X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/52afa962d1e74968713f6b04123512f445f19851..f377f69fec28013c79db4efe12bbb9d48987fb2c:/src/conflicts.c diff --git a/src/conflicts.c b/src/conflicts.c index bb6f8ac7..24f27cc8 100644 --- a/src/conflicts.c +++ b/src/conflicts.c @@ -1,5 +1,6 @@ /* Find and resolve or report look-ahead conflicts for bison, - Copyright 1984, 1989, 1992, 2000, 2001 Free Software Foundation, Inc. + Copyright (C) 1984, 1989, 1992, 2000, 2001, 2002 + Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -19,8 +20,10 @@ 02111-1307, USA. */ #include "system.h" +#include "bitset.h" #include "complain.h" #include "getargs.h" +#include "symtab.h" #include "files.h" #include "gram.h" #include "state.h" @@ -29,22 +32,101 @@ #include "reader.h" #include "LR0.h" -errs **err_table = NULL; /* -1 stands for not specified. */ int expected_conflicts = -1; static char *conflicts = NULL; +struct obstack solved_conflicts_obstack; + +static bitset shiftset; +static bitset lookaheadset; -static unsigned *shiftset = NULL; -static unsigned *lookaheadset = NULL; +enum conflict_resolution_e + { + shift_resolution, + reduce_resolution, + left_resolution, + right_resolution, + nonassoc_resolution + }; + + +/*----------------------------------------------------------------. +| Explain how an SR conflict between TOKEN and RULE was resolved: | +| RESOLUTION. | +`----------------------------------------------------------------*/ + static inline void -log_resolution (int state, int LAno, int token, char *resolution) +log_resolution (rule_t *rule, symbol_number_t token, + enum conflict_resolution_e resolution) { - obstack_fgrow4 (&output_obstack, - _("\ -Conflict in state %d between rule %d and token %s resolved as %s.\n"), - state, LAruleno[LAno], tags[token], resolution); + if (report_flag & report_solved_conflicts) + { + /* The description of the resolution. */ + switch (resolution) + { + case shift_resolution: + case right_resolution: + obstack_fgrow2 (&solved_conflicts_obstack, + _("\ + Conflict between rule %d and token %s resolved as shift"), + rule->number, + symbols[token]->tag); + break; + case reduce_resolution: + case left_resolution: + obstack_fgrow2 (&solved_conflicts_obstack, + _("\ + Conflict between rule %d and token %s resolved as reduce"), + rule->number, + symbols[token]->tag); + break; + case nonassoc_resolution: + obstack_fgrow2 (&solved_conflicts_obstack, + _("\ + Conflict between rule %d and token %s resolved as an error"), + rule->number, + symbols[token]->tag); + break; + } + + /* The reason. */ + switch (resolution) + { + case shift_resolution: + obstack_fgrow2 (&solved_conflicts_obstack, + " (%s < %s)", + rule->prec->tag, + symbols[token]->tag); + break; + + case reduce_resolution: + obstack_fgrow2 (&solved_conflicts_obstack, + " (%s < %s)", + symbols[token]->tag, + rule->prec->tag); + break; + + case left_resolution: + obstack_fgrow1 (&solved_conflicts_obstack, + " (%%left %s)", + symbols[token]->tag); + break; + + case right_resolution: + obstack_fgrow1 (&solved_conflicts_obstack, + " (%%right %s)", + symbols[token]->tag); + break; + case nonassoc_resolution: + obstack_fgrow1 (&solved_conflicts_obstack, + " (%%nonassoc %s)", + symbols[token]->tag); + break; + } + obstack_sgrow (&solved_conflicts_obstack, ".\n"); + } } @@ -55,23 +137,29 @@ Conflict in state %d between rule %d and token %s resolved as %s.