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dbgcnt.def revision 1.1.1.8 
      1 /* This file contains the list of the debug counter for GCC.
      2    Copyright (C) 2006-2020 Free Software Foundation, Inc.
      3 
      4 This file is part of GCC.
      5 
      6 GCC is free software; you can redistribute it and/or modify it under
      7 the terms of the GNU General Public License as published by the Free
      8 Software Foundation; either version 3, or (at your option) any later
      9 version.
     10 
     11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
     12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14 for more details.
     15 
     16 You should have received a copy of the GNU General Public License
     17 along with GCC; see the file COPYING3.  If not see
     18 <http://www.gnu.org/licenses/>.  */
     19 
     20 
     21 /* A debug counter provides you a way to count an event
     22    and return false after the counter has exceeded the threshold
     23    specified by the option.
     24 
     25    What is it used for ?
     26 
     27    This is primarily used to speed up the search for the bad transformation
     28    an optimization pass does. By doing a binary search on N,
     29    you can quickly narrow down to one transformation
     30    which is bad, or which triggers the bad behavior downstream
     31    (usually in the form of the badly generated code).
     32 
     33    How does it work ?
     34 
     35    Every time dbg_cnt(named-counter) is called,
     36    the counter is incremented for the named-counter.
     37    And the incremented value is compared against the threshold (limit)
     38    specified by the option.
     39    dbg_cnt () returns true if it is at or below threshold, and false if above.
     40 
     41    How to add a new one ?
     42 
     43    To add a new counter, simply add an entry below with some descriptive name,
     44    and add call(s) to dbg_cnt(your-counter-name) in appropriate places.
     45    Usually, you want to control at the finest granularity
     46    any particular transformation can happen.
     47    e.g. for each instruction in a dead code elimination,
     48    or for each copy instruction in register coalescing,
     49    or constant-propagation for each insn,
     50    or a block straightening, etc.
     51    See dce.c for an example. With the dbg_cnt () call in dce.c,
     52    now a developer can use -fdbg-cnt=dce:N
     53    to stop doing the dead code elimination after N times.
     54 
     55    How to use it ?
     56 
     57    By default, all limits are UINT_MAX.
     58    Since debug count is unsigned int, <= UINT_MAX returns true always.
     59    i.e.  dbg_cnt() returns true always regardless of the counter value
     60    (although it still counts the event).
     61    Use -fdbg-cnt=counter1:N,counter2:M,...
     62    which sets the limit for counter1 to N, and the limit for counter2 to M, etc.
     63    e.g. setting a limit to zero will make dbg_cnt () return false *always*.
     64 
     65    The following shell file can then be used to binary search for
     66    exact transformation that causes the bug.  A second shell script
     67    should be written, say "tryTest", which exits with 1 if the
     68    compiled program fails and exits with 0 if the program succeeds.
     69    This shell script should take 1 parameter, the value to be passed
     70    to set the counter of the compilation command in tryTest.  Then,
     71    assuming that the following script is called binarySearch,
     72    the command:
     73 
     74 	binarySearch tryTest
     75 
     76    will automatically find the highest value of the counter for which
     77    the program fails.  If tryTest never fails, binarySearch will
     78    produce unpredictable results as it will try to find an upper bound
     79    that does not exist.
     80 
     81    When dbgcnt does hits the limit, it writes a comment in the current
     82    dump_file of the form:
     83 
     84        ***dbgcnt: limit reached for %s.***
     85 
     86    Assuming that the dump file is logging the analysis/transformations
     87    it is making, this pinpoints the exact position in the log file
     88    where the problem transformation is being logged.
     89 
     90 =====================================
     91 #!/bin/bash
     92 
     93 while getopts "l:u:i:" opt
     94 do
     95     case $opt in
     96         l) lb="$OPTARG";;
     97         u) ub="$OPTARG";;
     98         i) init="$OPTARG";;
     99         ?) usage; exit 3;;
    100     esac
    101 done
    102 
    103 shift $(($OPTIND - 1))
    104 echo $@
    105 cmd=${1+"${@}"}
    106 
    107 lb=${lb:=0}
    108 init=${init:=100}
    109 
    110 $cmd $lb
    111 lb_val=$?
