/* Compute look-ahead criteria for bison,
- Copyright (C) 1984, 1986, 1989, 2000 Free Software Foundation, Inc.
+ Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
tokens they accept. */
#include "system.h"
+#include "reader.h"
#include "types.h"
#include "LR0.h"
-#include "xalloc.h"
+#include "symtab.h"
#include "gram.h"
#include "complain.h"
#include "lalr.h"
#include "nullable.h"
#include "derives.h"
+#include "getargs.h"
+
+/* All the decorated states, indexed by the state number. */
+state_t **states = NULL;
int tokensetsize;
-short *lookaheads;
short *LAruleno;
unsigned *LA;
-short *accessing_symbol;
-char *consistent;
-core **state_table;
-shifts **shift_table;
-reductions **reduction_table;
+size_t nLA;
+
+static int ngotos;
short *goto_map;
short *from_state;
short *to_state;
-extern void berror PARAMS ((const char *));
+/* And for the famous F variable, which name is so descriptive that a
+ comment is hardly needed. <grin>. */
+static unsigned *F = NULL;
+#define F(Rule) (F + (Rule) * tokensetsize)
-static int infinity;
-static int maxrhs;
-static int ngotos;
-static unsigned *F;
static short **includes;
static shorts **lookback;
+
+
+/*---------------------------------------------------------------.
+| digraph & traverse. |
+| |
+| The following variables are used as common storage between the |
+| two. |
+`---------------------------------------------------------------*/
+
static short **R;
static short *INDEX;
static short *VERTICES;
static int top;
-
+static int infinity;
static void
traverse (int i)
{
- unsigned *fp1;
- unsigned *fp2;
- unsigned *fp3;
int j;
- short *rp;
-
+ size_t k;
int height;
- unsigned *base;
+ size_t size = F (i + 1) - F(i);
VERTICES[++top] = i;
INDEX[i] = height = top;
- base = F + i * tokensetsize;
- fp3 = base + tokensetsize;
-
- rp = R[i];
- if (rp)
- {
- while ((j = *rp++) >= 0)
- {
- if (INDEX[j] == 0)
- traverse (j);
-
- if (INDEX[i] > INDEX[j])
- INDEX[i] = INDEX[j];
+ if (R[i])
+ for (j = 0; R[i][j] >= 0; ++j)
+ {
+ if (INDEX[R[i][j]] == 0)
+ traverse (R[i][j]);
- fp1 = base;
- fp2 = F + j * tokensetsize;
+ if (INDEX[i] > INDEX[R[i][j]])
+ INDEX[i] = INDEX[R[i][j]];
- while (fp1 < fp3)
- *fp1++ |= *fp2++;
- }
- }
+ for (k = 0; k < size; ++k)
+ F (i)[k] |= F (R[i][j])[k];
+ }
if (INDEX[i] == height)
- {
- for (;;)
- {
- j = VERTICES[top--];
- INDEX[j] = infinity;
-
- if (i == j)
- break;
+ for (;;)
+ {
+ j = VERTICES[top--];
+ INDEX[j] = infinity;
- fp1 = base;
- fp2 = F + j * tokensetsize;
+ if (i == j)
+ break;
- while (fp1 < fp3)
- *fp2++ = *fp1++;
- }
- }
+ for (k = 0; k < size; ++k)
+ F (j)[k] = F (i)[k];
+ }
}
INDEX[i] = 0;
for (i = 0; i < ngotos; i++)
- {
- if (INDEX[i] == 0 && R[i])
- traverse (i);
- }
+ if (INDEX[i] == 0 && R[i])
+ traverse (i);
XFREE (INDEX);
XFREE (VERTICES);
}
-static void
-set_state_table (void)
-{
- core *sp;
-
- state_table = XCALLOC (core *, nstates);
-
- for (sp = first_state; sp; sp = sp->next)
- state_table[sp->number] = sp;
-}
-
-
-static void
-set_accessing_symbol (void)
-{
- core *sp;
-
- accessing_symbol = XCALLOC (short, nstates);
