218 lines
6.5 KiB
Modula-2
218 lines
6.5 KiB
Modula-2
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/* This file contains the list of the debug counter for GCC.
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Copyright (C) 2006-2023 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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/* A debug counter provides you a way to count an event
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and return false after the counter has exceeded the threshold
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specified by the option.
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What is it used for ?
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This is primarily used to speed up the search for the bad transformation
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an optimization pass does. By doing a binary search on N,
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you can quickly narrow down to one transformation
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which is bad, or which triggers the bad behavior downstream
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(usually in the form of the badly generated code).
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How does it work ?
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Every time dbg_cnt(named-counter) is called,
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the counter is incremented for the named-counter.
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And the incremented value is compared against the threshold (limit)
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specified by the option.
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dbg_cnt () returns true if it is at or below threshold, and false if above.
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How to add a new one ?
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To add a new counter, simply add an entry below with some descriptive name,
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and add call(s) to dbg_cnt(your-counter-name) in appropriate places.
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Usually, you want to control at the finest granularity
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any particular transformation can happen.
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e.g. for each instruction in a dead code elimination,
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or for each copy instruction in register coalescing,
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or constant-propagation for each insn,
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or a block straightening, etc.
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See dce.cc for an example. With the dbg_cnt () call in dce.cc,
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now a developer can use -fdbg-cnt=dce:N
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to stop doing the dead code elimination after N times.
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How to use it ?
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By default, all limits are UINT_MAX.
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Since debug count is unsigned int, <= UINT_MAX returns true always.
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i.e. dbg_cnt() returns true always regardless of the counter value
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(although it still counts the event).
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Use -fdbg-cnt=counter1:N,counter2:M,...
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which sets the limit for counter1 to N, and the limit for counter2 to M, etc.
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e.g. setting a limit to zero will make dbg_cnt () return false *always*.
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The following shell file can then be used to binary search for
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exact transformation that causes the bug. A second shell script
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should be written, say "tryTest", which exits with 1 if the
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compiled program fails and exits with 0 if the program succeeds.
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This shell script should take 1 parameter, the value to be passed
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to set the counter of the compilation command in tryTest. Then,
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assuming that the following script is called binarySearch,
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the command:
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binarySearch tryTest
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will automatically find the highest value of the counter for which
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the program fails. If tryTest never fails, binarySearch will
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produce unpredictable results as it will try to find an upper bound
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that does not exist.
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When dbgcnt does hits the limit, it writes a comment in the current
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dump_file of the form:
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***dbgcnt: limit reached for %s.***
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Assuming that the dump file is logging the analysis/transformations
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it is making, this pinpoints the exact position in the log file
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where the problem transformation is being logged.
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=====================================
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#!/bin/bash
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while getopts "l:u:i:" opt
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do
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case $opt in
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l) lb="$OPTARG";;
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u) ub="$OPTARG";;
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i) init="$OPTARG";;
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?) usage; exit 3;;
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esac
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done
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shift $(($OPTIND - 1))
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echo $@
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cmd=${1+"${@}"}
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lb=${lb:=0}
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init=${init:=100}
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$cmd $lb
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lb_val=$?
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if [ -z "$ub" ]; then
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# find the upper bound
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ub=$(($init + $lb))
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true
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while [ $? -eq $lb_val ]; do
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ub=$(($ub * 10))
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#ub=`expr $ub \* 10`
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$cmd $ub
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done
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fi
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echo command: $cmd
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true
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while [ `expr $ub - $lb` -gt 1 ]; do
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try=$(($lb + ( $ub - $lb ) / 2))
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$cmd $try
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if [ $? -eq $lb_val ]; then
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lb=$try
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else
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ub=$try
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fi
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done
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echo lbound: $lb
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echo ubound: $ub
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=====================================
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*/
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/* Debug counter definitions.
