X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/b2ed6e5826e772162719db595446b2c58e4ac5d6..f259e4e63c65525a864413c251f796d77793bfe3:/src/lalr.c diff --git a/src/lalr.c b/src/lalr.c index 46e1a6d5..a214dc57 100644 --- a/src/lalr.c +++ b/src/lalr.c @@ -1,336 +1,135 @@ -/* Compute look-ahead criteria for bison, - Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc. +/* Compute lookahead criteria for Bison. + + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003, 2004, 2005, + 2006, 2007 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. - Bison is free software; you can redistribute it and/or modify + This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2, or (at your option) - any later version. + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. - Bison is distributed in the hope that it will be useful, + This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License - along with Bison; see the file COPYING. If not, write to - the Free Software Foundation, Inc., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ + along with this program. If not, see . */ /* Compute how to make the finite state machine deterministic; find which rules need lookahead in each state, and which lookahead tokens they accept. */ +#include #include "system.h" -#include "types.h" + +#include +#include +#include + #include "LR0.h" -#include "gram.h" #include "complain.h" +#include "derives.h" +#include "getargs.h" +#include "gram.h" #include "lalr.h" #include "nullable.h" -#include "derives.h" - -/* All the decorated states, indexed by the state number. Warning: - there is a state_TABLE in LR0.c, but it is different and static. - */ -state_t *state_table = NULL; - -int tokensetsize; -short *LAruleno; -unsigned *LA; - -short *goto_map; -short *from_state; -short *to_state; - -extern void berror PARAMS ((const char *)); - -static int infinity; -static int ngotos; - -/* And for the famous F variable, which named is so descriptive that a - comment is hardly needed. . */ -static unsigned *F = NULL; -#define F(Rule) (F + (Rule) * tokensetsize) - -static short **includes; -static shorts **lookback; -static short **R; -static short *INDEX; -static short *VERTICES; -static int top; - - -static void -traverse (int i) -{ - unsigned *fp1; - unsigned *fp2; - unsigned *fp3; - int j; - short *rp; - - int height; - unsigned *base; - - VERTICES[++top] = i; - INDEX[i] = height = top; - - base = F (i); - fp3 = F (i + 1); - - rp = R[i]; - if (rp) - { - while ((j = *rp++) >= 0) - { - if (INDEX[j] == 0) - traverse (j); - - if (INDEX[i] > INDEX[j]) - INDEX[i] = INDEX[j]; +#include "reader.h" +#include "relation.h" +#include "symtab.h" - fp1 = base; - fp2 = F (j); +goto_number *goto_map; +static goto_number ngotos; +state_number *from_state; +state_number *to_state; - while (fp1 < fp3) - *fp1++ |= *fp2++; - } - } - - if (INDEX[i] == height) - { - for (;;) - { - j = VERTICES[top--]; - INDEX[j] = infinity; - - if (i == j) - break; - - fp1 = base; - fp2 = F (j); - - while (fp1 < fp3) - *fp2++ = *fp1++; - } - } -} - - -static void -digraph (short **relation) +/* Linked list of goto numbers. */ +typedef struct goto_list { - int i; - - infinity = ngotos + 2; - INDEX = XCALLOC (short, ngotos + 1); - VERTICES = XCALLOC (short, ngotos + 1); - top = 0; + struct goto_list *next; + goto_number value; +} goto_list; - R = relation; - - for (i = 0; i < ngotos; i++) - INDEX[i] = 0; - for (i = 0; i < ngotos; i++) - if (INDEX[i] == 0 && R[i]) - traverse (i); - - XFREE (INDEX); - XFREE (VERTICES); -} +/* LA is an NLA by NTOKENS matrix of bits. LA[l, i] is 1 if the rule + LArule[l] is applicable in the appropriate state when the next + token is symbol i. If LA[l, i] and LA[l, j] are both 1 for i != j, + it is a conflict. */ +static bitsetv LA = NULL; +size_t nLA; -/*--------------------. -| Build STATE_TABLE. | -`--------------------*/ -static void -set_state_table (void) -{ - /* NSTATES + 1 because lookahead for the pseudo state number NSTATES - might be used (see conflicts.c). It is too opaque for me to - provide a probably less hacky implementation. --akim */ - state_table = XCALLOC (state_t, nstates + 1); - - { - core *sp; - for (sp = first_state; sp; sp = sp->next) - { - state_table[sp->number].state = sp; - state_table[sp->number].accessing_symbol = sp->accessing_symbol; - } - } - - { - shifts *sp; - for (sp = first_shift; sp; sp = sp->next) - state_table[sp->number].shift_table = sp; - } - - { - reductions *rp; - for (rp = first_reduction; rp; rp = rp->next) - state_table[rp->number].reduction_table = rp; - } - - /* Initializing the lookaheads members. Please note that it must be - performed after having set some of the other members which are - used below. Change with extreme caution. */ - { - int i; - int count = 0; - for (i = 0; i < nstates; i++) - { - int k; - reductions *rp = state_table[i].reduction_table; - shifts *sp = state_table[i].shift_table; - - state_table[i].lookaheads = count; - - if (rp - && (rp->nreds > 1 - || (sp && !ISVAR (state_table[sp->shifts[0]].accessing_symbol)))) - count += rp->nreds; - else - state_table[i].consistent = 1; - - if (sp) - for (k = 0; k < sp->nshifts; k++) - if (state_table[sp->shifts[k]].accessing_symbol - == error_token_number) - { - state_table[i].consistent = 0; - break; - } - } - state_table[nstates].lookaheads = count; - } -} - - -/* Return the size of the longest ride hand side of the rules. */ -static size_t -maxrhs (void) -{ - short *itemp; - int length; - int max; - - length = 0; - max = 0; - for (itemp = ritem; *itemp; itemp++) - { - if (*itemp > 0) - { - length++; - } - else - { - if (length > max) - max = length; - length = 0; - } - } - - return max; -} +/* And for the famous F variable, which name is so descriptive that a + comment is hardly needed. . */ +static bitsetv F = NULL; +static goto_number **includes; +static goto_list **lookback; -static void -initialize_LA (void) -{ - int i; - int j; - short *np; - reductions *rp; - size_t nLA = state_table[nstates].lookaheads; - if (!nLA) - nLA = 1; - - LA = XCALLOC (unsigned, nLA * tokensetsize); - LAruleno = XCALLOC (short, nLA); - lookback = XCALLOC (shorts *, nLA); - - np = LAruleno; - for (i = 0; i < nstates; i++) - if (!state_table[i].consistent) - if ((rp = state_table[i].reduction_table)) - for (j = 0; j < rp->nreds; j++) - *np++ = rp->rules[j]; -} static void set_goto_map (void) { - shifts *sp; - int i; - int symbol; - int k; - short *temp_map; - int state2; - int state1; + state_number s; + goto_number *temp_map; - goto_map = XCALLOC (short, nvars + 1) - ntokens; - temp_map = XCALLOC (short, nvars + 1) - ntokens; + goto_map = xcalloc (nvars + 1, sizeof *goto_map); + temp_map = xnmalloc (nvars + 1, sizeof *temp_map); ngotos = 0; - for (sp = first_shift; sp; sp = sp->next) + for (s = 0; s < nstates; ++s) { - for (i = sp->nshifts - 1; i >= 0; i--) + transitions *sp = states[s]->transitions; + int i; + for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - symbol = state_table[sp->shifts[i]].accessing_symbol; - - if (ISTOKEN (symbol)) - break; + ngotos++; - if (ngotos == MAXSHORT) - fatal (_("too many gotos (max %d)"), MAXSHORT); + /* Abort if (ngotos + 1) would overflow. */ + aver (ngotos != GOTO_NUMBER_MAXIMUM); - ngotos++; - goto_map[symbol]++; + goto_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; } } - k = 0; - for (i = ntokens; i < nsyms; i++) - { - temp_map[i] = k; - k += goto_map[i]; - } + { + goto_number k = 0; + int i; + for (i = ntokens; i < nsyms; i++) + { + temp_map[i - ntokens] = k; + k += goto_map[i - ntokens]; + } - for (i = ntokens; i < nsyms; i++) - goto_map[i] = temp_map[i]; + for (i = ntokens; i < nsyms; i++) + goto_map[i - ntokens] = temp_map[i - ntokens]; - goto_map[nsyms] = ngotos; - temp_map[nsyms] = ngotos; + goto_map[nsyms - ntokens] = ngotos; + temp_map[nsyms - ntokens] = ngotos; + } - from_state = XCALLOC (short, ngotos); - to_state = XCALLOC (short, ngotos); + from_state = xcalloc (ngotos, sizeof *from_state); + to_state = xcalloc (ngotos, sizeof *to_state); - for (sp = first_shift; sp; sp = sp->next) + for (s = 0; s < nstates; ++s) { - state1 = sp->number; - for (i = sp->nshifts - 1; i >= 0; i--) + transitions *sp = states[s]->transitions; + int i; + for (i = sp->num - 1; i >= 0 && TRANSITION_IS_GOTO (sp, i); --i) { - state2 = sp->shifts[i]; - symbol = state_table[state2].accessing_symbol; - - if (ISTOKEN (symbol)) - break; - - k = temp_map[symbol]++; - from_state[k] = state1; - to_state[k] = state2; + goto_number k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; + from_state[k] = s; + to_state[k] = sp->states[i]->number; } } - XFREE (temp_map + ntokens); + free (temp_map); } @@ -339,285 +138,161 @@ set_goto_map (void) | Map a state/symbol pair into its numeric representation. | `----------------------------------------------------------*/ -static int -map_goto (int state, int symbol) +static goto_number +map_goto (state_number s0, symbol_number sym) { - int high; - int low; - int middle; - int s; + goto_number high; + goto_number low; + goto_number middle; + state_number s; - low = goto_map[symbol]; - high = goto_map[symbol + 1] - 1; + low = goto_map[sym - ntokens]; + high = goto_map[sym - ntokens + 1] - 1; - while (low <= high) + for (;;) { + aver (low <= high); middle = (low + high) / 2; s = from_state[middle]; - if (s == state) + if (s == s0) return middle; - else if (s < state) + else if (s < s0) low = middle + 1; else high = middle - 1; } - - assert (0); - /* NOTREACHED */ - return 0; } static void initialize_F (void) { - int i; - int j; - int k; - shifts *sp; - short *edge; - unsigned *rowp; - short *rp; - short **reads; - int nedges; - int stateno; - int symbol; - int nwords; - - nwords = ngotos * tokensetsize; - F = XCALLOC (unsigned, nwords); - - reads = XCALLOC (short *, ngotos); - edge = XCALLOC (short, ngotos + 1); - nedges = 0; - - rowp = F; - for (i = 0; i < ngotos; i++) - { - stateno = to_state[i]; - sp = state_table[stateno].shift_table; + goto_number **reads = xnmalloc (ngotos, sizeof *reads); + goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge); + goto_number nedges = 0; - if (sp) - { - k = sp->nshifts; + goto_number i; - for (j = 0; j < k; j++) - { - symbol = state_table[sp->shifts[j]].accessing_symbol; - if (ISVAR (symbol)) - break; - SETBIT (rowp, symbol); - } + F = bitsetv_create (ngotos, ntokens, BITSET_FIXED); - for (; j < k; j++) - { - symbol = state_table[sp->shifts[j]].accessing_symbol; - if (nullable[symbol]) - edge[nedges++] = map_goto (stateno, symbol); - } - - if (nedges) - { - reads[i] = rp = XCALLOC (short, nedges + 1); + for (i = 0; i < ngotos; i++) + { + state_number stateno = to_state[i]; + transitions *sp = states[stateno]->transitions; - for (j = 0; j < nedges; j++) - rp[j] = edge[j]; + int j; + FOR_EACH_SHIFT (sp, j) + bitset_set (F[i], TRANSITION_SYMBOL (sp, j)); - rp[nedges] = -1; - nedges = 0; - } + for (; j < sp->num; j++) + { + symbol_number sym = TRANSITION_SYMBOL (sp, j); + if (nullable[sym - ntokens]) + edge[nedges++] = map_goto (stateno, sym); } - rowp += tokensetsize; + if (nedges == 0) + reads[i] = NULL; + else + { + reads[i] = xnmalloc (nedges + 1, sizeof reads[i][0]); + memcpy (reads[i], edge, nedges * sizeof edge[0]); + reads[i][nedges] = END_NODE; + nedges = 0; + } } - digraph (reads); + relation_digraph (reads, ngotos, &F); for (i = 0; i < ngotos; i++) - XFREE (reads[i]); + free (reads[i]); - XFREE (reads); - XFREE (edge); + free (reads); + free (edge); } static void -add_lookback_edge (int stateno, int ruleno, int gotono) +add_lookback_edge (state *s, rule *r, goto_number gotono) { - int i; - int k; - int found; - shorts *sp; - - i = state_table[stateno].lookaheads; - k = state_table[stateno + 1].lookaheads; - found = 0; - while (!found && i < k) - { - if (LAruleno[i] == ruleno) - found = 1; - else - i++; - } - - assert (found); - - sp = XCALLOC (shorts, 1); - sp->next = lookback[i]; + int ri = state_reduction_find (s, r); + goto_list *sp = xmalloc (sizeof *sp); + sp->next = lookback[(s->reductions->lookahead_tokens - LA) + ri]; sp->value = gotono; - lookback[i] = sp; + lookback[(s->reductions->lookahead_tokens - LA) + ri] = sp; } -static short ** -transpose (short **R_arg, int n) -{ - short **new_R; - short **temp_R; - short *nedges; - short *sp; - int i; - int k; - - nedges = XCALLOC (short, n); - - for (i = 0; i < n; i++) - { - sp = R_arg[i]; - if (sp) - { - while (*sp >= 0) - nedges[*sp++]++; - } - } - - new_R = XCALLOC (short *, n); - temp_R = XCALLOC (short *, n); - - for (i = 0; i < n; i++) - { - k = nedges[i]; - if (k > 0) - { - sp = XCALLOC (short, k + 1); - new_R[i] = sp; - temp_R[i] = sp; - sp[k] = -1; - } - } - - XFREE (nedges); - - for (i = 0; i < n; i++) - { - sp = R_arg[i]; - if (sp) - { - while (*sp >= 0) - *temp_R[*sp++]++ = i; - } - } - - XFREE (temp_R); - - return new_R; -} - static void build_relations (void) { - int i; - int j; - int k; - short *rulep; - short *rp; - shifts *sp; - int length; - int nedges; - int done; - int state1; - int stateno; - int symbol1; - int symbol2; - short *shortp; - short *edge; - short *states; - short **new_includes; - - includes = XCALLOC (short *, ngotos); - edge = XCALLOC (short, ngotos + 1); - states = XCALLOC (short, maxrhs () + 1); + goto_number *edge = xnmalloc (ngotos + 1, sizeof *edge); + state_number *states1 = xnmalloc (ritem_longest_rhs () + 1, sizeof *states1); + goto_number i; + + includes = xnmalloc (ngotos, sizeof *includes); for (i = 0; i < ngotos; i++) { - nedges = 0; - state1 = from_state[i]; - symbol1 = state_table[to_state[i]].accessing_symbol; + int nedges = 0; + symbol_number symbol1 = states[to_state[i]]->accessing_symbol; + rule **rulep; - for (rulep = derives[symbol1]; *rulep > 0; rulep++) + for (rulep = derives[symbol1 - ntokens]; *rulep; rulep++) { - length = 1; - states[0] = state1; - stateno = state1; + bool done; + int length = 1; + item_number const *rp; + state *s = states[from_state[i]]; + states1[0] = s->number; - for (rp = ritem + rule_table[*rulep].rhs; *rp > 0; rp++) + for (rp = (*rulep)->rhs; ! item_number_is_rule_number (*rp); rp++) { - symbol2 = *rp; - sp = state_table[stateno].shift_table; - k = sp->nshifts; - - for (j = 0; j < k; j++) - { - stateno = sp->shifts[j]; - if (state_table[stateno].accessing_symbol == symbol2) - break; - } - - states[length++] = stateno; + s = transitions_to (s->transitions, + item_number_as_symbol_number (*rp)); + states1[length++] = s->number; } - if (!state_table[stateno].consistent) - add_lookback_edge (stateno, *rulep, i); + if (!s->consistent) + add_lookback_edge (s, *rulep, i); length--; - done = 0; + done = false; while (!done) { - done = 1; + done = true; + /* Each rhs ends in a rule number, and there is a + sentinel before the first rhs, so it is safe to + decrement RP here. */ rp--; - /* JF added rp>=ritem && I hope to god its right! */ - if (rp >= ritem && ISVAR (*rp)) + if (ISVAR (*rp)) { - stateno = states[--length]; - edge[nedges++] = map_goto (stateno, *rp); - if (nullable[*rp]) - done = 0; + /* Downcasting from item_number to symbol_number. */ + edge[nedges++] = map_goto (states1[--length], + item_number_as_symbol_number (*rp)); + if (nullable[*rp - ntokens]) + done = false; } } } - if (nedges) + if (nedges == 0) + includes[i] = NULL; + else { - includes[i] = shortp = XCALLOC (short, nedges + 1); + int j; + includes[i] = xnmalloc (nedges + 1, sizeof includes[i][0]); for (j = 0; j < nedges; j++) - shortp[j] = edge[j]; - shortp[nedges] = -1; + includes[i][j] = edge[j]; + includes[i][nedges] = END_NODE; } } - new_includes = transpose (includes, ngotos); - - for (i = 0; i < ngotos; i++) - if (includes[i]) - XFREE (includes[i]); + free (edge); + free (states1); - XFREE (includes); - - includes = new_includes; - - XFREE (edge); - XFREE (states); + relation_transpose (&includes, ngotos); } @@ -625,58 +300,191 @@ build_relations (void) static void compute_FOLLOWS (void) { - int i; + goto_number i; - digraph (includes); + relation_digraph (includes, ngotos, &F); for (i = 0; i < ngotos; i++) - XFREE (includes[i]); + free (includes[i]); - XFREE (includes); + free (includes); } static void -compute_lookaheads (void) +compute_lookahead_tokens (void) { - int i; - shorts *sp; + size_t i; + goto_list *sp; - for (i = 0; i < state_table[nstates].lookaheads; i++) + for (i = 0; i < nLA; i++) for (sp = lookback[i]; sp; sp = sp->next) - { - unsigned *fp1 = LA (i); - unsigned *fp2 = F (sp->value); - while (fp1 < LA (i + 1)) - *fp1++ |= *fp2++; - } + bitset_or (LA[i], LA[i], F[sp->value]); /* Free LOOKBACK. */ - for (i = 0; i < state_table[nstates].lookaheads; i++) + for (i = 0; i < nLA; i++) + LIST_FREE (goto_list, lookback[i]); + + free (lookback); + bitsetv_free (F); +} + + +/*----------------------------------------------------. +| Count the number of lookahead tokens required for S | +| (N_LOOKAHEAD_TOKENS member). | +`----------------------------------------------------*/ + +static int +state_lookahead_tokens_count (state *s) +{ + int n_lookahead_tokens = 0; + reductions *rp = s->reductions; + transitions *sp = s->transitions; + + /* We need a lookahead either to distinguish different + reductions (i.e., there are two or more), or to distinguish a + reduction from a shift. Otherwise, it is straightforward, + and the state is `consistent'. There is no need to check that + transition 0 hasn't been disabled before checking if it is a + shift since transitions are only disabled during conflict + resolution, and that hasn't happened yet. */ + aver (sp->num == 0 || !TRANSITION_IS_DISABLED (sp, 0)); + if (rp->num > 1 + || (rp->num == 1 && sp->num && TRANSITION_IS_SHIFT (sp, 0))) + n_lookahead_tokens += rp->num; + else + s->consistent = 1; + + return n_lookahead_tokens; +} + + +/*----------------------------------------------------. +| Compute LA, NLA, and the lookahead_tokens members. | +`----------------------------------------------------*/ + +static void +initialize_LA (void) +{ + state_number i; + bitsetv pLA; + + /* Compute the total number of reductions requiring a lookahead. */ + nLA = 0; + for (i = 0; i < nstates; i++) + nLA += state_lookahead_tokens_count (states[i]); + /* Avoid having to special case 0. */ + if (!nLA) + nLA = 1; + + pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); + lookback = xcalloc (nLA, sizeof *lookback); + + /* Initialize the members LOOKAHEAD_TOKENS for each state whose reductions + require lookahead tokens. */ + for (i = 0; i < nstates; i++) { - shorts *sptmp; - for (sp = lookback[i]; sp; sp = sptmp) + int count = state_lookahead_tokens_count (states[i]); + if (count) { - sptmp = sp->next; - XFREE (sp); + states[i]->reductions->lookahead_tokens = pLA; + pLA += count; } } - - XFREE (lookback); - XFREE (F); } +/*---------------------------------------------. +| Output the lookahead tokens for each state. | +`---------------------------------------------*/ + +static void +lookahead_tokens_print (FILE *out) +{ + state_number i; + int j, k; + fprintf (out, "Lookahead tokens: BEGIN\n"); + for (i = 0; i < nstates; ++i) + { + reductions *reds = states[i]->reductions; + bitset_iterator iter; + int n_lookahead_tokens = 0; + + if (reds->lookahead_tokens) + for (k = 0; k < reds->num; ++k) + if (reds->lookahead_tokens[k]) + ++n_lookahead_tokens; + + fprintf (out, "State %d: %d lookahead tokens\n", + i, n_lookahead_tokens); + + if (reds->lookahead_tokens) + for (j = 0; j < reds->num; ++j) + BITSET_FOR_EACH (iter, reds->lookahead_tokens[j], k, 0) + { + fprintf (out, " on %d (%s) -> rule %d\n", + k, symbols[k]->tag, + reds->rules[j]->number); + }; + } + fprintf (out, "Lookahead tokens: END\n"); +} + void lalr (void) { - tokensetsize = WORDSIZE (ntokens); - - set_state_table (); initialize_LA (); set_goto_map (); initialize_F (); build_relations (); compute_FOLLOWS (); - compute_lookaheads (); + compute_lookahead_tokens (); + + if (trace_flag & trace_sets) + lookahead_tokens_print (stderr); +} + + +void +lalr_update_state_numbers (state_number old_to_new[], state_number nstates_old) +{ + goto_number ngotos_reachable = 0; + symbol_number nonterminal = 0; + aver (nsyms == nvars + ntokens); + { + goto_number i; + for (i = 0; i < ngotos; ++i) + { + while (i == goto_map[nonterminal]) + goto_map[nonterminal++] = ngotos_reachable; + /* If old_to_new[from_state[i]] = nstates_old, remove this goto + entry. */ + if (old_to_new[from_state[i]] != nstates_old) + { + /* from_state[i] is not removed, so it and thus to_state[i] are + reachable, so to_state[i] != nstates_old. */ + aver (old_to_new[to_state[i]] != nstates_old); + from_state[ngotos_reachable] = old_to_new[from_state[i]]; + to_state[ngotos_reachable] = old_to_new[to_state[i]]; + ++ngotos_reachable; + } + } + } + while (nonterminal <= nvars) + { + aver (ngotos == goto_map[nonterminal]); + goto_map[nonterminal++] = ngotos_reachable; + } + ngotos = ngotos_reachable; +} + + +void +lalr_free (void) +{ + state_number s; + for (s = 0; s < nstates; ++s) + states[s]->reductions->lookahead_tokens = NULL; + bitsetv_free (LA); }