-
- for (sp = first_state; sp; sp = sp->next)
- accessing_symbol[sp->number] = sp->accessing_symbol;
-}
-
-
-static void
-set_shift_table (void)
-{
- shifts *sp;
-
- shift_table = XCALLOC (shifts *, nstates);
-
- for (sp = first_shift; sp; sp = sp->next)
- shift_table[sp->number] = sp;
-}
-
-
-static void
-set_reduction_table (void)
-{
- reductions *rp;
-
- reduction_table = XCALLOC (reductions *, nstates);
-
- for (rp = first_reduction; rp; rp = rp->next)
- reduction_table[rp->number] = rp;
-}
-
-
-static void
-set_maxrhs (void)
-{
- short *itemp;
- int length;
- int max;
-
- length = 0;
- max = 0;
- for (itemp = ritem; *itemp; itemp++)
- {
- if (*itemp > 0)
- {
- length++;
- }
- else
- {
- if (length > max)
- max = length;
- length = 0;
- }
- }
-
- maxrhs = max;
-}
-
static void
initialize_LA (void)
{
int i;
int j;
- int count;
- reductions *rp;
- shifts *sp;
short *np;
- consistent = XCALLOC (char, nstates);
- lookaheads = XCALLOC (short, nstates + 1);
-
- count = 0;
- for (i = 0; i < nstates; i++)
- {
- int k;
+ /* Avoid having to special case 0. */
+ if (!nLA)
+ nLA = 1;
- lookaheads[i] = count;
-
- rp = reduction_table[i];
- sp = shift_table[i];
- if (rp && (rp->nreds > 1
- || (sp && !ISVAR (accessing_symbol[sp->shifts[0]]))))
- count += rp->nreds;
- else
- consistent[i] = 1;
-
- if (sp)
- for (k = 0; k < sp->nshifts; k++)
- {
- if (accessing_symbol[sp->shifts[k]] == error_token_number)
- {
- consistent[i] = 0;
- break;
- }
- }
- }
-
- lookaheads[nstates] = count;
-
- if (count == 0)
- {
- LA = XCALLOC (unsigned, 1 * tokensetsize);
- LAruleno = XCALLOC (short, 1);
- lookback = XCALLOC (shorts *, 1);
- }
- else
- {
- LA = XCALLOC (unsigned, count * tokensetsize);
- LAruleno = XCALLOC (short, count);
- lookback = XCALLOC (shorts *, count);
- }
+ LA = XCALLOC (unsigned, nLA * tokensetsize);
+ LAruleno = XCALLOC (short, nLA);
+ lookback = XCALLOC (shorts *, nLA);
np = LAruleno;
for (i = 0; i < nstates; i++)
- {
- if (!consistent[i])
- {
- if ((rp = reduction_table[i]))
- for (j = 0; j < rp->nreds; j++)
- *np++ = rp->rules[j];
- }
- }
+ if (!states[i]->consistent)
+ for (j = 0; j < states[i]->reductions->nreds; j++)
+ *np++ = states[i]->reductions->rules[j];
}
static void
set_goto_map (void)
{
- shifts *sp;
- int i;
- int symbol;
- int k;
+ int state, i;
short *temp_map;
- int state2;
- int state1;
goto_map = XCALLOC (short, nvars + 1) - ntokens;
temp_map = XCALLOC (short, nvars + 1) - ntokens;
ngotos = 0;
- for (sp = first_shift; sp; sp = sp->next)
+ for (state = 0; state < nstates; ++state)
{
- for (i = sp->nshifts - 1; i >= 0; i--)
+ shifts *sp = states[state]->shifts;
+ for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
{
- symbol = accessing_symbol[sp->shifts[i]];
-
- if (ISTOKEN (symbol))
- break;
-
if (ngotos == MAXSHORT)
fatal (_("too many gotos (max %d)"), MAXSHORT);
ngotos++;
- goto_map[symbol]++;
+ goto_map[SHIFT_SYMBOL (sp, i)]++;
}
}
- k = 0;
- for (i = ntokens; i < nsyms; i++)
- {
- temp_map[i] = k;
- k += goto_map[i];
- }
+ {
+ int k = 0;
+ for (i = ntokens; i < nsyms; i++)
+ {
