gdb/testsuite: add .debug_loclists tests

Add tests for the various issues fixed in the previous patches.

Add a new "loclists" procedure to the DWARF assembler, to allow
generating .debug_loclists sections.

gdb/testsuite/ChangeLog:

	PR gdb/26813
	* lib/dwarf.exp (_handle_DW_FORM): Handle DW_FORM_loclistx.
	(loclists): New proc.
	* gdb.dwarf2/loclists-multiple-cus.c: New.
	* gdb.dwarf2/loclists-multiple-cus.exp: New.
	* gdb.dwarf2/loclists-sec-offset.c: New.
	* gdb.dwarf2/loclists-sec-offset.exp: New.

Change-Id: I209bcb2a9482762ae943e518998d1f7761f76928

gdb/testsuite/ChangeLog

@@ -1,3 +1,13 @@
+2021-02-02  Simon Marchi  <simon.marchi@efficios.com>
+
+	PR gdb/26813
+	* lib/dwarf.exp (_handle_DW_FORM): Handle DW_FORM_loclistx.
+	(loclists): New proc.
+	* gdb.dwarf2/loclists-multiple-cus.c: New.
+	* gdb.dwarf2/loclists-multiple-cus.exp: New.
+	* gdb.dwarf2/loclists-sec-offset.c: New.
+	* gdb.dwarf2/loclists-sec-offset.exp: New.
+
 2021-02-02  Simon Marchi  <simon.marchi@efficios.com>
 
 	* lib/dwarf.exp (_location): Add parameters.

gdb/testsuite/gdb.dwarf2/loclists-multiple-cus.c

@@ -0,0 +1,37 @@
+/* Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+static int
+func1 (void)
+{
+  asm ("func1_label: .global func1_label\n");
+  return 1;
+}
+
+static int
+func2 (void)
+{
+  asm ("func2_label: .global func2_label\n");
+  return 2;
+}
+
+int
+main (void)
+{
+  func1 ();
+  func2 ();
+}

gdb/testsuite/gdb.dwarf2/loclists-multiple-cus.exp

@@ -0,0 +1,146 @@
+# Copyright 2020 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 to reproduce the crash described in PR 26813.
+#
+# When reading a list in any table in the .debug_loclists section, GDB would
+# read the header at offset 0 in the section (the header of the first table).
+# When the index of the list we read was greater than the number of lists of
+# the first table, GDB would erroneously report that the index is invalid.
+#
+# So this test creates a .debug_loclists section with two tables.  The second
+# table has more lists than the first one and we try to read a high index in
+# the second table.
+
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    return 0
+}
+
+# Test with 32-bit and 64-bit DWARF.
+foreach_with_prefix is_64 {false true} {
+    if { $is_64 } {
+	standard_testfile .c -dw64.S
+	set testfile ${testfile}-dw64
+    } else {
+	standard_testfile .c -dw32.S
+	set testfile ${testfile}-dw32
+    }
+
+    # Get the addresses / lengths of func1 and func2.
+    lassign [function_range func1 $srcdir/$subdir/$srcfile] func1_addr func1_len
+    lassign [function_range func2 $srcdir/$subdir/$srcfile] func2_addr func2_len
+
+    set asm_file [standard_output_file $srcfile2]
+    Dwarf::assemble $asm_file {
+	global func1_addr func1_len
+	global func2_addr func2_len
+	global is_64
+
+	# The CU uses the DW_FORM_loclistx form to refer to the .debug_loclists
+	# section.
+	cu {
+	    version 5
+	    is_64 $is_64
+	} {
+	    declare_labels int_type
+
+	    DW_TAG_compile_unit {
+		{DW_AT_loclists_base cu_table DW_FORM_sec_offset}
+	    } {
+		int_type: DW_TAG_base_type {
+		    {DW_AT_byte_size 4 DW_FORM_data1}
+		    {DW_AT_encoding @DW_ATE_signed}
+		    {DW_AT_name "int"}
+		}
+
+		DW_TAG_variable {
+		    {DW_AT_name "foo"}
+		    {DW_AT_location 1 DW_FORM_loclistx}
+		    {DW_AT_type :$int_type}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func1"}
+		    {DW_AT_low_pc $func1_addr}
+		    {DW_AT_high_pc $func1_len DW_FORM_udata}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func2"}
+		    {DW_AT_low_pc $func2_addr}
+		    {DW_AT_high_pc $func2_len DW_FORM_udata}
+		}
+	    }
+	}
+
+	loclists -is-64 $is_64 {
+	    # This table is unused, but exists so that the used table is not at
+	    # the beginning of the section.
+	    table {
+		list_ {
+		    start_length 0x1000 0x1000 { DW_OP_addr 0x100000 }
+		}
+	    }
+
+	    # The lists in this table are accessed by index (DW_FORM_rnglistx).
+	    table -post-header-label cu_table {
+		# This list is unused, but exists to offset the next ones.
+		list_ {
+		    start_length 0x1000 0x1000 { DW_OP_addr 0x100000 }
+		}
+
+		# For variable foo.
+		list_ {
+		    # When in func1.
+		    start_length $func1_addr $func1_len {
+			DW_OP_constu 0x123456
+			DW_OP_stack_value
+		    }
+
+		    # When in func2.
+		    start_length $func2_addr $func2_len {
+			DW_OP_constu 0x234567
+			DW_OP_stack_value
+		    }
+		}
+	    }
+	}
+    }
+
+    if { [prepare_for_testing "failed to prepare" ${testfile} \
+	      [list $srcfile $asm_file] {nodebug}] } {
+	return -1
+    }
+
+    if { ![runto_main] } {
+	fail "can't run to main"
+	return
+    }
+
+    gdb_breakpoint "func1"
+    gdb_breakpoint "func2"
+
+    gdb_continue_to_breakpoint "func1"
+    with_test_prefix "at func1" {
+	gdb_test "print /x foo" " = 0x123456"
+    }
+
+    gdb_continue_to_breakpoint "func2"
+    with_test_prefix "at func2" {
+	gdb_test "print /x foo" " = 0x234567"
+    }
+}

