cf1a7c8a3a
In case you're wondering, the gcc-2.7.2.1 import uses this to generate code. The size of the generated code is bigger than the entire bison release, making this a saving. The bison doc is pretty good apparently.
754 lines
15 KiB
C
754 lines
15 KiB
C
/* Find and resolve or report look-ahead conflicts for bison,
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Copyright (C) 1984, 1989, 1992 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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Bison is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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Bison is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Bison; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#include <stdio.h>
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#include "system.h"
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#include "machine.h"
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#include "new.h"
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#include "files.h"
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#include "gram.h"
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#include "state.h"
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extern char **tags;
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extern int tokensetsize;
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extern char *consistent;
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extern short *accessing_symbol;
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extern shifts **shift_table;
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extern unsigned *LA;
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extern short *LAruleno;
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extern short *lookaheads;
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extern int verboseflag;
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void set_conflicts();
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void resolve_sr_conflict();
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void flush_shift();
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void log_resolution();
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void total_conflicts();
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void count_sr_conflicts();
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void count_rr_conflicts();
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char any_conflicts;
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char *conflicts;
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errs **err_table;
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int expected_conflicts;
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static unsigned *shiftset;
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static unsigned *lookaheadset;
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static int src_total;
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static int rrc_total;
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static int src_count;
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static int rrc_count;
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void
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initialize_conflicts()
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{
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register int i;
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/* register errs *sp; JF unused */
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conflicts = NEW2(nstates, char);
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shiftset = NEW2(tokensetsize, unsigned);
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lookaheadset = NEW2(tokensetsize, unsigned);
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err_table = NEW2(nstates, errs *);
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any_conflicts = 0;
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for (i = 0; i < nstates; i++)
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set_conflicts(i);
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}
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void
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set_conflicts(state)
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int state;
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{
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register int i;
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register int k;
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register shifts *shiftp;
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register unsigned *fp2;
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register unsigned *fp3;
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register unsigned *fp4;
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register unsigned *fp1;
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register int symbol;
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if (consistent[state]) return;
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for (i = 0; i < tokensetsize; i++)
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lookaheadset[i] = 0;
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shiftp = shift_table[state];
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if (shiftp)
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{
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k = shiftp->nshifts;
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for (i = 0; i < k; i++)
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{
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symbol = accessing_symbol[shiftp->shifts[i]];
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if (ISVAR(symbol)) break;
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SETBIT(lookaheadset, symbol);
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}
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}
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k = lookaheads[state + 1];
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fp4 = lookaheadset + tokensetsize;
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/* loop over all rules which require lookahead in this state */
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/* first check for shift-reduce conflict, and try to resolve using precedence */
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for (i = lookaheads[state]; i < k; i++)
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if (rprec[LAruleno[i]])
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{
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fp1 = LA + i * tokensetsize;
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fp2 = fp1;
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fp3 = lookaheadset;
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while (fp3 < fp4)
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{
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if (*fp2++ & *fp3++)
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{
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resolve_sr_conflict(state, i);
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break;
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}
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}
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}
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/* loop over all rules which require lookahead in this state */
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/* Check for conflicts not resolved above. */
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for (i = lookaheads[state]; i < k; i++)
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{
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fp1 = LA + i * tokensetsize;
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fp2 = fp1;
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fp3 = lookaheadset;
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while (fp3 < fp4)
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{
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if (*fp2++ & *fp3++)
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{
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conflicts[state] = 1;
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any_conflicts = 1;
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}
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}
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fp2 = fp1;
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fp3 = lookaheadset;
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while (fp3 < fp4)
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*fp3++ |= *fp2++;
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}
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}
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/* Attempt to resolve shift-reduce conflict for one rule
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by means of precedence declarations.
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It has already been checked that the rule has a precedence.
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A conflict is resolved by modifying the shift or reduce tables
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so that there is no longer a conflict. */
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void
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resolve_sr_conflict(state, lookaheadnum)
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int state;
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int lookaheadnum;
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{
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register int i;
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register int mask;
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register unsigned *fp1;
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register unsigned *fp2;
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register int redprec;
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errs *errp = (errs *) xmalloc (sizeof(errs) + ntokens * sizeof(short));
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short *errtokens = errp->errs;
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/* find the rule to reduce by to get precedence of reduction */
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redprec = rprec[LAruleno[lookaheadnum]];
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mask = 1;
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fp1 = LA + lookaheadnum * tokensetsize;
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fp2 = lookaheadset;
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for (i = 0; i < ntokens; i++)
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{
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if ((mask & *fp2 & *fp1) && sprec[i])
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/* Shift-reduce conflict occurs for token number i
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and it has a precedence.
