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 /* Output instructions as GIMPLE trees to increment the edge
  73    execution count, and insert them on E.  We rely on
  74    bsi_insert_on_edge to preserve the order.  */
  75
  76 static void
  77 tree_gen_edge_profiler (int edgeno, edge e)
  78 {
  79   tree tmp1 = create_tmp_var (GCOV_TYPE_NODE, "PROF");
  80   tree tmp2 = create_tmp_var (GCOV_TYPE_NODE, "PROF");
  81   tree ref = tree_coverage_counter_ref (GCOV_COUNTER_ARCS, edgeno);
  82   tree stmt1 = build (MODIFY_EXPR, GCOV_TYPE_NODE, tmp1, ref);
  83   tree stmt2 = build (MODIFY_EXPR, GCOV_TYPE_NODE, tmp2,
  84                       build (PLUS_EXPR, GCOV_TYPE_NODE,
  85                              tmp1, integer_one_node));
  86   tree stmt3 = build (MODIFY_EXPR, GCOV_TYPE_NODE, ref, tmp2);
  87   bsi_insert_on_edge (e, stmt1);
  88   bsi_insert_on_edge (e, stmt2);
  89   bsi_insert_on_edge (e, stmt3);
  90 }
  91
  92 /* Output instructions as GIMPLE trees to increment the interval histogram
  93    counter.  VALUE is the expression whose value is profiled.  TAG is the
  94    tag of the section for counters, BASE is offset of the counter position.  */
  95
  96 static void
  97 tree_gen_interval_profiler (struct histogram_value *value ATTRIBUTE_UNUSED,
  98                             unsigned tag ATTRIBUTE_UNUSED,
  99                             unsigned base ATTRIBUTE_UNUSED)
 100 {
 101   /* FIXME implement this.  */
 102   abort ();
 103 }
 104
 105 /* Output instructions as GIMPLE trees to increment the power of two histogram
 106    counter.  VALUE is the expression whose value is profiled.  TAG is the tag
 107    of the section for counters, BASE is offset of the counter position.  */
 108
 109 static void
 110 tree_gen_pow2_profiler (struct histogram_value *value ATTRIBUTE_UNUSED,
 111                         unsigned tag ATTRIBUTE_UNUSED,
 112                         unsigned base ATTRIBUTE_UNUSED)
 113 {
 114   /* FIXME implement this.  */
 115   abort ();
 116 }
 117
 118 /* Output instructions as GIMPLE trees for code to find the most common value.
 119    VALUE is the expression whose value is profiled.  TAG is the tag of the
 120    section for counters, BASE is offset of the counter position.  */
 121
 122 static void
 123 tree_gen_one_value_profiler (struct histogram_value *value ATTRIBUTE_UNUSED,
 124                             unsigned tag ATTRIBUTE_UNUSED,
 125                             unsigned base ATTRIBUTE_UNUSED)
 126 {
 127   /* FIXME implement this.  */
 128   abort ();
 129 }
 130
 131 /* Output instructions as GIMPLE trees for code to find the most common value
 132    of a difference between two evaluations of an expression.
 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_const_delta_profiler (struct histogram_value *value ATTRIBUTE_UNUSED,
 138                                 unsigned tag ATTRIBUTE_UNUSED,
 139                                 unsigned base ATTRIBUTE_UNUSED)
 140 {
 141   /* FIXME implement this.  */
 142   abort ();
 143 }
 144
 145 /* Return 1 if tree-based profiling is in effect, else 0.
 146    If it is, set up hooks for tree-based profiling.
 147    Gate for pass_tree_profile.  */
 148
 149 static bool do_tree_profiling (void) {
 150   if (flag_tree_based_profiling)
 151     {
 152       tree_register_profile_hooks ();
 153       tree_register_value_prof_hooks ();
 154     }
 155   return flag_tree_based_profiling;
 156 }
 157
 158 /* Return the file on which profile dump output goes, if any.  */
 159
 160 static FILE *tree_profile_dump_file (void) {
 161   return dump_file;
 162 }
 163
 164 struct tree_opt_pass pass_tree_profile =
 165 {
 166   "tree_profile",                       /* name */
 167   do_tree_profiling,                    /* gate */
 168   branch_prob,                          /* execute */
 169   NULL,                                 /* sub */
 170   NULL,                                 /* next */
 171   0,                                    /* static_pass_number */
 172   TV_BRANCH_PROB,                       /* tv_id */
 173   PROP_gimple_leh | PROP_cfg,           /* properties_required */
 174   PROP_gimple_leh | PROP_cfg,           /* properties_provided */
 175   0,                                    /* properties_destroyed */
 176   0,                                    /* todo_flags_start */
 177   TODO_verify_stmts                     /* todo_flags_finish */
 178 };
 179
 180 struct profile_hooks tree_profile_hooks =
 181 {
 182   tree_gen_edge_profiler,       /* gen_edge_profiler */
 183   tree_gen_interval_profiler,   /* gen_interval_profiler */
 184   tree_gen_pow2_profiler,       /* gen_pow2_profiler */
 185   tree_gen_one_value_profiler,  /* gen_one_value_profiler */
 186   tree_gen_const_delta_profiler,/* gen_const_delta_profiler */
 187   tree_profile_dump_file        /* profile_dump_file */
 188 };