    112 if [ -z "$ub" ]; then
    113     # find the upper bound
    114     ub=$(($init + $lb))
    115     true
    116     while [ $? -eq $lb_val ]; do
    117         ub=$(($ub * 10))
    118         #ub=`expr $ub \* 10`
    119         $cmd $ub
    120     done
    121 fi
    122 
    123 echo command: $cmd
    124 
    125 true
    126 while [ `expr $ub - $lb` -gt 1 ]; do
    127     try=$(($lb + ( $ub - $lb ) / 2))
    128     $cmd $try
    129     if [ $? -eq $lb_val ]; then
    130         lb=$try
    131     else
    132         ub=$try
    133     fi
    134 done
    135 
    136 echo lbound: $lb
    137 echo ubound: $ub
    138 
    139 =====================================
    140 
    141 */
    142 
    143 /* Debug counter definitions.
    144    Please keep the list sorted in alphabetic order.  */
    145 DEBUG_COUNTER (asan_use_after_scope)
    146 DEBUG_COUNTER (auto_inc_dec)
    147 DEBUG_COUNTER (ccp)
    148 DEBUG_COUNTER (cfg_cleanup)
    149 DEBUG_COUNTER (cprop)
    150 DEBUG_COUNTER (cse2_move2add)
    151 DEBUG_COUNTER (dce)
    152 DEBUG_COUNTER (dce_fast)
    153 DEBUG_COUNTER (dce_ud)
    154 DEBUG_COUNTER (delete_trivial_dead)
    155 DEBUG_COUNTER (devirt)
    156 DEBUG_COUNTER (df_byte_scan)
    157 DEBUG_COUNTER (dom_unreachable_edges)
    158 DEBUG_COUNTER (dse)
    159 DEBUG_COUNTER (dse1)
    160 DEBUG_COUNTER (dse2)
    161 DEBUG_COUNTER (gcse2_delete)
    162 DEBUG_COUNTER (gimple_unroll)
    163 DEBUG_COUNTER (global_alloc_at_func)
    164 DEBUG_COUNTER (global_alloc_at_reg)
    165 DEBUG_COUNTER (graphite_scop)
    166 DEBUG_COUNTER (hoist)
    167 DEBUG_COUNTER (hoist_insn)
    168 DEBUG_COUNTER (ia64_sched2)
    169 DEBUG_COUNTER (if_after_combine)
    170 DEBUG_COUNTER (if_after_reload)
    171 DEBUG_COUNTER (if_conversion)
    172 DEBUG_COUNTER (if_conversion_tree)
    173 DEBUG_COUNTER (ipa_sra_params)
    174 DEBUG_COUNTER (ipa_sra_retvalues)
    175 DEBUG_COUNTER (ira_move)
    176 DEBUG_COUNTER (ivopts_loop)
    177 DEBUG_COUNTER (local_alloc_for_sched)
    178 DEBUG_COUNTER (match)
    179 DEBUG_COUNTER (merged_ipa_icf)
    180 DEBUG_COUNTER (postreload_cse)
    181 DEBUG_COUNTER (pre)
    182 DEBUG_COUNTER (pre_insn)
    183 DEBUG_COUNTER (prefetch)
    184 DEBUG_COUNTER (registered_jump_thread)
    185 DEBUG_COUNTER (sched2_func)
    186 DEBUG_COUNTER (sched_block)
    187 DEBUG_COUNTER (sched_breakdep)
    188 DEBUG_COUNTER (sched_func)
    189 DEBUG_COUNTER (sched_insn)
    190 DEBUG_COUNTER (sched_region)
    191 DEBUG_COUNTER (sel_sched_cnt)
    192 DEBUG_COUNTER (sel_sched_insn_cnt)
    193 DEBUG_COUNTER (sel_sched_region_cnt)
    194 DEBUG_COUNTER (sms_sched_loop)
    195 DEBUG_COUNTER (split_for_sched2)
    196 DEBUG_COUNTER (store_merging)
    197 DEBUG_COUNTER (store_motion)
    198 DEBUG_COUNTER (stv_conversion)
    199 DEBUG_COUNTER (tail_call)
    200 DEBUG_COUNTER (tree_sra)
    201 DEBUG_COUNTER (treepre_insert)
    202 DEBUG_COUNTER (vect_loop)
    203 DEBUG_COUNTER (vect_slp)
    204