--- /dev/null
+/* From NetBSD: optimize.c,v 1.3 1995/04/29 05:42:28 cgd Exp */
+
+/*
+ * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Optimization module for tcpdump intermediate representation.
+ */
+#ifndef lint
+static char rcsid[] =
+ "@(#) Header: optimize.c,v 1.45 94/06/20 19:07:55 leres Exp (LBL)";
+#endif
+
+#include <sys/types.h>
+#include <sys/time.h>
+
+#include <net/bpf.h>
+#include <net/ppp_defs.h>
+
+#include <stdio.h>
+#ifdef __osf__
+#include <stdlib.h>
+#include <malloc.h>
+#endif
+#ifdef __NetBSD__
+#include <stdlib.h>
+#endif
+#include <memory.h>
+
+#include "gencode.h"
+
+#ifndef __GNUC__
+#define inline
+#endif
+
+#define A_ATOM BPF_MEMWORDS
+#define X_ATOM (BPF_MEMWORDS+1)
+
+#define NOP -1
+
+/*
+ * This define is used to represent *both* the accumulator and
+ * x register in use-def computations.
+ * Currently, the use-def code assumes only one definition per instruction.
+ */
+#define AX_ATOM N_ATOMS
+
+/*
+ * A flag to indicate that further optimization is needed.
+ * Iterative passes are continued until a given pass yields no
+ * branch movement.
+ */
+static int done;
+
+/*
+ * A block is marked if only if its mark equals the current mark.
+ * Rather than traverse the code array, marking each item, 'cur_mark' is
+ * incremented. This automatically makes each element unmarked.
+ */
+static int cur_mark;
+#define isMarked(p) ((p)->mark == cur_mark)
+#define unMarkAll() cur_mark += 1
+#define Mark(p) ((p)->mark = cur_mark)
+
+static void opt_init(struct block *);
+static void opt_cleanup(void);
+
+static void make_marks(struct block *);
+static void mark_code(struct block *);
+
+static void intern_blocks(struct block *);
+
+static int eq_slist(struct slist *, struct slist *);
+
+static void find_levels_r(struct block *);
+
+static void find_levels(struct block *);
+static void find_dom(struct block *);
+static void propedom(struct edge *);
+static void find_edom(struct block *);
+static void find_closure(struct block *);
+static int atomuse(struct stmt *);
+static int atomdef(struct stmt *);
+static void compute_local_ud(struct block *);
+static void find_ud(struct block *);
+static void init_val(void);
+static long F(int, long, long);
+static inline void vstore(struct stmt *, long *, long, int);
+static void opt_blk(struct block *, int);
+static int use_conflict(struct block *, struct block *);
+static void opt_j(struct edge *);
+static void or_pullup(struct block *);
+static void and_pullup(struct block *);
+static void opt_blks(struct block *, int);
+static inline void link_inedge(struct edge *, struct block *);
+static void find_inedges(struct block *);
+static void opt_root(struct block **);
+static void opt_loop(struct block *, int);
+static void fold_op(struct stmt *, long, long);
+static inline struct slist *this_op(struct slist *);
+static void opt_not(struct block *);
+static void opt_peep(struct block *);
+static void opt_stmt(struct stmt *, long[], int);
+static void deadstmt(struct stmt *, struct stmt *[]);
+static void opt_deadstores(struct block *);
+static void opt_blk(struct block *, int);
+static int use_conflict(struct block *, struct block *);
+static void opt_j(struct edge *);
+static struct block *fold_edge(struct block *, struct edge *);
+static inline int eq_blk(struct block *, struct block *);
+static int slength(struct slist *);
+static int count_blocks(struct block *);
+static void number_blks_r(struct block *);
+static int count_stmts(struct block *);
+static void convert_code_r(struct block *);
+
+static int n_blocks;
+struct block **blocks;
+static int n_edges;
+struct edge **edges;
+
+/*
+ * A bit vector set representation of the dominators.
+ * We round up the set size to the next power of two.
+ */
+static int nodewords;
+static int edgewords;
+struct block **levels;
+u_long *space;
+#define BITS_PER_WORD (8*sizeof(u_long))
+/*
+ * True if a is in uset {p}
+ */
+#define SET_MEMBER(p, a) \
+((p)[(unsigned)(a) / BITS_PER_WORD] & (1 << ((unsigned)(a) % BITS_PER_WORD)))
+
+/*
+ * Add 'a' to uset p.
+ */
+#define SET_INSERT(p, a) \
+(p)[(unsigned)(a) / BITS_PER_WORD] |= (1 << ((unsigned)(a) % BITS_PER_WORD))
+
+/*
+ * Delete 'a' from uset p.
+ */
+#define SET_DELETE(p, a) \
+(p)[(unsigned)(a) / BITS_PER_WORD] &= ~(1 << ((unsigned)(a) % BITS_PER_WORD))
+
+/*
+ * a := a intersect b
+ */
+#define SET_INTERSECT(a, b, n)\
+{\
+ register u_long *_x = a, *_y = b;\
+ register int _n = n;\
+ while (--_n >= 0) *_x++ &= *_y++;\
+}
+
+/*
+ * a := a - b
+ */
+#define SET_SUBTRACT(a, b, n)\
+{\
+ register u_long *_x = a, *_y = b;\
+ register int _n = n;\
+ while (--_n >= 0) *_x++ &=~ *_y++;\
+}
+
+/*
+ * a := a union b
+ */
+#define SET_UNION(a, b, n)\
+{\
+ register u_long *_x = a, *_y = b;\
+ register int _n = n;\
+ while (--_n >= 0) *_x++ |= *_y++;\
+}
+
+static uset all_dom_sets;
+static uset all_closure_sets;
+static uset all_edge_sets;
+
+#ifndef MAX
+#define MAX(a,b) ((a)>(b)?(a):(b))
+#endif
+
+static void
+find_levels_r(b)
+ struct block *b;
+{
+ int level;
+
+ if (isMarked(b))
+ return;
+
+ Mark(b);
+ b->link = 0;
+
+ if (JT(b)) {
+ find_levels_r(JT(b));
+ find_levels_r(JF(b));
+ level = MAX(JT(b)->level, JF(b)->level) + 1;
+ } else
+ level = 0;
+ b->level = level;
+ b->link = levels[level];
+ levels[level] = b;
+}
+
+/*
+ * Level graph. The levels go from 0 at the leaves to
+ * N_LEVELS at the root. The levels[] array points to the
+ * first node of the level list, whose elements are linked
+ * with the 'link' field of the struct block.
