libgomp/oacc-init.c

   1 /* OpenACC Runtime initialization routines
   2
   3    Copyright (C) 2013-2019 Free Software Foundation, Inc.
   4
   5    Contributed by Mentor Embedded.
   6
   7    This file is part of the GNU Offloading and Multi Processing Library
   8    (libgomp).
   9
  10    Libgomp is free software; you can redistribute it and/or modify it
  11    under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3, or (at your option)
  13    any later version.
  14
  15    Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
  16    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  17    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  18    more details.
  19
  20    Under Section 7 of GPL version 3, you are granted additional
  21    permissions described in the GCC Runtime Library Exception, version
  22    3.1, as published by the Free Software Foundation.
  23
  24    You should have received a copy of the GNU General Public License and
  25    a copy of the GCC Runtime Library Exception along with this program;
  26    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  27    <http://www.gnu.org/licenses/>.  */
  28
  29 #include "libgomp.h"
  30 #include "oacc-int.h"
  31 #include "openacc.h"
  32 #include <assert.h>
  33 #include <stdlib.h>
  34 #include <strings.h>
  35 #include <stdbool.h>
  36 #include <string.h>
  37
  38 /* This lock is used to protect access to cached_base_dev, dispatchers and
  39    the (abstract) initialisation state of attached offloading devices.  */
  40
  41 static gomp_mutex_t acc_device_lock;
  42
  43 /* A cached version of the dispatcher for the global "current" accelerator type,
  44    e.g. used as the default when creating new host threads.  This is the
  45    device-type equivalent of goacc_device_num (which specifies which device to
  46    use out of potentially several of the same type).  If there are several
  47    devices of a given type, this points at the first one.  */
  48
  49 static struct gomp_device_descr *cached_base_dev = NULL;
  50
  51 #if defined HAVE_TLS || defined USE_EMUTLS
  52 __thread struct goacc_thread *goacc_tls_data;
  53 #else
  54 pthread_key_t goacc_tls_key;
  55 #endif
  56 static pthread_key_t goacc_cleanup_key;
  57
  58 static struct goacc_thread *goacc_threads;
  59 static gomp_mutex_t goacc_thread_lock;
  60
  61 /* An array of dispatchers for device types, indexed by the type.  This array
  62    only references "base" devices, and other instances of the same type are
  63    found by simply indexing from each such device (which are stored linearly,
  64    grouped by device in target.c:devices).  */
  65 static struct gomp_device_descr *dispatchers[_ACC_device_hwm] = { 0 };
  66
  67 attribute_hidden void
  68 goacc_register (struct gomp_device_descr *disp)
  69 {
  70   /* Only register the 0th device here.  */
  71   if (disp->target_id != 0)
  72     return;
  73
  74   gomp_mutex_lock (&acc_device_lock);
  75
  76   assert (acc_device_type (disp->type) != acc_device_none
  77           && acc_device_type (disp->type) != acc_device_default
  78           && acc_device_type (disp->type) != acc_device_not_host);
  79   assert (!dispatchers[disp->type]);
  80   dispatchers[disp->type] = disp;
  81
  82   gomp_mutex_unlock (&acc_device_lock);
  83 }
  84
  85 /* OpenACC names some things a little differently.  */
  86
  87 static const char *
  88 get_openacc_name (const char *name)
  89 {
  90   if (strcmp (name, "nvptx") == 0)
  91     return "nvidia";
  92   else
  93     return name;
  94 }
