gcc/omega.h

   1 /* Source code for an implementation of the Omega test, an integer
   2    programming algorithm for dependence analysis, by William Pugh,
   3    appeared in Supercomputing '91 and CACM Aug 92.
   4
   5    This code has no license restrictions, and is considered public
   6    domain.
   7
   8    Changes copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
   9    Contributed by Sebastian Pop <sebastian.pop@inria.fr>
  10
  11 This file is part of GCC.
  12
  13 GCC is free software; you can redistribute it and/or modify it under
  14 the terms of the GNU General Public License as published by the Free
  15 Software Foundation; either version 3, or (at your option) any later
  16 version.
  17
  18 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  19 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  20 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  21 for more details.
  22
  23 You should have received a copy of the GNU General Public License
  24 along with GCC; see the file COPYING3.  If not see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #include "config.h"
  28 #include "params.h"
  29
  30 #ifndef GCC_OMEGA_H
  31 #define GCC_OMEGA_H
  32
  33 #define OMEGA_MAX_VARS PARAM_VALUE (PARAM_OMEGA_MAX_VARS)
  34 #define OMEGA_MAX_GEQS PARAM_VALUE (PARAM_OMEGA_MAX_GEQS)
  35 #define OMEGA_MAX_EQS PARAM_VALUE (PARAM_OMEGA_MAX_EQS)
  36
  37 #define pos_infinity (0x7ffffff)
  38 #define neg_infinity (-0x7ffffff)
  39
  40 /* Results of the Omega solver.  */
  41 enum omega_result {
  42   omega_false = 0,
  43   omega_true = 1,
  44
  45   /* Value returned when the solver is unable to determine an
  46      answer.  */
  47   omega_unknown = 2,
  48
  49   /* Value used for asking the solver to simplify the system.  */
  50   omega_simplify = 3
  51 };
  52
  53 /* Values used for labeling equations.  Private (not used outside the
  54    solver).  */
  55 enum omega_eqn_color {
  56   omega_black = 0,
  57   omega_red = 1
  58 };
  59
  60 /* Structure for equations.  */
  61 typedef struct eqn
  62 {
  63   int key;
  64   int touched;
  65   enum omega_eqn_color color;
  66
  67   /* Array of coefficients for the equation.  The layout of the data
  68      is as follows: coef[0] is the constant, coef[i] for 1 <= i <=
  69      OMEGA_MAX_VARS, are the coefficients for each dimension.  Examples:
  70      the equation 0 = 9 + x + 0y + 5z is encoded as [9 1 0 5], the
  71      inequality 0 <= -8 + x + 2y + 3z is encoded as [-8 1 2 3].  */
  72   int *coef;
  73 } *eqn;
  74
  75 typedef struct omega_pb
  76 {
  77   /* The number of variables in the system of equations.  */
  78   int num_vars;
  79
  80   /* Safe variables are not eliminated during the Fourier-Motzkin
  81      simplification of the system.  Safe variables are all those
  82      variables that are placed at the beginning of the array of
  83      variables: PB->var[1, ..., SAFE_VARS].  PB->var[0] is not used,
  84      as PB->eqs[x]->coef[0] represents the constant of the equation.  */
  85   int safe_vars;
  86
  87   /* Number of elements in eqs[].  */
  88   int num_eqs;
  89   /* Number of elements in geqs[].  */
  90   int num_geqs;
  91   /* Number of elements in subs[].  */
  92   int num_subs;
  93
  94   int hash_version;
  95   bool variables_initialized;
  96   bool variables_freed;
  97
  98   /* Index or name of variables.  Negative integers are reserved for
  99      wildcard variables.  Maps the index of variables in the original
 100      problem to the new index of the variable.  The index for a
 101      variable in the coef array of an equation can change as some
 102      variables are eliminated.  */
