X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/80a697503460fcf0d52bed9fb3b86e4c276fb37e..a76ca263093deb77ff09c422c91723f600a74ebe:/src/lalr.c diff --git a/src/lalr.c b/src/lalr.c index 54b0391c..7273805a 100644 --- a/src/lalr.c +++ b/src/lalr.c @@ -1,5 +1,7 @@ -/* Compute look-ahead criteria for bison, - Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc. +/* Compute look-ahead criteria for Bison. + + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2003 + Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -24,298 +26,109 @@ tokens they accept. */ #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 name is so descriptive that a - comment is hardly needed. . */ -static unsigned *F = NULL; -#define F(Rule) (F + (Rule) * tokensetsize) +#include "reader.h" +#include "relation.h" +#include "symtab.h" -static short **includes; -static shorts **lookback; -static short **R; -static short *INDEX; -static short *VERTICES; -static int top; +goto_number *goto_map = NULL; +static goto_number ngotos = 0; +state_number *from_state = NULL; +state_number *to_state = NULL; - -static void -traverse (int i) +/* Linked list of goto numbers. */ +typedef struct goto_list { - int j; - size_t k; - int height; - size_t size = F (i + 1) - F(i); - - VERTICES[++top] = i; - INDEX[i] = height = top; - - if (R[i]) - for (j = 0; R[i][j] >= 0; ++j) - { - if (INDEX[R[i][j]] == 0) - traverse (R[i][j]); - - if (INDEX[i] > INDEX[R[i][j]]) - INDEX[i] = INDEX[R[i][j]]; - - for (k = 0; k < size; ++k) - F (i)[k] |= F (R[i][j])[k]; - } - - if (INDEX[i] == height) - for (;;) - { - j = VERTICES[top--]; - INDEX[j] = infinity; - - if (i == j) - break; - - for (k = 0; k < size; ++k) - F (i)[k] = F (j)[k]; - } -} - - -static void -digraph (short **relation) -{ - int i; - - infinity = ngotos + 2; - INDEX = XCALLOC (short, ngotos + 1); - VERTICES = XCALLOC (short, ngotos + 1); - top = 0; - - 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); -} - - -/*--------------------. -| 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; - } -} + struct goto_list *next; + goto_number value; +} goto_list; -/*------------------------------------------. -| Return the size of the longest rule RHS. | -`------------------------------------------*/ +/* LA is a LR 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 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; -} +static bitsetv LA = NULL; +size_t nLA; -static void -initialize_LA (void) -{ - int i; - int j; - short *np; - reductions *rp; +/* And for the famous F variable, which name is so descriptive that a + comment is hardly needed. . */ +static bitsetv F = NULL; - size_t nLA = state_table[nstates].lookaheads; - if (!nLA) - nLA = 1; +static goto_number **includes; +static goto_list **lookback; - 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; + CALLOC (goto_map, nvars + 1); + CALLOC (temp_map, nvars + 1); 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; - - if (ngotos == MAXSHORT) - fatal (_("too many gotos (max %d)"), MAXSHORT); - + if (ngotos >= GOTO_NUMBER_MAXIMUM) + abort (); 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]; - } + { + int 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); + CALLOC (from_state, ngotos); + CALLOC (to_state, ngotos); - 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; + int k = temp_map[TRANSITION_SYMBOL (sp, i) - ntokens]++; + from_state[k] = s; + to_state[k] = sp->states[i]->number; } } - XFREE (temp_map + ntokens); + XFREE (temp_map); } @@ -325,93 +138,69 @@ set_goto_map (void) `----------------------------------------------------------*/ static int -map_goto (int state, int symbol) +map_goto (state_number s0, symbol_number sym) { int high; int low; int middle; - int s; + 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 (;;) { + if (high < low) + abort (); 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; - short *edge; - unsigned *rowp; - short *rp; - short **reads; - int nedges; - 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++) - { - int stateno = to_state[i]; - shifts *sp = state_table[stateno].shift_table; + goto_number **reads = CALLOC (reads, ngotos); + goto_number *edge = CALLOC (edge, ngotos + 1); + int nedges = 0; - if (sp) - { - for (j = 0; j < sp->nshifts; j++) - { - symbol = state_table[sp->shifts[j]].accessing_symbol; - if (ISVAR (symbol)) - break; - SETBIT (rowp, symbol); - } + int i; - for (; j < sp->nshifts; j++) - { - symbol = state_table[sp->shifts[j]].accessing_symbol; - if (nullable[symbol]) - edge[nedges++] = map_goto (stateno, symbol); - } + F = bitsetv_create (ngotos, ntokens, BITSET_FIXED); - 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) + { + CALLOC (reads[i], nedges + 1); + memcpy (reads[i], edge, nedges * sizeof (edge[0])); + reads[i][nedges] = -1; + nedges = 0; + } } - digraph (reads); + relation_digraph (reads, ngotos, &F); for (i = 0; i < ngotos; i++) XFREE (reads[i]); @@ -422,167 +211,82 @@ initialize_F (void) static void -add_lookback_edge (int stateno, int ruleno, int gotono) +add_lookback_edge (state *s, rule *r, int 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 = MALLOC (sp, 1); + sp->next = lookback[(s->reductions->lookaheads - LA) + ri]; sp->value = gotono; - lookback[i] = sp; + lookback[(s->reductions->lookaheads - LA) + ri] = sp; } -static short ** -transpose (short **R_arg, int n) -{ - short **new_R; - short **temp_R; - short *nedges; - int i; - - nedges = XCALLOC (short, n); - - for (i = 0; i < n; i++) - { - short *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++) - if (nedges[i] > 0) - { - short *sp = XCALLOC (short, nedges[i] + 1); - new_R[i] = sp; - temp_R[i] = sp; - sp[nedges[i]] = -1; - } - - XFREE (nedges); - - for (i = 0; i < n; i++) - { - short *sp = R_arg[i]; - if (sp) - while (*sp >= 0) - *temp_R[*sp++]++ = i; - } - - XFREE (temp_R); - - return new_R; -} - static void build_relations (void) { + goto_number *edge = CALLOC (edge, ngotos + 1); + state_number *states1 = CALLOC (states1, ritem_longest_rhs () + 1); int i; - int j; - short *rulep; - short *rp; - int nedges; - int done; - int state1; - int stateno; - int symbol1; - short *edge; - short *states; - short **new_includes; - - includes = XCALLOC (short *, ngotos); - edge = XCALLOC (short, ngotos + 1); - states = XCALLOC (short, maxrhs () + 1); + + CALLOC (includes, ngotos); 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++) { + bool done; int length = 1; - states[0] = state1; - stateno = state1; + item_number *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; *rp >= 0; rp++) { - int symbol2 = *rp; - shifts *sp = state_table[stateno].shift_table; - - for (j = 0; j < sp->nshifts; 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; rp--; /* JF added rp>=ritem && I hope to god its right! */ if (rp >= ritem && 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) { - includes[i] = XCALLOC (short, nedges + 1); + int j; + CALLOC (includes[i], nedges + 1); for (j = 0; j < nedges; j++) includes[i][j] = edge[j]; includes[i][nedges] = -1; } } - new_includes = transpose (includes, ngotos); - - for (i = 0; i < ngotos; i++) - XFREE (includes[i]); - XFREE (includes); - - includes = new_includes; - XFREE (edge); - XFREE (states); + XFREE (states1); + + relation_transpose (&includes, ngotos); } @@ -592,7 +296,7 @@ compute_FOLLOWS (void) { int i; - digraph (includes); + relation_digraph (includes, ngotos, &F); for (i = 0; i < ngotos; i++) XFREE (includes[i]); @@ -604,37 +308,148 @@ compute_FOLLOWS (void) static void compute_lookaheads (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++) - LIST_FREE (shorts, lookback[i]); + for (i = 0; i < nLA; i++) + LIST_FREE (goto_list, lookback[i]); XFREE (lookback); - XFREE (F); + bitsetv_free (F); +} + + +/*-----------------------------------------------------------. +| Count the number of lookaheads required for S (NLOOKAHEADS | +| member). | +`-----------------------------------------------------------*/ + +static int +state_lookaheads_count (state *s) +{ + int k; + int nlookaheads = 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'. */ + if (rp->num > 1 + || (rp->num == 1 && sp->num && + !TRANSITION_IS_DISABLED (sp, 0) && TRANSITION_IS_SHIFT (sp, 0))) + nlookaheads += rp->num; + else + s->consistent = 1; + + for (k = 0; k < sp->num; k++) + if (!TRANSITION_IS_DISABLED (sp, k) && TRANSITION_IS_ERROR (sp, k)) + { + s->consistent = 0; + break; + } + + return nlookaheads; +} + + +/*----------------------------------------------. +| Compute LA, NLA, and the lookaheads 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_lookaheads_count (states[i]); + /* Avoid having to special case 0. */ + if (!nLA) + nLA = 1; + + pLA = LA = bitsetv_create (nLA, ntokens, BITSET_FIXED); + CALLOC (lookback, nLA); + + /* Initialize the members LOOKAHEADS for each state which reductions + require lookaheads. */ + for (i = 0; i < nstates; i++) + { + int count = state_lookaheads_count (states[i]); + if (count) + { + states[i]->reductions->lookaheads = pLA; + pLA += count; + } + } } +/*---------------------------------------. +| Output the lookaheads for each state. | +`---------------------------------------*/ + +static void +lookaheads_print (FILE *out) +{ + state_number i; + int j, k; + fprintf (out, "Lookaheads: BEGIN\n"); + for (i = 0; i < nstates; ++i) + { + reductions *reds = states[i]->reductions; + bitset_iterator iter; + int nlookaheads = 0; + + if (reds->lookaheads) + for (k = 0; k < reds->num; ++k) + if (reds->lookaheads[k]) + ++nlookaheads; + + fprintf (out, "State %d: %d lookaheads\n", + i, nlookaheads); + + if (reds->lookaheads) + for (j = 0; j < reds->num; ++j) + BITSET_FOR_EACH (iter, reds->lookaheads[j], k, 0) + { + fprintf (out, " on %d (%s) -> rule %d\n", + k, symbols[k]->tag, + reds->rules[j]->number); + }; + } + fprintf (out, "Lookaheads: END\n"); +} + void lalr (void) { - tokensetsize = WORDSIZE (ntokens); - - set_state_table (); initialize_LA (); set_goto_map (); initialize_F (); build_relations (); compute_FOLLOWS (); compute_lookaheads (); + + if (trace_flag & trace_sets) + lookaheads_print (stderr); +} + + +void +lalr_free (void) +{ + state_number s; + for (s = 0; s < nstates; ++s) + states[s]->reductions->lookaheads = NULL; + bitsetv_free (LA); }