gdb/testsuite/gdb.dwarf2/loclists-sec-offset.c

@@ -0,0 +1,37 @@
+/* Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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/>.  */
+
+static int
+func1 (void)
+{
+  asm ("func1_label: .global func1_label\n");
+  return 1;
+}
+
+static int
+func2 (void)
+{
+  asm ("func2_label: .global func2_label\n");
+  return 2;
+}
+
+int
+main (void)
+{
+  func1 ();
+  func2 ();
+}

gdb/testsuite/gdb.dwarf2/loclists-sec-offset.exp

@@ -0,0 +1,125 @@
+# Copyright 2020 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 DW_AT_location attributes referencing the .debug_loclists section using
+# the DW_FORM_sec_offset form.
+
+load_lib dwarf.exp
+
+if {![dwarf2_support]} {
+    return 0
+}
+
+# Test with 32-bit and 64-bit DWARF.
+foreach_with_prefix is_64 {false true} {
+    if { $is_64 } {
+	standard_testfile .c -dw64.S
+	set testfile ${testfile}-dw64
+    } else {
+	standard_testfile .c -dw32.S
+	set testfile ${testfile}-dw32
+    }
+
+    # Get the addresses / lengths of func1 and func2.
+    lassign [function_range func1 $srcdir/$subdir/$srcfile] func1_addr func1_len
+    lassign [function_range func2 $srcdir/$subdir/$srcfile] func2_addr func2_len
+
+    set asm_file [standard_output_file $srcfile2]
+    Dwarf::assemble $asm_file {
+	global func1_addr func1_len
+	global func2_addr func2_len
+	global is_64
+
+	declare_labels cu_range_list foo_range_list
+
+	# This CU uses the DW_FORM_sec_offset form to refer to the .debug_rnglists
+	# section.
+	cu {
+	    version 5
+	    is_64 $is_64
+	} {
+	    declare_labels int_type
+	    declare_labels foo_location_list
+
+	    DW_TAG_compile_unit {
+	    } {
+		int_type: DW_TAG_base_type {
+		    {DW_AT_byte_size 4 DW_FORM_data1}
+		    {DW_AT_encoding @DW_ATE_signed}
+		    {DW_AT_name "int"}
+		}
+
+		DW_TAG_variable {
+		    {DW_AT_name "foo"}
+		    {DW_AT_location $foo_location_list DW_FORM_sec_offset}
+		    {DW_AT_type :$int_type}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func1"}
+		    {DW_AT_low_pc $func1_addr}
+		    {DW_AT_high_pc $func1_len DW_FORM_udata}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func2"}
+		    {DW_AT_low_pc $func2_addr}
+		    {DW_AT_high_pc $func2_len DW_FORM_udata}
+		}
+	    }
+	}
+
+	loclists -is-64 $is_64 {
+	    # The lists in this table are accessed by direct offset
+	    # (DW_FORM_sec_offset).
+	    table {
+		foo_location_list: list_ {
+		    start_length $func1_addr $func1_len {
+			DW_OP_constu 0x123456
+			DW_OP_stack_value
+		    }
+
+		    start_length $func2_addr $func2_len {
+			DW_OP_constu 0x234567
+			DW_OP_stack_value
+		    }
+		}
+	    }
+	}
+    }
+
+    if { [prepare_for_testing "failed to prepare" ${testfile} \
+	      [list $srcfile $asm_file] {nodebug}] } {
+	return -1
+    }
+
+    if { ![runto_main] } {
+	fail "can't run to main"
+	return
+    }
+
+    gdb_breakpoint "func1"
+    gdb_breakpoint "func2"
+
+    gdb_continue_to_breakpoint "func1"
+    with_test_prefix "at func1" {
+	gdb_test "print /x foo" " = 0x123456"
+    }
+
+    gdb_continue_to_breakpoint "func2"
+    with_test_prefix "at func2" {
+	gdb_test "print /x foo" " = 0x234567"
+    }
+}

