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 (histogram_value value ATTRIBUTE_UNUSED,
  98                             unsigned tag ATTRIBUTE_UNUSED,
  99                             unsigned base ATTRIBUTE_UNUSED)
 100 {
 101   /* FIXME implement this.  */
 102 #ifdef ENABLE_CHECKING
 103   internal_error ("unimplemented functionality");
 104 #endif
 105   gcc_unreachable ();
 106 }
 107
 108 /* Output instructions as GIMPLE trees to increment the power of two histogram
 109    counter.  VALUE is the expression whose value is profiled.  TAG is the tag
 110    of the section for counters, BASE is offset of the counter position.  */
 111
 112 static void
 113 tree_gen_pow2_profiler (histogram_value value ATTRIBUTE_UNUSED,
 114                         unsigned tag ATTRIBUTE_UNUSED,
 115                         unsigned base ATTRIBUTE_UNUSED)
 116 {
 117   /* FIXME implement this.  */
 118 #ifdef ENABLE_CHECKING
 119   internal_error ("unimplemented functionality");
 120 #endif
 121   gcc_unreachable ();
 122 }
 123
 124 /* Output instructions as GIMPLE trees for code to find the most common value.
 125    VALUE is the expression whose value is profiled.  TAG is the tag of the
 126    section for counters, BASE is offset of the counter position.  */
 127
 128 static void
 129 tree_gen_one_value_profiler (histogram_value value ATTRIBUTE_UNUSED,
 130                             unsigned tag ATTRIBUTE_UNUSED,
 131                             unsigned base ATTRIBUTE_UNUSED)
 132 {
 133   /* FIXME implement this.  */
 134 #ifdef ENABLE_CHECKING
 135   internal_error ("unimplemented functionality");
 136 #endif
 137   gcc_unreachable ();
 138 }
 139
 140 /* Output instructions as GIMPLE trees for code to find the most common value
 141    of a difference between two evaluations of an expression.
 142    VALUE is the expression whose value is profiled.  TAG is the tag of the
 143    section for counters, BASE is offset of the counter position.  */
 144
 145 static void
 146 tree_gen_const_delta_profiler (histogram_value value ATTRIBUTE_UNUSED,
 147                                 unsigned tag ATTRIBUTE_UNUSED,
 148                                 unsigned base ATTRIBUTE_UNUSED)
 149 {
 150   /* FIXME implement this.  */
 151 #ifdef ENABLE_CHECKING
 152   internal_error ("unimplemented functionality");
 153 #endif
 154   gcc_unreachable ();
 155 }
 156
 157 /* Return 1 if tree-based profiling is in effect, else 0.
 158    If it is, set up hooks for tree-based profiling.
 159    Gate for pass_tree_profile.  */
 160
 161 static bool do_tree_profiling (void)
 162 {
 163   if (flag_tree_based_profiling)
 164     {
 165       tree_register_profile_hooks ();
 166       tree_register_value_prof_hooks ();
 167     }
 168   return flag_tree_based_profiling;
 169 }
 170
 171 /* Return the file on which profile dump output goes, if any.  */
 172
 173 static FILE *tree_profile_dump_file (void) {
 174   return dump_file;
 175 }
 176
 177 struct tree_opt_pass pass_tree_profile =
 178 {
 179   "tree_profile",                       /* name */
 180   do_tree_profiling,                    /* gate */
 181   branch_prob,                          /* execute */
 182   NULL,                                 /* sub */
 183   NULL,                                 /* next */
 184   0,                                    /* static_pass_number */
 185   TV_BRANCH_PROB,                       /* tv_id */
 186   PROP_gimple_leh | PROP_cfg,           /* properties_required */
 187   PROP_gimple_leh | PROP_cfg,           /* properties_provided */
 188   0,                                    /* properties_destroyed */
 189   0,                                    /* todo_flags_start */
 190   TODO_verify_stmts,                    /* todo_flags_finish */
 191   0                                     /* letter */
 192 };
 193
 194 struct profile_hooks tree_profile_hooks =
 195 {
 196   tree_gen_edge_profiler,       /* gen_edge_profiler */
 197   tree_gen_interval_profiler,   /* gen_interval_profiler */
 198   tree_gen_pow2_profiler,       /* gen_pow2_profiler */
 199   tree_gen_one_value_profiler,  /* gen_one_value_profiler */
 200   tree_gen_const_delta_profiler,/* gen_const_delta_profiler */
 201   tree_profile_dump_file        /* profile_dump_file */
 202 };