Fix problem where gold fails to issue an undefined symbol error during LTO.

During LTO, if (1) an IR file contains a COMDAT group that is kept,
(2) a later non-claimed file contains the same group, which we discard,
and (3) the plugin fails to provide a definition of the symbols in that
COMDAT group, gold silently resolves any references to those symbols
to 0.

This patch adds a check for a placeholder symbol when deciding
whether to issue an undefined symbol error. It also adds an extra
note after any undefined placeholder symbol error that explains
that a definition was expected from the plugin.

gold/
	PR gold/19842
	* errors.cc (Errors::undefined_symbol): Add info message when
	symbol should have been provided by a plugin.
	* target-reloc.h (issue_undefined_symbol_error): Check for
	placeholder symbols defined in discarded sections.
	* testsuite/Makefile.am (plugin_test_9b): New test case.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/plugin_test_9b_elf.cc: New test source file.
	* testsuite/plugin_test_9b_ir.cc: New test source file.
This commit is contained in:
Cary Coutant 2016-03-21 19:07:55 -07:00
parent 6f4c0a426c
commit 648c5cbbf3
7 changed files with 143 additions and 2 deletions

View file

@ -1,3 +1,15 @@
2016-03-21 Cary Coutant <ccoutant@gmail.com>
PR gold/19842
* errors.cc (Errors::undefined_symbol): Add info message when
symbol should have been provided by a plugin.
* target-reloc.h (issue_undefined_symbol_error): Check for
placeholder symbols defined in discarded sections.
* testsuite/Makefile.am (plugin_test_9b): New test case.
* testsuite/Makefile.in: Regenerate.
* testsuite/plugin_test_9b_elf.cc: New test source file.
* testsuite/plugin_test_9b_ir.cc: New test source file.
2016-03-20 Cary Coutant <ccoutant@gmail.com>
PR gold/19002

View file

@ -198,6 +198,9 @@ Errors::undefined_symbol(const Symbol* sym, const std::string& location)
gold_info(_("%s: the vtable symbol may be undefined because "
"the class is missing its key function"),
program_name);
if (sym->is_placeholder())
gold_info(_("%s: the symbol should have been defined by a plugin"),
program_name);
}
// Issue a debugging message.

View file

@ -186,8 +186,10 @@ issue_undefined_symbol_error(const Symbol* sym)
if (sym->is_weak_undefined())
return false;
// We don't report symbols defined in discarded sections.
if (sym->is_defined_in_discarded_section())
// We don't report symbols defined in discarded sections,
// unless they're placeholder symbols that should have been
// provided by a plugin.
if (sym->is_defined_in_discarded_section() && !sym->is_placeholder())
return false;
// If the target defines this symbol, don't report it here.

View file

@ -2015,6 +2015,25 @@ MOSTLYCLEANFILES += two_file_test_1c.o
two_file_test_1c.o: two_file_test_1.o
cp two_file_test_1.o $@
# As above, but check COMDAT case, where a non-IR file contains a duplicate
# of a COMDAT group in an IR file.
check_DATA += plugin_test_9b.err
MOSTLYCLEANFILES += plugin_test_9b.err
plugin_test_9b.err: plugin_test_9b_ir.o.syms plugin_test_9b_ir.o plugin_test_9b_elf.o gcctestdir/ld plugin_test.so
@echo $(CXXLINK) -Bgcctestdir/ -o plugin_test_9b -Wl,--no-demangle,--plugin,"./plugin_test.so",--plugin-opt,"_ZN1A5printEv" plugin_test_9b_ir.o plugin_test_9b_elf.o "2>$@"
@if $(CXXLINK) -Bgcctestdir/ -o plugin_test_9b -Wl,--no-demangle,--plugin,"./plugin_test.so",--plugin-opt,"_ZN1A5printEv" plugin_test_9b_ir.o plugin_test_9b_elf.o 2>$@; then \
echo 1>&2 "Link of plugin_test_9b should have failed"; \
rm -f $@; \
exit 1; \
fi
# Make a .syms file that claims to define a method in class A in a COMDAT group.
# The real plugin_test_9b_ir.o will be compiled without the -D, and will not
# define any methods in class A.
plugin_test_9b_ir.o.syms: plugin_test_9b_ir_witha.o
$(TEST_READELF) -sW $< >$@ 2>/dev/null
plugin_test_9b_ir_witha.o: plugin_test_9b_ir.cc
$(CXXCOMPILE) -c -DUSE_CLASS_A -o $@ $<
check_PROGRAMS += plugin_test_10
check_SCRIPTS += plugin_test_10.sh
check_DATA += plugin_test_10.sections

