gcc/ipa-inline.h

   1 /* Inlining decision heuristics.
   2    Copyright (C) 2003-2014 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 #include "ipa-prop.h"
  22
  23 /* Representation of inline parameters that do depend on context function is
  24    inlined into (i.e. known constant values of function parameters.
  25
  26    Conditions that are interesting for function body are collected into CONDS
  27    vector.  They are of simple for  function_param OP VAL, where VAL is
  28    IPA invariant.  The conditions are then referred by predicates.  */
  29
  30 struct GTY(()) condition
  31 {
  32   /* If agg_contents is set, this is the offset from which the used data was
  33      loaded.  */
  34   HOST_WIDE_INT offset;
  35   tree val;
  36   int operand_num;
  37   ENUM_BITFIELD(tree_code) code : 16;
  38   /* Set if the used data were loaded from an aggregate parameter or from
  39      data received by reference.  */
  40   unsigned agg_contents : 1;
  41   /* If agg_contents is set, this differentiates between loads from data
  42      passed by reference and by value.  */
  43   unsigned by_ref : 1;
  44 };
  45
  46 /* Inline hints are reasons why inline heuristics should preffer inlining given
  47    function.  They are represtented as bitmap of the following values.  */
  48 enum inline_hints_vals {
  49   /* When inlining turns indirect call into a direct call,
  50      it is good idea to do so.  */
  51   INLINE_HINT_indirect_call = 1,
  52   /* Inlining may make loop iterations or loop stride known.  It is good idea
  53      to do so because it enables loop optimizatoins.  */
  54   INLINE_HINT_loop_iterations = 2,
  55   INLINE_HINT_loop_stride = 4,
  56   /* Inlining within same strongly connected component of callgraph is often
  57      a loss due to increased stack frame usage and prologue setup costs.  */
  58   INLINE_HINT_same_scc = 8,
  59   /* Inlining functions in strongly connected component is not such a great
  60      win.  */
  61   INLINE_HINT_in_scc = 16,
  62   /* If function is declared inline by user, it may be good idea to inline
  63      it.  */
  64   INLINE_HINT_declared_inline = 32,
  65   /* Programs are usually still organized for non-LTO compilation and thus
  66      if functions are in different modules, inlining may not be so important.
  67    */
  68   INLINE_HINT_cross_module = 64,
  69   /* If array indexes of loads/stores become known there may be room for
  70      further optimization.  */
  71   INLINE_HINT_array_index = 128
  72 };
  73 typedef int inline_hints;
  74
  75
  76 typedef vec<condition, va_gc> *conditions;
  77
  78 /* Representation of predicates i.e. formulas using conditions defined
  79    above.  Predicates are simple logical formulas in conjunctive-disjunctive
  80    form.
  81
  82    Predicate is array of clauses terminated by 0.  Every clause must be true
  83    in order to make predicate true.
  84    Clauses are represented as bitmaps of conditions. One of conditions
  85    must be true in order for clause to be true.  */
  86
  87 #define MAX_CLAUSES 8
  88 typedef unsigned int clause_t;
  89 struct GTY(()) predicate
  90 {
  91   clause_t clause[MAX_CLAUSES + 1];
  92 };
  93
  94 /* Represnetation of function body size and time depending on the inline
  95    context.  We keep simple array of record, every containing of predicate
  96    and time/size to account.