\n"), `------------------------------------------------------------------*/ static void -flush_shift (int state, int token) +flush_shift (state_t *state, int token) { - shifts *shiftp; - int k, i; + transitions_t *transitions = state->transitions; + int i; - shiftp = state_table[state].shift_table; + bitset_reset (lookaheadset, token); + for (i = 0; i < transitions->num; i++) + if (!TRANSITION_IS_DISABLED (transitions, i) + && TRANSITION_SYMBOL (transitions, i) == token) + TRANSITION_DISABLE (transitions, i); +} - if (shiftp) - { - k = shiftp->nshifts; - for (i = 0; i < k; i++) - { - if (shiftp->shifts[i] - && token == state_table[shiftp->shifts[i]].accessing_symbol) - (shiftp->shifts[i]) = 0; - } - } + +/*-------------------------------------------------------------------. +| Turn off the reduce recorded for the specified token for the | +| specified lookahead. Used when we resolve a shift-reduce conflict | +| in favor of the shift. | +`-------------------------------------------------------------------*/ + +static void +flush_reduce (bitset lookaheads, int token) +{ + bitset_reset (lookaheads, token); } @@ -80,171 +168,159 @@ flush_shift (int state, int token) | precedence declarations. It has already been checked that the | | rule has a precedence. A conflict is resolved by modifying the | | shift or reduce tables so that there is no longer a conflict. | +| | +| LOOKAHEAD is the number of the lookahead bitset to consider. | +| | +| ERRS can be used to store discovered explicit errors. | `------------------------------------------------------------------*/ static void -resolve_sr_conflict (int state, int lookaheadnum) +resolve_sr_conflict (state_t *state, int ruleno, + symbol_t **errs) { - int i; - int mask; - unsigned *fp1; - unsigned *fp2; - int redprec; - errs *errp = ERRS_ALLOC (ntokens + 1); - short *errtokens = errp->errs; - - /* find the rule to reduce by to get precedence of reduction */ - redprec = rule_table[LAruleno[lookaheadnum]].prec; - - mask = 1; - fp1 = LA (lookaheadnum); - fp2 = lookaheadset; + symbol_number_t i; + reductions_t *reds = state->reductions; + /* Find the rule to reduce by to get precedence of reduction. */ + rule_t *redrule = reds->rules[ruleno]; + int redprec = redrule->prec->prec; + bitset lookaheads = reds->lookaheads[ruleno]; + int nerrs = 0; + for (i = 0; i < ntokens; i++) - { - if ((mask & *fp2 & *fp1) && sprec[i]) + if (bitset_test (lookaheads, i) + && bitset_test (lookaheadset, i) + && symbols[i]->prec) + { /* Shift-reduce conflict occurs for token number i and it has a precedence. The precedence of shifting is that of token i. */ - { - if (sprec[i] < redprec) + if (symbols[i]->prec < redprec) + { + log_resolution (redrule, i, reduce_resolution); + flush_shift (state, i); + } + else if (symbols[i]->prec > redprec) + { + log_resolution (redrule, i, shift_resolution); + flush_reduce (lookaheads, i); + } + else + /* Matching precedence levels. + For left association, keep only the reduction. + For right association, keep only the shift. + For nonassociation, keep neither. */ + + switch (symbols[i]->assoc) { - log_resolution (state, lookaheadnum, i, _("reduce")); - *fp2 &= ~mask; /* flush the shift for this token */ + case right_assoc: + log_resolution (redrule, i, right_resolution); + flush_reduce (lookaheads, i); + break; + + case left_assoc: + log_resolution (redrule, i, left_resolution); flush_shift (state, i); + break; + + case non_assoc: + log_resolution (redrule, i, nonassoc_resolution); + flush_shift (state, i); + flush_reduce (lookaheads, i); + /* Record an explicit error for this token. */ + errs[nerrs++] = symbols[i]; + break; + + case undef_assoc: + assert (symbols[i]->assoc != undef_assoc); + break; } - else if (sprec[i] > redprec) - { - log_resolution (state, lookaheadnum, i, _("shift")); - *fp1 &= ~mask; /* flush the reduce for this token */ - } - else - { - /* Matching precedence levels. - For left association, keep