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.

6 files changed, 362 insertions, 26 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 6aa90d9..1151dc8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-10  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* dwarf2read.c (dwarf2_ranges_read): Unify and fix base address
+	reading code.
+
 2015-12-09  Kevin Buettner  <kevinb@redhat.com>
 
 	* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Perform a pointer
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 298757c..4881d72 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -11894,7 +11894,6 @@ dwarf2_ranges_read (unsigned offset, CORE_ADDR *low_return,
   int found_base;
   unsigned int dummy;
   const gdb_byte *buffer;
-  CORE_ADDR marker;
   int low_set;
   CORE_ADDR low = 0;
   CORE_ADDR high = 0;
@@ -11913,18 +11912,6 @@ dwarf2_ranges_read (unsigned offset, CORE_ADDR *low_return,
     }
   buffer = dwarf2_per_objfile->ranges.buffer + offset;
 
-  /* Read in the largest possible address.  */
-  marker = read_address (obfd, buffer, cu, &dummy);
-  if ((marker & mask) == mask)
-    {
-      /* If we found the largest possible address, then
-	 read the base address.  */
-      base = read_address (obfd, buffer + addr_size, cu, &dummy);
-      buffer += 2 * addr_size;
-      offset += 2 * addr_size;
-      found_base = 1;
-    }
-
   low_set = 0;
 
   baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
@@ -11949,9 +11936,9 @@ dwarf2_ranges_read (unsigned offset, CORE_ADDR *low_return,
 	 the base address.  Check for a base address here.  */
       if ((range_beginning & mask) == mask)
 	{
-	  /* If we found the largest possible address, then
-	     read the base address.  */
-	  base = read_address (obfd, buffer + addr_size, cu, &dummy);
+	  /* If we found the largest possible address, then we already
+	     have the base address in range_end.  */
+	  base = range_end;
 	  found_base = 1;
 	  continue;
 	}
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index a367451..bad4382 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,13 @@
+2015-12-10  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* 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.
+
 2015-12-09  Kevin Buettner  <kevinb@redhat.com>
 
 	* gdb.base/async.exp (proc test_background): Add case for
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 0000000..4d52b6e
--- /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 0000000..9d64270
--- /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 .*"
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index c87da87..44200a1 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -303,6 +303,15 @@ namespace eval Dwarf {
     # Whether a file_name entry was seen.
     variable _line_saw_file
 
+    # Whether a line table program has been seen.
+    variable _line_saw_program
+
+    # A Label for line table header generation.
+    variable _line_header_end_label
+
+    # The address size for debug ranges section.
+    variable _debug_ranges_64_bit
+
     proc _process_one_constant {name value} {
 	variable _constants
 	variable _AT
@@ -992,7 +1001,7 @@ namespace eval Dwarf {
 	set _cu_label [_compute_label "cu${cu_num}_begin"]
 	set start_label [_compute_label "cu${cu_num}_start"]
 	set end_label [_compute_label "cu${cu_num}_end"]
-	
+
 	define_label $_cu_label
 	if {$is_64} {
 	    _op .4byte 0xffffffff
@@ -1129,6 +1138,78 @@ namespace eval Dwarf {
 	define_label $end_label
     }
 
+    # Emit a DWARF .debug_ranges unit.
+    # OPTIONS is a list with an even number of elements containing
+    # option-name and option-value pairs.
+    # Current options are:
+    # is_64 0|1    - boolean indicating if you want to emit 64-bit DWARF
+    #                default = 0 (32-bit)
+    #
+    # BODY is Tcl code that emits the content of the .debug_ranges
+    # unit, it is evaluated in the caller's context.
+    proc ranges {options body} {
+	variable _debug_ranges_64_bit
+
+	foreach { name value } $options {
+	    switch -exact -- $name {
+		is_64 { set _debug_ranges_64_bit [subst $value] }
+		default { error "unknown option $name" }
+	    }
+	}
+
+	set section ".debug_ranges"
+	_section $section
+
+	proc sequence {{ranges {}}} {
+	    variable _debug_ranges_64_bit
+
+	    # Emit the sequence of addresses.
+	    set base ""
+	    foreach range $ranges {
+		set range [uplevel 1 "subst \"$range\""]
+		set type [lindex $range 0]
+		switch -exact -- $type {
+		    base {
+			set base [lrange $range 1 end]
+
+			if { $_debug_ranges_64_bit } then {
+			    _op .8byte 0xffffffffffffffff "Base Marker"
+			    _op .8byte $base "Base Address"
+			} else {
+			    _op .4byte 0xffffffff "Base Marker"
+			    _op .4byte $base "Base Address"
+			}
+		    }
+		    range {
+			set start [lindex $range 1]
+			set end [lrange $range 2 end]
+
+			if { $_debug_ranges_64_bit } then {
+			    _op .8byte $start "Start Address"
+			    _op .8byte $end "End Address"
+			} else {
+			    _op .4byte $start "Start Address"
+			    _op .4byte $end "End Address"
+			}
+		    }
+		    default { error "unknown range type: $type " }
+		}
+	    }
+
+	    # End of the sequence.
+	    if { $_debug_ranges_64_bit } then {
+		_op .8byte 0x0 "End of Sequence Marker (Part 1)"
+		_op .8byte 0x0 "End of Sequence Marker (Part 2)"
+	    } else {
+		_op .4byte 0x0 "End of Sequence Marker (Part 1)"
+		_op .4byte 0x0 "End of Sequence Marker (Part 2)"
+	    }
+	}
+
+	uplevel $body
+    }
+
+
     # Emit a DWARF .debug_line unit.
     # OPTIONS is a list with an even number of elements containing
     # option-name and option-value pairs.
@@ -1157,6 +1238,8 @@ namespace eval Dwarf {
     proc lines {options label body} {
 	variable _line_count
 	variable _line_saw_file
+	variable _line_saw_program
+	variable _line_header_end_label
 