  97
  98    We keep values scaled up, so fractional sizes and times can be
  99    accounted.  */
 100 #define INLINE_SIZE_SCALE 2
 101 #define INLINE_TIME_SCALE (CGRAPH_FREQ_BASE * 2)
 102 struct GTY(()) size_time_entry
 103 {
 104   struct predicate predicate;
 105   int size;
 106   int time;
 107 };
 108
 109 /* Function inlining information.  */
 110 struct GTY(()) inline_summary
 111 {
 112   /* Information about the function body itself.  */
 113
 114   /* Estimated stack frame consumption by the function.  */
 115   HOST_WIDE_INT estimated_self_stack_size;
 116   /* Size of the function body.  */
 117   int self_size;
 118   /* Time of the function body.  */
 119   int self_time;
 120
 121   /* False when there something makes inlining impossible (such as va_arg).  */
 122   unsigned inlinable : 1;
 123
 124   /* Information about function that will result after applying all the
 125      inline decisions present in the callgraph.  Generally kept up to
 126      date only for functions that are not inline clones. */
 127
 128   /* Estimated stack frame consumption by the function.  */
 129   HOST_WIDE_INT estimated_stack_size;
 130   /* Expected offset of the stack frame of inlined function.  */
 131   HOST_WIDE_INT stack_frame_offset;
 132   /* Estimated size of the function after inlining.  */
 133   int time;
 134   int size;
 135
 136   /* Conditional size/time information.  The summaries are being
 137      merged during inlining.  */
 138   conditions conds;
 139   vec<size_time_entry, va_gc> *entry;
 140
 141   /* Predicate on when some loop in the function becomes to have known
 142      bounds.   */
 143   struct predicate * GTY((skip)) loop_iterations;
 144   /* Predicate on when some loop in the function becomes to have known
 145      stride.   */
 146   struct predicate * GTY((skip)) loop_stride;
 147   /* Predicate on when some array indexes become constants.  */
 148   struct predicate * GTY((skip)) array_index;
 149   /* Estimated growth for inlining all copies of the function before start
 150      of small functions inlining.
 151      This value will get out of date as the callers are duplicated, but
 152      using up-to-date value in the badness metric mean a lot of extra
 153      expenses.  */
 154   int growth;
 155   /* Number of SCC on the beginning of inlining process.  */
 156   int scc_no;
 157 };
 158
 159 /* Need a typedef for inline_summary because of inline function
 160    'inline_summary' below.  */
 161 typedef struct inline_summary inline_summary_t;
 162 extern GTY(()) vec<inline_summary_t, va_gc> *inline_summary_vec;
 163
 164 /* Information kept about parameter of call site.  */
 165 struct inline_param_summary
 166 {
 167   /* REG_BR_PROB_BASE based probability that parameter will change in between
 168      two invocation of the calls.
 169      I.e. loop invariant parameters
 170      REG_BR_PROB_BASE/estimated_iterations and regular
 171      parameters REG_BR_PROB_BASE.
 172
 173      Value 0 is reserved for compile time invariants. */
 174   int change_prob;
 175 };
 176
 177 /* Information kept about callgraph edges.  */
 178 struct inline_edge_summary
 179 {
 180   /* Estimated size and time of the call statement.  */
 181   int call_stmt_size;
 182   int call_stmt_time;
 183   /* Depth of loop nest, 0 means no nesting.  */
 184   unsigned short int loop_depth;
 185   struct predicate *predicate;
 186   /* Array indexed by parameters.
 187      0 means that parameter change all the time, REG_BR_PROB_BASE means
 188      that parameter is constant.  */
 189   vec<inline_param_summary> param;
 190 };
 191
 192 /* Need a typedef for inline_edge_summary because of inline function
 193    'inline_edge_summary' below.  */
 194 typedef struct inline_edge_summary inline_edge_summary_t;
 195 extern vec<inline_edge_summary_t> inline_edge_summary_vec;
 196
 197 struct edge_growth_cache_entry
 198 {
 199   int time, size;
 200   inline_hints hints;
 201 };
 202
 203 extern vec<int> node_growth_cache;
 204 extern vec<edge_growth_cache_entry> edge_growth_cache;
 205
 206 /* In ipa-inline-analysis.c  */
 207 void debug_inline_summary (struct cgraph_node *);
 208 void dump_inline_summaries (FILE *f);
 209 void dump_inline_summary (FILE *f, struct cgraph_node *node);
 210 void dump_inline_hints (FILE *f, inline_hints);
 211 void inline_generate_summary (void);
 212 void inline_read_summary (void);
 213 void inline_write_summary (void);
 214 void inline_free_summary (void);
 215 void initialize_inline_failed (struct cgraph_edge *);
 216 int estimate_time_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 217 int estimate_size_after_inlining (struct cgraph_node *, struct cgraph_edge *);
 218 void estimate_ipcp_clone_size_and_time (struct cgraph_node *,
 219                                         vec<tree>,  vec<tree>,
 220                                         vec<ipa_agg_jump_function_p>,
 221                                         int *, int *, inline_hints *);
 222 int do_estimate_growth (struct cgraph_node *);
 223 void inline_merge_summary (struct cgraph_edge *edge);
 224 void inline_update_overall_summary (struct cgraph_node *node);
 225 int do_estimate_edge_size (struct cgraph_edge *edge);
 226 int do_estimate_edge_time (struct cgraph_edge *edge);
 227 inline_hints do_estimate_edge_hints (struct cgraph_edge *edge);
 228 void initialize_growth_caches (void);
 229 void free_growth_caches (void);
 230 void compute_inline_parameters (struct cgraph_node *, bool);
 231 bool speculation_useful_p (struct cgraph_edge *e, bool anticipate_inlining);
 232
 233 /* In ipa-inline-transform.c  */
 234 bool inline_call (struct cgraph_edge *, bool, vec<cgraph_edge_p> *, int *, bool);
 235 unsigned int inline_transform (struct cgraph_node *);
 236 void clone_inlined_nodes (struct cgraph_edge *e, bool, bool, int *);
 237
 238 extern int ncalls_inlined;
 239 extern int nfunctions_inlined;
 240
 241 static inline struct inline_summary *
 242 inline_summary (struct cgraph_node *node)
 243 {
 244   return &(*inline_summary_vec)[node->uid];
 245 }
 246
 247 static inline struct inline_edge_summary *
 248 inline_edge_summary (struct cgraph_edge *edge)
 249 {
 250   return &inline_edge_summary_vec[edge->uid];
 251 }
 252
 253 /* Return estimated unit growth after inlning all calls to NODE.
