gdb/testsuite: add test for .debug_{rng,loc}lists section without offset array

It is possible for the tables in the .debug_{rng,loc}lists sections to
not have an array of offsets.  In that case, the offset_entry_count
field of the header is 0.  The forms DW_FORM_{rng,loc}listx (reference
by index) can't be used with that table.  Instead, the
DW_FORM_sec_offset form, which references a {rng,loc}list by direct
offset in the section, must be used.  From what I saw, this is what GCC
currently produces.

Add tests for this case.  I didn't see any bug related to this, I just
think that it would be nice to have coverage for this. A new
`-with-offset-array` option is added to the `table` procs, used when
generating {rng,loc}lists, to decide whether to generate the offset
array.

gdb/testsuite/ChangeLog:

	* lib/dwarf.exp (rnglists): Add -no-offset-array option to
	table proc.
	* gdb.dwarf2/rnglists-sec-offset.exp: Add test for
	.debug_rnglists table without offset array.
	* gdb.dwarf2/loclists-sec-offset.exp: Add test for
	.debug_loclists table without offset array.

Change-Id: I8e34a7bf68c9682215ffbbf66600da5b7db91ef7

gdb/testsuite/ChangeLog

@@ -1,3 +1,12 @@
+2021-02-02  Simon Marchi  <simon.marchi@efficios.com>
+
+	* lib/dwarf.exp (rnglists): Add -no-offset-array option to
+	table proc.
+	* gdb.dwarf2/rnglists-sec-offset.exp: Add test for
+	.debug_rnglists table without offset array.
+	* gdb.dwarf2/loclists-sec-offset.exp: Add test for
+	.debug_loclists table without offset array.
+
 2021-02-02  Simon Marchi  <simon.marchi@efficios.com>
 
 	* gdb.dwarf2/rnglists-sec-offset.exp: Add test for DW_AT_ranges

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

@@ -43,6 +43,20 @@ func4 (void)
   return 4;
 }
 
+static int
+func5 (void)
+{
+  asm ("func5_label: .global func5_label\n");
+  return 5;
+}
+
+static int
+func6 (void)
+{
+  asm ("func6_label: .global func6_label\n");
+  return 6;
+}
+
 int
 main (void)
 {
@@ -50,4 +64,6 @@ main (void)
   func2 ();
   func3 ();
   func4 ();
+  func5 ();
+  func6 ();
 }

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

@@ -37,6 +37,8 @@ foreach_with_prefix is_64 {false true} {
     lassign [function_range func2 $srcdir/$subdir/$srcfile] func2_addr func2_len
     lassign [function_range func3 $srcdir/$subdir/$srcfile] func3_addr func3_len
     lassign [function_range func4 $srcdir/$subdir/$srcfile] func4_addr func4_len
+    lassign [function_range func5 $srcdir/$subdir/$srcfile] func5_addr func5_len
+    lassign [function_range func6 $srcdir/$subdir/$srcfile] func6_addr func6_len
 
     set asm_file [standard_output_file $srcfile2]
     Dwarf::assemble $asm_file {
@@ -44,6 +46,8 @@ foreach_with_prefix is_64 {false true} {
 	global func2_addr func2_len
 	global func3_addr func3_len
 	global func4_addr func4_len
+	global func5_addr func5_len
+	global func6_addr func6_len
 	global is_64
 
 	declare_labels cu_range_list foo_range_list
@@ -56,7 +60,10 @@ foreach_with_prefix is_64 {false true} {
 	} {
 	    declare_labels int_type1
 	    declare_labels int_type2
-	    declare_labels foo_location_list bar_location_list
+	    declare_labels int_type3
+	    declare_labels foo_location_list
+	    declare_labels bar_location_list
+	    declare_labels baz_location_list
 
 	    DW_TAG_compile_unit {
 	    } {
@@ -123,6 +130,41 @@ foreach_with_prefix is_64 {false true} {
 	    }
 	}
 
