gcc/ipa-inline.h

   1 /* Inlining decision heuristics.
   2    Copyright (C) 2003-2016 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   /* Size of the access reading the data (or the PARM_DECL SSA_NAME).  */
  38   HOST_WIDE_INT size;
  39   tree val;
  40   int operand_num;
  41   ENUM_BITFIELD(tree_code) code : 16;
  42   /* Set if the used data were loaded from an aggregate parameter or from
  43      data received by reference.  */
  44   unsigned agg_contents : 1;
  45   /* If agg_contents is set, this differentiates between loads from data
  46      passed by reference and by value.  */
  47   unsigned by_ref : 1;
  48 };
  49
  50 /* Inline hints are reasons why inline heuristics should preffer inlining given
  51    function.  They are represtented as bitmap of the following values.  */
  52 enum inline_hints_vals {
  53   /* When inlining turns indirect call into a direct call,
  54      it is good idea to do so.  */
  55   INLINE_HINT_indirect_call = 1,
  56   /* Inlining may make loop iterations or loop stride known.  It is good idea
  57      to do so because it enables loop optimizatoins.  */
  58   INLINE_HINT_loop_iterations = 2,
  59   INLINE_HINT_loop_stride = 4,
  60   /* Inlining within same strongly connected component of callgraph is often
  61      a loss due to increased stack frame usage and prologue setup costs.  */
  62   INLINE_HINT_same_scc = 8,
  63   /* Inlining functions in strongly connected component is not such a great
  64      win.  */
  65   INLINE_HINT_in_scc = 16,
  66   /* If function is declared inline by user, it may be good idea to inline
  67      it.  */
  68   INLINE_HINT_declared_inline = 32,
  69   /* Programs are usually still organized for non-LTO compilation and thus
  70      if functions are in different modules, inlining may not be so important.
  71    */
  72   INLINE_HINT_cross_module = 64,
  73   /* If array indexes of loads/stores become known there may be room for
  74      further optimization.  */
  75   INLINE_HINT_array_index = 128,
  76   /* We know that the callee is hot by profile.  */
  77   INLINE_HINT_known_hot = 256
  78 };
  79 typedef int inline_hints;
  80
  81
  82 typedef vec<condition, va_gc> *conditions;
  83
  84 /* Representation of predicates i.e. formulas using conditions defined
  85    above.  Predicates are simple logical formulas in conjunctive-disjunctive
  86    form.
  87
  88    Predicate is array of clauses terminated by 0.  Every clause must be true
  89    in order to make predicate true.
  90    Clauses are represented as bitmaps of conditions. One of conditions
  91    must be true in order for clause to be true.  */
  92
  93 #define MAX_CLAUSES 8
  94 typedef unsigned int clause_t;
  95 struct GTY(()) predicate
  96 {
  97   clause_t clause[MAX_CLAUSES + 1];
  98 };
  99
 100 /* Represnetation of function body size and time depending on the inline
 101    context.  We keep simple array of record, every containing of predicate
 102    and time/size to account.
 103
 104    We keep values scaled up, so fractional sizes and times can be
 105    accounted.  */
 106 #define INLINE_SIZE_SCALE 2
 107 #define INLINE_TIME_SCALE (CGRAPH_FREQ_BASE * 2)
 108 struct GTY(()) size_time_entry
 109 {
 110   struct predicate predicate;
 111   int size;
 112   int time;
 113 };
 114
 115 /* Function inlining information.  */
 116 struct GTY(()) inline_summary
 117 {
 118   /* Information about the function body itself.  */
 119
 120   /* Estimated stack frame consumption by the function.  */
 121   HOST_WIDE_INT estimated_self_stack_size;
 122   /* Size of the function body.  */
 123   int self_size;
 124   /* Time of the function body.  */
 125   int self_time;
 126   /* Minimal size increase after inlining.  */
 127   int min_size;
 128
 129   /* False when there something makes inlining impossible (such as va_arg).  */
 130   unsigned inlinable : 1;
 131   /* True when function contains cilk spawn (and thus we can not inline
 132      into it).  */
 133   unsigned contains_cilk_spawn : 1;
 134   /* True wen there is only one caller of the function before small function
 135      inlining.  */
 136   unsigned int single_caller : 1;
 137
 138   /* Information about function that will result after applying all the
 139      inline decisions present in the callgraph.  Generally kept up to
 140      date only for functions that are not inline clones. */
 141
 142   /* Estimated stack frame consumption by the function.  */
 143   HOST_WIDE_INT estimated_stack_size;
 144   /* Expected offset of the stack frame of inlined function.  */
 145   HOST_WIDE_INT stack_frame_offset;
 146   /* Estimated size of the function after inlining.  */
 147   int time;
 148   int size;
 149
 150   /* Conditional size/time information.  The summaries are being
 151      merged during inlining.  */
 152   conditions conds;
 153   vec<size_time_entry, va_gc> *entry;
 154
 155   /* Predicate on when some loop in the function becomes to have known
 156      bounds.   */
 157   struct predicate * GTY((skip)) loop_iterations;
 158   /* Predicate on when some loop in the function becomes to have known
 159      stride.   */
 160   struct predicate * GTY((skip)) loop_stride;
 161   /* Predicate on when some array indexes become constants.  */
 162   struct predicate * GTY((skip)) array_index;
 163   /* Estimated growth for inlining all copies of the function before start
 164      of small functions inlining.