+ */
+static void
+find_levels(root)
+ struct block *root;
+{
+ memset((char *)levels, 0, n_blocks * sizeof(*levels));
+ unMarkAll();
+ find_levels_r(root);
+}
+
+/*
+ * Find dominator relationships.
+ * Assumes graph has been leveled.
+ */
+static void
+find_dom(root)
+ struct block *root;
+{
+ int i;
+ struct block *b;
+ u_long *x;
+
+ /*
+ * Initialize sets to contain all nodes.
+ */
+ x = all_dom_sets;
+ i = n_blocks * nodewords;
+ while (--i >= 0)
+ *x++ = ~0;
+ /* Root starts off empty. */
+ for (i = nodewords; --i >= 0;)
+ root->dom[i] = 0;
+
+ /* root->level is the highest level no found. */
+ for (i = root->level; i >= 0; --i) {
+ for (b = levels[i]; b; b = b->link) {
+ SET_INSERT(b->dom, b->id);
+ if (JT(b) == 0)
+ continue;
+ SET_INTERSECT(JT(b)->dom, b->dom, nodewords);
+ SET_INTERSECT(JF(b)->dom, b->dom, nodewords);
+ }
+ }
+}
+
+static void
+propedom(ep)
+ struct edge *ep;
+{
+ SET_INSERT(ep->edom, ep->id);
+ if (ep->succ) {
+ SET_INTERSECT(ep->succ->et.edom, ep->edom, edgewords);
+ SET_INTERSECT(ep->succ->ef.edom, ep->edom, edgewords);
+ }
+}
+
+/*
+ * Compute edge dominators.
+ * Assumes graph has been leveled and predecessors established.
+ */
+static void
+find_edom(root)
+ struct block *root;
+{
+ int i;
+ uset x;
+ struct block *b;
+
+ x = all_edge_sets;
+ for (i = n_edges * edgewords; --i >= 0; )
+ x[i] = ~0;
+
+ /* root->level is the highest level no found. */
+ memset(root->et.edom, 0, edgewords * sizeof(*(uset)0));
+ memset(root->ef.edom, 0, edgewords * sizeof(*(uset)0));
+ for (i = root->level; i >= 0; --i) {
+ for (b = levels[i]; b != 0; b = b->link) {
+ propedom(&b->et);
+ propedom(&b->ef);
+ }
+ }
+}
+
+/*
+ * Find the backwards transitive closure of the flow graph. These sets
+ * are backwards in the sense that we find the set of nodes that reach
+ * a given node, not the set of nodes that can be reached by a node.
+ *
+ * Assumes graph has been leveled.
+ */
+static void
+find_closure(root)
+ struct block *root;
+{
+ int i;
+ struct block *b;
+
+ /*
+ * Initialize sets to contain no nodes.
+ */
+ memset((char *)all_closure_sets, 0,
+ n_blocks * nodewords * sizeof(*all_closure_sets));
+
+ /* root->level is the highest level no found. */
+ for (i = root->level; i >= 0; --i) {
+ for (b = levels[i]; b; b = b->link) {
+ SET_INSERT(b->closure, b->id);
+ if (JT(b) == 0)
+ continue;
+ SET_UNION(JT(b)->closure, b->closure, nodewords);
+ SET_UNION(JF(b)->closure, b->closure, nodewords);
+ }
+ }
+}
+
+/*
+ * Return the register number that is used by s. If A and X are both
+ * used, return AX_ATOM. If no register is used, return -1.
+ *
+ * The implementation should probably change to an array access.
+ */
+static int
+atomuse(s)
+ struct stmt *s;
+{
+ register int c = s->code;
+
+ if (c == NOP)
+ return -1;
+
+ switch (BPF_CLASS(c)) {
+
+ case BPF_RET:
+ return (BPF_RVAL(c) == BPF_A) ? A_ATOM :
+ (BPF_RVAL(c) == BPF_X) ? X_ATOM : -1;
+
+ case BPF_LD:
+ case BPF_LDX:
+ return (BPF_MODE(c) == BPF_IND) ? X_ATOM :
+ (BPF_MODE(c) == BPF_MEM) ? s->k : -1;
+
+ case BPF_ST:
+ return A_ATOM;
+
+ case BPF_STX:
+ return X_ATOM;
+
+ case BPF_JMP:
+ case BPF_ALU:
+ if (BPF_SRC(c) == BPF_X)
+ return AX_ATOM;
+ return A_ATOM;
+
+ case BPF_MISC:
+ return BPF_MISCOP(c) == BPF_TXA ? X_ATOM : A_ATOM;
+ }
+ abort();
+ /* NOTREACHED */
+}
+
+/*
+ * Return the register number that is defined by 's'. We assume that
+ * a single stmt cannot define more than one register. If no register
+ * is defined, return -1.
+ *
+ * The implementation should probably change to an array access.
+ */
+static int
+atomdef(s)
+ struct stmt *s;
+{
+ if (s->code == NOP)
+ return -1;
+
+ switch (BPF_CLASS(s->code)) {
+
+ case BPF_LD:
+ case BPF_ALU:
+ return A_ATOM;
+
+ case BPF_LDX:
+ return X_ATOM;
+
+ case BPF_ST:
+ case BPF_STX:
+ return s->k;
+
+ case BPF_MISC:
+ return BPF_MISCOP(s->code) == BPF_TAX ? X_ATOM : A_ATOM;
+ }
+ return -1;
+}
+
+static void
+compute_local_ud(b)
+ struct block *b;
+{
+ struct slist *s;
+ atomset def = 0, use = 0, kill = 0;
+ int atom;
+
+ for (s = b->stmts; s; s = s->next) {
+ if (s->s.code == NOP)
+ continue;
+ atom = atomuse(&s->s);
+ if (atom >= 0) {
+ if (atom == AX_ATOM) {
+ if (!ATOMELEM(def, X_ATOM))
+ use |= ATOMMASK(X_ATOM);
+ if (!ATOMELEM(def, A_ATOM))
+ use |= ATOMMASK(A_ATOM);
+ }
+ else if (atom < N_ATOMS) {
+ if (!ATOMELEM(def, atom))
+ use |= ATOMMASK(atom);
+ }
+ else
+ abort();
+ }
+ atom = atomdef(&s->s);
+ if (atom >= 0) {
+ if (!ATOMELEM(use, atom))
+ kill |= ATOMMASK(atom);
+ def |= ATOMMASK(atom);
+ }
+ }
+ if (!ATOMELEM(def, A_ATOM) && BPF_CLASS(b->s.code) == BPF_JMP)
+ use |= ATOMMASK(A_ATOM);
+
+ b->def = def;
+ b->kill = kill;
+ b->in_use = use;
+}
+
+/*
+ * Assume graph is already leveled.