+	# This CU uses the DW_FORM_sec_offset form to refer to the
+	# .debug_loclists section.  The corresponding contribution in the
+	# .debug_loclists section has no offset array.
+	cu {
+	    version 5
+	    is_64 $is_64
+	} {
+	    DW_TAG_compile_unit {
+	    } {
+		int_type3: 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 "baz"}
+		    {DW_AT_location $baz_location_list DW_FORM_sec_offset}
+		    {DW_AT_type :$int_type3}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func5"}
+		    {DW_AT_low_pc $func5_addr}
+		    {DW_AT_high_pc $func5_len DW_FORM_udata}
+		}
+
+		DW_TAG_subprogram {
+		    {DW_AT_name "func6"}
+		    {DW_AT_low_pc $func6_addr}
+		    {DW_AT_high_pc $func6_len DW_FORM_udata}
+		}
+	    }
+	}
+
 	loclists -is-64 $is_64 {
 	    # The lists in this table are accessed by direct offset
 	    # (DW_FORM_sec_offset).
@@ -153,6 +195,20 @@ foreach_with_prefix is_64 {false true} {
 		    }
 		}
 	    }
+
+	    table -with-offset-array false {
+		baz_location_list: list_ {
+		    start_length $func5_addr $func5_len {
+			DW_OP_constu 0x567890
+			DW_OP_stack_value
+		    }
+
+		    start_length $func6_addr $func6_len {
+			DW_OP_constu 0x678901
+			DW_OP_stack_value
+		    }
+		}
+	    }
 	}
     }
 
@@ -170,6 +226,8 @@ foreach_with_prefix is_64 {false true} {
     gdb_breakpoint "func2"
     gdb_breakpoint "func3"
     gdb_breakpoint "func4"
+    gdb_breakpoint "func5"
+    gdb_breakpoint "func6"
 
     gdb_continue_to_breakpoint "func1"
     with_test_prefix "at func1" {
@@ -190,4 +248,14 @@ foreach_with_prefix is_64 {false true} {
     with_test_prefix "at func4" {
 	gdb_test "print /x bar" " = 0x456789"
     }
+
+    gdb_continue_to_breakpoint "func5"
+    with_test_prefix "at func5" {
+	gdb_test "print /x baz" " = 0x567890"
+    }
+
+    gdb_continue_to_breakpoint "func6"
+    with_test_prefix "at func6" {
+	gdb_test "print /x baz" " = 0x678901"
+    }
 }

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

@@ -35,8 +35,8 @@ foreach_with_prefix is_64 {false true} {
     Dwarf::assemble $asm_file {
 	global is_64
 
-	declare_labels cu1_range_list cu2_range_list
+	declare_labels cu1_range_list cu2_range_list cu3_range_list
-	declare_labels foo_range_list bar_range_list
+	declare_labels foo_range_list bar_range_list baz_range_list
 
 	# This CU uses the DW_FORM_sec_offset form to refer to the .debug_rnglists
 	# section.
@@ -73,6 +73,23 @@ foreach_with_prefix is_64 {false true} {
 	    }
 	}
 
+	# This CU uses the DW_FORM_sec_offset form to refer to the .debug_rnglists
+	# section.  The corresponding contribution in the .debug_rnglists has no
+	# offset array.
+	cu {
+	    version 5
+	    is_64 $is_64
+	} {
+	    DW_TAG_compile_unit {
+		{DW_AT_ranges $cu3_range_list DW_FORM_sec_offset}
+	    } {
+		DW_TAG_subprogram {
+		    {DW_AT_name "baz"}
+		    {DW_AT_ranges $baz_range_list DW_FORM_sec_offset}
+		}
+	    }
+	}
+
 	rnglists -is-64 $is_64 {
 	    # The lists in this table are accessed by direct offset
 	    # (DW_FORM_sec_offset).
@@ -99,6 +116,18 @@ foreach_with_prefix is_64 {false true} {
 		    start_end 0x5000 0x5010
 		}
 	    }
+
+	    table -with-offset-array false {
+		# For the third CU.
+		cu3_range_list: list_ {
+		    start_end 0x6000 0x7000
+		}
+
+		# For the baz function.
+		baz_range_list: list_ {
+		    start_end 0x6000 0x6010
+		}
+	    }
 	}
     }
 
