[PATCH] Add dw2-aranges.exp

["Alexandra Hájková" <ahajkova@redhat.com>]

This test tests GDB is able to load a file with the
.debug_aranges section Address size set to 0.

The test was originally written by Jan Kratochvil to test
commit 927aa2e778dce440f4de5de8fc37ead1683a804e
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Fri Dec 8 22:44:12 2017 +0000

      DWARF-5: .debug_names index consumer

The test was passing from the beginning.
This test has been living in the Fedora tree
for a long time, it seems to be a reasonable
some bad debug information.

If dwarf2/aranges.c is modified to turn off the
address_size check, GDB will crash with SIGPE
when loading the executable with the address size
set to zero.

I modified the DWARF assembler to make it possible
to set the Addres size to zero in a .debug_aranges section
and used a DWARF assembler to produce the assembly file.

Co-Authored-By: Jan Kratochvil <jan.kratochvil@redhat.com>
---
 gdb/testsuite/gdb.dwarf2/dw2-aranges.c   | 24 +++++++++++++
 gdb/testsuite/gdb.dwarf2/dw2-aranges.exp | 44 ++++++++++++++++++++++++
 gdb/testsuite/lib/dwarf.exp              | 15 ++++++--
 3 files changed, 81 insertions(+), 2 deletions(-)
 create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-aranges.c
 create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-aranges.exp

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-aranges.c b/gdb/testsuite/gdb.dwarf2/dw2-aranges.c
new file mode 100644
index 00000000000..28025188495
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-aranges.c
@@ -0,0 +1,24 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2024 Free Software Foundation, Inc.
+
+   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, see <http://www.gnu.org/licenses/>.  */
+
+/* Dummy main function.  */
+
+int
+main (void)
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-aranges.exp b/gdb/testsuite/gdb.dwarf2/dw2-aranges.exp
new file mode 100644
index 00000000000..59e7e27ac96
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-aranges.exp
@@ -0,0 +1,44 @@
+# Copyright 2004-2024 Free Software Foundation, Inc.
+
+# 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, see <http://www.gnu.org/licenses/>.
+
+# Test .debug_aranges containing zero address_size.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    verbose "Skipping $gdb_test_file_name."
+    return 0
+}
+
+standard_testfile .c -2.S
+set asm_file [standard_output_file $srcfile2]
+
+Dwarf::assemble $asm_file {
+    cu { label cu_start } {
+	compile_unit {{language @DW_LANG_C}} {
+	}
+    }
+    aranges { addr_zero true } cu_start {
+    }
+}
+
+if { [prepare_for_testing "failed to prepare" $binfile  [list $asm_file $srcfile ]] } {
+    return -1
+}
+
+# Failed gdb_load would abort the testcase execution earlier.
+pass "file loaded"
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 6a5afec3fc8..1002c75dd09 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -2759,8 +2759,11 @@ namespace eval Dwarf {
 	    set addr_op .4byte
 	}
 
-	_op $addr_op $arange_start "Address range start$comment"
-	_op $addr_op $arange_length "Address range length$comment"
+	# Do not emit address ranges when the Address size is set to 0.
+	if { $_addr_size > 0 } {
+	    _op $addr_op $arange_start "Address range start$comment"
+	    _op $addr_op $arange_length "Address range length$comment"
+	}
     }
 
     # Emit a DWARF .debug_aranges unit.
@@ -2797,6 +2800,7 @@ namespace eval Dwarf {
 	    { cu_is_64 0 }
 	    { section_version 2 }
 	    { seg_size 0 }
+	    { addr_zero false }
 	}
 	set _seg_size $seg_size
 
@@ -2806,6 +2810,10 @@ namespace eval Dwarf {
 	    set _addr_size 4
 	}
 
+	if { $addr_zero } {
+	    set _addr_size 0
+	}
+
 	# Switch to .debug_aranges section.
 	_section .debug_aranges
 
@@ -2853,6 +2861,9 @@ namespace eval Dwarf {
 
 	# Padding.
 	set tuple_size [expr 2 * $_addr_size + $_seg_size]
+	if {$tuple_size == 0} {
+	    set tuple_size 1
+	}
 	while { 1 } {
 	    if { [expr $offset % $tuple_size] == 0 } {
 		break
-- 
2.46.2