 165      This value will get out of date as the callers are duplicated, but
 166      using up-to-date value in the badness metric mean a lot of extra
 167      expenses.  */
 168   int growth;
 169   /* Number of SCC on the beginning of inlining process.  */
 170   int scc_no;
 171 };
 172
 173 class GTY((user)) inline_summary_t: public function_summary <inline_summary *>
 174 {
 175 public:
 176   inline_summary_t (symbol_table *symtab, bool ggc):
 177     function_summary <inline_summary *> (symtab, ggc) {}
 178
 179   static inline_summary_t *create_ggc (symbol_table *symtab)
 180   {
 181     struct inline_summary_t *summary = new (ggc_cleared_alloc <inline_summary_t> ())
 182       inline_summary_t(symtab, true);
 183     summary->disable_insertion_hook ();
 184     return summary;
 185   }
 186
 187
 188   virtual void insert (cgraph_node *, inline_summary *);
 189   virtual void remove (cgraph_node *node, inline_summary *);
 190   virtual void duplicate (cgraph_node *src, cgraph_node *dst,
 191                           inline_summary *src_data, inline_summary *dst_data);
 192 };
 193
 194 extern GTY(()) function_summary <inline_summary *> *inline_summaries;
 195
 196 /* Information kept about parameter of call site.  */
 197 struct inline_param_summary
 198 {
 199   /* REG_BR_PROB_BASE based probability that parameter will change in between
 200      two invocation of the calls.
 201      I.e. loop invariant parameters
 202      REG_BR_PROB_BASE/estimated_iterations and regular
 203      parameters REG_BR_PROB_BASE.
 204
 205      Value 0 is reserved for compile time invariants. */
 206   int change_prob;
 207 };
 208
 209 /* Information kept about callgraph edges.  */
 210 struct inline_edge_summary
 211 {
 212   /* Estimated size and time of the call statement.  */
 213   int call_stmt_size;
 214   int call_stmt_time;
 215   /* Depth of loop nest, 0 means no nesting.  */
 216   unsigned short int loop_depth;
 217   struct predicate *predicate;
 218   /* Array indexed by parameters.
 219      0 means that parameter change all the time, REG_BR_PROB_BASE means
 220      that parameter is constant.  */
 221   vec<inline_param_summary> param;
 222 };
 223
 224 /* Need a typedef for inline_edge_summary because of inline function
 225    'inline_edge_summary' below.  */
 226 typedef struct inline_edge_summary inline_edge_summary_t;
 227 extern vec<inline_edge_summary_t> inline_edge_summary_vec;
 228
 229 struct edge_growth_cache_entry
 230 {
 231   int time, size;
 232   inline_hints hints;
 233 };
 234
 235 extern vec<edge_growth_cache_entry> edge_growth_cache;
 236
 237 /* In ipa-inline-analysis.c  */
 238 void debug_inline_summary (struct cgraph_node *);
 239 void dump_inline_summaries (FILE *f);
 240 void dump_inline_summary (FILE *f, struct cgraph_node *node);
 241 void dump_inline_hints (FILE *f, inline_hints);
 242 void inline_generate_summary (void);
 243 void inline_read_summary (void);
 244 void inline_write_summary (void);
 245 void inline_free_summary (void);
 246 void inline_analyze_function (struct cgraph_node *node);
 247 void initialize_inline_failed (struct cgraph_edge *);
 248 int estimate_time_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 249 int estimate_size_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 250 void estimate_ipcp_clone_size_and_time (struct cgraph_node *,
 251                                         vec<tree>,
 252                                         vec<ipa_polymorphic_call_context>,
 253                                         vec<ipa_agg_jump_function_p>,
 254                                         int *, int *, inline_hints *);
 255 int estimate_growth (struct cgraph_node *);
 256 bool growth_likely_positive (struct cgraph_node *, int);
 257 void inline_merge_summary (struct cgraph_edge *edge);
 258 void inline_update_overall_summary (struct cgraph_node *node);
 259 int do_estimate_edge_size (struct cgraph_edge *edge);
 260 int do_estimate_edge_time (struct cgraph_edge *edge);
 261 inline_hints do_estimate_edge_hints (struct cgraph_edge *edge);
 262 void initialize_growth_caches (void);
 263 void free_growth_caches (void);
 264 void compute_inline_parameters (struct cgraph_node *, bool);
 265 bool speculation_useful_p (struct cgraph_edge *e, bool anticipate_inlining);
 266 unsigned int early_inliner (function *fun);
 267 bool inline_account_function_p (struct cgraph_node *node);
 268
 269
 270 /* In ipa-inline-transform.c  */
 271 bool inline_call (struct cgraph_edge *, bool, vec<cgraph_edge *> *, int *, bool,
 272                   bool *callee_removed = NULL);
 273 unsigned int inline_transform (struct cgraph_node *);
 274 void clone_inlined_nodes (struct cgraph_edge *e, bool, bool, int *,
 275                           int freq_scale);
 276
 277 extern int ncalls_inlined;
 278 extern int nfunctions_inlined;
 279
 280 static inline struct inline_edge_summary *
 281 inline_edge_summary (struct cgraph_edge *edge)
 282 {
 283   return &inline_edge_summary_vec[edge->uid];
 284 }
 285
 286
 287 /* Return estimated size of the inline sequence of EDGE.  */
 288
 289 static inline int
 290 estimate_edge_size (struct cgraph_edge *edge)
 291 {
 292   int ret;
 293   if ((int)edge_growth_cache.length () <= edge->uid
 294       || !(ret = edge_growth_cache[edge->uid].size))
 295     return do_estimate_edge_size (edge);
 296   return ret - (ret > 0);
 297 }
 298
 299 /* Return estimated callee growth after inlining EDGE.  */
 300
 301 static inline int
 302 estimate_edge_growth (struct cgraph_edge *edge)
 303 {
 304   gcc_checking_assert (inline_edge_summary (edge)->call_stmt_size
 305                        || !edge->callee->analyzed);
 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 */