@@ -110,4 +139,5 @@ foreach_with_prefix is_64 {false true} {
     # Sanity checks to make sure GDB slurped the symbols correctly.
     gdb_test "p/x &foo" " = 0x4000"
     gdb_test "p/x &bar" " = 0x5000"
+    gdb_test "p/x &baz" " = 0x6000"
 }

gdb/testsuite/lib/dwarf.exp

@@ -1392,6 +1392,10 @@ namespace eval Dwarf {
 	# 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_rnglists_base
 	# attribute will usually refer to.
+	#
+	# The `-with-offset-array true|false` option can be used to control
+	# whether the headers of the location list tables have an array of
+	# offset.  The default is true.
 
 	proc table { args } {
 	    variable _debug_rnglists_table_count
@@ -1399,7 +1403,10 @@ namespace eval Dwarf {
 	    variable _debug_rnglists_offset_size
 	    variable _debug_rnglists_is_64_dwarf
 
-	    parse_args {{post-header-label ""}}
+	    parse_args {
+		{post-header-label ""}
+		{with-offset-array true}
+	    }
 
 	    if { [llength $args] != 1 } {
 		error "table proc expects one positional argument (body)"
@@ -1477,7 +1484,12 @@ namespace eval Dwarf {
 	    _op .2byte 5 "dwarf version"
 	    _op .byte $_debug_rnglists_addr_size "address size"
 	    _op .byte 0 "segment selector size"
-	    _op .4byte "$_debug_rnglists_list_count" "offset entry count"
+
+	    if { ${with-offset-array} } {
+	      _op .4byte "$_debug_rnglists_list_count" "offset entry count"
+	    } else {
+	      _op .4byte 0 "offset entry count"
+	    }
 
 	    define_label $post_header_label
 
@@ -1487,9 +1499,11 @@ namespace eval Dwarf {
 	    }
 
 	    # Emit the offset array.
-	    for {set list_idx 0} {$list_idx < $_debug_rnglists_list_count} {incr list_idx} {
+	    if { ${with-offset-array} } {
-		set list_label [_compute_list_label $list_idx]
+		for {set list_idx 0} {$list_idx < $_debug_rnglists_list_count} {incr list_idx} {
-		_op .${_debug_rnglists_offset_size}byte "$list_label - $post_header_label" "offset of list $list_idx"
+		    set list_label [_compute_list_label $list_idx]
+		    _op .${_debug_rnglists_offset_size}byte "$list_label - $post_header_label" "offset of list $list_idx"
+		}
 	    }
 
 	    # Emit the actual list data.
@@ -1565,6 +1579,10 @@ namespace eval Dwarf {
 	# 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.
+	#
+	# The `-with-offset-array true|false` option can be used to control
+	# whether the headers of the location list tables have an array of
+	# offset.  The default is true.
 
 	proc table { args } {
 	    variable _debug_loclists_table_count
@@ -1572,7 +1590,10 @@ namespace eval Dwarf {
 	    variable _debug_loclists_offset_size
 	    variable _debug_loclists_is_64_dwarf
 
-	    parse_args {{post-header-label ""}}
+	    parse_args {
+		{post-header-label ""}
+		{with-offset-array true}
+	    }
 
 	    if { [llength $args] != 1 } {
 		error "table proc expects one positional argument (body)"
@@ -1672,7 +1693,12 @@ namespace eval Dwarf {
 	    _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"
+
+	    if { ${with-offset-array} } {
+	      _op .4byte "$_debug_loclists_list_count" "offset entry count"
+	    } else {
+	      _op .4byte 0 "offset entry count"
+	    }
 
 	    define_label $post_header_label
 
@@ -1682,9 +1708,11 @@ namespace eval Dwarf {
 	    }
 
 	    # Emit the offset array.
-	    for {set list_idx 0} {$list_idx < $_debug_loclists_list_count} {incr list_idx} {
+	    if { ${with-offset-array} } {
-		set list_label [_compute_list_label $list_idx]
+		for {set list_idx 0} {$list_idx < $_debug_loclists_list_count} {incr list_idx} {
-		_op .${_debug_loclists_offset_size}byte "$list_label - $post_header_label" "offset of list $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.