gcc/ipa-inline.h

   1 /* Inlining decision heuristics.
   2    Copyright (C) 2003-2015 Free Software Foundation, Inc.
   3    Contributed by Jan Hubicka
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_IPA_INLINE_H
  22 #define GCC_IPA_INLINE_H
  23
  24
  25 /* Representation of inline parameters that do depend on context function is
  26    inlined into (i.e. known constant values of function parameters.
  27
  28    Conditions that are interesting for function body are collected into CONDS
  29    vector.  They are of simple for  function_param OP VAL, where VAL is
  30    IPA invariant.  The conditions are then referred by predicates.  */
  31
  32 struct GTY(()) condition
  33 {
  34   /* If agg_contents is set, this is the offset from which the used data was
  35      loaded.  */
  36   HOST_WIDE_INT offset;
  37   tree val;
  38   int operand_num;
  39   ENUM_BITFIELD(tree_code) code : 16;
  40   /* Set if the used data were loaded from an aggregate parameter or from
  41      data received by reference.  */
  42   unsigned agg_contents : 1;
  43   /* If agg_contents is set, this differentiates between loads from data
  44      passed by reference and by value.  */
  45   unsigned by_ref : 1;
  46 };
  47
  48 /* Inline hints are reasons why inline heuristics should preffer inlining given
  49    function.  They are represtented as bitmap of the following values.  */
  50 enum inline_hints_vals {
  51   /* When inlining turns indirect call into a direct call,
  52      it is good idea to do so.  */
  53   INLINE_HINT_indirect_call = 1,
  54   /* Inlining may make loop iterations or loop stride known.  It is good idea
  55      to do so because it enables loop optimizatoins.  */
  56   INLINE_HINT_loop_iterations = 2,
  57   INLINE_HINT_loop_stride = 4,
  58   /* Inlining within same strongly connected component of callgraph is often
  59      a loss due to increased stack frame usage and prologue setup costs.  */
  60   INLINE_HINT_same_scc = 8,
  61   /* Inlining functions in strongly connected component is not such a great
  62      win.  */
  63   INLINE_HINT_in_scc = 16,
  64   /* If function is declared inline by user, it may be good idea to inline
  65      it.  */
  66   INLINE_HINT_declared_inline = 32,
  67   /* Programs are usually still organized for non-LTO compilation and thus
  68      if functions are in different modules, inlining may not be so important.
  69    */
  70   INLINE_HINT_cross_module = 64,
  71   /* If array indexes of loads/stores become known there may be room for
  72      further optimization.  */
  73   INLINE_HINT_array_index = 128,
  74   /* We know that the callee is hot by profile.  */
  75   INLINE_HINT_known_hot = 256
  76 };
  77 typedef int inline_hints;
  78
  79
  80 typedef vec<condition, va_gc> *conditions;
  81
  82 /* Representation of predicates i.e. formulas using conditions defined
  83    above.  Predicates are simple logical formulas in conjunctive-disjunctive
  84    form.
  85
  86    Predicate is array of clauses terminated by 0.  Every clause must be true
  87    in order to make predicate true.
  88    Clauses are represented as bitmaps of conditions. One of conditions
  89    must be true in order for clause to be true.  */
  90
  91 #define MAX_CLAUSES 8
  92 typedef unsigned int clause_t;
  93 struct GTY(()) predicate
  94 {
  95   clause_t clause[MAX_CLAUSES + 1];
  96 };
  97
  98 /* Represnetation of function body size and time depending on the inline
  99    context.  We keep simple array of record, every containing of predicate
 100    and time/size to account.
