From: Tom de Vries <tdevries@suse.de>
To: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
"gdb-patches@sourceware.org" <gdb-patches@sourceware.org>,
"cel@us.ibm.com" <cel@us.ibm.com>
Cc: "kevinb@redhat.com" <kevinb@redhat.com>,
"will_schmidt@vnet.ibm.com" <will_schmidt@vnet.ibm.com>,
"blarsen@redhat.com" <blarsen@redhat.com>
Subject: Re: [PATCH 2/2 ver 3] PowerPC, fix support for printing the function return value for non-trivial values.
Date: Tue, 15 Nov 2022 08:15:53 +0100 [thread overview]
Message-ID: <7f476265-c6a9-9fcf-ce13-ff550ea5e6f6@suse.de> (raw)
In-Reply-To: <2db5ad69b32f4cda9c53b252ad37cd783f827c14.camel@de.ibm.com>
On 11/14/22 17:47, Ulrich Weigand via Gdb-patches wrote:
> Carl Love <cel@us.ibm.com> wrote:
>
>> PowerPC, fix support for printing the function return value for non-trivial values.
>>
>> Currently, a non-trivial return value from a function cannot currently be
>> reliably determined on PowerPC. This is due to the fact that the PowerPC
>> ABI uses register r3 to store the address of the buffer containing the
>> non-trivial return value when the function is called. The PowerPC ABI
>> does not guarantee the value in register r3 is not modified in the
>> function. Thus the value in r3 cannot be reliably used to obtain the
>> return addreses on exit from the function.
>>
>> This patch adds a new gdbarch method to allow PowerPC to access the value
>> of r3 on entry to a function. On PowerPC, the new gdbarch method attempts
>> to use the DW_OP_entry_value for the DWARF entries, when exiting the
>> function, to determine the value of r3 on entry to the function. This
>> requires the use of the -fvar-tracking compiler option to compile the
>> user application thus generating the DW_OP_entry_value in the binary. The
>> DW_OP_entry_value entries in the binary file allows GDB to resolve the
>> DW_TAG_call_site entries. This new gdbarch method is used to get the
>> return buffer address, in the case of a function returning a nontrivial
>> data type, on exit from the function. The GDB function should_stop checks
>> to see if RETURN_BUF is non-zero. By default, RETURN_BUF will be set to
>> zero by the new gdbarch method call for all architectures except PowerPC.
>> The get_return_value function will be used to obtain the return value on
>> all other architectures as is currently being done if RETURN_BUF is zero.
>> On PowerPC, the new gdbarch method will return a nonzero address in
>> RETURN_BUF if the value can be determined. The value_at function uses the
>> return buffer address to get the return value.
>>
>> This patch fixes five testcase failures in gdb.cp/non-trivial-retval.exp.
>> The correct function return values are now reported.
>>
>> Note this patch is dependent on patch: "PowerPC, function
>> ppc64_sysv_abi_return_value add missing return value convention".
>>
>> This patch has been tested on Power 10 and x86-64 with no regressions.
>
> I believe all of Kevin's and Bruno's comments have been addressed
> in this version. I've reviewed it myself as well, and it looks
> good to me.
>
> This is OK.
>
On x86_64-linux, I run into a segfault:
...
PASS: gdb.asm/asm-source.exp: info source asmsrc1.s
ERROR: GDB process no longer exists
UNRESOLVED: gdb.asm/asm-source.exp: finish from foo3
...
Reproduced on command line:
...
$ gdb -q -batch -x outputs/gdb.asm/asm-source/gdb.in.1
...
The problem seems to be that:
...
Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
0x000000000043de7a in symbol::type (this=0x0) at
/home/vries/gdb_versions/devel/src/gdb/symtab.h:1287
1287 return m_type;
...
because:
...
(gdb) up
#1 0x0000000000852d94 in finish_command (arg=0x0, from_tty=0)
at /home/vries/gdb_versions/devel/src/gdb/infcmd.c:1887
1887 = check_typedef (sm->function->type ()->target_type ());
(gdb) p sm->function
$1 = (symbol *) 0x0
...