  95
  96 static const char *
  97 name_of_acc_device_t (enum acc_device_t type)
  98 {
  99   switch (type)
 100     {
 101     case acc_device_none: return "none";
 102     case acc_device_default: return "default";
 103     case acc_device_host: return "host";
 104     case acc_device_not_host: return "not_host";
 105     case acc_device_nvidia: return "nvidia";
 106     default: gomp_fatal ("unknown device type %u", (unsigned) type);
 107     }
 108 }
 109
 110 /* ACC_DEVICE_LOCK must be held before calling this function.  If FAIL_IS_ERROR
 111    is true, this function raises an error if there are no devices of type D,
 112    otherwise it returns NULL in that case.  */
 113
 114 static struct gomp_device_descr *
 115 resolve_device (acc_device_t d, bool fail_is_error)
 116 {
 117   acc_device_t d_arg = d;
 118
 119   switch (d)
 120     {
 121     case acc_device_default:
 122       {
 123         if (goacc_device_type)
 124           {
 125             /* Lookup the named device.  */
 126             while (++d != _ACC_device_hwm)
 127               if (dispatchers[d]
 128                   && !strcasecmp (goacc_device_type,
 129                                   get_openacc_name (dispatchers[d]->name))
 130                   && dispatchers[d]->get_num_devices_func () > 0)
 131                 goto found;
 132
 133             if (fail_is_error)
 134               {
 135                 gomp_mutex_unlock (&acc_device_lock);
 136                 gomp_fatal ("device type %s not supported", goacc_device_type);
 137               }
 138             else
 139               return NULL;
 140           }
 141
 142         /* No default device specified, so start scanning for any non-host
 143            device that is available.  */
 144         d = acc_device_not_host;
 145       }
 146       /* FALLTHROUGH */
 147
 148     case acc_device_not_host:
 149       /* Find the first available device after acc_device_not_host.  */
 150       while (++d != _ACC_device_hwm)
 151         if (dispatchers[d] && dispatchers[d]->get_num_devices_func () > 0)
 152           goto found;
 153       if (d_arg == acc_device_default)
 154         {
 155           d = acc_device_host;
 156           goto found;
 157         }
 158       if (fail_is_error)
 159         {
 160           gomp_mutex_unlock (&acc_device_lock);
 161           gomp_fatal ("no device found");
 162         }
 163       else
 164         return NULL;
 165       break;
 166
 167     case acc_device_host:
 168       break;
 169
 170     default:
 171       if (d > _ACC_device_hwm)
 172         {
 173           if (fail_is_error)
 174             goto unsupported_device;
 175           else
 176             return NULL;
 177         }
 178       break;
 179     }
 180  found:
 181
 182   assert (d != acc_device_none
 183           && d != acc_device_default
 184           && d != acc_device_not_host);
 185
 186   if (dispatchers[d] == NULL && fail_is_error)
 187     {
 188     unsupported_device:
 189       gomp_mutex_unlock (&acc_device_lock);
 190       gomp_fatal ("device type %s not supported", name_of_acc_device_t (d));
 191     }
 192
 193   return dispatchers[d];
 194 }
 195
 196 /* Emit a suitable error if no device of a particular type is available, or
 197    the given device number is out-of-range.  */
 198 static void
 199 acc_dev_num_out_of_range (acc_device_t d, int ord, int ndevs)
 200 {
 201   if (ndevs == 0)
 202     gomp_fatal ("no devices of type %s available", name_of_acc_device_t (d));
 203   else
 204     gomp_fatal ("device %u out of range", ord);
