X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/aa7815f5c6e8e07a85e47df9cd7b579468969efb..616429b50868bf9225d55143526442a024e32969:/src/reduce.c?ds=sidebyside diff --git a/src/reduce.c b/src/reduce.c index c2efee93..0beff91a 100644 --- a/src/reduce.c +++ b/src/reduce.c @@ -1,5 +1,5 @@ /* Grammar reduction for Bison. - Copyright 1988, 1989, 2000 Free Software Foundation, Inc. + Copyright 1988, 1989, 2000, 2001 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -28,8 +28,8 @@ #include "system.h" #include "getargs.h" #include "files.h" +#include "symtab.h" #include "gram.h" -#include "xalloc.h" #include "complain.h" #include "reduce.h" #include "reader.h" @@ -39,16 +39,23 @@ typedef unsigned *BSet; typedef short *rule; -/* N is set of all nonterminals which are not useless. P is set of - all rules which have no useless nonterminals in their RHS. V is - the set of all accessible symbols. */ +/* Set of all nonterminals which are not useless. */ +static BSet N; -static BSet N, P, V, V1; +/* Set of all rules which have no useless nonterminals in their RHS. */ +static BSet P; + +/* Set of all accessible symbols. */ +static BSet V; + +/* Set of symbols used to define rule precedence (so they are + `useless', but no warning should be issued). */ +static BSet V1; static int nuseful_productions; static int nuseless_productions; static int nuseful_nonterminals; -static int nuseless_nonterminals; +int nuseless_nonterminals; static bool bits_equal (BSet L, BSet R, int n) @@ -101,7 +108,7 @@ useful_production (int i, BSet N0) /* A production is useful if all of the nonterminals in its appear in the set of useful nonterminals. */ - for (r = &ritem[rrhs[i]]; *r > 0; r++) + for (r = &ritem[rules[i].rhs]; *r >= 0; r++) if (ISVAR (n = *r)) if (!BITISSET (N0, n - ntokens)) return FALSE; @@ -117,7 +124,7 @@ static void useless_nonterminals (void) { BSet Np, Ns; - int i, n; + int i; /* N is set as built. Np is set being built this iteration. P is set of all productions which have a RHS all in N. */ @@ -140,7 +147,6 @@ useless_nonterminals (void) saved to be used when finding useful productions: only productions in this set will appear in the final grammar. */ - n = 0; while (1) { for (i = WORDSIZE (nvars) - 1; i >= 0; i--) @@ -151,7 +157,7 @@ useless_nonterminals (void) { if (useful_production (i, N)) { - SETBIT (Np, rlhs[i] - ntokens); + SETBIT (Np, rules[i].lhs - ntokens); SETBIT (P, i); } } @@ -171,7 +177,7 @@ static void inaccessable_symbols (void) { BSet Vp, Vs, Pp; - int i, n; + int i; short t; rule r; @@ -202,39 +208,33 @@ inaccessable_symbols (void) Pp = XCALLOC (unsigned, WORDSIZE (nrules + 1)); /* If the start symbol isn't useful, then nothing will be useful. */ - if (!BITISSET (N, start_symbol - ntokens)) - goto end_iteration; - - SETBIT (V, start_symbol); - - n = 0; - while (1) + if (BITISSET (N, start_symbol - ntokens)) { - for (i = WORDSIZE (nsyms) - 1; i >= 0; i--) - Vp[i] = V[i]; - for (i = 1; i <= nrules; i++) + SETBIT (V, start_symbol); + + while (1) { - if (!BITISSET (Pp, i) && BITISSET (P, i) && BITISSET (V, rlhs[i])) + for (i = WORDSIZE (nsyms) - 1; i >= 0; i--) + Vp[i] = V[i]; + for (i = 1; i <= nrules; i++) { - for (r = &ritem[rrhs[i]]; *r >= 0; r++) + if (!BITISSET (Pp, i) + && BITISSET (P, i) + && BITISSET (V, rules[i].lhs)) { - if (ISTOKEN (t = *r) || BITISSET (N, t - ntokens)) - { + for (r = &ritem[rules[i].rhs]; *r >= 0; r++) + if (ISTOKEN (t = *r) || BITISSET (N, t - ntokens)) SETBIT (Vp, t); - } + SETBIT (Pp, i); } - SETBIT (Pp, i); } + if (bits_equal (V, Vp, WORDSIZE (nsyms))) + break; + Vs = Vp; + Vp = V; + V = Vs; } - if (bits_equal (V, Vp, WORDSIZE (nsyms))) - { - break; - } - Vs = Vp; - Vp = V; - V = Vs; } -end_iteration: XFREE (V); V = Vp; @@ -258,39 +258,46 @@ end_iteration: /* A token that was used in %prec should not be warned about. */ for (i = 1; i < nrules; i++) - if (rprecsym[i] != 0) - SETBIT (V1, rprecsym[i]); + if (rules[i].precsym != 0) + SETBIT (V1, rules[i].precsym); } static void reduce_grammar_tables (void) { -/* This is turned off because we would need to change the numbers - in the case statements in the actions file. */ -#if 0 - /* remove useless productions */ - if (nuseless_productions > 0) - { - short np, pn, ni, pi; + /* This is turned off because we would need to change the numbers in + the case statements in the actions file. - np = 0; - ni = 0; - for (pn = 1; pn <= nrules; pn++) - { + We don't disable it via CPP so that it is still checked with the + rest of the code, to avoid its becoming completely obsolete. + + FIXME: I think the comment above demonstrates this code must be + turned off for *semantic* parser, not in the general case. Try + to understand this better --akim. */ + + if (0) + /* remove useless productions */ + if (nuseless_productions > 0) + { + short np, pn, ni, pi; + + np = 0; + ni = 0; + for (pn = 1; pn <= nrules; pn++) if (BITISSET (P, pn)) { np++; if (pn != np) { - rlhs[np] = rlhs[pn]; - rline[np] = rline[pn]; - rprec[np] = rprec[pn]; - rassoc[np] = rassoc[pn]; - rrhs[np] = rrhs[pn]; - if (rrhs[np] != ni) + rules[np].lhs = rules[pn].lhs; + rules[np].line = rules[pn].line; + rules[np].prec = rules[pn].prec; + rules[np].assoc = rules[pn].assoc; + rules[np].rhs = rules[pn].rhs; + if (rules[np].rhs != ni) { - pi = rrhs[np]; - rrhs[np] = ni; + pi = rules[np].rhs; + rules[np].rhs = ni; while (ritem[pi] >= 0) ritem[ni++] = ritem[pi++]; ritem[ni++] = -np; @@ -298,215 +305,213 @@ reduce_grammar_tables (void) } else { - while (ritem[ni++] >= 0); + while (ritem[ni++] >= 0) + /* Nothing. */; } } - } - ritem[ni] = 0; - nrules -= nuseless_productions; - nitems = ni; - /* Is it worth it to reduce the amount of memory for the - grammar? Probably not. */ + ritem[ni] = 0; + nrules -= nuseless_productions; + nitems = ni; + nritems = ni; - } -#endif /* 0 */ - /* Disable useless productions, - since they may contain useless nonterms - that would get mapped below to -1 and confuse everyone. */ + /* Is it worth it to reduce the amount of memory for the + grammar? Probably not. */ + } + + /* Disable useless productions. */ if (nuseless_productions > 0) { int pn; - for (pn = 1; pn <= nrules; pn++) - { - if (!BITISSET (P, pn)) - { - rlhs[pn] = -1; - } - } + rules[pn].useful = BITISSET (P, pn); } +} - /* remove useless symbols */ - if (nuseless_nonterminals > 0) - { - int i, n; -/* short j; JF unused */ - short *nontermmap; - rule r; +/*------------------------------. +| Remove useless nonterminals. | +`------------------------------*/ - /* Create a map of nonterminal number to new nonterminal - number. -1 in the map means it was useless and is being - eliminated. */ +static void +nonterminals_reduce (void) +{ + int i, n; - nontermmap = XCALLOC (short, nvars) - ntokens; - for (i = ntokens; i < nsyms; i++) - nontermmap[i] = -1; + /* Map the nonterminals to their new index: useful first, useless + afterwards. Kept for later report. */ - n = ntokens; - for (i = ntokens; i < nsyms; i++) - if (BITISSET (V, i)) - nontermmap[i] = n++; + short *nontermmap = XCALLOC (short, nvars) - ntokens; + n = ntokens; + for (i = ntokens; i < nsyms; i++) + if (BITISSET (V, i)) + nontermmap[i] = n++; + for (i = ntokens; i < nsyms; i++) + if (!BITISSET (V, i)) + nontermmap[i] = n++; - /* Shuffle elements of tables indexed by symbol number. */ - for (i = ntokens; i < nsyms; i++) - { - n = nontermmap[i]; - if (n >= 0) - { - sassoc[n] = sassoc[i]; - sprec[n] = sprec[i]; - tags[n] = tags[i]; - } - else - { - free (tags[i]); - } - } + /* Shuffle elements of tables indexed by symbol number. */ + { + bucket **symbols_sorted = XMALLOC (bucket *, nvars) - ntokens; - /* Replace all symbol numbers in valid data structures. */ + for (i = ntokens; i < nsyms; i++) + symbols_sorted[nontermmap[i]] = symbols[i]; + for (i = ntokens; i < nsyms; i++) + symbols[i] = symbols_sorted[i]; + free (symbols_sorted + ntokens); + } - for (i = 1; i <= nrules; i++) - { - /* Ignore the rules disabled above. */ - if (rlhs[i] >= 0) - rlhs[i] = nontermmap[rlhs[i]]; - if (ISVAR (rprecsym[i])) - /* Can this happen? */ - rprecsym[i] = nontermmap[rprecsym[i]]; - } + /* Replace all symbol numbers in valid data structures. */ - for (r = ritem; *r; r++) - if (ISVAR (*r)) - *r = nontermmap[*r]; + for (i = 1; i <= nrules; i++) + { + rules[i].lhs = nontermmap[rules[i].lhs]; + if (ISVAR (rules[i].precsym)) + /* Can this happen? */ + rules[i].precsym = nontermmap[rules[i].precsym]; + } - start_symbol = nontermmap[start_symbol]; + for (i = 0; i < nritems; ++i) + if (ISVAR (ritem[i])) + ritem[i] = nontermmap[ritem[i]]; - nsyms -= nuseless_nonterminals; - nvars -= nuseless_nonterminals; + start_symbol = nontermmap[start_symbol]; - free (&nontermmap[ntokens]); - } + nsyms -= nuseless_nonterminals; + nvars -= nuseless_nonterminals; + + free (nontermmap + ntokens); } -static void -print_results (void) -{ - int i; -/* short j; JF unused */ - rule r; - bool b; +/*------------------------------------------------------------------. +| Output the detailed results of the reductions. For FILE.output. | +`------------------------------------------------------------------*/ + +void +reduce_output (FILE *out) +{ if (nuseless_nonterminals > 0) { - fputs (_("Useless nonterminals:"), foutput); - fputs ("\n\n", foutput); - for (i = ntokens; i < nsyms; i++) - if (!BITISSET (V, i)) - fprintf (foutput, " %s\n", tags[i]); + int