(#) Header: gencode.c,v 1.93 97/06/12 14:22:47 leres Exp (LBL)";
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#else
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__RCSID("$NetBSD: gencode.c,v 1.30 2002/05/16 19:57:22 wiz Exp $");
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__RCSID("$NetBSD: gencode.c,v 1.31 2002/08/26 11:21:18 yamt Exp $");
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#endif
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#endif
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@ -2635,16 +2635,16 @@ gen_relation(code, a0, a1, reversed)
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s0 = xfer_to_x(a1);
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s1 = xfer_to_a(a0);
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s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X);
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b = new_block(JMP(code));
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if (code == BPF_JGT || code == BPF_JGE) {
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reversed = !reversed;
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b->s.k = 0x80000000;
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if (code == BPF_JEQ) {
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s2 = new_stmt(BPF_ALU|BPF_SUB|BPF_X);
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b = new_block(JMP(code));
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sappend(s1, s2);
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}
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else
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b = new_block(BPF_JMP|code|BPF_X);
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if (reversed)
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gen_not(b);
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sappend(s1, s2);
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sappend(s0, s1);
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sappend(a1->s, s0);
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sappend(a0->s, a1->s);
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@ -1,4 +1,4 @@
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/* $NetBSD: optimize.c,v 1.14 2002/08/12 02:39:22 itojun Exp $ */
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/* $NetBSD: optimize.c,v 1.15 2002/08/26 11:21:19 yamt Exp $ */
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/*
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* Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994, 1995, 1996
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@ -28,7 +28,7 @@
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static const char rcsid[] =
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"@(#) Header: optimize.c,v 1.60 96/09/26 23:28:14 leres Exp (LBL)";
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#else
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__RCSID("$NetBSD: optimize.c,v 1.14 2002/08/12 02:39:22 itojun Exp $");
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__RCSID("$NetBSD: optimize.c,v 1.15 2002/08/26 11:21:19 yamt Exp $");
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#endif
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#endif
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@ -669,7 +669,7 @@ opt_peep(b)
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return;
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last = s;
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while (1) {
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for (/*empty*/; /*empty*/; s = next) {
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s = this_op(s);
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if (s == 0)
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break;
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@ -712,23 +712,23 @@ opt_peep(b)
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* any local dependencies.
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*/
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if (ATOMELEM(b->out_use, X_ATOM))
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break;
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continue;
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if (next->s.code != (BPF_LDX|BPF_MSH|BPF_B))
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add = next;
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else
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add = this_op(next->next);
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if (add == 0 || add->s.code != (BPF_ALU|BPF_ADD|BPF_X))
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break;
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continue;
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tax = this_op(add->next);
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if (tax == 0 || tax->s.code != (BPF_MISC|BPF_TAX))
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break;
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continue;
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ild = this_op(tax->next);
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if (ild == 0 || BPF_CLASS(ild->s.code) != BPF_LD ||
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BPF_MODE(ild->s.code) != BPF_IND)
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break;
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continue;
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/*
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* XXX We need to check that X is not
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* subsequently used. We know we can eliminate the
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@ -758,57 +758,45 @@ opt_peep(b)
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tax->s.code = NOP;
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done = 0;
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}
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s = next;
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}
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/*
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* If we have a subtract to do a comparison, and the X register
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* is a known constant, we can merge this value into the
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* comparison.
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*/
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if (last->s.code == (BPF_ALU|BPF_SUB|BPF_X) &&
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!ATOMELEM(b->out_use, A_ATOM)) {
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val = b->val[X_ATOM];
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if (vmap[val].is_const) {
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int op;
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b->s.k += vmap[val].const_val;
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op = BPF_OP(b->s.code);
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if (op == BPF_JGT || op == BPF_JGE) {
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struct block *t = JT(b);
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JT(b) = JF(b);
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JF(b) = t;
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b->s.k += 0x80000000;
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if (BPF_OP(b->s.code) == BPF_JEQ) {
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if (last->s.code == (BPF_ALU|BPF_SUB|BPF_X) &&
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!ATOMELEM(b->out_use, A_ATOM)) {
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val = b->val[X_ATOM];
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if (vmap[val].is_const) {
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/*
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* sub x -> nop
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* jeq #y jeq #(x+y)
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*/
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b->s.k += vmap[val].const_val;
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last->s.code = NOP;
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done = 0;
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} else if (b->s.k == 0) {
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/*
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* sub #x -> nop
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* jeq #0 jeq #x
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*/
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last->s.code = NOP;
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b->s.code = BPF_CLASS(b->s.code) |
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BPF_OP(b->s.code) | BPF_X;
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done = 0;
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}
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last->s.code = NOP;
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done = 0;
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} else if (b->s.k == 0) {
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/*
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* sub x -> nop
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* j #0 j x
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*/
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last->s.code = NOP;
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b->s.code = BPF_CLASS(b->s.code) | BPF_OP(b->s.code) |
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BPF_X;
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done = 0;
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}
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}
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/*
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* Likewise, a constant subtract can be simplified.
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*/
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else if (last->s.code == (BPF_ALU|BPF_SUB|BPF_K) &&
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!ATOMELEM(b->out_use, A_ATOM)) {
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int op;
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/*
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* Likewise, a constant subtract can be simplified.
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*/
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else if (last->s.code == (BPF_ALU|BPF_SUB|BPF_K) &&
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!ATOMELEM(b->out_use, A_ATOM)) {
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b->s.k += last->s.k;
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last->s.code = NOP;
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op = BPF_OP(b->s.code);
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if (op == BPF_JGT || op == BPF_JGE) {
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struct block *t = JT(b);
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JT(b) = JF(b);
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JF(b) = t;
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b->s.k += 0x80000000;
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last->s.code = NOP;
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b->s.k += last->s.k;
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done = 0;
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}
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done = 0;
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}
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/*
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* and #k nop
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@ -988,18 +976,17 @@ opt_stmt(s, val, alter)
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* that is 0, and simplify. This may not seem like
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* much of a simplification but it could open up further
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* optimizations.
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* XXX We could also check for mul by 1, and -1, etc.
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* XXX We could also check for mul by 1, etc.
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*/
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if (alter && vmap[val[A_ATOM]].is_const
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&& vmap[val[A_ATOM]].const_val == 0) {
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if (op == BPF_ADD || op == BPF_OR ||
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op == BPF_LSH || op == BPF_RSH || op == BPF_SUB) {
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if (op == BPF_ADD || op == BPF_OR) {
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s->code = BPF_MISC|BPF_TXA;
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vstore(s, &val[A_ATOM], val[X_ATOM], alter);
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break;
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}
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else if (op == BPF_MUL || op == BPF_DIV ||
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op == BPF_AND) {
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op == BPF_AND || op == BPF_LSH || op == BPF_RSH) {
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s->code = BPF_LD|BPF_IMM;
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s->k = 0;
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vstore(s, &val[A_ATOM], K(s->k), alter);
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