From 305ee902874b49351f4916e303c293523f11570b Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Fri, 22 May 2020 12:20:10 -0400 Subject: opt: Track data flow information about predicates This allows us to optimize things like -sparse -o -not -sparse <==> -true and -sparse -a -not -sparse <==> -false --- opt.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 174 insertions(+), 23 deletions(-) (limited to 'opt.c') diff --git a/opt.c b/opt.c index 57f5dbf..7d13b8d 100644 --- a/opt.c +++ b/opt.c @@ -43,6 +43,7 @@ #include "color.h" #include "eval.h" #include "expr.h" +#include "pwcache.h" #include #include #include @@ -116,7 +117,7 @@ static void range_union(struct range *result, const struct range *lhs, const str } /** Check if a range contains no values. */ -static bool range_impossible(const struct range *range) { +static bool range_is_impossible(const struct range *range) { return range->min > range->max; } @@ -143,7 +144,73 @@ enum range_type { /** User ID. */ UID_RANGE, /** The number of range_types. */ - MAX_RANGE, + RANGE_TYPES, +}; + +/** + * A possibly-known value of a predicate. + */ +enum known_pred { + /** The state is impossible to reach. */ + PRED_IMPOSSIBLE = -2, + /** The value of the predicate is not known. */ + PRED_UNKNOWN = -1, + /** The predicate is known to be false. */ + PRED_FALSE = false, + /** The predicate is known to be true. */ + PRED_TRUE = true, +}; + +/** Make a predicate known. */ +static void constrain_pred(enum known_pred *pred, bool value) { + if (*pred == PRED_UNKNOWN) { + *pred = value; + } else if (*pred == !value) { + *pred = PRED_IMPOSSIBLE; + } +} + +/** Compute the union of two known predicates. */ +static enum known_pred pred_union(enum known_pred lhs, enum known_pred rhs) { + if (lhs == PRED_IMPOSSIBLE) { + return rhs; + } else if (rhs == PRED_IMPOSSIBLE) { + return lhs; + } else if (lhs == rhs) { + return lhs; + } else { + return PRED_UNKNOWN; + } +} + +/** + * Types of predicates we track. + */ +enum pred_type { + /** -readable */ + READABLE_PRED, + /** -writable */ + WRITABLE_PRED, + /** -executable */ + EXECUTABLE_PRED, + /** -acl */ + ACL_PRED, + /** -capable */ + CAPABLE_PRED, + /** -empty */ + EMPTY_PRED, + /** -hidden */ + HIDDEN_PRED, + /** -nogroup */ + NOGROUP_PRED, + /** -nouser */ + NOUSER_PRED, + /** -sparse */ + SPARSE_PRED, + /** -xattr */ + XATTR_PRED, + /** The number of pred_types. */ + PRED_TYPES, }; /** @@ -151,7 +218,10 @@ enum range_type { */ struct opt_facts { /** The value ranges we track. */ - struct range ranges[MAX_RANGE]; + struct range ranges[RANGE_TYPES]; + + /** The predicates we track. */ + enum known_pred preds[PRED_TYPES]; /** Bitmask of possible file types. */ enum bftw_typeflag types; @@ -161,20 +231,28 @@ struct opt_facts { /** Initialize some data flow facts. */ static void facts_init(struct opt_facts *facts) { - for (int i = 0; i < MAX_RANGE; ++i) { - struct range *range = facts->ranges + i; + for (int i = 0; i < RANGE_TYPES; ++i) { + struct range *range = &facts->ranges[i]; range->min = 0; // All ranges we currently track are non-negative range->max = LLONG_MAX; } + for (int i = 0; i < PRED_TYPES; ++i) { + facts->preds[i] = PRED_UNKNOWN; + } + facts->types = ~0; facts->xtypes = ~0; } /** Compute the union of two fact sets. */ static void facts_union(struct opt_facts *result, const struct opt_facts *lhs, const struct opt_facts *rhs) { - for (int i = 0; i < MAX_RANGE; ++i) { - range_union(result->ranges + i, lhs->ranges + i, rhs->ranges + i); + for (int i = 0; i < RANGE_TYPES; ++i) { + range_union(&result->ranges[i], &lhs->ranges[i], &rhs->ranges[i]); + } + + for (int i = 0; i < PRED_TYPES; ++i) { + result->preds[i] = pred_union(lhs->preds[i], rhs->preds[i]); } result->types = lhs->types | rhs->types; @@ -182,9 +260,15 @@ static void facts_union(struct opt_facts *result, const struct opt_facts *lhs, c } /** Determine whether a fact set is impossible. */ -static bool facts_impossible(const struct opt_facts *facts) { - for (int i = 0; i < MAX_RANGE; ++i) { - if (range_impossible(facts->ranges + i)) { +static bool facts_are_impossible(const struct opt_facts *facts) { + for (int i = 0; i < RANGE_TYPES; ++i) { + if (range_is_impossible(&facts->ranges[i])) { + return true; + } + } + + for (int i = 0; i < PRED_TYPES; ++i) { + if (facts->preds[i] == PRED_IMPOSSIBLE) { return true; } } @@ -198,8 +282,12 @@ static bool facts_impossible(const struct opt_facts *facts) { /** Set some facts to be impossible. */ static void set_facts_impossible(struct opt_facts *facts) { - for (int i = 0; i < MAX_RANGE; ++i) { - set_range_impossible(facts->ranges + i); + for (int i = 0; i < RANGE_TYPES; ++i) { + set_range_impossible(&facts->ranges[i]); + } + + for (int i = 0; i < PRED_TYPES; ++i) { + facts->preds[i] = PRED_IMPOSSIBLE; } facts->types = 0; @@ -638,10 +726,29 @@ fail: return NULL; } -/** Infer data flow facts about an icmp-style ([+-]N) expression */ +/** Infer data flow facts about a predicate. */ +static void infer_pred_facts(struct opt_state *state, enum pred_type pred) { + constrain_pred(&state->facts_when_true.preds[pred], true); + constrain_pred(&state->facts_when_false.preds[pred], true); +} + +/** Infer data flow facts about an -{execut,read,writ}able expression. */ +static void infer_access_facts(struct opt_state *state, const struct expr *expr) { + if (expr->idata & R_OK) { + infer_pred_facts(state, READABLE_PRED); + } + if (expr->idata & W_OK) { + infer_pred_facts(state, WRITABLE_PRED); + } + if (expr->idata & X_OK) { + infer_pred_facts(state, EXECUTABLE_PRED); + } +} + +/** Infer data flow facts about an icmp-style ([+-]N) expression. */ static void infer_icmp_facts(struct opt_state *state, const struct expr *expr, enum range_type type) { - struct range *range_when_true = state->facts_when_true.ranges + type; - struct range *range_when_false = state->facts_when_false.ranges + type; + struct range *range_when_true = &state->facts_when_true.ranges[type]; + struct range *range_when_false =& state->facts_when_false.ranges[type]; long long value = expr->idata; switch (expr->cmp_flag) { @@ -665,9 +772,35 @@ static void infer_icmp_facts(struct opt_state *state, const struct expr *expr, e } } +/** Infer data flow facts about a -gid expression. */ +static void infer_gid_facts(struct opt_state *state, const struct expr *expr) { + infer_icmp_facts(state, expr, GID_RANGE); + + struct bfs_groups *groups = state->cmdline->groups; + struct range *range = &state->facts_when_true.ranges[GID_RANGE]; + if (groups && range->min == range->max) { + gid_t gid = range->min; + bool nogroup = !bfs_getgrgid(groups, gid); + constrain_pred(&state->facts_when_true.preds[NOGROUP_PRED], nogroup); + } +} + +/** Infer data flow facts about a -uid expression. */ +static void infer_uid_facts(struct opt_state *state, const struct expr *expr) { + infer_icmp_facts(state, expr, UID_RANGE); + + struct bfs_users *users = state->cmdline->users; + struct range *range = &state->facts_when_true.ranges[UID_RANGE]; + if (users && range->min == range->max) { + uid_t uid = range->min; + bool nouser = !bfs_getpwuid(users, uid); + constrain_pred(&state->facts_when_true.preds[NOUSER_PRED], nouser); + } +} + /** Infer