i; + fprintf (out, "%s\n\n", _("Useless nonterminals:")); + for (i = 0; i < nuseless_nonterminals; ++i) + fprintf (out, " %s\n", symbols[nsyms + i]->tag); + fputs ("\n\n", out); } - b = FALSE; - for (i = 0; i < ntokens; i++) - { + + { + bool b = FALSE; + int i; + for (i = 0; i < ntokens; i++) if (!BITISSET (V, i) && !BITISSET (V1, i)) { if (!b) - { - fputs ("\n\n", foutput); - fprintf (foutput, _("Terminals which are not used:")); - fputs ("\n\n", foutput); - b = TRUE; - } - fprintf (foutput, " %s\n", tags[i]); + fprintf (out, "%s\n\n", _("Terminals which are not used:")); + b = TRUE; + fprintf (out, " %s\n", symbols[i]->tag); } - } + if (b) + fputs ("\n\n", out); + } if (nuseless_productions > 0) { - fputs ("\n\n", foutput); - fprintf (foutput, _("Useless rules:")); - fputs ("\n\n", foutput); + int i; + fprintf (out, "%s\n\n", _("Useless rules:")); for (i = 1; i <= nrules; i++) - { - if (!BITISSET (P, i)) - { - fprintf (foutput, "#%-4d ", i); - fprintf (foutput, "%s :\t", tags[rlhs[i]]); - for (r = &ritem[rrhs[i]]; *r >= 0; r++) - { - fprintf (foutput, " %s", tags[*r]); - } - fprintf (foutput, ";\n"); - } - } + if (!rules[i].useful) + { + rule r; + fprintf (out, "#%-4d ", i - 1); + fprintf (out, "%s:", symbols[rules[i].lhs]->tag); + for (r = &ritem[rules[i].rhs]; *r >= 0; r++) + fprintf (out, " %s", symbols[*r]->tag); + fputs (";\n", out); + } + fputs ("\n\n", out); } - if (nuseless_nonterminals > 0 || nuseless_productions > 0 || b) - fputs ("\n\n", foutput); } -#if 0 /* XXX currently unused. */ static void -dump_grammar (void) +dump_grammar (FILE *out) { int i; rule r; - fprintf (foutput, + fprintf (out, "REDUCED GRAMMAR\n\n"); + fprintf (out, "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n", ntokens, nvars, nsyms, nrules, nitems); - fprintf (foutput, _("Variables\n---------\n\n")); - fprintf (foutput, _("Value Sprec Sassoc Tag\n")); + fprintf (out, "Variables\n---------\n\n"); + fprintf (out, "Value Sprec Sassoc Tag\n"); for (i = ntokens; i < nsyms; i++) - fprintf (foutput, "%5d %5d %5d %s\n", i, sprec[i], sassoc[i], tags[i]); - fprintf (foutput, "\n\n"); - fprintf (foutput, _("Rules\n-----\n\n")); + fprintf (out, "%5d %5d %5d %s\n", + i, + symbols[i]->prec, symbols[i]->assoc, symbols[i]->tag); + fprintf (out, "\n\n"); + fprintf (out, "Rules\n-----\n\n"); + fprintf (out, "Num (Prec, Assoc, Useful, Ritem Range) Lhs -> Rhs (Ritem range) [Num]\n"); for (i = 1; i <= nrules; i++) { - fprintf (foutput, "%-5d(%5d%5d)%5d : (@%-5d)", - i, rprec[i], rassoc[i], rlhs[i], rrhs[i]); - for (r = &ritem[rrhs[i]]; *r > 0; r++) - fprintf (foutput, "%5d", *r); - fprintf (foutput, " [%d]\n", -(*r)); + int rhs_count = 0; + /* Find the last RHS index in ritems. */ + for (r = &ritem[rules[i].rhs]; *r >= 0; ++r) + ++rhs_count; + fprintf (out, "%3d (%2d, %2d, %2d, %2d-%2d) %2d ->", + i - 1, + rules[i].prec, rules[i].assoc, rules[i].useful, + rules[i].rhs, rules[i].rhs + rhs_count - 1, + rules[i].lhs); + /* Dumped the RHS. */ + for (r = &ritem[rules[i].rhs]; *r >= 0; r++) + fprintf (out, "%3d", *r); + fprintf (out, " [%d]\n", -(*r) - 1); } - fprintf (foutput, "\n\n"); - fprintf (foutput, _("Rules interpreted\n-----------------\n\n")); + fprintf (out, "\n\n"); + fprintf (out, "Rules interpreted\n-----------------\n\n"); for (i = 1; i <= nrules; i++) { - fprintf (foutput, "%-5d %s :", i, tags[rlhs[i]]); - for (r = &ritem[rrhs[i]]; *r > 0; r++) - fprintf (foutput, " %s", tags[*r]); - fprintf (foutput, "\n"); + fprintf (out, "%-5d %s :", i, symbols[rules[i].lhs]->tag); + for (r = &ritem[rules[i].rhs]; *r >= 0; r++) + fprintf (out, " %s", symbols[*r]->tag); + fputc ('\n', out); } - fprintf (foutput, "\n\n"); + fprintf (out, "\n\n"); } -#endif +/*-------------------------------. +| Report the results to STDERR. | +`-------------------------------*/ + static void -print_notices (void) +reduce_print (void) { if (yacc_flag && nuseless_productions) - fprintf (stderr, _("%d rules never reduced\n"), nuseless_productions); + fprintf (stderr, ngettext ("%d rule never reduced\n", + "%d rules never reduced\n", + nuseless_productions), + nuseless_productions); fprintf (stderr, _("%s contains "), infile); if (nuseless_nonterminals > 0) - { - fprintf (stderr, _("%d useless nonterminal%s"), - nuseless_nonterminals, - (nuseless_nonterminals == 1 ? "" : "s")); - } + fprintf (stderr, ngettext ("%d useless nonterminal", + "%d useless nonterminals", + nuseless_nonterminals), + nuseless_nonterminals); + if (nuseless_nonterminals > 0 && nuseless_productions > 0) fprintf (stderr, _(" and ")); if (nuseless_productions > 0) - { - fprintf (stderr, _("%d useless rule%s"), - nuseless_productions, (nuseless_productions == 1 ? "" : "s")); - } + fprintf (stderr, ngettext ("%d useless rule", + "%d useless rules", + nuseless_productions), + nuseless_productions); fprintf (stderr, "\n"); fflush (stderr); } @@ -528,42 +533,39 @@ reduce_grammar (void) reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0); - if (verbose_flag) - print_results (); - - if (reduced == FALSE) - goto done_reducing; + if (!reduced) + return; - print_notices (); + reduce_print (); if (!BITISSET (N, start_symbol - ntokens)) fatal (_("Start symbol %s does not derive any sentence"), - tags[start_symbol]); + symbols[start_symbol]->tag); reduce_grammar_tables (); -#if 0 - if (verbose_flag) + if (nuseless_nonterminals > 0) + nonterminals_reduce (); + + if (trace_flag) { - fprintf (foutput, "REDUCED GRAMMAR\n\n"); - dump_grammar (); + dump_grammar (stderr); + + fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\ +, and %d productions.\n", + infile, ntokens, nvars, nrules); } -#endif - - if (statistics_flag) - fprintf (stderr, _("reduced %s defines %d terminal%s, %d nonterminal%s\ -, and %d production%s.\n"), - infile, - ntokens, - (ntokens == 1 ? "" : "s"), - nvars, - (nvars == 1 ? "" : "s"), - nrules, - (nrules == 1 ? "" : "s")); - -done_reducing: - /* Free the global sets used to compute the reduced grammar */ +} + + +/*-----------------------------------------------------------. +| Free the global sets used to compute the reduced grammar. | +`-----------------------------------------------------------*/ +void +reduce_free (void) +{ XFREE (N); XFREE (V); + XFREE (V1); XFREE (P); }