+ */
+static void
+find_ud(root)
+ struct block *root;
+{
+ int i, maxlevel;
+ struct block *p;
+
+ /*
+ * root->level is the highest level no found;
+ * count down from there.
+ */
+ maxlevel = root->level;
+ for (i = maxlevel; i >= 0; --i)
+ for (p = levels[i]; p; p = p->link) {
+ compute_local_ud(p);
+ p->out_use = 0;
+ }
+
+ for (i = 1; i <= maxlevel; ++i) {
+ for (p = levels[i]; p; p = p->link) {
+ p->out_use |= JT(p)->in_use | JF(p)->in_use;
+ p->in_use |= p->out_use &~ p->kill;
+ }
+ }
+}
+
+/*
+ * These data structures are used in a Cocke and Shwarz style
+ * value numbering scheme. Since the flowgraph is acyclic,
+ * exit values can be propagated from a node's predecessors
+ * provided it is uniquely defined.
+ */
+struct valnode {
+ int code;
+ long v0, v1;
+ long val;
+ struct valnode *next;
+};
+
+#define MODULUS 213
+static struct valnode *hashtbl[MODULUS];
+static int curval;
+static int maxval;
+
+/* Integer constants mapped with the load immediate opcode. */
+#define K(i) F(BPF_LD|BPF_IMM|BPF_W, i, 0L)
+
+struct vmapinfo {
+ int is_const;
+ long const_val;
+};
+
+struct vmapinfo *vmap;
+struct valnode *vnode_base;
+struct valnode *next_vnode;
+
+static void
+init_val()
+{
+ curval = 0;
+ next_vnode = vnode_base;
+ memset((char *)vmap, 0, maxval * sizeof(*vmap));
+ memset((char *)hashtbl, 0, sizeof hashtbl);
+}
+
+/* Because we really don't have an IR, this stuff is a little messy. */
+static long
+F(code, v0, v1)
+ int code;
+ long v0, v1;
+{
+ u_int hash;
+ int val;
+ struct valnode *p;
+
+ hash = (u_int)code ^ (v0 << 4) ^ (v1 << 8);
+ hash %= MODULUS;
+
+ for (p = hashtbl[hash]; p; p = p->next)
+ if (p->code == code && p->v0 == v0 && p->v1 == v1)
+ return p->val;
+
+ val = ++curval;
+ if (BPF_MODE(code) == BPF_IMM &&
+ (BPF_CLASS(code) == BPF_LD || BPF_CLASS(code) == BPF_LDX)) {
+ vmap[val].const_val = v0;
+ vmap[val].is_const = 1;
+ }
+ p = next_vnode++;
+ p->val = val;
+ p->code = code;
+ p->v0 = v0;
+ p->v1 = v1;
+ p->next = hashtbl[hash];
+ hashtbl[hash] = p;
+
+ return val;
+}
+
+static inline void
+vstore(s, valp, newval, alter)
+ struct stmt *s;
+ long *valp;
+ long newval;
+ int alter;
+{
+ if (alter && *valp == newval)
+ s->code = NOP;
+ else
+ *valp = newval;
+}
+
+static void
+fold_op(s, v0, v1)
+ struct stmt *s;
+ long v0, v1;
+{
+ long a, b;
+
+ a = vmap[v0].const_val;
+ b = vmap[v1].const_val;
+
+ switch (BPF_OP(s->code)) {
+ case BPF_ADD:
+ a += b;
+ break;
+
+ case BPF_SUB:
+ a -= b;
+ break;
+
+ case BPF_MUL:
+ a *= b;
+ break;
+
+ case BPF_DIV:
+ if (b == 0)
+ bpf_error("division by zero");
+ a /= b;
+ break;
+
+ case BPF_AND:
+ a &= b;
+ break;
+
+ case BPF_OR:
+ a |= b;
+ break;
+
+ case BPF_LSH:
+ a <<= b;
+ break;
+
+ case BPF_RSH:
+ a >>= b;
+ break;
+
+ case BPF_NEG:
+ a = -a;
+ break;
+
+ default:
+ abort();
+ }
+ s->k = a;
+ s->code = BPF_LD|BPF_IMM;
+ done = 0;
+}
+
+static inline struct slist *
+this_op(s)
+ struct slist *s;
+{
+ while (s != 0 && s->s.code == NOP)
+ s = s->next;
+ return s;
+}
+
+static void
+opt_not(b)
+ struct block *b;
+{
+ struct block *tmp = JT(b);
+
+ JT(b) = JF(b);
+ JF(b) = tmp;
+}
+
+static void
+opt_peep(b)
+ struct block *b;
+{
+ struct slist *s;
+ struct slist *next, *last;
+ int val;
+ long v;
+
+ s = b->stmts;
+ if (s == 0)
+ return;
+
+ last = s;
+ while (1) {
+ s = this_op(s);
+ if (s == 0)
+ break;
+ next = this_op(s->next);
+ if (next == 0)
+ break;
+ last = next;
+
+ /*
+ * st M[k] --> st M[k]
+ * ldx M[k] tax
+ */
+ if (s->s.code == BPF_ST &&
+ next->s.code == (BPF_LDX|BPF_MEM) &&
+ s->s.k == next->s.k) {
+ done = 0;
+ next->s.code = BPF_MISC|BPF_TAX;
+ }
+ /*
+ * ld #k --> ldx #k
+ * tax txa
+ */
+ if (s->s.code == (BPF_LD|BPF_IMM) &&
+ next->s.code == (BPF_MISC|BPF_TAX)) {
+ s->s.code = BPF_LDX|BPF_IMM;
+ next->s.code = BPF_MISC|BPF_TXA;
+ done = 0;
+ }
+ /*
+ * This is an ugly special case, but it happens
+ * when you say tcp[k] or udp[k] where k is a constant.
+ */
+ if (s->s.code == (BPF_LD|BPF_IMM)) {
+ struct slist *add, *tax, *ild;
+
+ /*
+ * Check that X isn't used on exit from this
+ * block (which the optimizer might cause).
+ * We know the code generator won't generate
+ * any local dependencies.
+ */
+ if (ATOMELEM(b->out_use, X_ATOM))
+ break;
+
+ if (next->s.code != (BPF_LDX|BPF_MSH|BPF_B))
+ add = next;
+ else
+ add = this_op(next->next);
+ if (add == 0 || add->s.code != (BPF_ALU|BPF_ADD|BPF_X))
+ break;
+
+ tax = this_op(add->next);
+ if (tax == 0 || tax->s.code != (BPF_MISC|BPF_TAX))
+ break;
+
+ ild = this_op(tax->next);
+ if (ild == 0 || BPF_CLASS(ild->s.code) != BPF_LD ||
+ BPF_MODE(ild->s.code) != BPF_IND)
+ break;
+ /*
+ * XXX We need to check that X is not
+ * subsequently used. We know we can eliminate the
+ * accumulator modifications since it is defined
+ * by the last stmt of this sequence.