+ temp_map[i] = k;
+ k += goto_map[i];
+ }
- for (i = ntokens; i < nsyms; i++)
- goto_map[i] = temp_map[i];
+ for (i = ntokens; i < nsyms; i++)
+ goto_map[i] = temp_map[i];
- goto_map[nsyms] = ngotos;
- temp_map[nsyms] = ngotos;
+ goto_map[nsyms] = ngotos;
+ temp_map[nsyms] = ngotos;
+ }
from_state = XCALLOC (short, ngotos);
to_state = XCALLOC (short, ngotos);
- for (sp = first_shift; sp; sp = sp->next)
+ for (state = 0; state < nstates; ++state)
{
- state1 = sp->number;
- for (i = sp->nshifts - 1; i >= 0; i--)
+ shifts *sp = states[state]->shifts;
+ for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
{
- state2 = sp->shifts[i];
- symbol = accessing_symbol[state2];
-
- if (ISTOKEN (symbol))
- break;
-
- k = temp_map[symbol]++;
- from_state[k] = state1;
- to_state[k] = state2;
+ int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
+ from_state[k] = state;
+ to_state[k] = sp->shifts[i];
}
}
-/* Map_goto maps a state/symbol pair into its numeric representation. */
+/*----------------------------------------------------------.
+| Map a state/symbol pair into its numeric representation. |
+`----------------------------------------------------------*/
static int
map_goto (int state, int symbol)
high = middle - 1;
}
- berror ("map_goto");
-/* NOTREACHED */
+ assert (0);
+ /* NOTREACHED */
return 0;
}
static void
initialize_F (void)
{
- int i;
- int j;
- int k;
- shifts *sp;
- short *edge;
- unsigned *rowp;
- short *rp;
- short **reads;
- int nedges;
- int stateno;
- int symbol;
- int nwords;
-
- nwords = ngotos * tokensetsize;
- F = XCALLOC (unsigned, nwords);
-
- reads = XCALLOC (short *, ngotos);
- edge = XCALLOC (short, ngotos + 1);
- nedges = 0;
-
- rowp = F;
- for (i = 0; i < ngotos; i++)
- {
- stateno = to_state[i];
- sp = shift_table[stateno];
-
- if (sp)
- {
- k = sp->nshifts;
+ short **reads = XCALLOC (short *, ngotos);
+ short *edge = XCALLOC (short, ngotos + 1);
+ int nedges = 0;
- for (j = 0; j < k; j++)
- {
- symbol = accessing_symbol[sp->shifts[j]];
- if (ISVAR (symbol))
- break;
- SETBIT (rowp, symbol);
- }
+ int i;
- for (; j < k; j++)
- {
- symbol = accessing_symbol[sp->shifts[j]];
- if (nullable[symbol])
- edge[nedges++] = map_goto (stateno, symbol);
- }
+ F = XCALLOC (unsigned, ngotos * tokensetsize);
- if (nedges)
- {
- reads[i] = rp = XCALLOC (short, nedges + 1);
+ for (i = 0; i < ngotos; i++)
+ {
+ int stateno = to_state[i];
+ shifts *sp = states[stateno]->shifts;
- for (j = 0; j < nedges; j++)
- rp[j] = edge[j];
+ int j;
+ for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
+ SETBIT (F (i), SHIFT_SYMBOL (sp, j));
- rp[nedges] = -1;
- nedges = 0;
- }
+ for (; j < sp->nshifts; j++)
+ {
+ int symbol = SHIFT_SYMBOL (sp, j);
+ if (nullable[symbol])
+ edge[nedges++] = map_goto (stateno, symbol);
}
- rowp += tokensetsize;
+ if (nedges)
+ {
+ reads[i] = XCALLOC (short, nedges + 1);
+ shortcpy (reads[i], edge, nedges);
+ reads[i][nedges] = -1;
+ nedges = 0;
+ }
}
digraph (reads);
for (i = 0; i < ngotos; i++)
- {
- if (reads[i])
- XFREE (reads[i]);
- }
+ XFREE (reads[i]);
XFREE (reads);
