libitm/dispatch.h

   1 /* Copyright (C) 2011-2020 Free Software Foundation, Inc.
   2    Contributed by Torvald Riegel <triegel@redhat.com>.
   3
   4    This file is part of the GNU Transactional Memory Library (libitm).
   5
   6    Libitm is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14    more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 #ifndef DISPATCH_H
  26 #define DISPATCH_H 1
  27
  28 #include "libitm.h"
  29 #include "common.h"
  30
  31 // Creates ABI load/store methods (can be made virtual or static using M,
  32 // use M2 to create separate methods names for virtual and static)
  33 // The _PV variants are for the pure-virtual methods in the base class.
  34 #define ITM_READ_M(T, LSMOD, M, M2)                                         \
  35   M _ITM_TYPE_##T ITM_REGPARM ITM_##LSMOD##T##M2 (const _ITM_TYPE_##T *ptr) \
  36   {                                                                         \
  37     return load(ptr, abi_dispatch::LSMOD);                                  \
  38   }
  39
  40 #define ITM_READ_M_PV(T, LSMOD, M, M2)                                      \
  41   M _ITM_TYPE_##T ITM_REGPARM ITM_##LSMOD##T##M2 (const _ITM_TYPE_##T *ptr) \
  42   = 0;
  43
  44 #define ITM_WRITE_M(T, LSMOD, M, M2)                         \
  45   M void ITM_REGPARM ITM_##LSMOD##T##M2 (_ITM_TYPE_##T *ptr, \
  46                                          _ITM_TYPE_##T val)  \
  47   {                                                          \
  48     store(ptr, val, abi_dispatch::LSMOD);                    \
  49   }
  50
  51 #define ITM_WRITE_M_PV(T, LSMOD, M, M2)                      \
  52   M void ITM_REGPARM ITM_##LSMOD##T##M2 (_ITM_TYPE_##T *ptr, \
  53                                          _ITM_TYPE_##T val)  \
  54   = 0;
  55
  56 // Creates ABI load/store methods for all load/store modifiers for a particular
  57 // type.
  58 #define CREATE_DISPATCH_METHODS_T(T, M, M2) \
  59   ITM_READ_M(T, R, M, M2)                \
  60   ITM_READ_M(T, RaR, M, M2)              \
  61   ITM_READ_M(T, RaW, M, M2)              \
  62   ITM_READ_M(T, RfW, M, M2)              \
  63   ITM_WRITE_M(T, W, M, M2)               \
  64   ITM_WRITE_M(T, WaR, M, M2)             \
  65   ITM_WRITE_M(T, WaW, M, M2)
  66 #define CREATE_DISPATCH_METHODS_T_PV(T, M, M2) \
  67   ITM_READ_M_PV(T, R, M, M2)                \
  68   ITM_READ_M_PV(T, RaR, M, M2)              \
  69   ITM_READ_M_PV(T, RaW, M, M2)              \
  70   ITM_READ_M_PV(T, RfW, M, M2)              \
  71   ITM_WRITE_M_PV(T, W, M, M2)               \
  72   ITM_WRITE_M_PV(T, WaR, M, M2)             \
  73   ITM_WRITE_M_PV(T, WaW, M, M2)
  74
  75 // Creates ABI load/store methods for all types.
  76 // See CREATE_DISPATCH_FUNCTIONS for comments.