Thanks,
- Tom
next prev parent reply other threads:[~2022-11-15 7:15 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 22:26 [PATCH] PowerPC, add support for printing non-trivial C++ object for the finish command Carl Love
2022-03-13 5:28 ` Joel Brobecker
2022-03-14 10:43 ` Luis Machado
2022-03-14 13:40 ` Tom Tromey
2022-03-14 13:45 ` Luis Machado
2022-03-14 14:58 ` Ulrich Weigand
[not found] ` <ce6c71356c4a58fcdfb655a6e50c3a24f812e66c.camel@us.ibm.com>
[not found] ` <d9f17525c9a03c20b54015a6a71c36cae50fe4e3.camel@de.ibm.com>
[not found] ` <6ca2276426343756e103995e07ff951d6e26837b.camel@us.ibm.com>
[not found] ` <939797b94ab71f3f7356747d84a1515939cb3dcc.camel@de.ibm.com>
[not found] ` <fccc34c438fda9a35b8a8565e0f5026237e7eab9.camel@us.ibm.com>
[not found] ` <bb5b9b137fc11886964113d4b524526b3c733f4a.camel@us.ibm.com>
[not found] ` <1edb818bd2873a3fa5278f28131089d228a0a4f6.camel@de.ibm.com>
[not found] ` <7c884a865d06890cb325225c65d7a52fdfbd20d2.camel@us.ibm.com>
[not found] ` <846ca96309d2732d3db0e4c323a81105c098fa5f.camel@de.ibm.com>
[not found] ` <5a858dd7b957ecf45cf5b00ffc140a839c8ef023.camel@us.ibm.com>
[not found] ` <b634fecae5e33a3d1a278191c37f306a3b8622f2.camel@de.ibm.com>
[not found] ` <25f2380ced176f58a8e3ea9b70c7e7786988d650.camel@us.ibm.com>
[not found] ` <2b0481466e9ecc33d52c74c3a3b4babb05435f47.camel@de.ibm.com>
[not found] ` <df3b049416ff666e7bd3e3a91e4ea90d34256ea5.camel@us.ibm.com>
[not found] ` <71370ce02bd57827d3b7958772b1594d3591bd16.camel@de.ibm.com>
[not found] ` <ec9dafb1671699b03b28ee4be528711c6988eaa5.camel@us.ibm.com>
[not found] ` <148d8d3efcc8d110119e566027bfd0c65dd02525.camel@de.ibm.com>
[not found] ` <eef62b295e97fc464c22f9d748ff818860137de9.camel@us.ibm.com>
[not found] ` <afd6fa576f479359618b1ee50b08be8932735da8.camel@de.ibm.com>
[not found] ` <cb6b19e9d287d2bae4b72627791f2a00af062c48.camel@us.ibm.com>
[not found] ` <ee7101f86b5c8581905c53347fa603dc23ddc2bd.camel@de.ibm.com>
[not found] ` <8decd662134d57e8caf43960a1cdc47723e2bfe3.camel@us.ibm.com>
[not found] ` <f7cad695cf64540bad8c95cf5fd31691711d0eeb.camel@de.ibm.com>
[not found] ` <79d82ed277308ed5ce312bff398e770ab234390a.camel@us.ibm.com>
[not found] ` <63f21a897f452d81a73fb386cb99110a359ef0b7.camel@de.ibm.com>
[not found] ` <be178bc4f356d7f1937458290cb5883eeee9eee1.camel@us.ibm.com>
[not found] ` <dfd935e9414d3dd2c27d1e877d3718ae7510aa07.camel@de.ibm.com>
[not found] ` <97275f61ef101a12cde8e5a45008ed8e479424eb.camel@us.ibm.com>
[not found] ` <b629440707165f46fb466e48b0c95de3bfa334d2.camel@de.ibm.com>
[not found] ` <191f5826b228a7614c084c9704b086851d418c78.camel@us.ibm.com>
[not found] ` <5405a79ecd6ed34646ad77eed0779063ee222d37.camel@de.ibm.com>
2022-10-06 16:36 ` [PATCH 0/2] PowerPC, fix support for printing the function return value for non-trivial values Carl Love
2022-10-18 18:55 ` [PATCH 0/2 version 2] " Carl Love
2022-10-06 16:37 ` [PATCH 2/2] " Carl Love
2022-10-08 4:36 ` Kevin Buettner
2022-10-12 17:01 ` Carl Love
2022-10-14 2:49 ` Kevin Buettner
2022-10-14 7:36 ` Bruno Larsen
2022-10-14 23:25 ` Carl Love
2022-10-14 23:23 ` Carl Love
2022-10-18 1:06 ` Kevin Buettner
2022-10-18 18:26 ` Carl Love
2022-10-18 18:55 ` [PATCH 2/2 ver 2] " Carl Love
2022-10-31 16:07 ` Carl Love
2022-11-07 14:56 ` Bruno Larsen
2022-11-07 19:53 ` Carl Love
2022-11-07 20:04 ` [PATCH 2/2 ver 3] " Carl Love
2022-11-14 16:47 ` Ulrich Weigand
2022-11-15 7:15 ` Tom de Vries [this message]
2022-11-15 10:16 ` Ulrich Weigand
2022-11-15 16:04 ` Carl Love
2022-11-15 16:55 ` Simon Marchi
2022-11-15 23:46 ` Carl Love
2022-11-15 17:24 ` Carl Love
2022-11-15 18:05 ` Ulrich Weigand
2022-11-16 1:01 ` Carl Love
2022-11-16 9:52 ` Ulrich Weigand
2022-11-16 10:12 ` Tom de Vries
2022-11-16 10:20 ` Lancelot SIX
2022-11-16 15:56 ` Carl Love
2022-11-16 20:55 ` [PATCH] Change NULL to nullptr in gdb/infcmd.c and gdb/infrun.c Carl Love
2022-11-16 21:15 ` Simon Marchi
[not found] ` <5a34aaeab59f0099b915d1780c701284a6cf691e.camel@us.ibm.com>
[not found] ` <8aa882863b2f4cef38c22386387c5705bf63c3d5.camel@de.ibm.com>
2022-10-06 16:37 ` [PATCH 1/2] PowerPC, function ppc64_sysv_abi_return_value add missing return value convention Carl Love
2022-10-08 4:20 ` Kevin Buettner
2022-10-14 23:20 ` Carl Love
2022-10-18 18:55 ` [PATCH 1/2 ver 2] " Carl Love
2022-11-07 20:04 ` [PATCH 1/2 ver 3] " Carl Love
2022-11-14 16:45 ` Ulrich Weigand
2022-11-14 19:38 ` Carl Love
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7f476265-c6a9-9fcf-ce13-ff550ea5e6f6@suse.de \
--to=tdevries@suse.de \
--cc=Ulrich.Weigand@de.ibm.com \
--cc=blarsen@redhat.com \
--cc=cel@us.ibm.com \
--cc=gdb-patches@sourceware.org \
--cc=kevinb@redhat.com \
--cc=will_schmidt@vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).