only the reduction. - For right association, keep only the shift. - For nonassociation, keep neither. */ - - switch (sassoc[i]) - { - case right_assoc: - log_resolution (state, lookaheadnum, i, _("shift")); - break; - - case left_assoc: - log_resolution (state, lookaheadnum, i, _("reduce")); - break; - - case non_assoc: - log_resolution (state, lookaheadnum, i, _("an error")); - break; - } - - if (sassoc[i] != right_assoc) - { - *fp2 &= ~mask; /* flush the shift for this token */ - flush_shift (state, i); - } - if (sassoc[i] != left_assoc) - { - *fp1 &= ~mask; /* flush the reduce for this token */ - } - if (sassoc[i] == non_assoc) - { - /* Record an explicit error for this token. */ - *errtokens++ = i; - } - } - } + } - mask <<= 1; - if (mask == 0) - { - mask = 1; - fp2++; - fp1++; - } - } - errp->nerrs = errtokens - errp->errs; - if (errp->nerrs) + /* Some tokens have been explicitly made errors. Allocate a + permanent errs structure for this state, to record them. */ + state_errs_set (state, nerrs, errs); + + if (obstack_object_size (&solved_conflicts_obstack)) { - /* Some tokens have been explicitly made errors. Allocate - a permanent errs structure for this state, to record them. */ - i = (char *) errtokens - (char *) errp; - err_table[state] = ERRS_ALLOC (i + 1); - bcopy (errp, err_table[state], i); + obstack_1grow (&solved_conflicts_obstack, '\0'); + state->solved_conflicts = obstack_finish (&solved_conflicts_obstack); } - else - err_table[state] = 0; - free (errp); } +/*-------------------------------------------------------------------. +| Solve the S/R conflicts of STATE using the | +| precedence/associativity, and flag it inconsistent if it still has | +| conflicts. ERRS can be used as storage to compute the list of | +| lookaheads on which this STATE raises a parse error (%nonassoc). | +`-------------------------------------------------------------------*/ + static void -set_conflicts (int state) +set_conflicts (state_t *state, symbol_t **errs) { - int i, j; - shifts *shiftp; - int symbol; + int i; + transitions_t *transitions = state->transitions; + reductions_t *reds = state->reductions; - if (state_table[state].consistent) + if (state->consistent) return; - for (i = 0; i < tokensetsize; i++) - lookaheadset[i] = 0; + bitset_zero (lookaheadset); - shiftp = state_table[state].shift_table; - if (shiftp) - for (i = 0; i < shiftp->nshifts; i++) - { - symbol = state_table[shiftp->shifts[i]].accessing_symbol; - if (ISVAR (symbol)) - break; - SETBIT (lookaheadset, symbol); - } + FOR_EACH_SHIFT (transitions, i) + bitset_set (lookaheadset, TRANSITION_SYMBOL (transitions, i)); /* Loop over all rules which require lookahead in this state. First check for shift-reduce conflict, and try to resolve using - precedence */ - for (i = state_table[state].lookaheads; - i < state_table[state + 1].lookaheads; - ++i) - if (rule_table[LAruleno[i]].prec) - for (j = 0; j < tokensetsize; ++j) - if (LA (i)[j] & lookaheadset[j]) - { - resolve_sr_conflict (state, i); - break; - } - + precedence. */ + for (i = 0; i < reds->num; ++i) + if (reds->rules[i]->prec && reds->rules[i]->prec->prec + && !bitset_disjoint_p (reds->lookaheads[i], lookaheadset)) + { + resolve_sr_conflict (state, i, errs); + break; + } /* Loop over all rules which require lookahead in this state. Check for conflicts not resolved above. */ - for (i = state_table[state].lookaheads; - i < state_table[state + 1].lookaheads; - ++i) + for (i = 0; i < reds->num; ++i) { - for (j = 0; j < tokensetsize; ++j) - if (LA (i)[j] & lookaheadset[j]) - conflicts[state] = 1; + if (!bitset_disjoint_p (reds->lookaheads[i], lookaheadset)) + conflicts[state->number] = 