  77 #define CREATE_DISPATCH_METHODS(M, M2)  \
  78   CREATE_DISPATCH_METHODS_T (U1, M, M2) \
  79   CREATE_DISPATCH_METHODS_T (U2, M, M2) \
  80   CREATE_DISPATCH_METHODS_T (U4, M, M2) \
  81   CREATE_DISPATCH_METHODS_T (U8, M, M2) \
  82   CREATE_DISPATCH_METHODS_T (F, M, M2)  \
  83   CREATE_DISPATCH_METHODS_T (D, M, M2)  \
  84   CREATE_DISPATCH_METHODS_T (E, M, M2)  \
  85   CREATE_DISPATCH_METHODS_T (CF, M, M2) \
  86   CREATE_DISPATCH_METHODS_T (CD, M, M2) \
  87   CREATE_DISPATCH_METHODS_T (CE, M, M2)
  88 #define CREATE_DISPATCH_METHODS_PV(M, M2)  \
  89   CREATE_DISPATCH_METHODS_T_PV (U1, M, M2) \
  90   CREATE_DISPATCH_METHODS_T_PV (U2, M, M2) \
  91   CREATE_DISPATCH_METHODS_T_PV (U4, M, M2) \
  92   CREATE_DISPATCH_METHODS_T_PV (U8, M, M2) \
  93   CREATE_DISPATCH_METHODS_T_PV (F, M, M2)  \
  94   CREATE_DISPATCH_METHODS_T_PV (D, M, M2)  \
  95   CREATE_DISPATCH_METHODS_T_PV (E, M, M2)  \
  96   CREATE_DISPATCH_METHODS_T_PV (CF, M, M2) \
  97   CREATE_DISPATCH_METHODS_T_PV (CD, M, M2) \
  98   CREATE_DISPATCH_METHODS_T_PV (CE, M, M2)
  99
 100 // Creates memcpy/memmove/memset methods.
 101 #define CREATE_DISPATCH_METHODS_MEM()  \
 102 virtual void memtransfer(void *dst, const void* src, size_t size,    \
 103     bool may_overlap, ls_modifier dst_mod, ls_modifier src_mod)       \
 104 {                                                                     \
 105   if (size > 0)                                                       \
 106     memtransfer_static(dst, src, size, may_overlap, dst_mod, src_mod); \
 107 }                                                                     \
 108 virtual void memset(void *dst, int c, size_t size, ls_modifier mod)  \
 109 {                                                                     \
 110   if (size > 0)                                                       \
 111     memset_static(dst, c, size, mod);                                 \
 112 }
 113
 114 #define CREATE_DISPATCH_METHODS_MEM_PV()  \
 115 virtual void memtransfer(void *dst, const void* src, size_t size,       \
 116     bool may_overlap, ls_modifier dst_mod, ls_modifier src_mod) = 0;     \
 117 virtual void memset(void *dst, int c, size_t size, ls_modifier mod) = 0;
 118
 119
 120 // Creates ABI load/store functions that can target either a class or an
 121 // object.
 122 #define ITM_READ(T, LSMOD, TARGET, M2)                                 \
 123   _ITM_TYPE_##T ITM_REGPARM _ITM_##LSMOD##T (const _ITM_TYPE_##T *ptr) \
 124   {                                                                    \
 125     return TARGET ITM_##LSMOD##T##M2(ptr);                            \
 126   }
 127
 128 #define ITM_WRITE(T, LSMOD, TARGET, M2)                                    \
 129   void ITM_REGPARM _ITM_##LSMOD##T (_ITM_TYPE_##T *ptr, _ITM_TYPE_##T val) \
 130   {                                                                        \
 131     TARGET ITM_##LSMOD##T##M2(ptr, val);                                  \
 132   }
 133
 134 // Creates ABI load/store functions for all load/store modifiers for a
 135 // particular type.
 136 #define CREATE_DISPATCH_FUNCTIONS_T(T, TARGET, M2) \
 137   ITM_READ(T, R, TARGET, M2)                \
 138   ITM_READ(T, RaR, TARGET, M2)              \
 139   ITM_READ(T, RaW, TARGET, M2)              \
 140   ITM_READ(T, RfW, TARGET, M2)              \
 141   ITM_WRITE(T, W, TARGET, M2)               \
 142   ITM_WRITE(T, WaR, TARGET, M2)             \
 143   ITM_WRITE(T, WaW, TARGET, M2)
 144
 145 // Creates ABI memcpy/memmove/memset functions.