+ *
+ * We want to turn this sequence:
+ *
+ * (004) ldi #0x2 {s}
+ * (005) ldxms [14] {next} -- optional
+ * (006) addx {add}
+ * (007) tax {tax}
+ * (008) ild [x+0] {ild}
+ *
+ * into this sequence:
+ *
+ * (004) nop
+ * (005) ldxms [14]
+ * (006) nop
+ * (007) nop
+ * (008) ild [x+2]
+ *
+ */
+ ild->s.k += s->s.k;
+ s->s.code = NOP;
+ add->s.code = NOP;
+ tax->s.code = NOP;
+ done = 0;
+ }
+ s = next;
+ }
+ /*
+ * If we have a subtract to do a comparison, and the X register
+ * 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) {
+ b->s.k += vmap[val].const_val;
+ 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)) {
+ b->s.k += last->s.k;
+ last->s.code = NOP;
+ done = 0;
+ }
+ /*
+ * and #k nop
+ * jeq #0 -> jset #k
+ */
+ if (last->s.code == (BPF_ALU|BPF_AND|BPF_K) &&
+ !ATOMELEM(b->out_use, A_ATOM) && b->s.k == 0) {
+ b->s.k = last->s.k;
+ b->s.code = BPF_JMP|BPF_K|BPF_JSET;
+ last->s.code = NOP;
+ done = 0;
+ opt_not(b);
+ }
+ /*
+ * If the accumulator is a known constant, we can compute the
+ * comparison result.
+ */
+ val = b->val[A_ATOM];
+ if (vmap[val].is_const && BPF_SRC(b->s.code) == BPF_K) {
+ v = vmap[val].const_val;
+ switch (BPF_OP(b->s.code)) {
+
+ case BPF_JEQ:
+ v = v == b->s.k;
+ break;
+
+ case BPF_JGT:
+ v = v > b->s.k;
+ break;
+
+ case BPF_JGE:
+ v = v >= b->s.k;
+ break;
+
+ case BPF_JSET:
+ v &= b->s.k;
+ break;
+
+ default:
+ abort();
+ }
+ if (JF(b) != JT(b))
+ done = 0;
+ if (v)
+ JF(b) = JT(b);
+ else
+ JT(b) = JF(b);
+ }
+}
+
+/*
+ * Compute the symbolic value of expression of 's', and update
+ * anything it defines in the value table 'val'. If 'alter' is true,
+ * do various optimizations. This code would be cleaner if symbolic
+ * evaluation and code transformations weren't folded together.
+ */
+static void
+opt_stmt(s, val, alter)
+ struct stmt *s;
+ long val[];
+ int alter;
+{
+ int op;
+ long v;
+
+ switch (s->code) {
+
+ case BPF_LD|BPF_ABS|BPF_W:
+ case BPF_LD|BPF_ABS|BPF_H:
+ case BPF_LD|BPF_ABS|BPF_B:
+ v = F(s->code, s->k, 0L);
+ vstore(s, &val[A_ATOM], v, alter);
+ break;
+
+ case BPF_LD|BPF_IND|BPF_W:
+ case BPF_LD|BPF_IND|BPF_H:
+ case BPF_LD|BPF_IND|BPF_B:
+ v = val[X_ATOM];
+ if (alter && vmap[v].is_const) {
+ s->code = BPF_LD|BPF_ABS|BPF_SIZE(s->code);
+ s->k += vmap[v].const_val;
+ v = F(s->code, s->k, 0L);
+ done = 0;
+ }
+ else
+ v = F(s->code, s->k, v);
+ vstore(s, &val[A_ATOM], v, alter);
+ break;
+
+ case BPF_LD|BPF_LEN:
+ v = F(s->code, 0L, 0L);
+ vstore(s, &val[A_ATOM], v, alter);
+ break;
+
+ case BPF_LD|BPF_IMM:
+ v = K(s->k);
+ vstore(s, &val[A_ATOM], v, alter);
+ break;
+
+ case BPF_LDX|BPF_IMM:
+ v = K(s->k);
+ vstore(s, &val[X_ATOM], v, alter);
+ break;
+
+ case BPF_LDX|BPF_MSH|BPF_B:
+ v = F(s->code, s->k, 0L);
+ vstore(s, &val[X_ATOM], v, alter);
+ break;
+
+ case BPF_ALU|BPF_NEG:
+ if (alter && vmap[val[A_ATOM]].is_const) {
+ s->code = BPF_LD|BPF_IMM;
+ s->k = -vmap[val[A_ATOM]].const_val;
+ val[A_ATOM] = K(s->k);
+ }
+ else
+ val[A_ATOM] = F(s->code, val[A_ATOM], 0L);
+ break;
+
+ case BPF_ALU|BPF_ADD|BPF_K:
+ case BPF_ALU|BPF_SUB|BPF_K:
+ case BPF_ALU|BPF_MUL|BPF_K:
+ case BPF_ALU|BPF_DIV|BPF_K:
+ case BPF_ALU|BPF_AND|BPF_K:
+ case BPF_ALU|BPF_OR|BPF_K:
+ case BPF_ALU|BPF_LSH|BPF_K:
+ case BPF_ALU|BPF_RSH|BPF_K:
+ op = BPF_OP(s->code);
+ if (alter) {
+ if (s->k == 0) {
+ if (op == BPF_ADD || op == BPF_SUB ||
+ op == BPF_LSH || op == BPF_RSH ||
+ op == BPF_OR) {
+ s->code = NOP;
+ break;
+ }
+ if (op == BPF_MUL || op == BPF_AND) {
+ s->code = BPF_LD|BPF_IMM;
+ val[A_ATOM] = K(s->k);
+ break;
+ }
+ }
+ if (vmap[val[A_ATOM]].is_const) {
+ fold_op(s, val[A_ATOM], K(s->k));
+ val[A_ATOM] = K(s->k);
+ break;
+ }
+ }
+ val[A_ATOM] = F(s->code, val[A_ATOM], K(s->k));
+ break;
+
+ case BPF_ALU|BPF_ADD|BPF_X:
+ case BPF_ALU|BPF_SUB|BPF_X:
+ case BPF_ALU|BPF_MUL|BPF_X:
+ case BPF_ALU|BPF_DIV|BPF_X:
+ case BPF_ALU|BPF_AND|BPF_X:
+ case BPF_ALU|BPF_OR|BPF_X:
+ case BPF_ALU|BPF_LSH|BPF_X:
+ case BPF_ALU|BPF_RSH|BPF_X:
+ op = BPF_OP(s->code);
+ if (alter && vmap[val[X_ATOM]].is_const) {
+ if (vmap[val[A_ATOM]].is_const) {
+ fold_op(s, val[A_ATOM], val[X_ATOM]);
+ val[A_ATOM] = K(s->k);
+ }
+ else {
+ s->code = BPF_ALU|BPF_K|op;
+ s->k = vmap[val[X_ATOM]].const_val;
+ done = 0;
+ val[A_ATOM] =
+ F(s->code, val[A_ATOM], K(s->k));
+ }
+ break;
+ }
+ /*
+ * Check if we're doing something to an accumulator
+ * 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.