 101
 102    We keep values scaled up, so fractional sizes and times can be
 103    accounted.  */
 104 #define INLINE_SIZE_SCALE 2
 105 #define INLINE_TIME_SCALE (CGRAPH_FREQ_BASE * 2)
 106 struct GTY(()) size_time_entry
 107 {
 108   struct predicate predicate;
 109   int size;
 110   int time;
 111 };
 112
 113 /* Function inlining information.  */
 114 struct GTY(()) inline_summary
 115 {
 116   /* Information about the function body itself.  */
 117
 118   /* Estimated stack frame consumption by the function.  */
 119   HOST_WIDE_INT estimated_self_stack_size;
 120   /* Size of the function body.  */
 121   int self_size;
 122   /* Time of the function body.  */
 123   int self_time;
 124   /* Minimal size increase after inlining.  */
 125   int min_size;
 126
 127   /* False when there something makes inlining impossible (such as va_arg).  */
 128   unsigned inlinable : 1;
 129   /* True when function contains cilk spawn (and thus we can not inline
 130      into it).  */
 131   unsigned contains_cilk_spawn : 1;
 132   /* True wen there is only one caller of the function before small function
 133      inlining.  */
 134   unsigned int single_caller : 1;
 135
 136   /* Information about function that will result after applying all the
 137      inline decisions present in the callgraph.  Generally kept up to
 138      date only for functions that are not inline clones. */
 139
 140   /* Estimated stack frame consumption by the function.  */
 141   HOST_WIDE_INT estimated_stack_size;
 142   /* Expected offset of the stack frame of inlined function.  */
 143   HOST_WIDE_INT stack_frame_offset;
 144   /* Estimated size of the function after inlining.  */
 145   int time;
 146   int size;
 147
 148   /* Conditional size/time information.  The summaries are being
 149      merged during inlining.  */
 150   conditions conds;
 151   vec<size_time_entry, va_gc> *entry;
 152
 153   /* Predicate on when some loop in the function becomes to have known
 154      bounds.   */
 155   struct predicate * GTY((skip)) loop_iterations;
 156   /* Predicate on when some loop in the function becomes to have known
 157      stride.   */
 158   struct predicate * GTY((skip)) loop_stride;
 159   /* Predicate on when some array indexes become constants.  */
 160   struct predicate * GTY((skip)) array_index;
 161   /* Estimated growth for inlining all copies of the function before start
 162      of small functions inlining.
 163      This value will get out of date as the callers are duplicated, but
 164      using up-to-date value in the badness metric mean a lot of extra
 165      expenses.  */
 166   int growth;
 167   /* Number of SCC on the beginning of inlining process.  */
 168   int scc_no;
 169 };
 170
 171 class GTY((user)) inline_summary_t: public function_summary <inline_summary *>
 172 {
 173 public:
 174   inline_summary_t (symbol_table *symtab, bool ggc):
 175     function_summary <inline_summary *> (symtab, ggc) {}
 176
 177   static inline_summary_t *create_ggc (symbol_table *symtab)
 178   {
 179     struct inline_summary_t *summary = new (ggc_cleared_alloc <inline_summary_t> ())
 180       inline_summary_t(symtab, true);
 181     summary->disable_insertion_hook ();
 182     return summary;
 183   }
 184
 185
 186   virtual void insert (cgraph_node *, inline_summary *);
 187   virtual void remove (cgraph_node *node, inline_summary *);
 188   virtual void duplicate (cgraph_node *src, cgraph_node *dst,
 189                           inline_summary *src_data, inline_summary *dst_data);
 190 };
 191
 192 extern GTY(()) function_summary <inline_summary *> *inline_summaries;
 193
 194 /* Information kept about parameter of call site.  */
 195 struct inline_param_summary
 196 {
 197   /* REG_BR_PROB_BASE based probability that parameter will change in between
 198      two invocation of the calls.
 199      I.e. loop invariant parameters
 200      REG_BR_PROB_BASE/estimated_iterations and regular
 201      parameters REG_BR_PROB_BASE.
 202
 203      Value 0 is reserved for compile time invariants. */
 204   int change_prob;
 205 };
 206
 207 /* Information kept about callgraph edges.  */
 208 struct inline_edge_summary
 209 {
 210   /* Estimated size and time of the call statement.  */
 211   int call_stmt_size;
 212   int call_stmt_time;
 213   /* Depth of loop nest, 0 means no nesting.  */
 214   unsigned short int loop_depth;
 215   struct predicate *predicate;
 216   /* Array indexed by parameters.