View file

@ -452,6 +452,9 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
# Test that symbols known in the IR file but not in the replacement file
# produce an unresolved symbol error.
# As above, but check COMDAT case, where a non-IR file contains a duplicate
# of a COMDAT group in an IR file.
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@am__append_39 = \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_1.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_2.err \
@ -461,6 +464,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_7.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_7.o.syms \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_9.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_9b.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_10.sections \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_11.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_start_lib.err
@ -475,6 +479,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_7.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_9.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ two_file_test_1c.o \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_9b.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_10.sections \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_11.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ plugin_test_thin.a \
@ -6089,6 +6094,20 @@ uninstall-am:
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ mv -f $@.tmp $@
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@two_file_test_1c.o: two_file_test_1.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ cp two_file_test_1.o $@
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_test_9b.err: plugin_test_9b_ir.o.syms plugin_test_9b_ir.o plugin_test_9b_elf.o gcctestdir/ld plugin_test.so
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ @echo $(CXXLINK) -Bgcctestdir/ -o plugin_test_9b -Wl,--no-demangle,--plugin,"./plugin_test.so",--plugin-opt,"_ZN1A5printEv" plugin_test_9b_ir.o plugin_test_9b_elf.o "2>$@"
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ @if $(CXXLINK) -Bgcctestdir/ -o plugin_test_9b -Wl,--no-demangle,--plugin,"./plugin_test.so",--plugin-opt,"_ZN1A5printEv" plugin_test_9b_ir.o plugin_test_9b_elf.o 2>$@; then \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ echo 1>&2 "Link of plugin_test_9b should have failed"; \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ rm -f $@; \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ exit 1; \
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ fi
# Make a .syms file that claims to define a method in class A in a COMDAT group.
# The real plugin_test_9b_ir.o will be compiled without the -D, and will not
# define any methods in class A.
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_test_9b_ir.o.syms: plugin_test_9b_ir_witha.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(TEST_READELF) -sW $< >$@ 2>/dev/null
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_test_9b_ir_witha.o: plugin_test_9b_ir.cc
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXCOMPILE) -c -DUSE_CLASS_A -o $@ $<
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_test_10: plugin_common_test_1.o.syms plugin_common_test_2.o gcctestdir/ld plugin_test.so
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@ $(CXXLINK) -Bgcctestdir/ -Wl,--no-demangle,--plugin,"./plugin_test.so" plugin_common_test_1.o.syms plugin_common_test_2.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@@PLUGINS_TRUE@plugin_test_10.sections: plugin_test_10

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@ -0,0 +1,40 @@
// plugin_test_9b_ir.cc -- a test case for gold plugins
// Copyright (C) 2016 Free Software Foundation, Inc.
// Written by Cary Coutant <ccoutant@gmail.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.
#include <iostream>
using namespace std;
class A {
public:
virtual void
print() __attribute__ ((noinline))
{ cout << "A::print" << endl; }
};
void
foo()
{
A a;
a.print();
cout << "foo returning" << endl;
}

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@ -0,0 +1,46 @@
// plugin_test_9b_ir.cc -- a test case for gold plugins
// Copyright (C) 2016 Free Software Foundation, Inc.
// Written by Cary Coutant <ccoutant@gmail.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.
#include <iostream>
using namespace std;
class A {
public:
virtual void
print() __attribute__ ((noinline))
{ cout << "A::print" << endl; }
};
extern void foo();
int
main()
{
#ifdef USE_CLASS_A
A a;
a.print();
#endif
cout << "calling foo" << endl;
foo();
return 0;
}