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binutils-gdb/gold/testsuite/pie_copyrelocs_shared_test.cc

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Optimizing accesses to Globals with -fpie -pie: With -pie and x86, the linker complains if it sees a PC-relative relocation to access a global as it expects a GOTPCREL relocation. This is really not necessary as the linker could use a copy relocation to get around it. This patch enables copy relocations with pie. Context: This is useful because currently the GCC compiler with option -fpie makes every extern global access go through the GOT. That is because the compiler cannot tell if a global will end up being defined in the executable or not and is conservative. This ends up hurting performance when the binary is linked as mostly static where most of the globals do end up being defined in the executable. By allowing copy relocs with fPIE, the compiler need not generate a GOTPCREL(GOT access) for any global access. It can safely assume that all globals will be defined in the executable and generate a PC-relative access instead. Gold can then create a copy reloc for only the undefined globals.
2014-05-14 01:33:59 +08:00
// pie_copyrelocs_shared_test.cc -- a test case for gold, used
// by pie_copyrelocs_test
Update year range in copyright notice of binutils files
2018-01-03 13:17:27 +08:00
// Copyright (C) 2014-2018 Free Software Foundation, Inc.
Optimizing accesses to Globals with -fpie -pie: With -pie and x86, the linker complains if it sees a PC-relative relocation to access a global as it expects a GOTPCREL relocation. This is really not necessary as the linker could use a copy relocation to get around it. This patch enables copy relocations with pie. Context: This is useful because currently the GCC compiler with option -fpie makes every extern global access go through the GOT. That is because the compiler cannot tell if a global will end up being defined in the executable or not and is conservative. This ends up hurting performance when the binary is linked as mostly static where most of the globals do end up being defined in the executable. By allowing copy relocs with fPIE, the compiler need not generate a GOTPCREL(GOT access) for any global access. It can safely assume that all globals will be defined in the executable and generate a PC-relative access instead. Gold can then create a copy reloc for only the undefined globals.
2014-05-14 01:33:59 +08:00
// Written by Sriraman Tallam <tmsriram@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
int glob_a = 128;
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