--- /dev/null
+/* Find and resolve or report look-ahead conflicts for bison,
+ Copyright (C) 1984, 1989 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
+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.
+
+Bison 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, 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+#ifdef _AIX
+ #pragma alloca
+#endif
+#include <stdio.h>
+#include "system.h"
+#include "machine.h"
+#include "new.h"
+#include "files.h"
+#include "gram.h"
+#include "state.h"
+
+
+#ifdef __GNUC__
+#define alloca __builtin_alloca
+#else
+#ifdef HAVE_ALLOCA_H
+#include <alloca.h>
+#else
+#ifndef _AIX
+extern char *alloca ();
+#endif
+#endif
+#endif
+
+extern char **tags;
+extern int tokensetsize;
+extern char *consistent;
+extern short *accessing_symbol;
+extern shifts **shift_table;
+extern unsigned *LA;
+extern short *LAruleno;
+extern short *lookaheads;
+extern int verboseflag;
+
+void set_conflicts();
+void resolve_sr_conflict();
+void flush_shift();
+void log_resolution();
+void total_conflicts();
+void count_sr_conflicts();
+void count_rr_conflicts();
+
+char any_conflicts;
+char *conflicts;
+errs **err_table;
+int expected_conflicts;
+
+
+static unsigned *shiftset;
+static unsigned *lookaheadset;
+static int src_total;
+static int rrc_total;
+static int src_count;
+static int rrc_count;
+
+
+void
+initialize_conflicts()
+{
+ register int i;
+/* register errs *sp; JF unused */
+
+ conflicts = NEW2(nstates, char);
+ shiftset = NEW2(tokensetsize, unsigned);
+ lookaheadset = NEW2(tokensetsize, unsigned);
+
+ err_table = NEW2(nstates, errs *);
+
+ any_conflicts = 0;
+
+ for (i = 0; i < nstates; i++)
+ set_conflicts(i);
+}
+
+
+void
+set_conflicts(state)
+int state;
+{
+ register int i;
+ register int k;
+ register shifts *shiftp;
+ register unsigned *fp2;
+ register unsigned *fp3;
+ register unsigned *fp4;
+ register unsigned *fp1;
+ register int symbol;
+
+ if (consistent[state]) return;
+
+ for (i = 0; i < tokensetsize; i++)
+ lookaheadset[i] = 0;
+
+ shiftp = shift_table[state];
+ if (shiftp)
+ {
+ k = shiftp->nshifts;
+ for (i = 0; i < k; i++)
+ {
+ symbol = accessing_symbol[shiftp->shifts[i]];
+ if (ISVAR(symbol)) break;
+ SETBIT(lookaheadset, symbol);
+ }
+ }
+
+ k = lookaheads[state + 1];
+ fp4 = lookaheadset + tokensetsize;
+
+ /* loop over all rules which require lookahead in this state */
+ /* first check for shift-reduce conflict, and try to resolve using precedence */
+
+ for (i = lookaheads[state]; i < k; i++)
+ if (rprec[LAruleno[i]])
+ {
+ fp1 = LA + i * tokensetsize;
+ fp2 = fp1;
+ fp3 = lookaheadset;
+
+ while (fp3 < fp4)
+ {
+ if (*fp2++ & *fp3++)
+ {
+ resolve_sr_conflict(state, i);
+ break;
+ }
+ }
+ }
+
+ /* loop over all rules which require lookahead in this state */
+ /* Check for conflicts not resolved above. */
+
+ for (i = lookaheads[state]; i < k; i++)
+ {
+ fp1 = LA + i * tokensetsize;
+ fp2 = fp1;
+ fp3 = lookaheadset;
+
+ while (fp3 < fp4)
+ {
+ if (*fp2++ & *fp3++)
+ {
+ conflicts[state] = 1;
+ any_conflicts = 1;
+ }
+ }
+
+ fp2 = fp1;
+ fp3 = lookaheadset;
+
+ while (fp3 < fp4)
+ *fp3++ |= *fp2++;
+ }
+}
+
+
+
+/* Attempt to resolve shift-reduce conflict for one rule