data flow facts about a -samefile expression. */ static void infer_samefile_facts(struct opt_state *state, const struct expr *expr) { - struct range *range_when_true = state->facts_when_true.ranges + INUM_RANGE; + struct range *range_when_true = &state->facts_when_true.ranges[INUM_RANGE]; constrain_min(range_when_true, expr->ino); constrain_max(range_when_true, expr->ino); } @@ -688,22 +821,40 @@ static struct expr *optimize_expr_recursive(struct opt_state *state, struct expr state->facts_when_true = state->facts; state->facts_when_false = state->facts; - if (expr->eval == eval_depth) { + if (expr->eval == eval_access) { + infer_access_facts(state, expr); + } else if (expr->eval == eval_acl) { + infer_pred_facts(state, ACL_PRED); + } else if (expr->eval == eval_capable) { + infer_pred_facts(state, CAPABLE_PRED); + } else if (expr->eval == eval_depth) { infer_icmp_facts(state, expr, DEPTH_RANGE); + } else if (expr->eval == eval_empty) { + infer_pred_facts(state, EMPTY_PRED); } else if (expr->eval == eval_gid) { - infer_icmp_facts(state, expr, GID_RANGE); + infer_gid_facts(state, expr); + } else if (expr->eval == eval_hidden) { + infer_pred_facts(state, HIDDEN_PRED); } else if (expr->eval == eval_inum) { infer_icmp_facts(state, expr, INUM_RANGE); } else if (expr->eval == eval_links) { infer_icmp_facts(state, expr, LINKS_RANGE); + } else if (expr->eval == eval_nogroup) { + infer_pred_facts(state, NOGROUP_PRED); + } else if (expr->eval == eval_nouser) { + infer_pred_facts(state, NOUSER_PRED); } else if (expr->eval == eval_samefile) { infer_samefile_facts(state, expr); } else if (expr->eval == eval_size) { infer_icmp_facts(state, expr, SIZE_RANGE); + } else if (expr->eval == eval_sparse) { + infer_pred_facts(state, SPARSE_PRED); } else if (expr->eval == eval_type) { infer_type_facts(state, expr); } else if (expr->eval == eval_uid) { - infer_icmp_facts(state, expr, UID_RANGE); + infer_uid_facts(state, expr); + } else if (expr->eval == eval_xattr) { + infer_pred_facts(state, XATTR_PRED); } else if (expr->eval == eval_xtype) { infer_xtype_facts(state, expr); } else if (expr->eval == eval_not) { @@ -746,7 +897,7 @@ static struct expr *optimize_expr_recursive(struct opt_state *state, struct expr goto done; } - if (facts_impossible(&state->facts_when_true)) { + if (facts_are_impossible(&state->facts_when_true)) { if (expr->pure) { debug_opt(state, "-O2: data flow: %e --> %e\n", expr, &expr_false); free_expr(expr); @@ -755,7 +906,7 @@ static struct expr *optimize_expr_recursive(struct opt_state *state, struct expr expr->always_false = true; expr->probability = 0.0; } - } else if (facts_impossible(&state->facts_when_false)) { + } else if (facts_are_impossible(&state->facts_when_false)) { if (expr->pure) { debug_opt(state, "-O2: data flow: %e --> %e\n", expr, &expr_true); free_expr(expr); @@ -826,7 +977,7 @@ int optimize_cmdline(struct cmdline *cmdline) { }; facts_init(&state.facts); - struct range *depth = state.facts.ranges + DEPTH_RANGE; + struct range *depth = &state.facts.ranges[DEPTH_RANGE]; depth->min = cmdline->mindepth; depth->max = cmdline->maxdepth; @@ -848,7 +999,7 @@ int optimize_cmdline(struct cmdline *cmdline) { cmdline->expr = ignore_result(&state, cmdline->expr); - const struct range *depth_when_impure = facts_when_impure.ranges + DEPTH_RANGE; + const struct range *depth_when_impure = &facts_when_impure.ranges[DEPTH_RANGE]; long long mindepth = depth_when_impure->min; long long maxdepth = depth_when_impure->max; 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