 205 }
 206
 207 /* This is called when plugins have been initialized, and serves to call
 208    (indirectly) the target's device_init hook.  Calling multiple times without
 209    an intervening acc_shutdown_1 call is an error.  ACC_DEVICE_LOCK must be
 210    held before calling this function.  */
 211
 212 static struct gomp_device_descr *
 213 acc_init_1 (acc_device_t d)
 214 {
 215   struct gomp_device_descr *base_dev, *acc_dev;
 216   int ndevs;
 217
 218   base_dev = resolve_device (d, true);
 219
 220   ndevs = base_dev->get_num_devices_func ();
 221
 222   if (ndevs <= 0 || goacc_device_num >= ndevs)
 223     acc_dev_num_out_of_range (d, goacc_device_num, ndevs);
 224
 225   acc_dev = &base_dev[goacc_device_num];
 226
 227   gomp_mutex_lock (&acc_dev->lock);
 228   if (acc_dev->state == GOMP_DEVICE_INITIALIZED)
 229     {
 230       gomp_mutex_unlock (&acc_dev->lock);
 231       gomp_fatal ("device already active");
 232     }
 233
 234   gomp_init_device (acc_dev);
 235   gomp_mutex_unlock (&acc_dev->lock);
 236
 237   return base_dev;
 238 }
 239
 240 /* ACC_DEVICE_LOCK must be held before calling this function.  */
 241
 242 static void
 243 acc_shutdown_1 (acc_device_t d)
 244 {
 245   struct gomp_device_descr *base_dev;
 246   struct goacc_thread *walk;
 247   int ndevs, i;
 248   bool devices_active = false;
 249
 250   /* Get the base device for this device type.  */
 251   base_dev = resolve_device (d, true);
 252
 253   ndevs = base_dev->get_num_devices_func ();
 254
 255   /* Unload all the devices of this type that have been opened.  */
 256   for (i = 0; i < ndevs; i++)
 257     {
 258       struct gomp_device_descr *acc_dev = &base_dev[i];
 259
 260       gomp_mutex_lock (&acc_dev->lock);
 261       gomp_unload_device (acc_dev);
 262       gomp_mutex_unlock (&acc_dev->lock);
 263     }
 264
 265   gomp_mutex_lock (&goacc_thread_lock);
 266
 267   /* Free target-specific TLS data and close all devices.  */
 268   for (walk = goacc_threads; walk != NULL; walk = walk->next)
 269     {
 270       if (walk->target_tls)
 271         base_dev->openacc.destroy_thread_data_func (walk->target_tls);
 272
 273       walk->target_tls = NULL;
 274
 275       /* This would mean the user is shutting down OpenACC in the middle of an
 276          "acc data" pragma.  Likely not intentional.  */
 277       if (walk->mapped_data)
 278         {
 279           gomp_mutex_unlock (&goacc_thread_lock);
 280           gomp_fatal ("shutdown in 'acc data' region");
 281         }
 282
 283       /* Similarly, if this happens then user code has done something weird.  */
 284       if (walk->saved_bound_dev)
 285         {
 286           gomp_mutex_unlock (&goacc_thread_lock);
 287           gomp_fatal ("shutdown during host fallback");
 288         }
 289
 290       if (walk->dev)
 291         {
 292           gomp_mutex_lock (&walk->dev->lock);
 293           gomp_free_memmap (&walk->dev->mem_map);
 294           gomp_mutex_unlock (&walk->dev->lock);
 295
 296           walk->dev = NULL;
 297           walk->base_dev = NULL;
 298         }
 299     }
 300
 301   gomp_mutex_unlock (&goacc_thread_lock);
 302
 303   /* Close all the devices of this type that have been opened.  */
 304   bool ret = true;
 305   for (i = 0; i < ndevs; i++)
 306     {
 307       struct gomp_device_descr *acc_dev = &base_dev[i];
 308       gomp_mutex_lock (&acc_dev->lock);
 309       if (acc_dev->state == GOMP_DEVICE_INITIALIZED)
 310         {
 311           devices_active = true;
 312           ret &= gomp_fini_device (acc_dev);