+ */
+ 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) {
+ 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) {
+ s->code = BPF_LD|BPF_IMM;
+ s->k = 0;
+ vstore(s, &val[A_ATOM], K(s->k), alter);
+ break;
+ }
+ else if (op == BPF_NEG) {
+ s->code = NOP;
+ break;
+ }
+ }
+ val[A_ATOM] = F(s->code, val[A_ATOM], val[X_ATOM]);
+ break;
+
+ case BPF_MISC|BPF_TXA:
+ vstore(s, &val[A_ATOM], val[X_ATOM], alter);
+ break;
+
+ case BPF_LD|BPF_MEM:
+ v = val[s->k];
+ if (alter && vmap[v].is_const) {
+ s->code = BPF_LD|BPF_IMM;
+ s->k = vmap[v].const_val;
+ done = 0;
+ }
+ vstore(s, &val[A_ATOM], v, alter);
+ break;
+
+ case BPF_MISC|BPF_TAX:
+ vstore(s, &val[X_ATOM], val[A_ATOM], alter);
+ break;
+
+ case BPF_LDX|BPF_MEM:
+ v = val[s->k];
+ if (alter && vmap[v].is_const) {
+ s->code = BPF_LDX|BPF_IMM;
+ s->k = vmap[v].const_val;
+ done = 0;
+ }
+ vstore(s, &val[X_ATOM], v, alter);
+ break;
+
+ case BPF_ST:
+ vstore(s, &val[s->k], val[A_ATOM], alter);
+ break;
+
+ case BPF_STX:
+ vstore(s, &val[s->k], val[X_ATOM], alter);
+ break;
+ }
+}
+
+static void
+deadstmt(s, last)
+ register struct stmt *s;
+ register struct stmt *last[];
+{
+ register int atom;
+
+ atom = atomuse(s);
+ if (atom >= 0) {
+ if (atom == AX_ATOM) {
+ last[X_ATOM] = 0;
+ last[A_ATOM] = 0;
+ }
+ else
+ last[atom] = 0;
+ }
+ atom = atomdef(s);
+ if (atom >= 0) {
+ if (last[atom]) {
+ done = 0;
+ last[atom]->code = NOP;
+ }
+ last[atom] = s;
+ }
+}
+
+static void
+opt_deadstores(b)
+ register struct block *b;
+{
+ register struct slist *s;
+ register int atom;
+ struct stmt *last[N_ATOMS];
+
+ memset((char *)last, 0, sizeof last);
+
+ for (s = b->stmts; s != 0; s = s->next)
+ deadstmt(&s->s, last);
+ deadstmt(&b->s, last);
+
+ for (atom = 0; atom < N_ATOMS; ++atom)
+ if (last[atom] && !ATOMELEM(b->out_use, atom)) {
+ last[atom]->code = NOP;
+ done = 0;
+ }
+}
+
+static void
+opt_blk(b, do_stmts)
+ struct block *b;
+ int do_stmts;
+{
+ struct slist *s;
+ struct edge *p;
+ int i;
+ long aval;
+
+ /*
+ * Initialize the atom values.
+ * If we have no predecessors, everything is undefined.
+ * Otherwise, we inherent our values from our predecessors.
+ * If any register has an ambiguous value (i.e. control paths are
+ * merging) give it the undefined value of 0.
+ */
+ p = b->in_edges;
+ if (p == 0)
+ memset((char *)b->val, 0, sizeof(b->val));
+ else {
+ memcpy((char *)b->val, (char *)p->pred->val, sizeof(b->val));
+ while ((p = p->next) != NULL) {
+ for (i = 0; i < N_ATOMS; ++i)
+ if (b->val[i] != p->pred->val[i])
+ b->val[i] = 0;
+ }
+ }
+ aval = b->val[A_ATOM];
+ for (s = b->stmts; s; s = s->next)
+ opt_stmt(&s->s, b->val, do_stmts);
+
+ /*
+ * This is a special case: if we don't use anything from this
+ * block, and we load the accumulator with value that is
+ * already there, eliminate all the statements.
+ */
+ if (do_stmts && b->out_use == 0 && aval != 0 &&
+ b->val[A_ATOM] == aval)
+ b->stmts = 0;
+ else {
+ opt_peep(b);
+ opt_deadstores(b);
+ }
+ /*
+ * Set up values for branch optimizer.
+ */
+ if (BPF_SRC(b->s.code) == BPF_K)
+ b->oval = K(b->s.k);
+ else
+ b->oval = b->val[X_ATOM];
+ b->et.code = b->s.code;
+ b->ef.code = -b->s.code;
+}
+
+/*
+ * Return true if any register that is used on exit from 'succ', has
+ * an exit value that is different from the corresponding exit value
+ * from 'b'.
+ */
+static int
+use_conflict(b, succ)
+ struct block *b, *succ;
+{
+ int atom;
+ atomset use = succ->out_use;
+
+ if (use == 0)
+ return 0;
+
+ for (atom = 0; atom < N_ATOMS; ++atom)
+ if (ATOMELEM(use, atom))
+ if (b->val[atom] != succ->val[atom])
+ return 1;
+ return 0;
+}
+
+static struct block *
+fold_edge(child, ep)
+ struct block *child;
+ struct edge *ep;
+{
+ int sense;
+ int aval0, aval1, oval0, oval1;
+ int code = ep->code;
+
+ if (code < 0) {
+ code = -code;
+ sense = 0;
+ } else
+ sense = 1;
+
+ if (child->s.code != code)
+ return 0;
+
+ aval0 = child->val[A_ATOM];
+ oval0 = child->oval;
+ aval1 = ep->pred->val[A_ATOM];
+ oval1 = ep->pred->oval;
+
+ if (aval0 != aval1)
+ return 0;
+
+ if (oval0 == oval1)
+ /*
+ * The operands are identical, so the
+ * result is true if a true branch was
+ * taken to get here, otherwise false.
