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
 133   /* Information about function that will result after applying all the
 134      inline decisions present in the callgraph.  Generally kept up to
 135      date only for functions that are not inline clones. */
 136
 137   /* Estimated stack frame consumption by the function.  */
 138   HOST_WIDE_INT estimated_stack_size;
 139   /* Expected offset of the stack frame of inlined function.  */
 140   HOST_WIDE_INT stack_frame_offset;
 141   /* Estimated size of the function after inlining.  */
 142   int time;
 143   int size;
 144
 145   /* Conditional size/time information.  The summaries are being
 146      merged during inlining.  */
 147   conditions conds;
 148   vec<size_time_entry, va_gc> *entry;
 149
 150   /* Predicate on when some loop in the function becomes to have known
 151      bounds.   */
 152   struct predicate * GTY((skip)) loop_iterations;
 153   /* Predicate on when some loop in the function becomes to have known
 154      stride.   */
 155   struct predicate * GTY((skip)) loop_stride;
 156   /* Predicate on when some array indexes become constants.  */
 157   struct predicate * GTY((skip)) array_index;
 158   /* Estimated growth for inlining all copies of the function before start
 159      of small functions inlining.
 160      This value will get out of date as the callers are duplicated, but
 161      using up-to-date value in the badness metric mean a lot of extra
 162      expenses.  */
 163   int growth;
 164   /* Number of SCC on the beginning of inlining process.  */
 165   int scc_no;
 166 };
 167
 168 class GTY((user)) inline_summary_t: public function_summary <inline_summary *>
 169 {
 170 public:
 171   inline_summary_t (symbol_table *symtab, bool ggc):
 172     function_summary <inline_summary *> (symtab, ggc) {}
 173
 174   static inline_summary_t *create_ggc (symbol_table *symtab)
 175   {
 176     struct inline_summary_t *summary = new (ggc_cleared_alloc <inline_summary_t> ())
 177       inline_summary_t(symtab, true);
 178     summary->disable_insertion_hook ();
 179     return summary;
 180   }
 181
 182
 183   virtual void insert (cgraph_node *, inline_summary *);
 184   virtual void remove (cgraph_node *node, inline_summary *);
 185   virtual void duplicate (cgraph_node *src, cgraph_node *dst,
 186                           inline_summary *src_data, inline_summary *dst_data);
 187 };
 188
 189 extern GTY(()) function_summary <inline_summary *> *inline_summaries;
 190
 191 /* Information kept about parameter of call site.  */
 192 struct inline_param_summary
 193 {
 194   /* REG_BR_PROB_BASE based probability that parameter will change in between
 195      two invocation of the calls.
 196      I.e. loop invariant parameters
 197      REG_BR_PROB_BASE/estimated_iterations and regular
 198      parameters REG_BR_PROB_BASE.
 199
 200      Value 0 is reserved for compile time invariants. */
 201   int change_prob;
 202 };
 203
 204 /* Information kept about callgraph edges.  */
 205 struct inline_edge_summary
 206 {
 207   /* Estimated size and time of the call statement.  */
 208   int call_stmt_size;
 209   int call_stmt_time;
 210   /* Depth of loop nest, 0 means no nesting.  */
 211   unsigned short int loop_depth;
 212   struct predicate *predicate;
 213   /* Array indexed by parameters.