XFREE (edge);
static void
-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state_t *state, int ruleno, int gotono)
{
int i;
- int k;
- int found;
shorts *sp;
- i = lookaheads[stateno];
- k = lookaheads[stateno + 1];
- found = 0;
- while (!found && i < k)
- {
- if (LAruleno[i] == ruleno)
- found = 1;
- else
- i++;
- }
+ for (i = 0; i < state->nlookaheads; ++i)
+ if (LAruleno[state->lookaheadsp + i] == ruleno)
+ break;
- assert (found);
+ assert (LAruleno[state->lookaheadsp + i] == ruleno);
sp = XCALLOC (shorts, 1);
- sp->next = lookback[i];
+ sp->next = lookback[state->lookaheadsp + i];
sp->value = gotono;
- lookback[i] = sp;
+ lookback[state->lookaheadsp + i] = sp;
}
-static short **
-transpose (short **R_arg, int n)
+static void
+matrix_print (FILE *out, short **matrix, int n)
{
- short **new_R;
- short **temp_R;
- short *nedges;
- short *sp;
- int i;
- int k;
+ int i, j;
+
+ for (i = 0; i < n; ++i)
+ {
+ fprintf (out, "%3d: ", i);
+ if (matrix[i])
+ for (j = 0; matrix[i][j] != -1; ++j)
+ fprintf (out, "%3d ", matrix[i][j]);
+ fputc ('\n', out);
+ }
+ fputc ('\n', out);
+}
- nedges = XCALLOC (short, n);
+/*-------------------------------------------------------------------.
+| Return the transpose of R_ARG, of size N. Destroy R_ARG, as it is |
+| replaced with the result. |
+| |
+| R_ARG[I] is NULL or a -1 terminated list of numbers. |
+| |
+| RESULT[NUM] is NULL or the -1 terminated list of the I such as NUM |
+| is in R_ARG[I]. |
+`-------------------------------------------------------------------*/
- for (i = 0; i < n; i++)
+static short **
+transpose (short **R_arg, int n)
+{
+ /* The result. */
+ short **new_R = XCALLOC (short *, n);
+ /* END_R[I] -- next entry of NEW_R[I]. */
+ short **end_R = XCALLOC (short *, n);
+ /* NEDGES[I] -- total size of NEW_R[I]. */
+ short *nedges = XCALLOC (short, n);
+ int i, j;
+
+ if (trace_flag)
{
- sp = R_arg[i];
- if (sp)
- {
- while (*sp >= 0)
- nedges[*sp++]++;
- }
+ fputs ("transpose: input\n", stderr);
+ matrix_print (stderr, R_arg, n);
}
- new_R = XCALLOC (short *, n);
- temp_R = XCALLOC (short *, n);
+ /* Count. */
+ for (i = 0; i < n; i++)
+ if (R_arg[i])
+ for (j = 0; R_arg[i][j] >= 0; ++j)
+ ++nedges[R_arg[i][j]];
+ /* Allocate. */
for (i = 0; i < n; i++)
- {
- k = nedges[i];
- if (k > 0)
+ if (nedges[i] > 0)
+ {
+ short *sp = XCALLOC (short, nedges[i] + 1);
+ sp[nedges[i]] = -1;
+ new_R[i] = sp;
+ end_R[i] = sp;
+ }
+
+ /* Store. */
+ for (i = 0; i < n; i++)
+ if (R_arg[i])
+ for (j = 0; R_arg[i][j] >= 0; ++j)
{
- sp = XCALLOC (short, k + 1);
- new_R[i] = sp;
- temp_R[i] = sp;
- sp[k] = -1;
+ *end_R[R_arg[i][j]] = i;
+ ++end_R[R_arg[i][j]];
}
- }
- XFREE (nedges);
+ free (nedges);
+ free (end_R);
+ /* Free the input: it is replaced with the result. */
for (i = 0; i < n; i++)
+ XFREE (R_arg[i]);
+ free (R_arg);
+
+ if (trace_flag)
{
- sp = R_arg[i];
- if (sp)
- {
- while (*sp >= 0)
- *temp_R[*sp++]++ = i;
- }
+ fputs ("transpose: output\n", stderr);
+ matrix_print (stderr, new_R, n);
}
- XFREE (temp_R);
-
return new_R;
}
static void
build_relations (void)