+ */
+ return sense ? JT(child) : JF(child);
+
+ if (sense && code == (BPF_JMP|BPF_JEQ|BPF_K))
+ /*
+ * At this point, we only know the comparison if we
+ * came down the true branch, and it was an equality
+ * comparison with a constant. We rely on the fact that
+ * distinct constants have distinct value numbers.
+ */
+ return JF(child);
+
+ return 0;
+}
+
+static void
+opt_j(ep)
+ struct edge *ep;
+{
+ register int i, k;
+ register struct block *target;
+
+ if (JT(ep->succ) == 0)
+ return;
+
+ if (JT(ep->succ) == JF(ep->succ)) {
+ /*
+ * Common branch targets can be eliminated, provided
+ * there is no data dependency.
+ */
+ if (!use_conflict(ep->pred, ep->succ->et.succ)) {
+ done = 0;
+ ep->succ = JT(ep->succ);
+ }
+ }
+ /*
+ * For each edge dominator that matches the successor of this
+ * edge, promote the edge successor to the its grandchild.
+ *
+ * XXX We violate the set abstraction here in favor a reasonably
+ * efficient loop.
+ */
+ top:
+ for (i = 0; i < edgewords; ++i) {
+ register u_long x = ep->edom[i];
+
+ while (x != 0) {
+ k = ffs(x) - 1;
+ x &=~ (1 << k);
+ k += i * BITS_PER_WORD;
+
+ target = fold_edge(ep->succ, edges[k]);
+ /*
+ * Check that there is no data dependency between
+ * nodes that will be violated if we move the edge.
+ */
+ if (target != 0 && !use_conflict(ep->pred, target)) {
+ done = 0;
+ ep->succ = target;
+ if (JT(target) != 0)
+ /*
+ * Start over unless we hit a leaf.
+ */
+ goto top;
+ return;
+ }
+ }
+ }
+}
+
+
+static void
+or_pullup(b)
+ struct block *b;
+{
+ int val, at_top;
+ struct block *pull;
+ struct block **diffp, **samep;
+ struct edge *ep;
+
+ ep = b->in_edges;
+ if (ep == 0)
+ return;
+
+ /*
+ * Make sure each predecessor loads the same value.
+ * XXX why?
+ */
+ val = ep->pred->val[A_ATOM];
+ for (ep = ep->next; ep != 0; ep = ep->next)
+ if (val != ep->pred->val[A_ATOM])
+ return;
+
+ if (JT(b->in_edges->pred) == b)
+ diffp = &JT(b->in_edges->pred);
+ else
+ diffp = &JF(b->in_edges->pred);
+
+ at_top = 1;
+ while (1) {
+ if (*diffp == 0)
+ return;
+
+ if (JT(*diffp) != JT(b))
+ return;
+
+ if (!SET_MEMBER((*diffp)->dom, b->id))
+ return;
+
+ if ((*diffp)->val[A_ATOM] != val)
+ break;
+
+ diffp = &JF(*diffp);
+ at_top = 0;
+ }
+ samep = &JF(*diffp);
+ while (1) {
+ if (*samep == 0)
+ return;
+
+ if (JT(*samep) != JT(b))
+ return;
+
+ if (!SET_MEMBER((*samep)->dom, b->id))
+ return;
+
+ if ((*samep)->val[A_ATOM] == val)
+ break;
+
+ /* XXX Need to check that there are no data dependencies
+ between dp0 and dp1. Currently, the code generator
+ will not produce such dependencies. */
+ samep = &JF(*samep);
+ }
+#ifdef notdef
+ /* XXX This doesn't cover everything. */
+ for (i = 0; i < N_ATOMS; ++i)
+ if ((*samep)->val[i] != pred->val[i])
+ return;
+#endif
+ /* Pull up the node. */
+ pull = *samep;
+ *samep = JF(pull);
+ JF(pull) = *diffp;
+
+ /*
+ * At the top of the chain, each predecessor needs to point at the
+ * pulled up node. Inside the chain, there is only one predecessor
+ * to worry about.
+ */
+ if (at_top) {
+ for (ep = b->in_edges; ep != 0; ep = ep->next) {
+ if (JT(ep->pred) == b)
+ JT(ep->pred) = pull;
+ else
+ JF(ep->pred) = pull;
+ }
+ }
+ else
+ *diffp = pull;
+
+ done = 0;
+}
+
+static void
+and_pullup(b)
+ struct block *b;
+{
+ int val, at_top;
+ struct block *pull;
+ struct block **diffp, **samep;
+ struct edge *ep;
+
+ ep = b->in_edges;
+ if (ep == 0)
+ return;
+
+ /*
+ * Make sure each predecessor loads the same value.
+ */
+ val = ep->pred->val[A_ATOM];
+ for (ep = ep->next; ep != 0; ep = ep->next)
+ if (val != ep->pred->val[A_ATOM])
+ return;
+
+ if (JT(b->in_edges->pred) == b)
+ diffp = &JT(b->in_edges->pred);
+ else
+ diffp = &JF(b->in_edges->pred);
+
+ at_top = 1;
+ while (1) {
+ if (*diffp == 0)
+ return;
+
+ if (JF(*diffp) != JF(b))
+ return;
+
+ if (!SET_MEMBER((*diffp)->dom, b->id))
+ return;
+
+ if ((*diffp)->val[A_ATOM] != val)
+ break;
+
+ diffp = &JT(*diffp);
+ at_top = 0;
+ }
+ samep = &JT(*diffp);
+ while (1) {
+ if (*samep == 0)
+ return;
+
+ if (JF(*samep) != JF(b))
+ return;
+
+ if (!SET_MEMBER((*samep)->dom, b->id))
+ return;
+
+ if ((*samep)->val[A_ATOM] == val)
+ break;
+
+ /* XXX Need to check that there are no data dependencies
+ between diffp and samep. Currently, the code generator
+ will not produce such dependencies. */
+ samep = &JT(*samep);
+ }
+#ifdef notdef
+ /* XXX This doesn't cover everything. */
+ for (i = 0; i < N_ATOMS; ++i)
+ if ((*samep)->val[i] != pred->val[i])
+ return;
+#endif
+ /* Pull up the node. */
+ pull = *samep;
+ *samep = JT(pull);
+ JT(pull) = *diffp;
+
+ /*
+ * At the top of the chain, each predecessor needs to point at the
+ * pulled up node. Inside the chain, there is only one predecessor
+ * to worry about.