 146 #define ITM_MEMTRANSFER_DEF(TARGET, M2, NAME, READ, WRITE) \
 147 void ITM_REGPARM _ITM_memcpy##NAME(void *dst, const void *src, size_t size)  \
 148 {                                                                            \
 149   TARGET memtransfer##M2 (dst, src, size,                                   \
 150              false, GTM::abi_dispatch::WRITE, GTM::abi_dispatch::READ);      \
 151 }                                                                            \
 152 void ITM_REGPARM _ITM_memmove##NAME(void *dst, const void *src, size_t size) \
 153 {                                                                            \
 154   TARGET memtransfer##M2 (dst, src, size,                                   \
 155       GTM::abi_dispatch::memmove_overlap_check(dst, src, size,               \
 156           GTM::abi_dispatch::WRITE, GTM::abi_dispatch::READ),                \
 157       GTM::abi_dispatch::WRITE, GTM::abi_dispatch::READ);                    \
 158 }
 159
 160 #define ITM_MEMSET_DEF(TARGET, M2, WRITE) \
 161 void ITM_REGPARM _ITM_memset##WRITE(void *dst, int c, size_t size) \
 162 {                                                                  \
 163   TARGET memset##M2 (dst, c, size, GTM::abi_dispatch::WRITE);     \
 164 }                                                                  \
 165
 166
 167 // ??? The number of virtual methods is large (7*4 for integers, 7*6 for FP,
 168 // 7*3 for vectors). Is the cache footprint so costly that we should go for
 169 // a small table instead (i.e., only have two virtual load/store methods for
 170 // each supported type)? Note that this doesn't affect custom code paths at
 171 // all because these use only direct calls.
 172 // A large cache footprint could especially decrease HTM performance (due
 173 // to HTM capacity). We could add the modifier (RaR etc.) as parameter, which
 174 // would give us just 4*2+6*2+3*2 functions (so we'd just need one line for
 175 // the integer loads/stores), but then the modifier can be checked only at
 176 // runtime.
 177 // For memcpy/memmove/memset, we just have two virtual methods (memtransfer
 178 // and memset).
 179 #define CREATE_DISPATCH_FUNCTIONS(TARGET, M2)  \
 180   CREATE_DISPATCH_FUNCTIONS_T (U1, TARGET, M2) \
 181   CREATE_DISPATCH_FUNCTIONS_T (U2, TARGET, M2) \
 182   CREATE_DISPATCH_FUNCTIONS_T (U4, TARGET, M2) \
 183   CREATE_DISPATCH_FUNCTIONS_T (U8, TARGET, M2) \
 184   CREATE_DISPATCH_FUNCTIONS_T (F, TARGET, M2)  \
 185   CREATE_DISPATCH_FUNCTIONS_T (D, TARGET, M2)  \
 186   CREATE_DISPATCH_FUNCTIONS_T (E, TARGET, M2)  \
 187   CREATE_DISPATCH_FUNCTIONS_T (CF, TARGET, M2) \
 188   CREATE_DISPATCH_FUNCTIONS_T (CD, TARGET, M2) \
 189   CREATE_DISPATCH_FUNCTIONS_T (CE, TARGET, M2) \
 190   ITM_MEMTRANSFER_DEF(TARGET, M2, RnWt,     NONTXNAL, W)      \
 191   ITM_MEMTRANSFER_DEF(TARGET, M2, RnWtaR,   NONTXNAL, WaR)    \
 192   ITM_MEMTRANSFER_DEF(TARGET, M2, RnWtaW,   NONTXNAL, WaW)    \
 193   ITM_MEMTRANSFER_DEF(TARGET, M2, RtWn,     R,      NONTXNAL) \
 194   ITM_MEMTRANSFER_DEF(TARGET, M2, RtWt,     R,      W)        \
 195   ITM_MEMTRANSFER_DEF(TARGET, M2, RtWtaR,   R,      WaR)      \
 196   ITM_MEMTRANSFER_DEF(TARGET, M2, RtWtaW,   R,      WaW)      \
 197   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaRWn,   RaR,    NONTXNAL) \
 198   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaRWt,   RaR,    W)        \
 199   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaRWtaR, RaR,    WaR)      \
 200   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaRWtaW, RaR,    WaW)      \
 201   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaWWn,   RaW,    NONTXNAL) \
 202   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaWWt,   RaW,    W)        \
 203   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaWWtaR, RaW,    WaR)      \
 204   ITM_MEMTRANSFER_DEF(TARGET, M2, RtaWWtaW, RaW,    WaW)      \
 205   ITM_MEMSET_DEF(TARGET, M2, W)   \
 206   ITM_MEMSET_DEF(TARGET, M2, WaR) \
 207   ITM_MEMSET_DEF(TARGET, M2, WaW)
 208
 209
 210 // Creates ABI load/store functions that delegate to a transactional memcpy.