{
+ short *edge = XCALLOC (short, ngotos + 1);
+ short *states1 = XCALLOC (short, ritem_longest_rhs () + 1);
int i;
- int j;
- int k;
- short *rulep;
- short *rp;
- shifts *sp;
- int length;
- int nedges;
- int done;
- int state1;
- int stateno;
- int symbol1;
- int symbol2;
- short *shortp;
- short *edge;
- short *states;
- short **new_includes;
includes = XCALLOC (short *, ngotos);
- edge = XCALLOC (short, ngotos + 1);
- states = XCALLOC (short, maxrhs + 1);
for (i = 0; i < ngotos; i++)
{
- nedges = 0;
- state1 = from_state[i];
- symbol1 = accessing_symbol[to_state[i]];
+ int nedges = 0;
+ int symbol1 = states[to_state[i]]->accessing_symbol;
+ short *rulep;
for (rulep = derives[symbol1]; *rulep > 0; rulep++)
{
- length = 1;
- states[0] = state1;
- stateno = state1;
+ int done;
+ int length = 1;
+ short *rp;
+ state_t *state = states[from_state[i]];
+ states1[0] = state->number;
- for (rp = ritem + rrhs[*rulep]; *rp > 0; rp++)
+ for (rp = &ritem[rules[*rulep].rhs]; *rp >= 0; rp++)
{
- symbol2 = *rp;
- sp = shift_table[stateno];
- k = sp->nshifts;
-
- for (j = 0; j < k; j++)
+ shifts *sp = state->shifts;
+ int j;
+ for (j = 0; j < sp->nshifts; j++)
{
- stateno = sp->shifts[j];
- if (accessing_symbol[stateno] == symbol2)
+ state = states[sp->shifts[j]];
+ if (state->accessing_symbol == *rp)
break;
}
- states[length++] = stateno;
+ states1[length++] = state->number;
}
- if (!consistent[stateno])
- add_lookback_edge (stateno, *rulep, i);
+ if (!state->consistent)
+ add_lookback_edge (state, *rulep, i);
length--;
done = 0;
/* JF added rp>=ritem && I hope to god its right! */
if (rp >= ritem && ISVAR (*rp))
{
- stateno = states[--length];
- edge[nedges++] = map_goto (stateno, *rp);
+ edge[nedges++] = map_goto (states1[--length], *rp);
if (nullable[*rp])
done = 0;
}
if (nedges)
{
- includes[i] = shortp = XCALLOC (short, nedges + 1);
+ int j;
+ includes[i] = XCALLOC (short, nedges + 1);
for (j = 0; j < nedges; j++)
- shortp[j] = edge[j];
- shortp[nedges] = -1;
+ includes[i][j] = edge[j];
+ includes[i][nedges] = -1;
}
}
- new_includes = transpose (includes, ngotos);
-
- for (i = 0; i < ngotos; i++)
- if (includes[i])
- XFREE (includes[i]);
-
- XFREE (includes);
-
- includes = new_includes;
-
XFREE (edge);
- XFREE (states);
+ XFREE (states1);
+
+ includes = transpose (includes, ngotos);
}
digraph (includes);
for (i = 0; i < ngotos; i++)
- {
- if (includes[i])
- XFREE (includes[i]);
- }
+ XFREE (includes[i]);
XFREE (includes);
}
static void
compute_lookaheads (void)
{
- int i;
- int n;
- unsigned *fp1;
- unsigned *fp2;
- unsigned *fp3;
+ size_t i;
shorts *sp;
- unsigned *rowp;
- shorts *sptmp; /* JF */
- rowp = LA;
- n = lookaheads[nstates];
- for (i = 0; i < n; i++)
+ for (i = 0; i < nLA; i++)
+ for (sp = lookback[i]; sp; sp = sp->next)
+ {
+ int size = LA (i + 1) - LA (i);
+ int j;
+ for (j = 0; j < size; ++j)
+ LA (i)[j] |= F (sp->value)[j];
+ }
+
+ /* Free LOOKBACK. */
+ for (i = 0; i < nLA; i++)
+ LIST_FREE (shorts, lookback[i]);
+
+ XFREE (lookback);
+ XFREE (F);
+}
+
+
+/*--------------------------------------.