+ */
+ if (at_top) {
+ for (ep = b->in_edges; ep != 0; ep = ep->next) {
+ if (JT(ep->pred) == b)
+ JT(ep->pred) = pull;
+ else
+ JF(ep->pred) = pull;
+ }
+ }
+ else
+ *diffp = pull;
+
+ done = 0;
+}
+
+static void
+opt_blks(root, do_stmts)
+ struct block *root;
+ int do_stmts;
+{
+ int i, maxlevel;
+ struct block *p;
+
+ init_val();
+ maxlevel = root->level;
+ for (i = maxlevel; i >= 0; --i)
+ for (p = levels[i]; p; p = p->link)
+ opt_blk(p, do_stmts);
+
+ if (do_stmts)
+ /*
+ * No point trying to move branches; it can't possibly
+ * make a difference at this point.
+ */
+ return;
+
+ for (i = 1; i <= maxlevel; ++i) {
+ for (p = levels[i]; p; p = p->link) {
+ opt_j(&p->et);
+ opt_j(&p->ef);
+ }
+ }
+ for (i = 1; i <= maxlevel; ++i) {
+ for (p = levels[i]; p; p = p->link) {
+ or_pullup(p);
+ and_pullup(p);
+ }
+ }
+}
+
+static inline void
+link_inedge(parent, child)
+ struct edge *parent;
+ struct block *child;
+{
+ parent->next = child->in_edges;
+ child->in_edges = parent;
+}
+
+static void
+find_inedges(root)
+ struct block *root;
+{
+ int i;
+ struct block *b;
+
+ for (i = 0; i < n_blocks; ++i)
+ blocks[i]->in_edges = 0;
+
+ /*
+ * Traverse the graph, adding each edge to the predecessor
+ * list of its successors. Skip the leaves (i.e. level 0).
+ */
+ for (i = root->level; i > 0; --i) {
+ for (b = levels[i]; b != 0; b = b->link) {
+ link_inedge(&b->et, JT(b));
+ link_inedge(&b->ef, JF(b));
+ }
+ }
+}
+
+static void
+opt_root(b)
+ struct block **b;
+{
+ struct slist *tmp, *s;
+
+ s = (*b)->stmts;
+ (*b)->stmts = 0;
+ while (BPF_CLASS((*b)->s.code) == BPF_JMP && JT(*b) == JF(*b))
+ *b = JT(*b);
+
+ tmp = (*b)->stmts;
+ if (tmp != 0)
+ sappend(s, tmp);
+ (*b)->stmts = s;
+}
+
+static void
+opt_loop(root, do_stmts)
+ struct block *root;
+ int do_stmts;
+{
+
+#ifdef BDEBUG
+ if (dflag > 1)
+ opt_dump(root);
+#endif
+ do {
+ done = 1;
+ find_levels(root);
+ find_dom(root);
+ find_closure(root);
+ find_inedges(root);
+ find_ud(root);
+ find_edom(root);
+ opt_blks(root, do_stmts);
+#ifdef BDEBUG
+ if (dflag > 1)
+ opt_dump(root);
+#endif
+ } while (!done);
+}
+
+/*
+ * Optimize the filter code in its dag representation.
+ */
+void
+bpf_optimize(rootp)
+ struct block **rootp;
+{
+ struct block *root;
+
+ root = *rootp;
+
+ opt_init(root);
+ opt_loop(root, 0);
+ opt_loop(root, 1);
+ intern_blocks(root);
+ opt_root(rootp);
+ opt_cleanup();
+}
+
+static void
+make_marks(p)
+ struct block *p;
+{
+ if (!isMarked(p)) {
+ Mark(p);
+ if (BPF_CLASS(p->s.code) != BPF_RET) {
+ make_marks(JT(p));
+ make_marks(JF(p));
+ }
+ }
+}
+
+/*
+ * Mark code array such that isMarked(i) is true
+ * only for nodes that are alive.
+ */
+static void
+mark_code(p)
+ struct block *p;
+{
+ cur_mark += 1;
+ make_marks(p);
+}
+
+/*
+ * True iff the two stmt lists load the same value from the packet into
+ * the accumulator.
+ */
+static int
+eq_slist(x, y)
+ struct slist *x, *y;
+{
+ while (1) {
+ while (x && x->s.code == NOP)
+ x = x->next;
+ while (y && y->s.code == NOP)
+ y = y->next;
+ if (x == 0)
+ return y == 0;
+ if (y == 0)
+ return x == 0;
+ if (x->s.code != y->s.code || x->s.k != y->s.k)
+ return 0;
+ x = x->next;
+ y = y->next;
+ }
+}
+
+static inline int
+eq_blk(b0, b1)
+ struct block *b0, *b1;
+{
+ if (b0->s.code == b1->s.code &&
+ b0->s.k == b1->s.k &&
+ b0->et.succ == b1->et.succ &&
+ b0->ef.succ == b1->ef.succ)
+ return eq_slist(b0->stmts, b1->stmts);
+ return 0;
+}
+
+static void
+intern_blocks(root)
+ struct block *root;
+{
+ struct block *p;
+ int i, j;
+ int done;
+ top:
+ done = 1;
+ for (i = 0; i < n_blocks; ++i)
+ blocks[i]->link = 0;
+
+ mark_code(root);
+
+ for (i = n_blocks - 1; --i >= 0; ) {
+ if (!isMarked(blocks[i]))
+ continue;
+ for (j = i + 1; j < n_blocks; ++j) {
+ if (!isMarked(blocks[j]))
+ continue;
+ if (eq_blk(blocks[i], blocks[j])) {
+ blocks[i]->link = blocks[j]->link ?
+ blocks[j]->link : blocks[j];
+ break;
+ }
+ }
+ }
+ for (i = 0; i < n_blocks; ++i) {
+ p = blocks[i];
+ if (JT(p) == 0)
+ continue;
+ if (JT(p)->link) {
+ done = 0;
+ JT(p) = JT(p)->link;
+ }
+ if (JF(p)->link) {
+ done = 0;
+ JF(p) = JF(p)->link;
+ }
+ }
+ if (!done)
+ goto top;
+}
+
+static void
+opt_cleanup()
+{
+ free((void *)vnode_base);
+ free((void *)vmap);
+ free((void *)edges);
+ free((void *)space);
+ free((void *)levels);
+ free((void *)blocks);
+}
+
+/*
+ * Return the number of stmts in 's'.
+ */
+static int
+slength(s)
+ struct slist *s;
+{
+ int n = 0;
+
+ for (; s; s = s->next)
+ if (s->s.code != NOP)
+ ++n;
+ return n;
+}
+
+/*
+ * Return the number of nodes reachable by 'p'.