+by means of 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. */
+
+void
+resolve_sr_conflict(state, lookaheadnum)
+int state;
+int lookaheadnum;
+{
+ register int i;
+ register int mask;
+ register unsigned *fp1;
+ register unsigned *fp2;
+ register int redprec;
+ /* Extra parens avoid errors on Ultrix 4.3. */
+ errs *errp = (errs *) alloca ((sizeof(errs) + ntokens * sizeof(short)));
+ short *errtokens = errp->errs;
+
+ /* find the rule to reduce by to get precedence of reduction */
+ redprec = rprec[LAruleno[lookaheadnum]];
+
+ mask = 1;
+ fp1 = LA + lookaheadnum * tokensetsize;
+ fp2 = lookaheadset;
+ for (i = 0; i < ntokens; i++)
+ {
+ if ((mask & *fp2 & *fp1) && sprec[i])
+ /* 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 (verboseflag) log_resolution(state, lookaheadnum, i, "reduce");
+ *fp2 &= ~mask; /* flush the shift for this token */
+ flush_shift(state, i);
+ }
+ else if (sprec[i] > redprec)
+ {
+ if (verboseflag) 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:
+ if (verboseflag) log_resolution(state, lookaheadnum, i, "shift");
+ break;
+
+ case LEFT_ASSOC:
+ if (verboseflag) log_resolution(state, lookaheadnum, i, "reduce");
+ break;
+
+ case NON_ASSOC:
+ if (verboseflag) 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. */
+ i = (char *) errtokens - (char *) errp;
+ err_table[state] = (errs *) xmalloc ((unsigned int)i);
+ bcopy (errp, err_table[state], i);
+ }
+ else
+ err_table[state] = 0;
+}
+
+
+
+/* turn off the shift recorded for the specified token in the specified state.
+Used when we resolve a shift-reduce conflict in favor of the reduction. */
+
+void
+flush_shift(state, token)
+int state;
+int token;
+{
+ register shifts *shiftp;
+ register int k, i;
+/* register unsigned symbol; JF unused */
+
+ shiftp = shift_table[state];
+
+ if (shiftp)
+ {
+ k = shiftp->nshifts;
+ for (i = 0; i < k; i++)
+ {
+ if (shiftp->shifts[i] && token == accessing_symbol[shiftp->shifts[i]])
+ (shiftp->shifts[i]) = 0;
+ }
+ }
+}
+
+
+void
+log_resolution(state, LAno, token, resolution)
+int state, LAno, token;
+char *resolution;
+{
+ fprintf(foutput,
+ "Conflict in state %d between rule %d and token %s resolved as %s.\n",
+ state, LAruleno[LAno], tags[token], resolution);
+}
+
+
+void
+conflict_log()
+{
+ register int i;
+
+ src_total = 0;
+ rrc_total = 0;
+
+ for (i = 0; i < nstates; i++)
+ {
+ if (conflicts[i])
+ {
+ count_sr_conflicts(i);
+ count_rr_conflicts(i);
+ src_total += src_count;
+ rrc_total += rrc_count;
+ }
+ }
+
+ total_conflicts();
+}
+
+
+void
+verbose_conflict_log()
+{
+ register int i;
+
+ src_total = 0;
+ rrc_total = 0;
+
+ for (i = 0; i < nstates; i++)
+ {
+ if (conflicts[i])
+ {
+ count_sr_conflicts(i);
+ count_rr_conflicts(i);
+ src_total += src_count;
+ rrc_total += rrc_count;
+
+ fprintf(foutput, "State %d contains", i);
+
+ if (src_count == 1)
+ fprintf(foutput, " 1 shift/reduce conflict");
+ else if (src_count > 1)
+ fprintf(foutput, " %d shift/reduce conflicts", src_count);
+
+ if (src_count > 0 && rrc_count > 0)
+ fprintf(foutput, " and");
+
+ if (rrc_count == 1)
+ fprintf(foutput, " 1 reduce/reduce conflict");
+ else if (rrc_count > 1)
+ fprintf(foutput, " %d reduce/reduce conflicts", rrc_count);
