1/* This file contains the list of the debug counter for GCC. 2 Copyright (C) 2006-2021 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along 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 93while getopts "l:u:i:" opt 94do 95 case $opt in 96 l) lb="$OPTARG";; 97 u) ub="$OPTARG";; 98 i) init="$OPTARG";; 99 ?) usage; exit 3;; 100 esac 101done 102 103shift $(($OPTIND - 1)) 104echo $@ 105cmd=${1+"${@}"} 106 107lb=${lb:=0} 108init=${init:=100} 109 110$cmd $lb 111lb_val=$? 112if [ -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 121fi 122 123echo command: $cmd 124 125true 126while [ `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 134done 135 136echo lbound: $lb 137echo ubound: $ub 138 139===================================== 140 141*/ 142 143/* Debug counter definitions. 144 Please keep the list sorted in alphabetic order. */ 145DEBUG_COUNTER (asan_use_after_scope) 146DEBUG_COUNTER (auto_inc_dec) 147DEBUG_COUNTER (ccp) 148DEBUG_COUNTER (cfg_cleanup) 149DEBUG_COUNTER (cprop) 150DEBUG_COUNTER (cse2_move2add) 151DEBUG_COUNTER (dce) 152DEBUG_COUNTER (dce_fast) 153DEBUG_COUNTER (dce_ud) 154DEBUG_COUNTER (delete_trivial_dead) 155DEBUG_COUNTER (devirt) 156DEBUG_COUNTER (df_byte_scan) 157DEBUG_COUNTER (dom_unreachable_edges) 158DEBUG_COUNTER (dse) 159DEBUG_COUNTER (dse1) 160DEBUG_COUNTER (dse2) 161DEBUG_COUNTER (gcse2_delete) 162DEBUG_COUNTER (gimple_unroll) 163DEBUG_COUNTER (global_alloc_at_func) 164DEBUG_COUNTER (global_alloc_at_reg) 165DEBUG_COUNTER (graphite_scop) 166DEBUG_COUNTER (hoist) 167DEBUG_COUNTER (hoist_insn) 168DEBUG_COUNTER (ia64_sched2) 169DEBUG_COUNTER (if_after_combine) 170DEBUG_COUNTER (if_after_reload) 171DEBUG_COUNTER (if_conversion) 172DEBUG_COUNTER (if_conversion_tree) 173DEBUG_COUNTER (if_to_switch) 174DEBUG_COUNTER (ipa_cp_bits) 175DEBUG_COUNTER (ipa_cp_values) 176DEBUG_COUNTER (ipa_cp_vr) 177DEBUG_COUNTER (ipa_mod_ref) 178DEBUG_COUNTER (ipa_sra_params) 179DEBUG_COUNTER (ipa_sra_retvalues) 180DEBUG_COUNTER (ira_move) 181DEBUG_COUNTER (ivopts_loop) 182DEBUG_COUNTER (lim) 183DEBUG_COUNTER (local_alloc_for_sched) 184DEBUG_COUNTER (match) 185DEBUG_COUNTER (merged_ipa_icf) 186DEBUG_COUNTER (postreload_cse) 187DEBUG_COUNTER (pre) 188DEBUG_COUNTER (pre_insn) 189DEBUG_COUNTER (prefetch) 190DEBUG_COUNTER (registered_jump_thread) 191DEBUG_COUNTER (sched2_func) 192DEBUG_COUNTER (sched_block) 193DEBUG_COUNTER (sched_breakdep) 194DEBUG_COUNTER (sched_func) 195DEBUG_COUNTER (sched_insn) 196DEBUG_COUNTER (sched_region) 197DEBUG_COUNTER (sel_sched_cnt) 198DEBUG_COUNTER (sel_sched_insn_cnt) 199DEBUG_COUNTER (sel_sched_region_cnt) 200DEBUG_COUNTER (sms_sched_loop) 201DEBUG_COUNTER (split_for_sched2) 202DEBUG_COUNTER (store_merging) 203DEBUG_COUNTER (store_motion) 204DEBUG_COUNTER (stv_conversion) 205DEBUG_COUNTER (tail_call) 206DEBUG_COUNTER (tree_sra) 207DEBUG_COUNTER (treepre_insert) 208DEBUG_COUNTER (vect_loop) 209DEBUG_COUNTER (vect_slp) 210