+ * All nodes should be initially unmarked.
+ */
+static int
+count_blocks(p)
+ struct block *p;
+{
+ if (p == 0 || isMarked(p))
+ return 0;
+ Mark(p);
+ return count_blocks(JT(p)) + count_blocks(JF(p)) + 1;
+}
+
+/*
+ * Do a depth first search on the flow graph, numbering the
+ * the basic blocks, and entering them into the 'blocks' array.`
+ */
+static void
+number_blks_r(p)
+ struct block *p;
+{
+ int n;
+
+ if (p == 0 || isMarked(p))
+ return;
+
+ Mark(p);
+ n = n_blocks++;
+ p->id = n;
+ blocks[n] = p;
+
+ number_blks_r(JT(p));
+ number_blks_r(JF(p));
+}
+
+/*
+ * Return the number of stmts in the flowgraph reachable by 'p'.
+ * The nodes should be unmarked before calling.
+ */
+static int
+count_stmts(p)
+ struct block *p;
+{
+ int n;
+
+ if (p == 0 || isMarked(p))
+ return 0;
+ Mark(p);
+ n = count_stmts(JT(p)) + count_stmts(JF(p));
+ return slength(p->stmts) + n + 1;
+}
+
+/*
+ * Allocate memory. All allocation is done before optimization
+ * is begun. A linear bound on the size of all data structures is computed
+ * from the total number of blocks and/or statements.
+ */
+static void
+opt_init(root)
+ struct block *root;
+{
+ u_long *p;
+ int i, n, max_stmts;
+
+ /*
+ * First, count the blocks, so we can malloc an array to map
+ * block number to block. Then, put the blocks into the array.
+ */
+ unMarkAll();
+ n = count_blocks(root);
+ blocks = (struct block **)malloc(n * sizeof(*blocks));
+ unMarkAll();
+ n_blocks = 0;
+ number_blks_r(root);
+
+ n_edges = 2 * n_blocks;
+ edges = (struct edge **)malloc(n_edges * sizeof(*edges));
+
+ /*
+ * The number of levels is bounded by the number of nodes.
+ */
+ levels = (struct block **)malloc(n_blocks * sizeof(*levels));
+
+ edgewords = n_edges / (8 * sizeof(u_long)) + 1;
+ nodewords = n_blocks / (8 * sizeof(u_long)) + 1;
+
+ /* XXX */
+ space = (u_long *)malloc(2 * n_blocks * nodewords * sizeof(*space)
+ + n_edges * edgewords * sizeof(*space));
+ p = space;
+ all_dom_sets = p;
+ for (i = 0; i < n; ++i) {
+ blocks[i]->dom = p;
+ p += nodewords;
+ }
+ all_closure_sets = p;
+ for (i = 0; i < n; ++i) {
+ blocks[i]->closure = p;
+ p += nodewords;
+ }
+ all_edge_sets = p;
+ for (i = 0; i < n; ++i) {
+ register struct block *b = blocks[i];
+
+ b->et.edom = p;
+ p += edgewords;
+ b->ef.edom = p;
+ p += edgewords;
+ b->et.id = i;
+ edges[i] = &b->et;
+ b->ef.id = n_blocks + i;
+ edges[n_blocks + i] = &b->ef;
+ b->et.pred = b;
+ b->ef.pred = b;
+ }
+ max_stmts = 0;
+ for (i = 0; i < n; ++i)
+ max_stmts += slength(blocks[i]->stmts) + 1;
+ /*
+ * We allocate at most 3 value numbers per statement,
+ * so this is an upper bound on the number of valnodes
+ * we'll need.
+ */
+ maxval = 3 * max_stmts;
+ vmap = (struct vmapinfo *)malloc(maxval * sizeof(*vmap));
+ vnode_base = (struct valnode *)malloc(maxval * sizeof(*vmap));
+}
+
+/*
+ * Some pointers used to convert the basic block form of the code,
+ * into the array form that BPF requires. 'fstart' will point to
+ * the malloc'd array while 'ftail' is used during the recursive traversal.
+ */
+static struct bpf_insn *fstart;
+static struct bpf_insn *ftail;
+
+#ifdef BDEBUG
+int bids[1000];
+#endif
+
+static void
+convert_code_r(p)
+ struct block *p;
+{
+ struct bpf_insn *dst;
+ struct slist *src;
+ int slen;
+ u_int off;
+
+ if (p == 0 || isMarked(p))
+ return;
+ Mark(p);
+
+ convert_code_r(JF(p));
+ convert_code_r(JT(p));
+
+ slen = slength(p->stmts);
+ dst = ftail -= slen + 1;
+
+ p->offset = dst - fstart;
+
+ for (src = p->stmts; src; src = src->next) {
+ if (src->s.code == NOP)
+ continue;
+ dst->code = (u_short)src->s.code;
+ dst->k = src->s.k;
+ ++dst;
+ }
+#ifdef BDEBUG
+ bids[dst - fstart] = p->id + 1;
+#endif
+ dst->code = (u_short)p->s.code;
+ dst->k = p->s.k;
+ if (JT(p)) {
+ off = JT(p)->offset - (p->offset + slen) - 1;
+ if (off >= 256)
+ bpf_error("long jumps not supported");
+ dst->jt = off;
+ off = JF(p)->offset - (p->offset + slen) - 1;
+ if (off >= 256)
+ bpf_error("long jumps not supported");
+ dst->jf = off;
+ }
+}
+
+
+/*
+ * Convert flowgraph intermediate representation to the
+ * BPF array representation. Set *lenp to the number of instructions.
+ */
+struct bpf_insn *
+icode_to_fcode(root, lenp)
+ struct block *root;
+ int *lenp;
+{
+ int n;
+ struct bpf_insn *fp;
+
+ unMarkAll();
+ n = *lenp = count_stmts(root);
+
+ fp = (struct bpf_insn *)malloc(sizeof(*fp) * n);
+ memset((char *)fp, 0, sizeof(*fp) * n);
+ fstart = fp;
+ ftail = fp + n;
+
+ unMarkAll();
+ convert_code_r(root);
+
+ return fp;
+}
+
+#ifdef BDEBUG
+opt_dump(root)
+ struct block *root;
+{
+ struct bpf_program f;
+
+ memset(bids, 0, sizeof bids);
+ f.bf_insns = icode_to_fcode(root, &f.bf_len);
+ bpf_dump(&f, 1);
+ putchar('\n');
+ free((char *)f.bf_insns);
+}
+#endif
projects / ppp.git / blobdiff