 211 #define ITM_READ_MEMCPY(T, LSMOD, TARGET, M2)                         \
 212   _ITM_TYPE_##T ITM_REGPARM _ITM_##LSMOD##T (const _ITM_TYPE_##T *ptr)\
 213   {                                                                   \
 214     _ITM_TYPE_##T v;                                                  \
 215     TARGET memtransfer##M2(&v, ptr, sizeof(_ITM_TYPE_##T), false,    \
 216         GTM::abi_dispatch::NONTXNAL, GTM::abi_dispatch::LSMOD);       \
 217     return v;                                                         \
 218   }
 219
 220 #define ITM_WRITE_MEMCPY(T, LSMOD, TARGET, M2)                            \
 221   void ITM_REGPARM _ITM_##LSMOD##T (_ITM_TYPE_##T *ptr, _ITM_TYPE_##T val)\
 222   {                                                                       \
 223     TARGET memtransfer##M2(ptr, &val, sizeof(_ITM_TYPE_##T), false,      \
 224         GTM::abi_dispatch::LSMOD, GTM::abi_dispatch::NONTXNAL);           \
 225   }
 226
 227 #define CREATE_DISPATCH_FUNCTIONS_T_MEMCPY(T, TARGET, M2) \
 228   ITM_READ_MEMCPY(T, R, TARGET, M2)                \
 229   ITM_READ_MEMCPY(T, RaR, TARGET, M2)              \
 230   ITM_READ_MEMCPY(T, RaW, TARGET, M2)              \
 231   ITM_READ_MEMCPY(T, RfW, TARGET, M2)              \
 232   ITM_WRITE_MEMCPY(T, W, TARGET, M2)               \
 233   ITM_WRITE_MEMCPY(T, WaR, TARGET, M2)             \
 234   ITM_WRITE_MEMCPY(T, WaW, TARGET, M2)
 235
 236
 237 namespace GTM HIDDEN {
 238
 239 struct gtm_transaction_cp;
 240
 241 struct method_group
 242 {
 243   // Start using a TM method from this group. This constructs required meta
 244   // data on demand when this method group is actually used. Will be called
 245   // either on first use or after a previous call to fini().
 246   virtual void init() = 0;
 247   // Stop using any method from this group for now. This can be used to
 248   // destruct meta data as soon as this method group is not used anymore.
 249   virtual void fini() = 0;
 250   // This can be overriden to implement more light-weight re-initialization.
 251   virtual void reinit()
 252   {
 253     fini();
 254     init();
 255   }
 256 };
 257
 258
 259 // This is the base interface that all TM methods have to implement.
 260 struct abi_dispatch
 261 {
 262 public:
 263   enum ls_modifier { NONTXNAL, R, RaR, RaW, RfW, W, WaR, WaW };
 264
 265 private:
 266   // Disallow copies
 267   abi_dispatch(const abi_dispatch &) = delete;
 268   abi_dispatch& operator=(const abi_dispatch &) = delete;
 269
 270 public:
 271   // Starts or restarts a transaction. Is called right before executing the
 272   // transactional application code (by either returning from
 273   // gtm_thread::begin_transaction or doing the longjmp when restarting).