+
+ putc('.', foutput);
+ putc('\n', foutput);
+ }
+ }
+
+ total_conflicts();
+}
+
+
+void
+total_conflicts()
+{
+ extern int fixed_outfiles;
+
+ if (src_total == expected_conflicts && rrc_total == 0)
+ return;
+
+ if (fixed_outfiles)
+ {
+ /* If invoked under the name `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);
+ }
+ else
+ {
+ fprintf(stderr, "%s contains", infile);
+
+ if (src_total == 1)
+ fprintf(stderr, " 1 shift/reduce conflict");
+ else if (src_total > 1)
+ fprintf(stderr, " %d shift/reduce conflicts", src_total);
+
+ if (src_total > 0 && rrc_total > 0)
+ fprintf(stderr, " and");
+
+ if (rrc_total == 1)
+ fprintf(stderr, " 1 reduce/reduce conflict");
+ else if (rrc_total > 1)
+ fprintf(stderr, " %d reduce/reduce conflicts", rrc_total);
+
+ putc('.', stderr);
+ putc('\n', stderr);
+ }
+}
+
+
+void
+count_sr_conflicts(state)
+int state;
+{
+ register int i;
+ register int k;
+ register int mask;
+ register shifts *shiftp;
+ register unsigned *fp1;
+ register unsigned *fp2;
+ register unsigned *fp3;
+ register int symbol;
+
+ src_count = 0;
+
+ shiftp = shift_table[state];
+ if (!shiftp) return;
+
+ for (i = 0; i < tokensetsize; i++)
+ {
+ shiftset[i] = 0;
+ lookaheadset[i] = 0;
+ }
+
+ k = shiftp->nshifts;
+ for (i = 0; i < k; i++)
+ {
+ if (! shiftp->shifts[i]) continue;
+ symbol = accessing_symbol[shiftp->shifts[i]];
+ if (ISVAR(symbol)) break;
+ SETBIT(shiftset, symbol);
+ }
+
+ k = lookaheads[state + 1];
+ fp3 = lookaheadset + tokensetsize;
+
+ for (i = lookaheads[state]; i < k; i++)
+ {
+ fp1 = LA + i * tokensetsize;
+ fp2 = lookaheadset;
+
+ while (fp2 < fp3)
+ *fp2++ |= *fp1++;
+ }
+
+ fp1 = shiftset;
+ fp2 = lookaheadset;
+
+ while (fp2 < fp3)
+ *fp2++ &= *fp1++;
+
+ mask = 1;
+ fp2 = lookaheadset;
+ for (i = 0; i < ntokens; i++)
+ {
+ if (mask & *fp2)
+ src_count++;
+
+ mask <<= 1;
+ if (mask == 0)
+ {
+ mask = 1;
+ fp2++;
+ }
+ }
+}
+
+
+void
+count_rr_conflicts(state)
+int state;
+{
+ register int i;
+ register int j;
+ register int count;
+ register unsigned mask;
+ register unsigned *baseword;
+ register unsigned *wordp;
+ register int m;
+ register int n;
+
+ rrc_count = 0;
+
+ m = lookaheads[state];
+ n = lookaheads[state + 1];
+
+ if (n - m < 2) return;
+
+ mask = 1;
+ baseword = LA + m * tokensetsize;
+ for (i = 0; i < ntokens; i++)
+ {
+ wordp = baseword;
+
+ count = 0;
+ for (j = m; j < n; j++)
+ {
+ if (mask & *wordp)
+ count++;
+
+ wordp += tokensetsize;
+ }
+
+ if (count >= 2) rrc_count++;
+
+ mask <<= 1;
+ if (mask == 0)
+ {
+ mask = 1;
+ baseword++;
+ }
+ }
+}
+
+
+void
+print_reductions(state)
+int state;
+{
+ register int i;
+ register int j;
+ register int k;
+ register unsigned *fp1;
+ register unsigned *fp2;
+ register unsigned *fp3;
+ register unsigned *fp4;
+ register int rule;
+ register int symbol;
+ register unsigned mask;
+ register int m;
+ register int n;
+ register int default_LA;
+ register int default_rule;
+ register int cmax;
+ register int count;
+ register shifts *shiftp;
+ register errs *errp;
+ int nodefault = 0;
+
+ for (i = 0; i < tokensetsize; i++)
+ shiftset[i] = 0;
+
+ shiftp = shift_table[state];
+ if (shiftp)
+ {
+ k = shiftp->nshifts;
