gcc/tree-profile.c

   1 /* Calculate branch probabilities, and basic block execution counts.
   2    Copyright (C) 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998, 1999,
   3    2000, 2001, 2002, 2003, 2004  Free Software Foundation, Inc.
   4    Contributed by James E. Wilson, UC Berkeley/Cygnus Support;
   5    based on some ideas from Dain Samples of UC Berkeley.
   6    Further mangling by Bob Manson, Cygnus Support.
   7    Converted to use trees by Dale Johannesen, Apple Computer.
   8
   9 This file is part of GCC.
  10
  11 GCC is free software; you can redistribute it and/or modify it under
  12 the terms of the GNU General Public License as published by the Free
  13 Software Foundation; either version 2, or (at your option) any later
  14 version.
  15
  16 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  17 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19 for more details.
  20
  21 You should have received a copy of the GNU General Public License
  22 along with GCC; see the file COPYING.  If not, write to the Free
  23 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  24 02111-1307, USA.  */
  25
  26 /* Generate basic block profile instrumentation and auxiliary files.
  27    Profile generation is optimized, so that not all arcs in the basic
  28    block graph need instrumenting. First, the BB graph is closed with
  29    one entry (function start), and one exit (function exit).  Any
  30    ABNORMAL_EDGE cannot be instrumented (because there is no control
  31    path to place the code). We close the graph by inserting fake
  32    EDGE_FAKE edges to the EXIT_BLOCK, from the sources of abnormal
  33    edges that do not go to the exit_block. We ignore such abnormal
  34    edges.  Naturally these fake edges are never directly traversed,
  35    and so *cannot* be directly instrumented.  Some other graph
  36    massaging is done. To optimize the instrumentation we generate the
  37    BB minimal span tree, only edges that are not on the span tree
  38    (plus the entry point) need instrumenting. From that information
  39    all other edge counts can be deduced.  By construction all fake
  40    edges must be on the spanning tree. We also attempt to place
  41    EDGE_CRITICAL edges on the spanning tree.
  42
  43    The auxiliary file generated is <dumpbase>.bbg. The format is
  44    described in full in gcov-io.h.  */
  45
  46 /* ??? Register allocation should use basic block execution counts to
  47    give preference to the most commonly executed blocks.  */
  48
  49 /* ??? Should calculate branch probabilities before instrumenting code, since
  50    then we can use arc counts to help decide which arcs to instrument.  */
  51
  52 #include "config.h"
  53 #include "system.h"
  54 #include "coretypes.h"
  55 #include "tm.h"
  56 #include "rtl.h"
  57 #include "flags.h"
  58 #include "output.h"
  59 #include "regs.h"
  60 #include "expr.h"
  61 #include "function.h"
  62 #include "toplev.h"
  63 #include "coverage.h"
  64 #include "tree.h"
  65 #include "tree-flow.h"
  66 #include "tree-dump.h"
  67 #include "tree-pass.h"
  68 #include "timevar.h"
  69 #include "value-prof.h"
  70
  71 \f
  72
  73 /* Do initialization work for the edge profiler.  */
  74
  75 static void
  76 tree_init_edge_profiler (void)
  77 {
  78 }
  79
  80 /* Output instructions as GIMPLE trees to increment the edge
  81    execution count, and insert them on E.  We rely on
  82    bsi_insert_on_edge to preserve the order.  */
  83
  84 static void
  85 tree_gen_edge_profiler (int edgeno, edge e)
  86 {
  87   tree tmp1 = create_tmp_var (GCOV_TYPE_NODE, "PROF");
  88   tree tmp2 = create_tmp_var (GCOV_TYPE_NODE, "PROF");
  89   tree ref = tree_coverage_counter_ref (GCOV_COUNTER_ARCS, edgeno);
  90   tree stmt1 = build (MODIFY_EXPR, GCOV_TYPE_NODE, tmp1, ref);
  91   tree stmt2 = build (MODIFY_EXPR, GCOV_TYPE_NODE, tmp2,
  92                       build (PLUS_EXPR, GCOV_TYPE_NODE,
  93                              tmp1, integer_one_node));
  94   tree stmt3 = build (MODIFY_EXPR, GCOV_TYPE_NODE, ref, tmp2);
  95   bsi_insert_on_edge (e, stmt1);
  96   bsi_insert_on_edge (e, stmt2);
  97   bsi_insert_on_edge (e, stmt3);
  98 }
  99
 100 /* Output instructions as GIMPLE trees to increment the interval histogram
 101    counter.  VALUE is the expression whose value is profiled.  TAG is the
 102    tag of the section for counters, BASE is offset of the counter position.  */
 103
 104 static void
 105 tree_gen_interval_profiler (histogram_value value ATTRIBUTE_UNUSED,
 106                             unsigned tag ATTRIBUTE_UNUSED,
 107                             unsigned base ATTRIBUTE_UNUSED)
 108 {
 109   /* FIXME implement this.  */
 110 #ifdef ENABLE_CHECKING
 111   internal_error ("unimplemented functionality");
 112 #endif
 113   gcc_unreachable ();
 114 }
 115
 116 /* Output instructions as GIMPLE trees to increment the power of two histogram
 117    counter.  VALUE is the expression whose value is profiled.  TAG is the tag
 118    of the section for counters, BASE is offset of the counter position.  */
 119
 120 static void
 121 tree_gen_pow2_profiler (histogram_value value ATTRIBUTE_UNUSED,
 122                         unsigned tag ATTRIBUTE_UNUSED,
 123                         unsigned base ATTRIBUTE_UNUSED)
 124 {
 125   /* FIXME implement this.  */
 126 #ifdef ENABLE_CHECKING
 127   internal_error ("unimplemented functionality");
 128 #endif
 129   gcc_unreachable ();
 130 }
 131
 132 /* Output instructions as GIMPLE trees for code to find the most common value.