 254    Quick accesors to the inline growth caches.
 255    For convenience we keep zero 0 as unknown.  Because growth
 256    can be both positive and negative, we simply increase positive
 257    growths by 1. */
 258 static inline int
 259 estimate_growth (struct cgraph_node *node)
 260 {
 261   int ret;
 262   if ((int)node_growth_cache.length () <= node->uid
 263       || !(ret = node_growth_cache[node->uid]))
 264     return do_estimate_growth (node);
 265   return ret - (ret > 0);
 266 }
 267
 268
 269 /* Return estimated size of the inline sequence of EDGE.  */
 270
 271 static inline int
 272 estimate_edge_size (struct cgraph_edge *edge)
 273 {
 274   int ret;
 275   if ((int)edge_growth_cache.length () <= edge->uid
 276       || !(ret = edge_growth_cache[edge->uid].size))
 277     return do_estimate_edge_size (edge);
 278   return ret - (ret > 0);
 279 }
 280
 281 /* Return estimated callee growth after inlining EDGE.  */
 282
 283 static inline int
 284 estimate_edge_growth (struct cgraph_edge *edge)
 285 {
 286 #ifdef ENABLE_CHECKING
 287   gcc_checking_assert (inline_edge_summary (edge)->call_stmt_size);
 288 #endif
 289   return (estimate_edge_size (edge)
 290           - inline_edge_summary (edge)->call_stmt_size);
 291 }
 292
 293 /* Return estimated callee runtime increase after inlning
 294    EDGE.  */
 295
 296 static inline int
 297 estimate_edge_time (struct cgraph_edge *edge)
 298 {
 299   int ret;
 300   if ((int)edge_growth_cache.length () <= edge->uid
 301       || !(ret =  edge_growth_cache[edge->uid].time))
 302     return do_estimate_edge_time (edge);
 303   return ret - (ret > 0);
 304 }
 305
 306
 307 /* Return estimated callee runtime increase after inlning
 308    EDGE.  */
 309
 310 static inline inline_hints
 311 estimate_edge_hints (struct cgraph_edge *edge)
 312 {
 313   inline_hints ret;
 314   if ((int)edge_growth_cache.length () <= edge->uid
 315       || !(ret = edge_growth_cache[edge->uid].hints))
 316     return do_estimate_edge_hints (edge);
 317   return ret - 1;
 318 }
 319
 320
 321 /* Reset cached value for NODE.  */
 322
 323 static inline void
 324 reset_node_growth_cache (struct cgraph_node *node)
 325 {
 326   if ((int)node_growth_cache.length () > node->uid)
 327     node_growth_cache[node->uid] = 0;
 328 }
 329
 330 /* Reset cached value for EDGE.  */
 331
 332 static inline void
 333 reset_edge_growth_cache (struct cgraph_edge *edge)
 334 {
 335   if ((int)edge_growth_cache.length () > edge->uid)
 336     {
 337       struct edge_growth_cache_entry zero = {0, 0, 0};
 338       edge_growth_cache[edge->uid] = zero;
 339     }
 340 }