+| Initializing the lookaheads members. |
+`--------------------------------------*/
+
+static void
+initialize_lookaheads (void)
+{
+ int i;
+ nLA = 0;
+ for (i = 0; i < nstates; i++)
{
- fp3 = rowp + tokensetsize;
- for (sp = lookback[i]; sp; sp = sp->next)
- {
- fp1 = rowp;
- fp2 = F + tokensetsize * sp->value;
- while (fp1 < fp3)
- *fp1++ |= *fp2++;
- }
+ int k;
+ int nlookaheads = 0;
+ reductions *rp = states[i]->reductions;
+ shifts *sp = states[i]->shifts;
+
+ /* We need a lookahead either to distinguish different
+ reductions (i.e., there are two or more), or to distinguish a
+ reduction from a shift. Otherwise, it is straightforward,
+ and the state is `consistent'. */
+ if (rp->nreds > 1
+ || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))
+ nlookaheads += rp->nreds;
+ else
+ states[i]->consistent = 1;
- rowp = fp3;
+ for (k = 0; k < sp->nshifts; k++)
+ if (SHIFT_IS_ERROR (sp, k))
+ {
+ states[i]->consistent = 0;
+ break;
+ }
+
+ states[i]->nlookaheads = nlookaheads;
+ states[i]->lookaheadsp = nLA;
+ nLA += nlookaheads;
}
+}
- for (i = 0; i < n; i++)
+
+/*---------------------------------------.
+| Output the lookaheads for each state. |
+`---------------------------------------*/
+
+static void
+lookaheads_print (FILE *out)
+{
+ int i, j, k;
+ fprintf (out, "Lookaheads: BEGIN\n");
+ for (i = 0; i < nstates; ++i)
{
- /* JF removed ref to freed storage */
- for (sp = lookback[i]; sp; sp = sptmp)
- {
- sptmp = sp->next;
- XFREE (sp);
- }
+ fprintf (out, "State %d: %d lookaheads\n",
+ i, states[i]->nlookaheads);
+
+ for (j = 0; j < states[i]->nlookaheads; ++j)
+ for (k = 0; k < ntokens; ++k)
+ if (BITISSET (LA (states[i]->lookaheadsp + j), j))
+ fprintf (out, " on %d (%s) -> rule %d\n",
+ k, symbols[k]->tag,
+ -LAruleno[states[i]->lookaheadsp + j] - 1);
}
-
- XFREE (lookback);
- XFREE (F);
+ fprintf (out, "Lookaheads: END\n");
}
-
void
lalr (void)
{
tokensetsize = WORDSIZE (ntokens);
- set_state_table ();
- set_accessing_symbol ();
- set_shift_table ();
- set_reduction_table ();
- set_maxrhs ();
+ initialize_lookaheads ();
initialize_LA ();
set_goto_map ();
initialize_F ();
build_relations ();
compute_FOLLOWS ();
compute_lookaheads ();
+
+ if (trace_flag)
+ lookaheads_print (stderr);
}
projects / bison.git / blobdiff