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Please keep the list sorted in alphabetic order. */
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DEBUG_COUNTER (asan_use_after_scope)
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DEBUG_COUNTER (auto_inc_dec)
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DEBUG_COUNTER (back_thread1)
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DEBUG_COUNTER (back_thread2)
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DEBUG_COUNTER (back_threadfull1)
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DEBUG_COUNTER (back_threadfull2)
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DEBUG_COUNTER (ccp)
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DEBUG_COUNTER (cfg_cleanup)
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DEBUG_COUNTER (cprop)
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DEBUG_COUNTER (cse2_move2add)
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DEBUG_COUNTER (dce)
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DEBUG_COUNTER (dce_fast)
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DEBUG_COUNTER (dce_ud)
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DEBUG_COUNTER (delete_trivial_dead)
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DEBUG_COUNTER (devirt)
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DEBUG_COUNTER (df_byte_scan)
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DEBUG_COUNTER (dom_unreachable_edges)
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DEBUG_COUNTER (dse)
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DEBUG_COUNTER (dse1)
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DEBUG_COUNTER (dse2)
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DEBUG_COUNTER (gcse2_delete)
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DEBUG_COUNTER (gimple_unroll)
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DEBUG_COUNTER (global_alloc_at_func)
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DEBUG_COUNTER (global_alloc_at_reg)
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DEBUG_COUNTER (graphite_scop)
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DEBUG_COUNTER (hoist)
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DEBUG_COUNTER (hoist_insn)
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DEBUG_COUNTER (ia64_sched2)
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DEBUG_COUNTER (if_after_combine)
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DEBUG_COUNTER (if_after_reload)
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DEBUG_COUNTER (if_conversion)
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DEBUG_COUNTER (if_conversion_tree)
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DEBUG_COUNTER (if_to_switch)
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DEBUG_COUNTER (ipa_attr)
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DEBUG_COUNTER (ipa_cp_bits)
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DEBUG_COUNTER (ipa_cp_values)
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DEBUG_COUNTER (ipa_cp_vr)
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DEBUG_COUNTER (ipa_mod_ref)
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DEBUG_COUNTER (ipa_mod_ref_pta)
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DEBUG_COUNTER (ipa_sra_params)
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DEBUG_COUNTER (ipa_sra_retvalues)
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DEBUG_COUNTER (ira_move)
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DEBUG_COUNTER (ivopts_loop)
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DEBUG_COUNTER (lim)
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DEBUG_COUNTER (local_alloc_for_sched)
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DEBUG_COUNTER (loop_unswitch)
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DEBUG_COUNTER (match)
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DEBUG_COUNTER (merged_ipa_icf)
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DEBUG_COUNTER (phiopt_edge_range)
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DEBUG_COUNTER (postreload_cse)
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DEBUG_COUNTER (pre)
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DEBUG_COUNTER (pre_insn)
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DEBUG_COUNTER (prefetch)
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DEBUG_COUNTER (registered_jump_thread)
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DEBUG_COUNTER (sched2_func)
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DEBUG_COUNTER (sched_block)
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DEBUG_COUNTER (sched_breakdep)
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DEBUG_COUNTER (sched_func)
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DEBUG_COUNTER (sched_insn)
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DEBUG_COUNTER (sched_region)
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DEBUG_COUNTER (sel_sched_cnt)
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DEBUG_COUNTER (sel_sched_insn_cnt)
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DEBUG_COUNTER (sel_sched_region_cnt)
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DEBUG_COUNTER (sms_sched_loop)
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DEBUG_COUNTER (split_for_sched2)
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DEBUG_COUNTER (store_merging)
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DEBUG_COUNTER (store_motion)
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DEBUG_COUNTER (stv_conversion)
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DEBUG_COUNTER (tail_call)
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DEBUG_COUNTER (tree_sra)
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DEBUG_COUNTER (treepre_insert)
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DEBUG_COUNTER (vect_loop)
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DEBUG_COUNTER (vect_slp)
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