 313           acc_dev->state = GOMP_DEVICE_UNINITIALIZED;
 314         }
 315       gomp_mutex_unlock (&acc_dev->lock);
 316     }
 317
 318   if (!ret)
 319     gomp_fatal ("device finalization failed");
 320
 321   if (!devices_active)
 322     gomp_fatal ("no device initialized");
 323 }
 324
 325 static struct goacc_thread *
 326 goacc_new_thread (void)
 327 {
 328   struct goacc_thread *thr = gomp_malloc (sizeof (struct goacc_thread));
 329
 330 #if defined HAVE_TLS || defined USE_EMUTLS
 331   goacc_tls_data = thr;
 332 #else
 333   pthread_setspecific (goacc_tls_key, thr);
 334 #endif
 335
 336   pthread_setspecific (goacc_cleanup_key, thr);
 337
 338   gomp_mutex_lock (&goacc_thread_lock);
 339   thr->next = goacc_threads;
 340   goacc_threads = thr;
 341   gomp_mutex_unlock (&goacc_thread_lock);
 342
 343   return thr;
 344 }
 345
 346 static void
 347 goacc_destroy_thread (void *data)
 348 {
 349   struct goacc_thread *thr = data, *walk, *prev;
 350
 351   gomp_mutex_lock (&goacc_thread_lock);
 352
 353   if (thr)
 354     {
 355       struct gomp_device_descr *acc_dev = thr->dev;
 356
 357       if (acc_dev && thr->target_tls)
 358         {
 359           acc_dev->openacc.destroy_thread_data_func (thr->target_tls);
 360           thr->target_tls = NULL;
 361         }
 362
 363       assert (!thr->mapped_data);
 364
 365       /* Remove from thread list.  */
 366       for (prev = NULL, walk = goacc_threads; walk;
 367            prev = walk, walk = walk->next)
 368         if (walk == thr)
 369           {
 370             if (prev == NULL)
 371               goacc_threads = walk->next;
 372             else
 373               prev->next = walk->next;
 374
 375             free (thr);
 376
 377             break;
 378           }
 379
 380       assert (walk);
 381     }
 382
 383   gomp_mutex_unlock (&goacc_thread_lock);
 384 }
 385
 386 /* Use the ORD'th device instance for the current host thread (or -1 for the
 387    current global default).  The device (and the runtime) must be initialised
 388    before calling this function.  */
 389
 390 void
 391 goacc_attach_host_thread_to_device (int ord)
 392 {
 393   struct goacc_thread *thr = goacc_thread ();
 394   struct gomp_device_descr *acc_dev = NULL, *base_dev = NULL;
 395   int num_devices;
 396
 397   if (thr && thr->dev && (thr->dev->target_id == ord || ord < 0))
 398     return;
 399
 400   if (ord < 0)
 401     ord = goacc_device_num;
 402
 403   /* Decide which type of device to use.  If the current thread has a device
 404      type already (e.g. set by acc_set_device_type), use that, else use the
 405      global default.  */
 406   if (thr && thr->base_dev)
 407     base_dev = thr->base_dev;
 408   else
 409     {
 410       assert (cached_base_dev);
 411       base_dev = cached_base_dev;
 412     }
 413
 414   num_devices = base_dev->get_num_devices_func ();
 415   if (num_devices <= 0 || ord >= num_devices)
 416     acc_dev_num_out_of_range (acc_device_type (base_dev->type), ord,
 417                               num_devices);
 418
 419   if (!thr)
 420     thr = goacc_new_thread ();
 421
 422   thr->base_dev = base_dev;
 423   thr->dev = acc_dev = &base_dev[ord];
 424   thr->saved_bound_dev = NULL;
 425   thr->mapped_data = NULL;
 426
 427   thr->target_tls
 428     = acc_dev->openacc.create_thread_data_func (ord);
 429 }
 430
 431 /* OpenACC 2.0a (3.2.12, 3.2.13) doesn't specify whether the serialization of
 432    init/shutdown is per-process or per-thread.  We choose per-process.  */
 433
 434 void
 435 acc_init (acc_device_t d)