 274   // Returns NO_RESTART if the transaction started successfully. Returns
 275   // a real restart reason if it couldn't start and does need to abort. This
 276   // allows TM methods to just give up and delegate ensuring progress to the
 277   // restart mechanism. If it returns a restart reason, this call must be
 278   // idempotent because it will trigger the restart mechanism, which could
 279   // switch to a different TM method.
 280   virtual gtm_restart_reason begin_or_restart() = 0;
 281   // Tries to commit the transaction. Iff this returns true, the transaction
 282   // got committed and all per-transaction data will have been reset.
 283   // Currently, this is called only for the commit of the outermost
 284   // transaction, or when switching to serial mode (which can happen in a
 285   // nested transaction).
 286   // If privatization safety must be ensured in a quiescence-based way, set
 287   // priv_time to a value different to 0. Nontransactional code will not be
 288   // executed after this commit until all registered threads' shared_state is
 289   // larger than or equal to this value.
 290   virtual bool trycommit(gtm_word& priv_time) = 0;
 291   // Rolls back a transaction. Called on abort or after trycommit() returned
 292   // false.
 293   virtual void rollback(gtm_transaction_cp *cp = 0) = 0;
 294   // Returns true iff the snapshot is most recent, which will be the case if
 295   // this transaction cannot be the reason why other transactions cannot
 296   // ensure privatization safety.
 297   virtual bool snapshot_most_recent() = 0;
 298
 299   // Return an alternative method that is compatible with the current
 300   // method but supports closed nesting. Return zero if there is none.
 301   // Note that too be compatible, it must be possible to switch to this other
 302   // method on begin of a nested transaction without committing or restarting
 303   // the parent method.
 304   virtual abi_dispatch* closed_nesting_alternative() { return 0; }
 305   // Returns true iff this method group supports the current situation.
 306   // NUMBER_OF_THREADS is the current number of threads that might execute
 307   // transactions.
 308   virtual bool supports(unsigned number_of_threads) { return true; }
 309
 310   bool read_only () const { return m_read_only; }
 311   bool write_through() const { return m_write_through; }
 312   bool can_run_uninstrumented_code() const
 313   {
 314     return m_can_run_uninstrumented_code;
 315   }
 316   // Returns true iff this TM method supports closed nesting.
 317   bool closed_nesting() const { return m_closed_nesting; }
 318   // Returns STATE_SERIAL or STATE_SERIAL | STATE_IRREVOCABLE iff the TM
 319   // method only works for serial-mode transactions.
 320   uint32_t requires_serial() const { return m_requires_serial; }
 321   method_group* get_method_group() const { return m_method_group; }
 322
 323   static void *operator new(size_t s) { return xmalloc (s); }
 324   static void operator delete(void *p) { free (p); }
 325
 326 public:
 327   static bool memmove_overlap_check(void *dst, const void *src, size_t size,
 328       ls_modifier dst_mod, ls_modifier src_mod);
 329
 330   // Creates the ABI dispatch methods for loads and stores.
 331   // ??? Should the dispatch table instead be embedded in the dispatch object
 332   // to avoid the indirect lookup in the vtable?
 333   CREATE_DISPATCH_METHODS_PV(virtual, )
 334   // Creates the ABI dispatch methods for memcpy/memmove/memset.
 335   CREATE_DISPATCH_METHODS_MEM_PV()
 336
 337 protected:
 338   const bool m_read_only;
 339   const bool m_write_through;
 340   const bool m_can_run_uninstrumented_code;
 341   const bool m_closed_nesting;
 342   const uint32_t m_requires_serial;
 343   method_group* const m_method_group;
 344   abi_dispatch(bool ro, bool wt, bool uninstrumented, bool closed_nesting,
 345       uint32_t requires_serial, method_group* mg) :
 346     m_read_only(ro), m_write_through(wt),
 347     m_can_run_uninstrumented_code(uninstrumented),
 348     m_closed_nesting(closed_nesting), m_requires_serial(requires_serial),
 349     m_method_group(mg)
 350   { }
 351 };
 352
 353 }
 354
 355 #endif // DISPATCH_H