[PATCHv2] Fix setting breakpoints or stepping on line 65535

Bernd Edlinger
2019-12-02T18:04:19Z

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Hi Andrew,

On 12/1/19 11:08 PM, Andrew Burgess wrote:
> * Bernd Edlinger <bernd.edlinger@hotmail.de> [2019-11-24 11:54:23 +0000]:
>
>> Hi,
>>
>> this removes code that is present from the very first git revisison
>> 7b4ac7e1ed2c4616bce56d1760807798be87ac9e from 1988. It was in the
>> gdb/dbxread.c at the time (and makes more sense for dbx line info format
>> since line numbers are 16-bit entities in that debug format and debugging
>> files with more than 65535 lines would not work anyway) but moved from
>> there to gdb/buildsym.c which is used for dwarf line info as well, and
>> excluding an arbitrary line number does certainly not make sense nowadays.
>>
>>
>> Thanks
>> Bernd.
>
>> From f202ae765b72ad6d17600eb661993a63191309f7 Mon Sep 17 00:00:00 2001
>> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>> Date: Sat, 23 Nov 2019 07:37:26 +0100
>> Subject: [PATCH 1/2] Fix setting breakpoints or stepping on line 65535
>>
>
> Bernd,
>
> Thanks for looking into this, and especially thanks for adding a test!
>
> Normally you should include the git commit message and ChangeLog along
> with your patch submission so that these can be reviewed too. 'git
> format-patch' and 'git send-email' can be useful for this, if you can
> get them setup.
>

Okay, I added changelog messages for gdb/ChangeLog and gdb/testsuite/ChangeLog,
and improved the commit messages.
I hope you can handle the format-patch files as attachments.

> Given the age of the code you're removing I think this change sounds
> reasonable. I assume there's no test that covers why this code should
> be there, so you see no regressions with this code removed?
>

No, there were no regressions (last full test on 24-11-19).

> I have a couple of minor issues with the test. If you address those
> and repost with commit message and ChangeLog this can be approved.
>

Fixed the test.

Thanks a lot for your review.
Is it OK for trunk?

Thanks
Bernd.

> Thanks,
> Andrew
>
>
>
>
>> ---
>> gdb/buildsym.c | 6 ------
>> 1 file changed, 6 deletions(-)
>>
>> diff --git a/gdb/buildsym.c b/gdb/buildsym.c
>> index 79f8305..6c14f3f 100644
>> --- a/gdb/buildsym.c
>> +++ b/gdb/buildsym.c
>> @@ -670,12 +670,6 @@ buildsym_compunit::record_line (struct subfile *subfile, int line,
>> {
>> struct linetable_entry *e;
>>
>> - /* Ignore the dummy line number in libg.o */
>> - if (line == 0xffff)
>> - {
>> - return;
>> - }
>> -
>> /* Make sure line vector exists and is big enough. */
>> if (!subfile->line_vector)
>> {
>> --
>> 1.9.1
>>
>
>> From 54a7631206a2cf54573fb4cc94474cb2f6f99245 Mon Sep 17 00:00:00 2001
>> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>> Date: Sun, 24 Nov 2019 09:37:22 +0100
>> Subject: [PATCH 2/2] Add a test case for line 65535
>>
>> ---
>> gdb/testsuite/gdb.base/line65535.c | 19 +++++++++++++++++++
>> gdb/testsuite/gdb.base/line65535.exp | 26 ++++++++++++++++++++++++++
>> 2 files changed, 45 insertions(+)
>> create mode 100644 gdb/testsuite/gdb.base/line65535.c
>> create mode 100644 gdb/testsuite/gdb.base/line65535.exp
>>
>> diff --git a/gdb/testsuite/gdb.base/line65535.c b/gdb/testsuite/gdb.base/line65535.c
>> new file mode 100644
>> index 0000000..d80a294
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.base/line65535.c
>> @@ -0,0 +1,19 @@
>> +/* This testcase is part of GDB, the GNU debugger.
>> +
>> + Copyright 2019 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/>. */
>> +
>> +#line 65535 "line65535.c"
>> +int main() { return 0; }
>> diff --git a/gdb/testsuite/gdb.base/line65535.exp b/gdb/testsuite/gdb.base/line65535.exp
>> new file mode 100644
>> index 0000000..2535ba5
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.base/line65535.exp
>> @@ -0,0 +1,26 @@
>> +# Copyright 2019 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/>.
>> +
>
> Normally we like to add a short description of what the test is doing
> here - for new tests. Many old ones don't have this thought.
>