 133    VALUE is the expression whose value is profiled.  TAG is the tag of the
 134    section for counters, BASE is offset of the counter position.  */
 135
 136 static void
 137 tree_gen_one_value_profiler (histogram_value value ATTRIBUTE_UNUSED,
 138                             unsigned tag ATTRIBUTE_UNUSED,
 139                             unsigned base ATTRIBUTE_UNUSED)
 140 {
 141   /* FIXME implement this.  */
 142 #ifdef ENABLE_CHECKING
 143   internal_error ("unimplemented functionality");
 144 #endif
 145   gcc_unreachable ();
 146 }
 147
 148 /* Output instructions as GIMPLE trees for code to find the most common value
 149    of a difference between two evaluations of an expression.
 150    VALUE is the expression whose value is profiled.  TAG is the tag of the
 151    section for counters, BASE is offset of the counter position.  */
 152
 153 static void
 154 tree_gen_const_delta_profiler (histogram_value value ATTRIBUTE_UNUSED,
 155                                 unsigned tag ATTRIBUTE_UNUSED,
 156                                 unsigned base ATTRIBUTE_UNUSED)
 157 {
 158   /* FIXME implement this.  */
 159 #ifdef ENABLE_CHECKING
 160   internal_error ("unimplemented functionality");
 161 #endif
 162   gcc_unreachable ();
 163 }
 164
 165 /* Return 1 if tree-based profiling is in effect, else 0.
 166    If it is, set up hooks for tree-based profiling.
 167    Gate for pass_tree_profile.  */
 168
 169 static bool do_tree_profiling (void)
 170 {
 171   if (flag_tree_based_profiling
 172       && (profile_arc_flag || flag_test_coverage || flag_branch_probabilities))
 173     {
 174       tree_register_profile_hooks ();
 175       tree_register_value_prof_hooks ();
 176       return true;
 177     }
 178   return false;
 179 }
 180
 181 /* Return the file on which profile dump output goes, if any.  */
 182
 183 static FILE *tree_profile_dump_file (void) {
 184   return dump_file;
 185 }
 186
 187 struct tree_opt_pass pass_tree_profile =
 188 {
 189   "tree_profile",                       /* name */
 190   do_tree_profiling,                    /* gate */
 191   branch_prob,                          /* execute */
 192   NULL,                                 /* sub */
 193   NULL,                                 /* next */
 194   0,                                    /* static_pass_number */
 195   TV_BRANCH_PROB,                       /* tv_id */
 196   PROP_gimple_leh | PROP_cfg,           /* properties_required */
 197   PROP_gimple_leh | PROP_cfg,           /* properties_provided */
 198   0,                                    /* properties_destroyed */
 199   0,                                    /* todo_flags_start */
 200   TODO_verify_stmts,                    /* todo_flags_finish */
 201   0                                     /* letter */
 202 };
 203
 204 struct profile_hooks tree_profile_hooks =
 205 {
 206   tree_init_edge_profiler,      /* init_edge_profiler */
 207   tree_gen_edge_profiler,       /* gen_edge_profiler */
 208   tree_gen_interval_profiler,   /* gen_interval_profiler */
 209   tree_gen_pow2_profiler,       /* gen_pow2_profiler */
 210   tree_gen_one_value_profiler,  /* gen_one_value_profiler */
 211   tree_gen_const_delta_profiler,/* gen_const_delta_profiler */
 212   tree_profile_dump_file        /* profile_dump_file */
 213 };