 	# Establish the defaults.
 	set is_64 0
@@ -1192,7 +1275,7 @@ namespace eval Dwarf {
 	set unit_len_label [_compute_label "line${_line_count}_start"]
 	set unit_end_label [_compute_label "line${_line_count}_end"]
 	set header_len_label [_compute_label "line${_line_count}_header_start"]
-	set header_end_label [_compute_label "line${_line_count}_header_end"]
+	set _line_header_end_label [_compute_label "line${_line_count}_header_end"]
 
 	if {$is_64} {
 	    _op .4byte 0xffffffff
@@ -1206,20 +1289,34 @@ namespace eval Dwarf {
 	_op .2byte $_unit_version version
 
 	if {$is_64} {
-	    _op .8byte "$header_end_label - $header_len_label" "header_length"
+	    _op .8byte "$_line_header_end_label - $header_len_label" "header_length"
 	} else {
-	    _op .4byte "$header_end_label - $header_len_label" "header_length"
+	    _op .4byte "$_line_header_end_label - $header_len_label" "header_length"
 	}
 
 	define_label $header_len_label
 
 	_op .byte 1 "minimum_instruction_length"
-	_op .byte 0 "default_is_stmt"
+	_op .byte 1 "default_is_stmt"
 	_op .byte 1 "line_base"
 	_op .byte 1 "line_range"
-	_op .byte 1 "opcode_base"
-	# Since we emit opcode_base==1, we skip
-	# standard_opcode_length table altogether.
+	_op .byte 10 "opcode_base"
+
+	# The standard_opcode_lengths table.  The number of arguments
+	# for each of the standard opcodes.  Generating 9 entries here
+	# matches the use of 10 in the opcode_base above.  These 9
+	# entries match the 9 standard opcodes for DWARF2, making use
+	# of only 9 should be fine, even if we are generating DWARF3
+	# or DWARF4.
+	_op .byte 0 "standard opcode 1"
+	_op .byte 1 "standard opcode 2"
+	_op .byte 1 "standard opcode 3"
+	_op .byte 1 "standard opcode 4"
+	_op .byte 1 "standard opcode 5"
+	_op .byte 0 "standard opcode 6"
+	_op .byte 0 "standard opcode 7"
+	_op .byte 0 "standard opcode 8"
+	_op .byte 1 "standard opcode 9"
 
 	proc include_dir {dirname} {
 	    _op .ascii [_quote $dirname]
@@ -1239,6 +1336,57 @@ namespace eval Dwarf {
 	    _op .sleb128 0 "length"
 	}
 
+	proc program {statements} {
+	    variable _line_saw_program
+	    variable _line_header_end_label
+
+	    if "! $_line_saw_program" {
+		# Terminate the file list.
+		_op .byte 0 "Terminator."
+		define_label $_line_header_end_label
+		set _line_saw_program 1
+	    }
+
+	    proc DW_LNE_set_address {addr} {
+		_op .byte 0
+		set start [new_label "set_address_start"]
+		set end [new_label "set_address_end"]
+		_op .uleb128 "${end} - ${start}"
+		define_label ${start}
+		_op .byte 2
+		if {[is_64_target]} {
+		    _op .8byte ${addr}
+		} else {
+		    _op .4byte ${addr}
+		}
+		define_label ${end}
+	    }
+
+	    proc DW_LNE_end_sequence {} {
+		_op .byte 0
+		_op .uleb128 1
+		_op .byte 1
+	    }
+
+	    proc DW_LNS_copy {} {
+		_op .byte 1
+	    }
+
+	    proc DW_LNS_advance_pc {offset} {
+		_op .byte 2
+		_op .uleb128 ${offset}
+	    }
+
+	    proc DW_LNS_advance_line {offset} {
+		_op .byte 3
+		_op .sleb128 ${offset}
+	    }
+
+	    foreach statement $statements {
+		uplevel 1 $statement
+	    }
+	}
+
 	uplevel $body
 
 	rename include_dir ""
@@ -1250,9 +1398,11 @@ namespace eval Dwarf {
 	}
 
 	# Terminate the file list.
-	_op .byte 0 "Terminator."
+	if "! $_line_saw_program" {
+	    _op .byte 0 "Terminator."
+	    define_label $_line_header_end_label
+	}
 
-	define_label $header_end_label
 	define_label $unit_end_label
     }
 
@@ -1337,6 +1487,9 @@ namespace eval Dwarf {
 	variable _cu_count
 	variable _line_count
 	variable _line_saw_file
+	variable _line_saw_program
+	variable _line_header_end_label
+	variable _debug_ranges_64_bit
 
 	if {!$_initialized} {
 	    _read_constants
@@ -1352,6 +1505,8 @@ namespace eval Dwarf {
 
 	set _line_count 0
 	set _line_saw_file 0
+	set _line_saw_program 0
+	set _debug_ranges_64_bit [is_64_target]
 
 	# Not "uplevel" here, because we want to evaluate in this
 	# namespace.  This is somewhat bad because it means we can't