From: Simon Marchi <simon.marchi@polymtl.ca>
To: Zoran Zaric <Zoran.Zaric@amd.com>, gdb-patches@sourceware.org
Cc: Simon Marchi <simon.marchi@efficios.com>
Subject: Re: [PATCH 07/13] gdb/dwarf: read DW_AT_ranges value as unsigned in partial_die_info::read
Date: Thu, 28 Jan 2021 10:51:53 -0500 [thread overview]
Message-ID: <acb82f89-a3be-df83-b460-9d8fe53de126@polymtl.ca> (raw)
In-Reply-To: <2d20d449-857b-0b1d-aebc-96ff07828342@amd.com>
On 2021-01-28 10:41 a.m., Zoran Zaric wrote:
>> From: Simon Marchi <simon.marchi@efficios.com>
>>
>> While writing a test for this series, I made a function
>> (DW_AT_subprogram) with a DW_AT_ranges attribute using the
>> DW_FORM_rnglistx form:
>>
>> 0x00000012: DW_TAG_subprogram
>> DW_AT_name [DW_FORM_string] ("foo")
>> DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x0) rangelist = 0x00000036
>> [0x0000000000004000, 0x0000000000005000))
>>
>> And strangely I couldn't print it:
>>
>> (gdb) p foo
>> No symbol "foo" in current context.
>>
>> This is because of the `attr.constant_value (0)` in the DW_AT_ranges
>> handling of partial_die_info::read. Since DW_FORM_rnglistx is not
>> recognized as a constant value by attribute::constant_value, the default
>> value (0) is returned. Down the line, this causes
>> dwarf2_rnglists_process to try read a range list at offset 0 in the
>> .debug_rnglists section, which is obviously wrong. In the end, no
>> symbol is created for foo because we didn't find an address range.
>>
>> Use attr->as_unsigned instead. This is what is done for the equivalent
>> code in dwarf2_get_pc_bounds. With this, GDB processes the subprogram
>> DIE and we are able to print the function symbol:
>>
>> (gdb) p foo
>> $1 = {void (void)} 0x4000
>>
>> Note that I didn't see an actual compiler use DW_FORM_rnglistx for a
>> subprogram's range. However, in the binary attached to PR 26813, there
>> are some lexical blocks with it:
>>
>> 0x0000d34a: DW_TAG_lexical_block
>> DW_AT_ranges [DW_FORM_rnglistx] (indexed (0x2) rangelist = 0x000000d4
>> [0x0000000000005db1, 0x0000000000005e36)
>> [0x0000000000005e48, 0x0000000000005f3c)
>> [0x0000000000006045, 0x0000000000006053))
>>
>> Their ranges are read incorrectly just like the ranges of the
>> subprograms. With this patch applied, they are read correctly.
>>
>
> Good find.
>
> Zoran
Note that an identical change was already merged:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=9f6c202e573b796a9e7328cc5fdab7c0c63776bf
So this patch will probably disappear when I rebase.
Simon
next prev parent reply other threads:[~2021-01-28 15:52 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 5:39 [PATCH 00/13] DWARF 5 rnglists & loclists fixes (PR 26813) Simon Marchi
2021-01-20 5:39 ` [PATCH 01/13] gdb/dwarf: change read_loclist_index complaints into errors Simon Marchi
2021-01-28 15:17 ` Zoran Zaric
2021-01-28 15:42 ` Simon Marchi
2021-02-25 19:20 ` Tom Tromey
2021-01-20 5:39 ` [PATCH 02/13] gdb/dwarf: fix bound check in read_rnglist_index Simon Marchi
2021-01-28 15:22 ` Zoran Zaric
2021-01-20 5:39 ` [PATCH 03/13] gdb/dwarf: add missing bound check to read_loclist_index Simon Marchi
2021-01-20 5:39 ` [PATCH 04/13] gdb/dwarf: remove unnecessary check in read_{rng, loc}list_index Simon Marchi
2021-01-20 5:39 ` [PATCH 05/13] gdb/dwarf: few fixes for handling DW_FORM_{rng, loc}listx Simon Marchi
2021-01-28 15:30 ` [PATCH 05/13] gdb/dwarf: few fixes for handling DW_FORM_{rng,loc}listx Zoran Zaric
2021-01-20 5:39 ` [PATCH 06/13] gdb/dwarf: read correct rnglist/loclist header in read_{rng, loc}list_index Simon Marchi
2021-01-28 15:39 ` [PATCH 06/13] gdb/dwarf: read correct rnglist/loclist header in read_{rng,loc}list_index Zoran Zaric
2021-01-28 15:49 ` Simon Marchi
2021-01-28 15:54 ` Zoran Zaric
2021-01-20 5:39 ` [PATCH 07/13] gdb/dwarf: read DW_AT_ranges value as unsigned in partial_die_info::read Simon Marchi
2021-01-28 15:41 ` Zoran Zaric
2021-01-28 15:51 ` Simon Marchi [this message]
2021-01-20 5:39 ` [PATCH 08/13] gdb/testsuite: add .debug_rnglists tests Simon Marchi
2021-01-28 16:24 ` Zoran Zaric
2021-01-20 5:39 ` [PATCH 09/13] gdb/testsuite: DWARF assembler: add context parameters to _location Simon Marchi
2021-01-28 16:30 ` Zoran Zaric
2021-01-20 5:39 ` [PATCH 10/13] gdb/testsuite: add .debug_loclists tests Simon Marchi
2021-01-28 16:52 ` Zoran Zaric
2021-01-28 17:47 ` Simon Marchi
2021-01-29 10:13 ` Zoran Zaric
2021-01-29 15:57 ` Simon Marchi
2021-01-29 16:58 ` Zoran Zaric
2021-01-29 17:37 ` Simon Marchi
2021-01-20 5:39 ` [PATCH 11/13] gdb/dwarf: split dwarf2_cu::ranges_base in two Simon Marchi
2021-01-20 5:39 ` [PATCH 12/13] gdb/dwarf: make read_{loc, rng}list_index return sect_offset Simon Marchi
2021-02-25 19:26 ` Tom Tromey
2021-01-20 5:39 ` [PATCH 13/13] gdb/testsuite: add test for .debug_{rng, loc}lists section without offset array Simon Marchi
2021-02-02 15:43 ` [PATCH 00/13] DWARF 5 rnglists & loclists fixes (PR 26813) Simon Marchi
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