1; - for (j = 0; j < tokensetsize; ++j) - lookaheadset[j] |= LA (i)[j]; + bitset_or (lookaheadset, lookaheadset, reds->lookaheads[i]); } } + +/*----------------------------------------------------------------. +| Solve all the S/R conflicts using the precedence/associativity, | +| and flag as inconsistent the states that still have conflicts. | +`----------------------------------------------------------------*/ + void -solve_conflicts (void) +conflicts_solve (void) { - int i; + state_number_t i; + /* List of lookaheads on which we explicitly raise a parse error. */ + symbol_t **errs = XMALLOC (symbol_t *, ntokens + 1); conflicts = XCALLOC (char, nstates); - shiftset = XCALLOC (unsigned, tokensetsize); - lookaheadset = XCALLOC (unsigned, tokensetsize); - - err_table = XCALLOC (errs *, nstates); + shiftset = bitset_create (ntokens, BITSET_FIXED); + lookaheadset = bitset_create (ntokens, BITSET_FIXED); + obstack_init (&solved_conflicts_obstack); for (i = 0; i < nstates; i++) - set_conflicts (i); + { + set_conflicts (states[i], errs); + + /* For uniformity of the code, make sure all the states have a valid + `errs' member. */ + if (!states[i]->errs) + states[i]->errs = errs_new (0, 0); + } + + free (errs); } @@ -253,75 +329,63 @@ solve_conflicts (void) `---------------------------------------------*/ static int -count_sr_conflicts (int state) +count_sr_conflicts (state_t *state) { - int i, k; + int i; int src_count = 0; - shifts *shiftp = state_table[state].shift_table; + transitions_t *transitions = state->transitions; + reductions_t *reds = state->reductions; - if (!shiftp) + if (!transitions) return 0; - for (i = 0; i < tokensetsize; i++) - { - shiftset[i] = 0; - lookaheadset[i] = 0; - } + bitset_zero (lookaheadset); + bitset_zero (shiftset); - for (i = 0; i < shiftp->nshifts && SHIFT_IS_SHIFT (shiftp, i); i++) - { - int symbol = state_table[shiftp->shifts[i]].accessing_symbol; - SETBIT (shiftset, symbol); - } + FOR_EACH_SHIFT (transitions, i) + bitset_set (shiftset, TRANSITION_SYMBOL (transitions, i)); - for (i = state_table[state].lookaheads; - i < state_table[state + 1].lookaheads; - ++i) - for (k = 0; k < tokensetsize; ++k) - lookaheadset[k] |= LA (i)[k]; + for (i = 0; i < reds->num; ++i) + bitset_or (lookaheadset, lookaheadset, reds->lookaheads[i]); - for (k = 0; k < tokensetsize; ++k) - lookaheadset[k] &= shiftset[k]; + bitset_and (lookaheadset, lookaheadset, shiftset); - for (i = 0; i < ntokens; i++) - if (BITISSET (lookaheadset, i)) - src_count++; + src_count = bitset_count (lookaheadset); return src_count; } -/*----------------------------------------------. -| Count the number of reduce/reduce conflicts. | -`----------------------------------------------*/ +/*----------------------------------------------------------------. +| Count the number of reduce/reduce conflicts. If ONE_PER_TOKEN, | +| count one conflict for each token that has any reduce/reduce | +| conflicts. Otherwise, count one conflict for each pair of | +| conflicting reductions. | ++`----------------------------------------------------------------*/ static int -count_rr_conflicts (int state) +count_rr_conflicts (state_t *state, int one_per_token) { int i; + reductions_t *reds = state->reductions; int rrc_count = 0; - int m = state_table[state].lookaheads; - int n = state_table[state + 1].lookaheads; - - if (n - m < 2) - return 0; - for (i = 0; i < ntokens; i++) { int count = 0; int j; - for (j = m; j < n; j++) - if (BITISSET (LA (m), j)) + for (j = 0; j < reds->num; ++j) + if (bitset_test (reds->lookaheads[j], i)) count++; if (count >= 2) - rrc_count++; + rrc_count += one_per_token ? 