 103   int *var;
 104
 105   int *forwarding_address;
 106
 107   /* Inequalities in the system of constraints.  */
 108   eqn geqs;
 109
 110   /* Equations in the system of constraints.  */
 111   eqn eqs;
 112
 113   /* A map of substituted variables.  */
 114   eqn subs;
 115 } *omega_pb;
 116
 117 extern void omega_initialize (void);
 118 extern omega_pb omega_alloc_problem (int, int);
 119 extern enum omega_result omega_solve_problem (omega_pb, enum omega_result);
 120 extern enum omega_result omega_simplify_problem (omega_pb);
 121 extern enum omega_result omega_simplify_approximate (omega_pb);
 122 extern enum omega_result omega_constrain_variable_sign (omega_pb,
 123                                                         enum omega_eqn_color,
 124                                                         int, int);
 125 extern void debug_omega_problem (omega_pb);
 126 extern void omega_print_problem (FILE *, omega_pb);
 127 extern void omega_print_red_equations (FILE *, omega_pb);
 128 extern int omega_count_red_equations (omega_pb);
 129 extern void omega_pretty_print_problem (FILE *, omega_pb);
 130 extern void omega_unprotect_variable (omega_pb, int var);
 131 extern void omega_negate_geq (omega_pb, int);
 132 extern void omega_convert_eq_to_geqs (omega_pb, int eq);
 133 extern void omega_print_eqn (FILE *, omega_pb, eqn, bool, int);
 134 extern bool omega_problem_has_red_equations (omega_pb);
 135 extern enum omega_result omega_eliminate_redundant (omega_pb, bool);
 136 extern void omega_eliminate_red (omega_pb, bool);
 137 extern void omega_constrain_variable_value (omega_pb, enum omega_eqn_color,
 138                                             int, int);
 139 extern bool omega_query_variable (omega_pb, int, int *, int *);
 140 extern int omega_query_variable_signs (omega_pb, int, int, int, int,
 141                                        int, int, bool *, int *);
 142 extern bool omega_query_variable_bounds (omega_pb, int, int *, int *);
 143 extern void (*omega_when_reduced) (omega_pb);
 144 extern void omega_no_procedure (omega_pb);
 145
 146 /* Return true when variable I in problem PB is a wildcard.  */
 147
 148 static inline bool
 149 omega_wildcard_p (omega_pb pb, int i)
 150 {
 151   return (pb->var[i] < 0);
 152 }
 153
 154 /* Return true when variable I in problem PB is a safe variable.  */
 155
 156 static inline bool
 157 omega_safe_var_p (omega_pb pb, int i)
 158 {
 159   /* The constant of an equation is not a variable.  */
 160   gcc_assert (0 < i);
 161   return (i <= pb->safe_vars);
 162 }
 163
 164 /* Print to FILE equality E from PB.  */
 165
 166 static inline void
 167 omega_print_eq (FILE *file, omega_pb pb, eqn e)
 168 {
 169   omega_print_eqn (file, pb, e, false, 0);
 170 }
 171
 172 /* Print to FILE inequality E from PB.  */
 173
 174 static inline void
 175 omega_print_geq (FILE *file, omega_pb pb, eqn e)
 176 {
 177   omega_print_eqn (file, pb, e, true, 0);
 178 }
 179
 180 /* Print to FILE inequality E from PB.  */
 181
 182 static inline void
 183 omega_print_geq_extra (FILE *file, omega_pb pb, eqn e)
 184 {
 185   omega_print_eqn (file, pb, e, true, 1);
 186 }
 187
 188 /* E1 = E2, make a copy of E2 into E1.  Equations contain S variables.  */
 189
 190 static inline void
 191 omega_copy_eqn (eqn e1, eqn e2, int s)
 192 {
 193   e1->key = e2->key;
 194   e1->touched = e2->touched;
 195   e1->color = e2->color;
 196
 197   memcpy (e1->coef, e2->coef, (s + 1) * sizeof (int));
 198 }
 199
 200 /* Initialize E = 0.  Equation E contains S variables.  */
 201
 202 static inline void
 203 omega_init_eqn_zero (eqn e, int s)
 204 {
 205   e->key = 0;
 206   e->touched = 0;
 207   e->color = omega_black;
 208