gdb/testsuite/lib/dwarf.exp

@@ -474,6 +474,7 @@ namespace eval Dwarf {
 
 	    DW_FORM_ref_udata -
 	    DW_FORM_udata -
+	    DW_FORM_loclistx -
 	    DW_FORM_rnglistx {
 		_op .uleb128 $value
 	    }
@@ -1502,6 +1503,201 @@ namespace eval Dwarf {
 	uplevel $body
     }
 
+    # Emit a DWARF .debug_loclists section.
+    #
+    # The target address size is based on the current target's address size.
+    #
+    # There is one mandatory positional argument, BODY, which must be Tcl code
+    # that emits the content of the section.  It is evaluated in the caller's
+    # context.
+    #
+    # The following option can be used:
+    #
+    #  - -is-64 true|false: Whether to use 64-bit DWARF instead of 32-bit DWARF.
+    #                       The default is 32-bit.
+
+    proc loclists { args } {
+	variable _debug_loclists_addr_size
+	variable _debug_loclists_offset_size
+	variable _debug_loclists_is_64_dwarf
+
+	parse_args {{"is-64" "false"}}
+
+	if { [llength $args] != 1 } {
+	    error "loclists proc expects one positional argument (body)"
+	}
+
+	lassign $args body
+
+	if [is_64_target] {
+	    set _debug_loclists_addr_size 8
+	} else {
+	    set _debug_loclists_addr_size 4
+	}
+
+	if { ${is-64} } {
+	    set _debug_loclists_offset_size 8
+	    set _debug_loclists_is_64_dwarf true
+	} else {
+	    set _debug_loclists_offset_size 4
+	    set _debug_loclists_is_64_dwarf false
+	}
+
+	_section ".debug_loclists"
+
+	# Count of tables in the section.
+	variable _debug_loclists_table_count 0
+
+	# Compute the label name for list at index LIST_IDX, for the current
+	# table.
+
+	proc _compute_list_label { list_idx } {
+	    variable _debug_loclists_table_count
+
+	    return ".Lloclists_table_${_debug_loclists_table_count}_list_${list_idx}"
+	}
+
+	# Generate one table (header + offset array + location lists).
+	#
+	# Accepts one position argument, BODY.  BODY may call the LIST_
+	# procedure to generate loclists.
+	#
+	# The -post-header-label option can be used to define a label just after the
+	# header of the table.  This is the label that a DW_AT_loclists_base
+	# attribute will usually refer to.
+
+	proc table { args } {
+	    variable _debug_loclists_table_count
+	    variable _debug_loclists_addr_size
+	    variable _debug_loclists_offset_size
+	    variable _debug_loclists_is_64_dwarf
+
+	    parse_args {{post-header-label ""}}
+
+	    if { [llength $args] != 1 } {
+		error "table proc expects one positional argument (body)"
+	    }
+
+	    lassign $args body
+
+	    # Generate one location list.
+	    #
+	    # BODY may call the various procs defined below to generate list
+	    # entries.  They correspond to the location list entry kinds
+	    # described in section 2.6.2 of the DWARF 5 spec.
+	    #
+	    # To define a label pointing to the beginning of the list, use
+	    # the conventional way of declaring and defining labels:
+	    #
+	    #   declare_labels the_list
+	    #
+	    #   the_list: list_ {
+	    #     ...
+	    #   }
+
+	    proc list_ { body } {
+		variable _debug_loclists_list_count
+
+		# Count the location descriptions in this list.
+		variable _debug_loclists_locdesc_count 0
+
+		# Define a label for this list.  It is used to build the offset
+		# array later.