 436 {
 437   gomp_init_targets_once ();
 438
 439   gomp_mutex_lock (&acc_device_lock);
 440
 441   cached_base_dev = acc_init_1 (d);
 442
 443   gomp_mutex_unlock (&acc_device_lock);
 444
 445   goacc_attach_host_thread_to_device (-1);
 446 }
 447
 448 ialias (acc_init)
 449
 450 void
 451 acc_shutdown (acc_device_t d)
 452 {
 453   gomp_init_targets_once ();
 454
 455   gomp_mutex_lock (&acc_device_lock);
 456
 457   acc_shutdown_1 (d);
 458
 459   gomp_mutex_unlock (&acc_device_lock);
 460 }
 461
 462 ialias (acc_shutdown)
 463
 464 int
 465 acc_get_num_devices (acc_device_t d)
 466 {
 467   int n = 0;
 468   struct gomp_device_descr *acc_dev;
 469
 470   if (d == acc_device_none)
 471     return 0;
 472
 473   gomp_init_targets_once ();
 474
 475   gomp_mutex_lock (&acc_device_lock);
 476   acc_dev = resolve_device (d, false);
 477   gomp_mutex_unlock (&acc_device_lock);
 478
 479   if (!acc_dev)
 480     return 0;
 481
 482   n = acc_dev->get_num_devices_func ();
 483   if (n < 0)
 484     n = 0;
 485
 486   return n;
 487 }
 488
 489 ialias (acc_get_num_devices)
 490
 491 /* Set the device type for the current thread only (using the current global
 492    default device number), initialising that device if necessary.  Also set the
 493    default device type for new threads to D.  */
 494
 495 void
 496 acc_set_device_type (acc_device_t d)
 497 {
 498   struct gomp_device_descr *base_dev, *acc_dev;
 499   struct goacc_thread *thr = goacc_thread ();
 500
 501   gomp_init_targets_once ();
 502
 503   gomp_mutex_lock (&acc_device_lock);
 504
 505   cached_base_dev = base_dev = resolve_device (d, true);
 506   acc_dev = &base_dev[goacc_device_num];
 507
 508   gomp_mutex_lock (&acc_dev->lock);
 509   if (acc_dev->state == GOMP_DEVICE_UNINITIALIZED)
 510     gomp_init_device (acc_dev);
 511   gomp_mutex_unlock (&acc_dev->lock);
 512
 513   gomp_mutex_unlock (&acc_device_lock);
 514
 515   /* We're changing device type: invalidate the current thread's dev and
 516      base_dev pointers.  */
 517   if (thr && thr->base_dev != base_dev)
 518     {
 519       thr->base_dev = thr->dev = NULL;
 520       if (thr->mapped_data)
 521         gomp_fatal ("acc_set_device_type in 'acc data' region");
 522     }
 523
 524   goacc_attach_host_thread_to_device (-1);
 525 }
 526
 527 ialias (acc_set_device_type)
 528
 529 acc_device_t
 530 acc_get_device_type (void)
 531 {
 532   acc_device_t res = acc_device_none;
 533   struct gomp_device_descr *dev;
 534   struct goacc_thread *thr = goacc_thread ();
 535
 536   if (thr && thr->base_dev)
 537     res = acc_device_type (thr->base_dev->type);
 538   else
 539     {
 540       gomp_init_targets_once ();
 541
 542       gomp_mutex_lock (&acc_device_lock);
 543       dev = resolve_device (acc_device_default, true);
 544       gomp_mutex_unlock (&acc_device_lock);
 545       res = acc_device_type (dev->type);
 546     }
 547
 548   assert (res != acc_device_default
 549           && res != acc_device_not_host);
 550
 551   return res;
 552 }
 553
 554 ialias (acc_get_device_type)
 555
 556 int
 557 acc_get_device_num (acc_device_t d)
 558 {
 559   const struct gomp_device_descr *dev;
 560   struct goacc_thread *thr = goacc_thread ();
 561
 562   if (d >= _ACC_device_hwm)
 563     gomp_fatal ("unknown device type %u", (unsigned) d);
 564
 565   gomp_init_targets_once ();
 566
 567   gomp_mutex_lock (&acc_device_lock);
 568   dev = resolve_device (d, true);
 569   gomp_mutex_unlock (&acc_device_lock);
 570
 571   if (thr && thr->base_dev == dev && thr->dev)
