203 lines
6.8 KiB
Diff
203 lines
6.8 KiB
Diff
From e2f41776aa9ca2f625bbc50e9bb498e2a95dba25 Mon Sep 17 00:00:00 2001
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From: Tom de Vries <tdevries@suse.de>
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Date: Sat, 5 Aug 2023 17:57:13 +0200
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Subject: [PATCH] [gdb/symtab] Find main language without symtab expansion
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When loading an executable using "file a.out", the language is set according
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to a.out, which can involve looking up the language of symbol "main", which
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will cause the symtab expansion for the containing CU.
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Expansion of lto debug info can be slow, so in commit d3214198119 ("[gdb] Use
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partial symbol table to find language for main") a feature was added to avoid
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the symtab expansion.
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This feature stopped working after commit 7f4307436fd ("Fix "start" for D,
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Rust, etc").
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[ The commit addresses problems related to command start, which requires finding
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the main function:
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- for language D, "main" was found instead of "D main", and
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- for Rust, the correct function was found, but attributed the wrong name
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(not fully qualified). ]
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Reimplement the feature by adding
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cooked_index_functions::lookup_global_symbol_language.
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Tested on x86_64-linux.
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PR symtab/30661
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Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30661
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---
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gdb/dwarf2/read.c | 41 +++++++++++++++++++++++++++++++
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gdb/testsuite/gdb.base/main-c.exp | 33 +++++++++++++++++++++++++
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gdb/testsuite/gdb.cp/main-cp.exp | 33 +++++++++++++++++++++++++
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gdb/testsuite/gdb.cp/main.cc | 22 +++++++++++++++++
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4 files changed, 129 insertions(+)
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create mode 100644 gdb/testsuite/gdb.base/main-c.exp
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create mode 100644 gdb/testsuite/gdb.cp/main-cp.exp
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create mode 100644 gdb/testsuite/gdb.cp/main.cc
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diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
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index 04bc0e1cbbd..8aa7f8c31e5 100644
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--- a/gdb/dwarf2/read.c
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+++ b/gdb/dwarf2/read.c
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@@ -18621,6 +18621,47 @@ struct cooked_index_functions : public dwarf2_base_index_functions
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if (dwarf2_has_info (objfile, nullptr))
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dwarf2_build_psymtabs (objfile);
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}
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+
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+ enum language lookup_global_symbol_language (struct objfile *objfile,
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+ const char *name,
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+ domain_enum domain,
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+ bool *symbol_found_p) override
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+ {
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+ *symbol_found_p = false;
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+
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+ if (!(domain == VAR_DOMAIN && streq (name, "main")))
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+ return language_unknown;
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+
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+ dwarf2_per_objfile *per_objfile = get_dwarf2_per_objfile (objfile);
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+ struct dwarf2_per_bfd *per_bfd = per_objfile->per_bfd;
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+ if (per_bfd->index_table == nullptr)
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+ return language_unknown;
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+
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+ /* Expansion of large CUs can be slow. By returning the language of main
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+ here for C and C++, we avoid CU expansion during set_initial_language.
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+ But by doing a symbol lookup in the cooked index, we are forced to wait
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+ for finalization to complete. See PR symtab/30174 for ideas how to
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+ bypass that as well. */
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+ cooked_index_vector *table
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+ = (gdb::checked_static_cast<cooked_index_vector *>
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+ (per_objfile->per_bfd->index_table.get ()));
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+ table->wait ();
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+
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+ for (const cooked_index_entry *entry : table->find (name, false))
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+ {
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+ if (entry->tag != DW_TAG_subprogram)
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+ continue;
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+
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+ enum language lang = entry->per_cu->lang ();
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+ if (!(lang == language_c || lang == language_cplus))
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+ continue;
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+
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+ *symbol_found_p = true;
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+ return lang;
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+ }
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+
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+ return language_unknown;
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+ }
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};
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dwarf2_per_cu_data *
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diff --git a/gdb/testsuite/gdb.base/main-c.exp b/gdb/testsuite/gdb.base/main-c.exp
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new file mode 100644
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index 00000000000..bcbd0fca7e4
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--- /dev/null
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+++ b/gdb/testsuite/gdb.base/main-c.exp
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@@ -0,0 +1,33 @@
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+# Copyright 2023 Free Software Foundation, Inc.
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+
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+# This program is free software; you can redistribute it and/or modify
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+# it under the terms of the GNU General Public License as published by
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+# the Free Software Foundation; either version 3 of the License, or
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+# (at your option) any later version.
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+#
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+# This program is distributed in the hope that it will be useful,
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+# but WITHOUT ANY WARRANTY; without even the implied warranty of
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+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+# GNU General Public License for more details.
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+#
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+# You should have received a copy of the GNU General Public License
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+# along with this program. If not, see <http://www.gnu.org/licenses/>.
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+
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+# Check that finding main to set the current language doesn't cause any symtab
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+# to be expanded.
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+
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+standard_testfile main.c
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+
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+if { [readnow] } {
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+ return -1
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+}
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+
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+if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
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+ return -1
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+}
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+
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+if { ![string eq [have_index $binfile] ""] } {
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+ return -1
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+}
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+
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+gdb_test_no_output "maint info symtabs"
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diff --git a/gdb/testsuite/gdb.cp/main-cp.exp b/gdb/testsuite/gdb.cp/main-cp.exp
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new file mode 100644
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index 00000000000..86d626bdbaf
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--- /dev/null
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+++ b/gdb/testsuite/gdb.cp/main-cp.exp
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@@ -0,0 +1,33 @@
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+# Copyright 2023 Free Software Foundation, Inc.
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+
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+# This program is free software; you can redistribute it and/or modify
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+# it under the terms of the GNU General Public License as published by
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+# the Free Software Foundation; either version 3 of the License, or
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+# (at your option) any later version.
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+#
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+# This program is distributed in the hope that it will be useful,
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+# but WITHOUT ANY WARRANTY; without even the implied warranty of
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+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+# GNU General Public License for more details.
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+#
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+# You should have received a copy of the GNU General Public License
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+# along with this program. If not, see <http://www.gnu.org/licenses/>.
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+
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+# Check that finding main to set the current language doesn't cause any symtab
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+# to be expanded.
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+
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+standard_testfile main.cc
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+
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+if { [readnow] } {
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+ return -1
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+}
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+
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+if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
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+ return -1
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+}
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+
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+if { ![string eq [have_index $binfile] ""] } {
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+ return -1
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+}
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+
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+gdb_test_no_output "maint info symtabs"
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diff --git a/gdb/testsuite/gdb.cp/main.cc b/gdb/testsuite/gdb.cp/main.cc
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new file mode 100644
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index 00000000000..c6beff77dbe
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--- /dev/null
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+++ b/gdb/testsuite/gdb.cp/main.cc
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@@ -0,0 +1,22 @@
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+/* This testcase is part of GDB, the GNU debugger.
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+
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+ Copyright 2023 Free Software Foundation, Inc.
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+
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+ This program is free software; you can redistribute it and/or modify
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+ it under the terms of the GNU General Public License as published by
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+ the Free Software Foundation; either version 3 of the License, or
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+ (at your option) any later version.
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+
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+ This program is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ GNU General Public License for more details.
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+
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+ You should have received a copy of the GNU General Public License
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+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
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+
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+int
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+main (void)
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+{
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+ return 0;
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+}
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base-commit: ebceffa1196651683a7a6d31abb4b3b5adc6c168
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--
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2.35.3
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