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The precedence of shifting is that of token i. */
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{
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if (sprec[i] < redprec)
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{
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if (verboseflag) log_resolution(state, lookaheadnum, i, "reduce");
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*fp2 &= ~mask; /* flush the shift for this token */
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flush_shift(state, i);
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}
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else if (sprec[i] > redprec)
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{
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if (verboseflag) log_resolution(state, lookaheadnum, i, "shift");
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*fp1 &= ~mask; /* flush the reduce for this token */
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}
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else
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{
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/* Matching precedence levels.
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For left association, keep only the reduction.
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For right association, keep only the shift.
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For nonassociation, keep neither. */
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switch (sassoc[i])
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{
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case RIGHT_ASSOC:
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if (verboseflag) log_resolution(state, lookaheadnum, i, "shift");
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break;
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case LEFT_ASSOC:
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if (verboseflag) log_resolution(state, lookaheadnum, i, "reduce");
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break;
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case NON_ASSOC:
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if (verboseflag) log_resolution(state, lookaheadnum, i, "an error");
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break;
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}
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if (sassoc[i] != RIGHT_ASSOC)
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{
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*fp2 &= ~mask; /* flush the shift for this token */
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flush_shift(state, i);
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}
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if (sassoc[i] != LEFT_ASSOC)
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{
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*fp1 &= ~mask; /* flush the reduce for this token */
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}
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if (sassoc[i] == NON_ASSOC)
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{
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/* Record an explicit error for this token. */
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*errtokens++ = i;
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}
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}
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}
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mask <<= 1;
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if (mask == 0)
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{
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mask = 1;
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fp2++; fp1++;
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}
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}
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errp->nerrs = errtokens - errp->errs;
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if (errp->nerrs)
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{
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/* Some tokens have been explicitly made errors. Allocate
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a permanent errs structure for this state, to record them. */
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i = (char *) errtokens - (char *) errp;
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err_table[state] = (errs *) xmalloc ((unsigned int)i);
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bcopy (errp, err_table[state], i);
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}
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else
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err_table[state] = 0;
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free(errp);
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}
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/* turn off the shift recorded for the specified token in the specified state.
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Used when we resolve a shift-reduce conflict in favor of the reduction. */
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void
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flush_shift(state, token)
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int state;
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int token;
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{
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register shifts *shiftp;
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register int k, i;
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/* register unsigned symbol; JF unused */
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shiftp = shift_table[state];
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if (shiftp)
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{
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k = shiftp->nshifts;
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for (i = 0; i < k; i++)
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{
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if (shiftp->shifts[i] && token == accessing_symbol[shiftp->shifts[i]])
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(shiftp->shifts[i]) = 0;
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}
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}
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}
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void
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log_resolution(state, LAno, token, resolution)
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int state, LAno, token;
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char *resolution;
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{
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fprintf(foutput,
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"Conflict in state %d between rule %d and token %s resolved as %s.\n",
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state, LAruleno[LAno], tags[token], resolution);
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}
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void
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conflict_log()
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{
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register int i;
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src_total = 0;
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rrc_total = 0;
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for (i = 0; i < nstates; i++)
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{
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if (conflicts[i])
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{
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count_sr_conflicts(i);
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count_rr_conflicts(i);
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src_total += src_count;
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rrc_total += rrc_count;
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}
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}
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total_conflicts();
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}
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void
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verbose_conflict_log()
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{
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register int i;
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src_total = 0;
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rrc_total = 0;
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for (i = 0; i < nstates; i++)
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{
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if (conflicts[i])
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{
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count_sr_conflicts(i);
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count_rr_conflicts(i);
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src_total += src_count;
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rrc_total += rrc_count;
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fprintf(foutput, "State %d contains", i);
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if (src_count == 1)
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fprintf(foutput, " 1 shift/reduce conflict");
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else if (src_count > 1)
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fprintf(foutput, " %d shift/reduce conflicts", src_count);
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if (src_count > 0 && rrc_count > 0)
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fprintf(foutput, " and");
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if (rrc_count == 1)
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fprintf(foutput, " 1 reduce/reduce conflict");
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else if (rrc_count > 1)
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fprintf(foutput, " %d reduce/reduce conflicts", rrc_count);
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putc('.', foutput);
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putc('\n', foutput);
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}
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}
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total_conflicts();
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}
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void
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total_conflicts()
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{
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extern int fixed_outfiles;
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if (src_total == expected_conflicts && rrc_total == 0)
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return;
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if (fixed_outfiles)
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{
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/* If invoked under the name `yacc', use the output format
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specified by POSIX. */
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fprintf(stderr, "conflicts: ");
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if (src_total > 0)
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fprintf(stderr, " %d shift/reduce", src_total);
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if (src_total > 0 && rrc_total > 0)
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fprintf(stderr, ",");
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if (rrc_total > 0)
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fprintf(stderr, " %d reduce/reduce", rrc_total);
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putc('\n', stderr);
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}
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else
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{
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fprintf(stderr, "%s contains", infile);
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if (src_total == 1)
