gdb: Handle multiple base address in debug_ranges data.

It is possible to use multiple base addresses within a single address
range series, within the .debug_ranges section.  The following is a
simplified example for 32-bit addresses:

  .section ".debug_ranges"
  .4byte	0xffffffff
  .4byte	BASE_1
  .4byte	START_OFFSET_1
  .4byte	END_OFFSET_1
  .4byte	START_OFFSET_2
  .4byte	END_OFFSET_2
  .4byte	0xffffffff
  .4byte	BASE_2
  .4byte	START_OFFSET_3
  .4byte	END_OFFSET_3
  .4byte	0
  .4byte	0

In this example START/END 1 and 2 are relative to BASE_1, while
START/END 3 are relative to BASE_2.

Currently gdb does not correctly parse this DWARF, resulting in
corrupted address range information.  This commit fixes this issue, and
adds a new test to cover this case.

In order to support testing of this feature extensions were made to the
testsuite dwarf assembler, additional functionality was added to the
.debug_line generation function, and a new function for generating the
.debug_ranges section was added.

gdb/ChangeLog:

	* dwarf2read.c (dwarf2_ranges_read): Unify and fix base address
	reading code.

gdb/testsuite/ChangeLog:

	* gdb.dwarf2/dw2-ranges-base.c: New file.
	* gdb.dwarf2/dw2-ranges-base.exp: New file.
	* lib/dwarf.exp (namespace eval Dwarf): Add new variables to
	support additional line table, and debug ranges generation.
	(Dwarf::ranges): New function, generate .debug_ranges.
	(Dwarf::lines): Support generating simple line table programs.
	(Dwarf::assemble): Initialise new namespace variables.

2 files changed, 179 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.c b/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.c
new file mode 100644
index 00000000000..4d52b6e8726
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.c
@@ -0,0 +1,36 @@
+/*
+   Copyright 2015 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/>.  */
+
+void __attribute__ ((section (".text.3")))
+frame3 (void)
+{
+  asm ("frame3_label: .globl frame3_label");
+}
+
+void __attribute__ ((section (".text.2")))
+frame2 (void)
+{
+  asm ("frame2_label: .globl frame2_label");
+  frame3 ();
+}
+
+void __attribute__ ((section (".text.1")))
+main (void)
+{
+  asm ("main_label: .globl main_label");
+  frame2 ();
+}
+
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.exp b/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.exp
new file mode 100644
index 00000000000..9d642703b9f
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-ranges-base.exp
@@ -0,0 +1,143 @@
+# Copyright 2015 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/>.
+load_lib dwarf.exp
+
+# Test DW_TAG_compile_unit with no children and with neither DW_AT_low_pc nor
+# DW_AT_high_pc but with DW_AT_ranges instead.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    verbose "Skipping DW_AT_ranges test."
+    return 0
+}
+
+# The .c files use __attribute__.
+if [get_compiler_info] {
+    return -1
+}
+if !$gcc_compiled {
+    verbose "Skipping DW_AT_ranges test."
+    return 0
+}
+
+standard_testfile dw2-ranges-base.c dw2-ranges-base-dw.S
+
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    global srcdir subdir srcfile srcfile2
+    declare_labels ranges_label
+    declare_labels L
+
+    # Find start address and length for our functions.
+    set main_func \
+	[function_range main [list ${srcdir}/${subdir}/$srcfile]]
+    set frame2_func \
+	[function_range frame2 [list ${srcdir}/${subdir}/$srcfile]]
+    set frame3_func \
+	[function_range frame3 [list ${srcdir}/${subdir}/$srcfile]]
+
+    # Very simple info for this test program.  We don't care about
+    # this information being correct (w.r.t. funtion / argument types)
+    # just so long as the compilation using makes use of the
+    # .debug_ranges data then the test achieves its objective.
+    cu {} {
+	compile_unit {
+	    {language @DW_LANG_C}
+	    {name dw-ranges-base.c}
+	    {stmt_list $L DW_FORM_sec_offset}
+	    {ranges ${ranges_label} DW_FORM_sec_offset}
+	} {
+	    subprogram {
+		{external 1 flag}
+		{name main}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name frame2}
+	    }
+	    subprogram {
+		{external 1 flag}
+		{name frame3}
+	    }
+	}
+    }
+
+    lines {version 2} L {
+	include_dir "${srcdir}/${subdir}"
+	file_name "$srcfile" 1
+
+	# Generate simple line table program.  The line table
+	# information contained here is not correct, and we really
+	# don't care, just so long as each function has some line
+	# table data associated with it.  We do make use of the fake
+	# line numbers that we pick here in the tests below.
+	program {
+	    {DW_LNE_set_address [lindex $main_func 0]}
+	    {DW_LNS_advance_line 10}
+	    {DW_LNS_copy}
+	    {DW_LNS_advance_pc [lindex $main_func 1]}
+	    {DW_LNS_advance_line 19}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address [lindex $frame2_func 0]}
+	    {DW_LNS_advance_line 20}
+	    {DW_LNS_copy}
+	    {DW_LNS_advance_pc [lindex $frame2_func 1]}
+	    {DW_LNS_advance_line 29}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+
+	    {DW_LNE_set_address [lindex $frame3_func 0]}
+	    {DW_LNS_advance_line 30}
+	    {DW_LNS_copy}
+	    {DW_LNS_advance_pc [lindex $frame3_func 1]}
+	    {DW_LNS_advance_line 39}
+	    {DW_LNS_copy}
+	    {DW_LNE_end_sequence}
+	}
+    }
+
+    # Generate ranges data.  This is the point of this whole test
+    # file, we must have multiple bases specified, so we use a new
+    # base for each function.
+    ranges {is_64 [is_64_target]} {
+	ranges_label: sequence {
+	    {base [lindex $main_func 0]}
+	    {range 0 [lindex $main_func 1]}
+	    {base [lindex $frame2_func 0]}
+	    {range 0 [lindex $frame2_func 1]}
+	    {base [lindex $frame3_func 0]}
+	    {range 0 [lindex $frame3_func 1]}
+	}
+    }
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+# Make use of the line numbers we faked in the .debug_line table above.
+gdb_test "info line main" \
+    "Line 11 of .* starts at address .* and ends at .*"
+gdb_test "info line frame2" \
+    "Line 21 of .* starts at address .* and ends at .*"
+gdb_test "info line frame3" \
+    "Line 31 of .* starts at address .* and ends at .*"