 217      0 means that parameter change all the time, REG_BR_PROB_BASE means
 218      that parameter is constant.  */
 219   vec<inline_param_summary> param;
 220 };
 221
 222 /* Need a typedef for inline_edge_summary because of inline function
 223    'inline_edge_summary' below.  */
 224 typedef struct inline_edge_summary inline_edge_summary_t;
 225 extern vec<inline_edge_summary_t> inline_edge_summary_vec;
 226
 227 struct edge_growth_cache_entry
 228 {
 229   int time, size;
 230   inline_hints hints;
 231 };
 232
 233 extern vec<edge_growth_cache_entry> edge_growth_cache;
 234
 235 /* In ipa-inline-analysis.c  */
 236 void debug_inline_summary (struct cgraph_node *);
 237 void dump_inline_summaries (FILE *f);
 238 void dump_inline_summary (FILE *f, struct cgraph_node *node);
 239 void dump_inline_hints (FILE *f, inline_hints);
 240 void inline_generate_summary (void);
 241 void inline_read_summary (void);
 242 void inline_write_summary (void);
 243 void inline_free_summary (void);
 244 void inline_analyze_function (struct cgraph_node *node);
 245 void initialize_inline_failed (struct cgraph_edge *);
 246 int estimate_time_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 247 int estimate_size_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 248 void estimate_ipcp_clone_size_and_time (struct cgraph_node *,
 249                                         vec<tree>,
 250                                         vec<ipa_polymorphic_call_context>,
 251                                         vec<ipa_agg_jump_function_p>,
 252                                         int *, int *, inline_hints *);
 253 int estimate_growth (struct cgraph_node *);
 254 bool growth_likely_positive (struct cgraph_node *, int);
 255 void inline_merge_summary (struct cgraph_edge *edge);
 256 void inline_update_overall_summary (struct cgraph_node *node);
 257 int do_estimate_edge_size (struct cgraph_edge *edge);
 258 int do_estimate_edge_time (struct cgraph_edge *edge);
 259 inline_hints do_estimate_edge_hints (struct cgraph_edge *edge);
 260 void initialize_growth_caches (void);
 261 void free_growth_caches (void);
 262 void compute_inline_parameters (struct cgraph_node *, bool);
 263 bool speculation_useful_p (struct cgraph_edge *e, bool anticipate_inlining);
 264 unsigned int early_inliner (function *fun);
 265 bool inline_account_function_p (struct cgraph_node *node);
 266
 267
 268 /* In ipa-inline-transform.c  */
 269 bool inline_call (struct cgraph_edge *, bool, vec<cgraph_edge *> *, int *, bool,
 270                   bool *callee_removed = NULL);
 271 unsigned int inline_transform (struct cgraph_node *);
 272 void clone_inlined_nodes (struct cgraph_edge *e, bool, bool, int *,
 273                           int freq_scale);
 274
 275 extern int ncalls_inlined;
 276 extern int nfunctions_inlined;
 277
 278 static inline struct inline_edge_summary *
 279 inline_edge_summary (struct cgraph_edge *edge)
 280 {
 281   return &inline_edge_summary_vec[edge->uid];
 282 }
 283
 284
 285 /* Return estimated size of the inline sequence of EDGE.  */
 286
 287 static inline int
 288 estimate_edge_size (struct cgraph_edge *edge)
 289 {
 290   int ret;
 291   if ((int)edge_growth_cache.length () <= edge->uid
 292       || !(ret = edge_growth_cache[edge->uid].size))
 293     return do_estimate_edge_size (edge);
 294   return ret - (ret > 0);
 295 }
 296
 297 /* Return estimated callee growth after inlining EDGE.  */
 298
 299 static inline int
 300 estimate_edge_growth (struct cgraph_edge *edge)
 301 {
 302 #ifdef ENABLE_CHECKING
 303   gcc_checking_assert (inline_edge_summary (edge)->call_stmt_size
 304                        || !edge->callee->analyzed);
 305 #endif
 306   return (estimate_edge_size (edge)
 307           - inline_edge_summary (edge)->call_stmt_size);
 308 }
 309
 310 /* Return estimated callee runtime increase after inlning
 311    EDGE.  */
 312
 313 static inline int
 314 estimate_edge_time (struct cgraph_edge *edge)
 315 {
 316   int ret;
 317   if ((int)edge_growth_cache.length () <= edge->uid
 318       || !(ret =  edge_growth_cache[edge->uid].time))
 319     return do_estimate_edge_time (edge);
 320   return ret - (ret > 0);
 321 }
 322
 323
 324 /* Return estimated callee runtime increase after inlning
 325    EDGE.  */
 326
 327 static inline inline_hints
 328 estimate_edge_hints (struct cgraph_edge *edge)
 329 {
 330   inline_hints ret;
 331   if ((int)edge_growth_cache.length () <= edge->uid
 332       || !(ret = edge_growth_cache[edge->uid].hints))
 333     return do_estimate_edge_hints (edge);
 334   return ret - 1;
 335 }
 336
 337 /* Reset cached value for EDGE.  */
 338
 339 static inline void
 340 reset_edge_growth_cache (struct cgraph_edge *edge)
 341 {
 342   if ((int)edge_growth_cache.length () > edge->uid)
 343     {
 344       struct edge_growth_cache_entry zero = {0, 0, 0};
 345       edge_growth_cache[edge->uid] = zero;
 346     }
 347 }
 348
 349 #endif /* GCC_IPA_INLINE_H */