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fprintf(stderr, " 1 shift/reduce conflict");
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else if (src_total > 1)
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fprintf(stderr, " %d shift/reduce conflicts", src_total);
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if (src_total > 0 && rrc_total > 0)
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fprintf(stderr, " and");
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if (rrc_total == 1)
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fprintf(stderr, " 1 reduce/reduce conflict");
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else if (rrc_total > 1)
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fprintf(stderr, " %d reduce/reduce conflicts", rrc_total);
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putc('.', stderr);
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putc('\n', stderr);
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}
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}
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void
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count_sr_conflicts(state)
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int state;
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{
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register int i;
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register int k;
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register int mask;
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register shifts *shiftp;
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register unsigned *fp1;
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register unsigned *fp2;
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register unsigned *fp3;
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register int symbol;
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src_count = 0;
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shiftp = shift_table[state];
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if (!shiftp) return;
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for (i = 0; i < tokensetsize; i++)
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{
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shiftset[i] = 0;
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lookaheadset[i] = 0;
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}
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k = shiftp->nshifts;
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for (i = 0; i < k; i++)
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{
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if (! shiftp->shifts[i]) continue;
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symbol = accessing_symbol[shiftp->shifts[i]];
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if (ISVAR(symbol)) break;
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SETBIT(shiftset, symbol);
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}
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k = lookaheads[state + 1];
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fp3 = lookaheadset + tokensetsize;
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for (i = lookaheads[state]; i < k; i++)
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{
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fp1 = LA + i * tokensetsize;
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fp2 = lookaheadset;
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while (fp2 < fp3)
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*fp2++ |= *fp1++;
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}
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fp1 = shiftset;
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fp2 = lookaheadset;
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while (fp2 < fp3)
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*fp2++ &= *fp1++;
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mask = 1;
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fp2 = lookaheadset;
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for (i = 0; i < ntokens; i++)
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{
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if (mask & *fp2)
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src_count++;
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mask <<= 1;
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if (mask == 0)
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{
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mask = 1;
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fp2++;
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}
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}
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}
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void
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count_rr_conflicts(state)
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int state;
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{
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register int i;
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register int j;
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register int count;
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register unsigned mask;
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register unsigned *baseword;
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register unsigned *wordp;
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register int m;
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register int n;
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rrc_count = 0;
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m = lookaheads[state];
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n = lookaheads[state + 1];
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if (n - m < 2) return;
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mask = 1;
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baseword = LA + m * tokensetsize;
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for (i = 0; i < ntokens; i++)
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{
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wordp = baseword;
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count = 0;
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for (j = m; j < n; j++)
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{
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if (mask & *wordp)
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count++;
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wordp += tokensetsize;
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}
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if (count >= 2) rrc_count++;
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mask <<= 1;
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if (mask == 0)
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{
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mask = 1;
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baseword++;
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}
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}
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}
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void
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print_reductions(state)
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int state;
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{
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register int i;
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register int j;
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register int k;
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register unsigned *fp1;
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register unsigned *fp2;
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register unsigned *fp3;
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register unsigned *fp4;
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register int rule;
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register int symbol;
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register unsigned mask;
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register int m;
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register int n;
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register int default_LA;
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register int default_rule;
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register int cmax;
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register int count;
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register shifts *shiftp;
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register errs *errp;
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int nodefault = 0;
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for (i = 0; i < tokensetsize; i++)
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shiftset[i] = 0;
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shiftp = shift_table[state];
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if (shiftp)
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{
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k = shiftp->nshifts;
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for (i = 0; i < k; i++)
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{
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if (! shiftp->shifts[i]) continue;
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symbol = accessing_symbol[shiftp->shifts[i]];
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if (ISVAR(symbol)) break;
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/* if this state has a shift for the error token,
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don't use a default rule. */
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if (symbol == error_token_number) nodefault = 1;
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SETBIT(shiftset, symbol);
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}
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}
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errp = err_table[state];
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if (errp)
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{
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k = errp->nerrs;
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for (i = 0; i < k; i++)
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{
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if (! errp->errs[i]) continue;
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symbol = errp->errs[i];
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SETBIT(shiftset, symbol);
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}
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}
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m = lookaheads[state];
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n = lookaheads[state + 1];
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if (n - m == 1 && ! nodefault)
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{
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default_rule = LAruleno[m];
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fp1 = LA + m * tokensetsize;
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fp2 = shiftset;
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fp3 = lookaheadset;
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fp4 = lookaheadset + tokensetsize;
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while (fp3 < fp4)
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*fp3++ = *fp1++ & *fp2++;
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mask = 1;
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fp3 = lookaheadset;
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for (i = 0; i < ntokens; i++)
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{
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if (mask & *fp3)
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fprintf(foutput, " %-4s\t[reduce using rule %d (%s)]\n",
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|
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;
|
|
/* We tried incrementing just fp1, and just fp2; both seem wrong.
|
|
It seems necessary to increment both in sync. */
|
|
fp1++;
|
|
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);
|
|
}
|