1 : count-1; } return rrc_count; } + /*--------------------------------------------------------------. | Return a human readable string which reports shift/reduce and | | reduce/reduce conflict numbers (SRC_NUM, RRC_NUM). | @@ -353,14 +417,32 @@ conflict_report (int src_num, int rrc_num) cp += strlen (cp); } - *cp++ = '.'; - *cp++ = '\n'; *cp++ = '\0'; return res; } +/*----------------------------------------------------------------. +| Same as above, but report the number of conflicts a` la POSIX. | +`----------------------------------------------------------------*/ + +static void +conflict_report_yacc (int src_num, int rrc_num) +{ + /* If invoked with `--yacc', use the output format specified by + POSIX. */ + fprintf (stderr, _("conflicts: ")); + if (src_num > 0) + fprintf (stderr, _(" %d shift/reduce"), src_num); + if (src_num > 0 && rrc_num > 0) + fprintf (stderr, ","); + if (rrc_num > 0) + fprintf (stderr, _(" %d reduce/reduce"), rrc_num); + putc ('\n', stderr); +} + + /*-----------------------------------------------------------. | Output the detailed description of states with conflicts. | `-----------------------------------------------------------*/ @@ -369,17 +451,45 @@ void conflicts_output (FILE *out) { bool printed_sth = FALSE; - int i; + state_number_t i; + for (i = 0; i < nstates; i++) + { + state_t *s = states[i]; + if (conflicts[i]) + { + fprintf (out, _("State %d contains "), i); + fprintf (out, "%s.\n", + conflict_report (count_sr_conflicts (s), + count_rr_conflicts (s, TRUE))); + printed_sth = TRUE; + } + } + if (printed_sth) + fputs ("\n\n", out); +} + +/*--------------------------------------------------------. +| Total the number of S/R and R/R conflicts. Unlike the | +| code in conflicts_output, however, count EACH pair of | +| reductions for the same state and lookahead as one | +| conflict. | +`--------------------------------------------------------*/ + +int +conflicts_total_count (void) +{ + state_number_t i; + int count; + + /* Conflicts by state. */ + count = 0; for (i = 0; i < nstates; i++) if (conflicts[i]) { - fprintf (out, _("State %d contains "), i); - fputs (conflict_report (count_sr_conflicts (i), - count_rr_conflicts (i)), out); - printed_sth = TRUE; + count += count_sr_conflicts (states[i]); + count += count_rr_conflicts (states[i], FALSE); } - if (printed_sth) - fputs ("\n\n", out); + return count; } @@ -390,8 +500,6 @@ conflicts_output (FILE *out) void conflicts_print (void) { - int i; - /* Is the number of SR conflicts OK? Either EXPECTED_CONFLICTS is not set, and then we want 0 SR, or else it is specified, in which case we want equality. */ @@ -401,12 +509,16 @@ conflicts_print (void) int rrc_total = 0; /* Conflicts by state. */ - for (i = 0; i < nstates; i++) - if (conflicts[i]) - { - src_total += count_sr_conflicts (i); - rrc_total += count_rr_conflicts (i); - } + { + state_number_t i; + + for (i = 0; i < nstates; i++) + if (conflicts[i]) + { + src_total += count_sr_conflicts (states[i]); + rrc_total += count_rr_conflicts (states[i], TRUE); + } + } src_ok = src_total == (expected_conflicts == -1 ? 0 : expected_conflicts); @@ -417,189 +529,23 @@ conflicts_print (void) /* Report the total number of conflicts on STDERR. */ if (yacc_flag) - { - /* If invoked with `--yacc', use the output format specified by - POSIX. */ - fprintf (stderr, _("conflicts: ")); - if (src_total > 0) - fprintf (stderr, _(" %d shift/reduce"), src_total); - if (src_total > 0 && rrc_total > 0) - fprintf (stderr, ","); - if (rrc_total > 0) - fprintf (stderr, _(" %d reduce/reduce"), rrc_total); - putc ('\n', stderr); - } + conflict_report_yacc (src_total, rrc_total); else - { - fprintf (stderr, _("%s contains "), infile); - fputs (conflict_report (src_total, rrc_total), stderr); - } + warn ("%s", conflict_report (src_total, rrc_total)); if (expected_conflicts != -1 && !src_ok) - { - complain_message_count++; - fprintf (stderr, ngettext ("expected %d shift/reduce conflict\n", - "expected %d shift/reduce conflicts\n", - expected_conflicts), - expected_conflicts); - } -} - - -void -print_reductions (FILE *out, int state) -{ - int i; - int j; - int symbol; - int m; - int n; - shifts *shiftp; - errs *errp; - int nodefault = 0; - - for (i = 0; i < tokensetsize; i++) - shiftset[i] = 0; - - shiftp = state_table[state].shift_table; - if (shiftp) - for (i = 0; i < shiftp->nshifts; i++) - { - if (!shiftp->shifts[i]) - continue; - symbol = state_table[shiftp->shifts[i]].accessing_symbol; - if (ISVAR (symbol)) - break; - /* if this state has a shift for the error token, - don't use a default rule. */ - if (symbol == error_token_number) - nodefault = 1; - SETBIT (shiftset, symbol); - } - - errp = err_table[state]; - if (errp) - for (i = 0; i < errp->nerrs; i++) - if (errp->errs[i]) - SETBIT (shiftset, errp->errs[i]); - - m = state_table[state].lookaheads; - n = state_table[state + 1].lookaheads; - - if (n - m == 1 && !nodefault) - { - int k; - int default_rule = LAruleno[m]; - - for (k = 0; k < tokensetsize; ++k) - lookaheadset[k] = LA (m)[k] & shiftset[k]; - - for (i = 0; i < ntokens; i++) - if (BITISSET (lookaheadset, i)) - fprintf (out, _(" %-4s\t[reduce using rule %d (%s)]\n"), - tags[i], default_rule, - tags[rule_table[default_rule].lhs]); - - fprintf (out, _(" $default\treduce using rule %d (%s)\n\n"), - default_rule, tags[rule_table[default_rule].lhs]); - } - else if (n - m >= 1) - { - int k; - - int cmax = 0; - int default_LA = -1; - int default_rule = 0; - - if (!nodefault) - for (i = m; i < n; i++) - { - int count = 0; - - for (k = 0; k < tokensetsize; ++k) - lookaheadset[k] = LA (i)[k] & ~shiftset[k]; - - for (j = 0; j < ntokens; j++) - if (BITISSET (lookaheadset, j)) - count++; - - if (count > cmax) - { - cmax = count; - default_LA = i; - default_rule = LAruleno[i]; - } - - for (k = 0; k < tokensetsize; ++k) - shiftset[k] |= lookaheadset[k]; - } - - for (i = 0; i < tokensetsize; i++) - shiftset[i] = 0; - - if (shiftp) - for (i = 0; i < shiftp->nshifts; i++) - { - if (!shiftp->shifts[i]) - continue; - symbol = state_table[shiftp->shifts[i]].accessing_symbol; - if (ISVAR (symbol)) - break; - SETBIT (shiftset, symbol); - } - - for (i = 0; i < ntokens; i++) - { - int defaulted = 0; - int count = BITISSET (shiftset, i); - - for (j = m; j < n; j++) - { - if (BITISSET (LA (m), j)) - { - if (count == 0) - { - if (j != default_LA) - fprintf (out, - _(" %-4s\treduce using rule %d (%s)\n"), - tags[i], - LAruleno[j], - tags[rule_table[LAruleno[j]].lhs]); - else - defaulted = 1; - - count++; - } - else - { - if (defaulted) - fprintf (out, - _(" %-4s\treduce using rule %d (%s)\n"), - tags[i], - LAruleno[default_LA], - tags[rule_table[LAruleno[default_LA]].lhs]); - defaulted = 0; - fprintf (out, - _(" %-4s\t[reduce using rule %d (%s)]\n"), - tags[i], - LAruleno[j], - tags[rule_table[LAruleno[j]].lhs]); - } - } - } - } - - if (default_LA >= 0) - fprintf (out, _(" $default\treduce using rule %d (%s)\n"), - default_rule, tags[rule_table[default_rule].lhs]); - } + complain (ngettext ("expected %d shift/reduce conflict", + "expected %d shift/reduce conflicts", + expected_conflicts), + expected_conflicts); } void -free_conflicts (void) +conflicts_free (void) { XFREE (conflicts); - XFREE (shiftset); - XFREE (lookaheadset); + bitset_free (shiftset); + bitset_free (lookaheadset); + obstack_free (&solved_conflicts_obstack, NULL); }