 209   memset (e->coef, 0, (s + 1) * sizeof (int));
 210 }
 211
 212 /* Allocate N equations with S variables.  */
 213
 214 static inline eqn
 215 omega_alloc_eqns (int s, int n)
 216 {
 217   int i;
 218   eqn res = (eqn) (xcalloc (n, sizeof (struct eqn)));
 219
 220   for (i = n - 1; i >= 0; i--)
 221     {
 222       res[i].coef = (int *) (xcalloc (OMEGA_MAX_VARS + 1, sizeof (int)));
 223       omega_init_eqn_zero (&res[i], s);
 224     }
 225
 226   return res;
 227 }
 228
 229 /* Free N equations from array EQ.  */
 230
 231 static inline void
 232 omega_free_eqns (eqn eq, int n)
 233 {
 234   int i;
 235
 236   for (i = n - 1; i >= 0; i--)
 237     free (eq[i].coef);
 238
 239   free (eq);
 240 }
 241
 242 /* Returns true when E is an inequality with a single variable.  */
 243
 244 static inline bool
 245 single_var_geq (eqn e, int nv ATTRIBUTE_UNUSED)
 246 {
 247   return (e->key != 0
 248           && -OMEGA_MAX_VARS <= e->key && e->key <= OMEGA_MAX_VARS);
 249 }
 250
 251 /* Allocate a new equality with all coefficients 0, and tagged with
 252    COLOR.  Return the index of this equality in problem PB.  */
 253
 254 static inline int
 255 omega_add_zero_eq (omega_pb pb, enum omega_eqn_color color)
 256 {
 257   int idx = pb->num_eqs++;
 258
 259   gcc_assert (pb->num_eqs <= OMEGA_MAX_EQS);
 260   omega_init_eqn_zero (&pb->eqs[idx], pb->num_vars);
 261   pb->eqs[idx].color = color;
 262   return idx;
 263 }
 264
 265 /* Allocate a new inequality with all coefficients 0, and tagged with
 266    COLOR.  Return the index of this inequality in problem PB.  */
 267
 268 static inline int
 269 omega_add_zero_geq (omega_pb pb, enum omega_eqn_color color)
 270 {
 271   int idx = pb->num_geqs;
 272
 273   pb->num_geqs++;
 274   gcc_assert (pb->num_geqs <= OMEGA_MAX_GEQS);
 275   omega_init_eqn_zero (&pb->geqs[idx], pb->num_vars);
 276   pb->geqs[idx].touched = 1;
 277   pb->geqs[idx].color = color;
 278   return idx;
 279 }
 280
 281 /* Initialize variables for problem PB.  */
 282
 283 static inline void
 284 omega_initialize_variables (omega_pb pb)
 285 {
 286   int i;
 287
 288   for (i = pb->num_vars; i >= 0; i--)
 289     pb->forwarding_address[i] = pb->var[i] = i;
 290
 291   pb->variables_initialized = true;
 292 }
 293
 294 /* Free problem PB.  */
 295
 296 static inline void
 297 omega_free_problem (omega_pb pb)
 298 {
 299   free (pb->var);
 300   free (pb->forwarding_address);
 301   omega_free_eqns (pb->geqs, OMEGA_MAX_GEQS);
 302   omega_free_eqns (pb->eqs, OMEGA_MAX_EQS);
 303   omega_free_eqns (pb->subs, OMEGA_MAX_VARS + 1);
 304   free (pb);
 305 }
 306
 307 /* Copy omega problems: P1 = P2.  */
 308
 309 static inline void
 310 omega_copy_problem (omega_pb p1, omega_pb p2)
 311 {
 312   int e, i;
 313
 314   p1->num_vars = p2->num_vars;
 315   p1->hash_version = p2->hash_version;
 316   p1->variables_initialized = p2->variables_initialized;
 317   p1->variables_freed = p2->variables_freed;
 318   p1->safe_vars = p2->safe_vars;
 319   p1->num_eqs = p2->num_eqs;
 320   p1->num_subs = p2->num_subs;
 321   p1->num_geqs = p2->num_geqs;
 322
 323   for (e = p2->num_eqs - 1; e >= 0; e--)
 324     omega_copy_eqn (&(p1->eqs[e]), &(p2->eqs[e]), p2->num_vars);
 325
 326   for (e = p2->num_geqs - 1; e >= 0; e--)
 327     omega_copy_eqn (&(p1->geqs[e]), &(p2->geqs[e]), p2->num_vars);
 328
 329   for (e = p2->num_subs - 1; e >= 0; e--)
 330     omega_copy_eqn (&(p1->subs[e]), &(p2->subs[e]), p2->num_vars);
 331
 332   for (i = p2->num_vars; i >= 0; i--)
 333     p1->var[i] = p2->var[i];
 334
 335   for (i = OMEGA_MAX_VARS; i >= 0; i--)
 336     p1->forwarding_address[i] = p2->forwarding_address[i];
 337 }
 338
 339 #endif /* GCC_OMEGA_H */