 214      0 means that parameter change all the time, REG_BR_PROB_BASE means
 215      that parameter is constant.  */
 216   vec<inline_param_summary> param;
 217 };
 218
 219 /* Need a typedef for inline_edge_summary because of inline function
 220    'inline_edge_summary' below.  */
 221 typedef struct inline_edge_summary inline_edge_summary_t;
 222 extern vec<inline_edge_summary_t> inline_edge_summary_vec;
 223
 224 struct edge_growth_cache_entry
 225 {
 226   int time, size;
 227   inline_hints hints;
 228 };
 229
 230 extern vec<edge_growth_cache_entry> edge_growth_cache;
 231
 232 /* In ipa-inline-analysis.c  */
 233 void debug_inline_summary (struct cgraph_node *);
 234 void dump_inline_summaries (FILE *f);
 235 void dump_inline_summary (FILE *f, struct cgraph_node *node);
 236 void dump_inline_hints (FILE *f, inline_hints);
 237 void inline_generate_summary (void);
 238 void inline_read_summary (void);
 239 void inline_write_summary (void);
 240 void inline_free_summary (void);
 241 void inline_analyze_function (struct cgraph_node *node);
 242 void initialize_inline_failed (struct cgraph_edge *);
 243 int estimate_time_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 244 int estimate_size_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 245 void estimate_ipcp_clone_size_and_time (struct cgraph_node *,
 246                                         vec<tree>,
 247                                         vec<ipa_polymorphic_call_context>,
 248                                         vec<ipa_agg_jump_function_p>,
 249                                         int *, int *, inline_hints *);
 250 int estimate_growth (struct cgraph_node *);
 251 bool growth_likely_positive (struct cgraph_node *, int);
 252 void inline_merge_summary (struct cgraph_edge *edge);
 253 void inline_update_overall_summary (struct cgraph_node *node);
 254 int do_estimate_edge_size (struct cgraph_edge *edge);
 255 int do_estimate_edge_time (struct cgraph_edge *edge);
 256 inline_hints do_estimate_edge_hints (struct cgraph_edge *edge);
 257 void initialize_growth_caches (void);
 258 void free_growth_caches (void);
 259 void compute_inline_parameters (struct cgraph_node *, bool);
 260 bool speculation_useful_p (struct cgraph_edge *e, bool anticipate_inlining);
 261 unsigned int early_inliner (function *fun);
 262 bool inline_account_function_p (struct cgraph_node *node);
 263
 264
 265 /* In ipa-inline-transform.c  */
 266 bool inline_call (struct cgraph_edge *, bool, vec<cgraph_edge *> *, int *, bool,
 267                   bool *callee_removed = NULL);
 268 unsigned int inline_transform (struct cgraph_node *);
 269 void clone_inlined_nodes (struct cgraph_edge *e, bool, bool, int *,
 270                           int freq_scale);
 271
 272 extern int ncalls_inlined;
 273 extern int nfunctions_inlined;
 274
 275 static inline struct inline_edge_summary *
 276 inline_edge_summary (struct cgraph_edge *edge)
 277 {
 278   return &inline_edge_summary_vec[edge->uid];
 279 }
 280
 281
 282 /* Return estimated size of the inline sequence of EDGE.  */
 283
 284 static inline int
 285 estimate_edge_size (struct cgraph_edge *edge)
 286 {
 287   int ret;
 288   if ((int)edge_growth_cache.length () <= edge->uid
 289       || !(ret = edge_growth_cache[edge->uid].size))
 290     return do_estimate_edge_size (edge);
 291   return ret - (ret > 0);
 292 }
 293
 294 /* Return estimated callee growth after inlining EDGE.  */
 295
 296 static inline int
 297 estimate_edge_growth (struct cgraph_edge *edge)
 298 {
 299 #ifdef ENABLE_CHECKING
 300   gcc_checking_assert (inline_edge_summary (edge)->call_stmt_size
 301                        || !edge->callee->analyzed);
 302 #endif
 303   return (estimate_edge_size (edge)
 304           - inline_edge_summary (edge)->call_stmt_size);
 305 }
 306
 307 /* Return estimated callee runtime increase after inlning
 308    EDGE.  */
 309
 310 static inline int
 311 estimate_edge_time (struct cgraph_edge *edge)
 312 {
 313   int ret;
 314   if ((int)edge_growth_cache.length () <= edge->uid
 315       || !(ret =  edge_growth_cache[edge->uid].time))
 316     return do_estimate_edge_time (edge);
 317   return ret - (ret > 0);
 318 }
 319
 320
 321 /* Return estimated callee runtime increase after inlning
 322    EDGE.  */
 323
 324 static inline inline_hints
 325 estimate_edge_hints (struct cgraph_edge *edge)
 326 {
 327   inline_hints ret;
 328   if ((int)edge_growth_cache.length () <= edge->uid
 329       || !(ret = edge_growth_cache[edge->uid].hints))
 330     return do_estimate_edge_hints (edge);
 331   return ret - 1;
 332 }
 333
 334 /* Reset cached value for EDGE.  */
 335
 336 static inline void
 337 reset_edge_growth_cache (struct cgraph_edge *edge)
 338 {
 339   if ((int)edge_growth_cache.length () > edge->uid)
 340     {
 341       struct edge_growth_cache_entry zero = {0, 0, 0};
 342       edge_growth_cache[edge->uid] = zero;
 343     }
 344 }
 345
 346 #endif /* GCC_IPA_INLINE_H */