<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Unfortunately I do not have an answer or workaround, but I want to add that I am also hitting this issue. The performance of --keep-symbols with a large list of symbols is quite slow.<div class=""><br class=""></div><div class="">Have you filed a bug to track this?<br class=""><div class=""><br class=""></div><div class="">(For other reasons in my specific case I cannot fall back to GNU objcopy, so this performance penalty must be paid today.)</div><div class=""><br class=""></div><div class="">Thanks,</div><div class=""><br class=""></div><div class="">Justin<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On May 18, 2021, at 12:11 AM, Brian Cain via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta charset="UTF-8" class=""><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">While investigating an issue with android build performance, I found that llvm-objcopy performance is far from parity with GNU objcopy for the “--keep-symbols” case, when the keep symbols list is very large.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">I can see that llvm objcopy creates a list of NameOrPattern-s to represent the keep symbol list, but it looks like it exhaustively compares each symbol in the keep list against each symbol in the input file. Not sure what GNU objcopy does but merging the non-pattern symbol names into a sorted list would make searching much faster.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Below is a script to reproduce the problem and its output. The test case below demonstrates a significant performance difference. The android build failure case reported had a shared obj with ~700k symbols and the keep list was ~300k symbols and it took ~8 minutes to execute.<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">~~~<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">#!/bin/bash<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">set -euo pipefail<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo creating init file<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo <<EOF > input.S<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">.section .text<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">EOF<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo '' > keep_syms.txt<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">for i in $(seq 0 100000)<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">do<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> echo -e "sym_${i}:\nnop\n" >> input.S<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> if [[ ${i} -lt 30000 ]]; then<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> echo "sym_${i}" >> keep_syms.txt<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> fi<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">done<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo <<EOF >> input.S<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">.section .ballast<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">nop<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">EOF<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo creating obj file<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">llvm-mc -triple arm-linux-androideabi -filetype=obj input.S -o out.o<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo creating shared obj file<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">ld.lld -shared out.o -o libtestcase.so<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo performing llvm objcopy<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">\time llvm-objcopy -S --remove-section .ballast \<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> --keep-symbols=keep_syms.txt \<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> libtestcase.so libtestcase_smaller.so<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">echo performing GNU objcopy<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">\time arm-linux-androideabi-objcopy -S --remove-section .ballast \<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> --keep-symbols=keep_syms.txt \<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""> libtestcase.so libtestcase_smaller.so<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">~~~<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Here’s the output I get when I run it on ToT-within-last-week-or-so:<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">$ PATH=$PWD/bin:$PATH ../../tmp/qt66370/32/objcopy_perf.sh<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">creating init file<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">creating obj file<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">creating shared obj file<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">ld.lld: warning: lld uses blx instruction, no object with architecture supporting feature detected<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">performing llvm objcopy<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">12.34user 0.00system 0:12.35elapsed 99%CPU (0avgtext+0avgdata 20228maxresident)k<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">0inputs+2288outputs (0major+3815minor)pagefaults 0swaps<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">performing GNU objcopy<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">0.03user 0.00system 0:00.04elapsed 97%CPU (0avgtext+0avgdata 20396maxresident)k<o:p class=""></o:p></div><div style="margin: 0in 0in 0in 0.5in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">0inputs+2288outputs (0major+5895minor)pagefaults 0swaps<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">Alternate access to the script above:<o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><a href="https://gist.github.com/androm3da/83560d92f3fe637b58aa115ba6b68456" style="color: rgb(5, 99, 193); text-decoration: underline;" class="">https://gist.github.com/androm3da/83560d92f3fe637b58aa115ba6b68456</a><o:p class=""></o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class=""><o:p class=""> </o:p></div><div style="margin: 0in; font-size: 11pt; font-family: Calibri, sans-serif;" class="">-Brian<o:p class=""></o:p></div></div><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">_______________________________________________</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; 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