+ for (i = 0; i < k; i++)
+ {
+ if (! shiftp->shifts[i]) continue;
+ symbol = accessing_symbol[shiftp->shifts[i]];
+ 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)
+ {
+ k = errp->nerrs;
+ for (i = 0; i < k; i++)
+ {
+ if (! errp->errs[i]) continue;
+ symbol = errp->errs[i];
+ SETBIT(shiftset, symbol);
+ }
+ }
+
+ m = lookaheads[state];
+ n = lookaheads[state + 1];
+
+ if (n - m == 1 && ! nodefault)
+ {
+ default_rule = LAruleno[m];
+
+ fp1 = LA + m * tokensetsize;
+ fp2 = shiftset;
+ fp3 = lookaheadset;
+ fp4 = lookaheadset + tokensetsize;
+
+ while (fp3 < fp4)
+ *fp3++ = *fp1++ & *fp2++;
+
+ mask = 1;
+ fp3 = lookaheadset;
+
+ for (i = 0; i < ntokens; i++)
+ {
+ if (mask & *fp3)
+ fprintf(foutput, " %-4s\t[reduce using rule %d (%s)]\n",
+ tags[i], default_rule, tags[rlhs[default_rule]]);
+
+ mask <<= 1;
+ if (mask == 0)
+ {
+ mask = 1;
+ fp3++;
+ }
+ }
+
+ fprintf(foutput, " $default\treduce using rule %d (%s)\n\n",
+ default_rule, tags[rlhs[default_rule]]);
+ }
+ else if (n - m >= 1)
+ {
+ cmax = 0;
+ default_LA = -1;
+ fp4 = lookaheadset + tokensetsize;
+
+ if (! nodefault)
+ for (i = m; i < n; i++)
+ {
+ fp1 = LA + i * tokensetsize;
+ fp2 = shiftset;
+ fp3 = lookaheadset;
+
+ while (fp3 < fp4)
+ *fp3++ = *fp1++ & ( ~ (*fp2++));
+
+ count = 0;
+ mask = 1;
+ fp3 = lookaheadset;
+ for (j = 0; j < ntokens; j++)
+ {
+ if (mask & *fp3)
+ count++;
+
+ mask <<= 1;
+ if (mask == 0)
+ {
+ mask = 1;
+ fp3++;
+ }
+ }
+
+ if (count > cmax)
+ {
+ cmax = count;
+ default_LA = i;
+ default_rule = LAruleno[i];
+ }
+
+ fp2 = shiftset;
+ fp3 = lookaheadset;
+
+ while (fp3 < fp4)
+ *fp2++ |= *fp3++;
+ }
+
+ for (i = 0; i < tokensetsize; i++)
+ shiftset[i] = 0;
+
+ if (shiftp)
+ {
+ k = shiftp->nshifts;
+ for (i = 0; i < k; i++)
+ {
+ if (! shiftp->shifts[i]) continue;
+ symbol = accessing_symbol[shiftp->shifts[i]];
+ if (ISVAR(symbol)) break;
+ SETBIT(shiftset, symbol);
+ }
+ }
+
+ mask = 1;
+ fp1 = LA + m * tokensetsize;
+ fp2 = shiftset;
+ for (i = 0; i < ntokens; i++)
+ {
+ int defaulted = 0;
+
+ if (mask & *fp2)
+ count = 1;
+ else
+ count = 0;
+
+ fp3 = fp1;
+ for (j = m; j < n; j++)
+ {
+ if (mask & *fp3)
+ {
+ if (count == 0)
+ {
+ if (j != default_LA)
+ {
+ rule = LAruleno[j];
+ fprintf(foutput, " %-4s\treduce using rule %d (%s)\n",
+ tags[i], rule, tags[rlhs[rule]]);
+ }
+ else defaulted = 1;
+
+ count++;
+ }
+ else
+ {
+ if (defaulted)
+ {
+ rule = LAruleno[default_LA];
+ fprintf(foutput, " %-4s\treduce using rule %d (%s)\n",
+ tags[i], rule, tags[rlhs[rule]]);
+ defaulted = 0;
+ }
+ rule = LAruleno[j];
+ fprintf(foutput, " %-4s\t[reduce using rule %d (%s)]\n",
+ tags[i], rule, tags[rlhs[rule]]);
+ }
+ }
+
+ fp3 += tokensetsize;
+ }
+
+ mask <<= 1;
+ if (mask == 0)
+ {
+ mask = 1;
+ /* This used to be fp1, but I think fp2 is right
+ because fp2 is where the words are fetched to test with mask
+ in this loop. */
+ fp2++;
+ }
+ }
+
+ if (default_LA >= 0)
+ {
+ fprintf(foutput, " $default\treduce using rule %d (%s)\n",
+ default_rule, tags[rlhs[default_rule]]);
+ }
+
+ putc('\n', foutput);
+ }
+}
+
+
+void
+finalize_conflicts()
+{
+ FREE(conflicts);
+ FREE(shiftset);
+ FREE(lookaheadset);
+}
projects / bison.git / commitdiff