+		set list_label [_compute_list_label $_debug_loclists_list_count]
+		define_label $list_label
+
+		# Emit a DW_LLE_start_length entry.
+
+		proc start_length { start length locdesc } {
+		    variable _debug_loclists_is_64_dwarf
+		    variable _debug_loclists_addr_size
+		    variable _debug_loclists_offset_size
+		    variable _debug_loclists_table_count
+		    variable _debug_loclists_list_count
+		    variable _debug_loclists_locdesc_count
+
+		    _op .byte 0x08 "DW_LLE_start_length"
+
+		    # Start and end of the address range.
+		    _op .${_debug_loclists_addr_size}byte $start "start"
+		    _op .uleb128 $length "length"
+
+		    # Length of location description.
+		    set locdesc_start_label ".Lloclists_table_${_debug_loclists_table_count}_list_${_debug_loclists_list_count}_locdesc_${_debug_loclists_locdesc_count}_start"
+		    set locdesc_end_label ".Lloclists_table_${_debug_loclists_table_count}_list_${_debug_loclists_list_count}_locdesc_${_debug_loclists_locdesc_count}_end"
+		    _op .uleb128 "$locdesc_end_label - $locdesc_start_label" "locdesc length"
+
+		    define_label $locdesc_start_label
+		    set dwarf_version 5
+		    _location $locdesc $dwarf_version $_debug_loclists_addr_size $_debug_loclists_offset_size
+		    define_label $locdesc_end_label
+
+		    incr _debug_loclists_locdesc_count
+		}
+
+		uplevel $body
+
+		# Emit end of list.
+		_op .byte 0x00 "DW_LLE_end_of_list"
+
+		incr _debug_loclists_list_count
+	    }
+
+	    # Count of lists in the table.
+	    variable _debug_loclists_list_count 0
+
+	    # Generate the lists ops first, because we need to know how many
+	    # lists there are to generate the header and offset table.
+	    set lists_ops [_defer_to_string {
+		uplevel $body
+	    }]
+
+	    set post_unit_len_label \
+		[_compute_label "loclists_table_${_debug_loclists_table_count}_post_unit_len"]
+	    set post_header_label \
+		[_compute_label "loclists_table_${_debug_loclists_table_count}_post_header"]
+	    set table_end_label \
+		[_compute_label "loclists_table_${_debug_loclists_table_count}_end"]
+
+	    # Emit the table header.
+	    if { $_debug_loclists_is_64_dwarf } {
+		_op .4byte 0xffffffff "unit length 1/2"
+		_op .8byte "$table_end_label - $post_unit_len_label" "unit length 2/2"
+	    } else {
+		_op .4byte "$table_end_label - $post_unit_len_label" "unit length"
+	    }
+
+	    define_label $post_unit_len_label
+
+	    _op .2byte 5 "DWARF version"
+	    _op .byte $_debug_loclists_addr_size "address size"
+	    _op .byte 0 "segment selector size"
+	    _op .4byte $_debug_loclists_list_count "offset entry count"
+
+	    define_label $post_header_label
+
+	    # Define the user post-header label, if provided.
+	    if { ${post-header-label} != "" } {
+		define_label ${post-header-label}
+	    }
+
+	    # Emit the offset array.
+	    for {set list_idx 0} {$list_idx < $_debug_loclists_list_count} {incr list_idx} {
+		set list_label [_compute_list_label $list_idx]
+		_op .${_debug_loclists_offset_size}byte "$list_label - $post_header_label" "offset of list $list_idx"
+	    }
+
+	    # Emit the actual list data.
+	    _emit "$lists_ops"
+
+	    define_label $table_end_label
+
+	    incr _debug_loclists_table_count
+	}
+
+	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.