 572     return thr->dev->target_id;
 573
 574   return goacc_device_num;
 575 }
 576
 577 ialias (acc_get_device_num)
 578
 579 void
 580 acc_set_device_num (int ord, acc_device_t d)
 581 {
 582   struct gomp_device_descr *base_dev, *acc_dev;
 583   int num_devices;
 584
 585   gomp_init_targets_once ();
 586
 587   if (ord < 0)
 588     ord = goacc_device_num;
 589
 590   if ((int) d == 0)
 591     /* Set whatever device is being used by the current host thread to use
 592        device instance ORD.  It's unclear if this is supposed to affect other
 593        host threads too (OpenACC 2.0 (3.2.4) acc_set_device_num).  */
 594     goacc_attach_host_thread_to_device (ord);
 595   else
 596     {
 597       gomp_mutex_lock (&acc_device_lock);
 598
 599       cached_base_dev = base_dev = resolve_device (d, true);
 600
 601       num_devices = base_dev->get_num_devices_func ();
 602
 603       if (num_devices <= 0 || ord >= num_devices)
 604         acc_dev_num_out_of_range (d, ord, num_devices);
 605
 606       acc_dev = &base_dev[ord];
 607
 608       gomp_mutex_lock (&acc_dev->lock);
 609       if (acc_dev->state == GOMP_DEVICE_UNINITIALIZED)
 610         gomp_init_device (acc_dev);
 611       gomp_mutex_unlock (&acc_dev->lock);
 612
 613       gomp_mutex_unlock (&acc_device_lock);
 614
 615       goacc_attach_host_thread_to_device (ord);
 616     }
 617
 618   goacc_device_num = ord;
 619 }
 620
 621 ialias (acc_set_device_num)
 622
 623 /* For -O and higher, the compiler always attempts to expand acc_on_device, but
 624    if the user disables the builtin, or calls it via a pointer, we'll need this
 625    version.
 626
 627    Compile this with optimization, so that the compiler expands
 628    this, rather than generating infinitely recursive code.  */
 629
 630 int __attribute__ ((__optimize__ ("O2")))
 631 acc_on_device (acc_device_t dev)
 632 {
 633   return __builtin_acc_on_device (dev);
 634 }
 635
 636 ialias (acc_on_device)
 637
 638 attribute_hidden void
 639 goacc_runtime_initialize (void)
 640 {
 641   gomp_mutex_init (&acc_device_lock);
 642
 643 #if !(defined HAVE_TLS || defined USE_EMUTLS)
 644   pthread_key_create (&goacc_tls_key, NULL);
 645 #endif
 646
 647   pthread_key_create (&goacc_cleanup_key, goacc_destroy_thread);
 648
 649   cached_base_dev = NULL;
 650
 651   goacc_threads = NULL;
 652   gomp_mutex_init (&goacc_thread_lock);
 653
 654   /* Initialize and register the 'host' device type.  */
 655   goacc_host_init ();
 656 }
 657
 658 /* Compiler helper functions */
 659
 660 attribute_hidden void
 661 goacc_save_and_set_bind (acc_device_t d)
 662 {
 663   struct goacc_thread *thr = goacc_thread ();
 664
 665   assert (!thr->saved_bound_dev);
 666
 667   thr->saved_bound_dev = thr->dev;
 668   thr->dev = dispatchers[d];
 669 }
 670
 671 attribute_hidden void
 672 goacc_restore_bind (void)
 673 {
 674   struct goacc_thread *thr = goacc_thread ();
 675
 676   thr->dev = thr->saved_bound_dev;
 677   thr->saved_bound_dev = NULL;
 678 }
 679
 680 /* This is called from any OpenACC support function that may need to implicitly
 681    initialize the libgomp runtime, either globally or from a new host thread.
 682    On exit "goacc_thread" will return a valid & populated thread block.  */
 683
 684 attribute_hidden void
 685 goacc_lazy_initialize (void)
 686 {
 687   struct goacc_thread *thr = goacc_thread ();
 688
 689   if (thr && thr->dev)
 690     return;
 691
 692   if (!cached_base_dev)
 693     acc_init (acc_device_default);
 694   else
 695     goacc_attach_host_thread_to_device (-1);
 696 }