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- /* 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"
#if defined(STDC_HEADERS) || defined(__GNU_LIBRARY__) || defined(THINK_C)
#define bcopy(s, d, n) memcpy ((d), (s), (n))
#else
#ifdef USG
#include <memory.h>
#define bcopy(src, dst, num) memcpy((dst), (src), (num))
#endif /* usg */
#endif /* stdc_headers || gnu_library|| THINK_C */
#ifdef __GNUC__
#define alloca __builtin_alloca
#else
#ifdef sparc
#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;
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 *) mallocate ((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;
fp1++;
}
}
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);
}
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