Okay, done.

>> +standard_testfile
>> +
>> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
>> + return -1
>> +}
>> +
>> +gdb_test "break $srcfile:65535" \
>> + ".*Breakpoint 1 at .*: file $srcfile, line 65535\\..*" \
>> + "break at line 65535"
>> +
>> +return 0
>
> I don't think this return is needed at the end of a test.
>

Okay, done. Works without.

>> --
>> 1.9.1
>>
>

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gdb:
2019-12-02 Bernd Edlinger <bernd.edlinger@hotmail.de>

* buildsym.c (buildsym_compunit::record_line): Do no longer ignore
line 65535.

gdb/testsuite:
2019-12-02 Bernd Edlinger <bernd.edlinger@hotmail.de>

* gdb.base/line65535.exp: New file.
* gdb.base/line65535.c: New file.

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From 7cee9fbe408af0a2da8e7812c2f86d2b9e4a809e Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Sat, 23 Nov 2019 07:37:26 +0100
Subject: [PATCH 1/2] Fix setting breakpoints or stepping on line 65535

This removes code that was present from the very first git revisison
7b4ac7e1ed2c4616bce56d1760807798be87ac9e from 1988. It was in the
gdb/dbxread.c at the time (and makes more sense for dbx line info format
since line numbers are 16-bit entities in that debug format and debugging
files with more than 65535 lines would not work anyway) but moved from
there to gdb/buildsym.c which is used for dwarf line info as well, and
excluding an arbitrary line number does certainly not make sense nowadays.
---
gdb/buildsym.c | 6 ------
1 file changed, 6 deletions(-)

diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index 79f8305..6c14f3f 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -670,12 +670,6 @@ buildsym_compunit::record_line (struct subfile *subfile, int line,
{
struct linetable_entry *e;

- /* Ignore the dummy line number in libg.o */
- if (line == 0xffff)
- {
- return;
- }
-
/* Make sure line vector exists and is big enough. */
if (!subfile->line_vector)
{
--
1.9.1

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From 46fe1ccfb2a1df701cb3bfeb6f882ca49f11ec0f Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Sun, 24 Nov 2019 09:37:22 +0100
Subject: [PATCH 2/2] Add a test case for line 65535

This adds a test case for setting a breakpoint on line 65535.
---
gdb/testsuite/gdb.base/line65535.c | 19 +++++++++++++++++++
gdb/testsuite/gdb.base/line65535.exp | 28 ++++++++++++++++++++++++++++
2 files changed, 47 insertions(+)
create mode 100644 gdb/testsuite/gdb.base/line65535.c
create mode 100644 gdb/testsuite/gdb.base/line65535.exp

diff --git a/gdb/testsuite/gdb.base/line65535.c b/gdb/testsuite/gdb.base/line65535.c
new file mode 100644
index 0000000..d80a294
--- /dev/null
+++ b/gdb/testsuite/gdb.base/line65535.c
@@ -0,0 +1,19 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2019 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/>. */
+
+#line 65535 "line65535.c"
+int main() { return 0; }
diff --git a/gdb/testsuite/gdb.base/line65535.exp b/gdb/testsuite/gdb.base/line65535.exp
new file mode 100644
index 0000000..095f151
--- /dev/null
+++ b/gdb/testsuite/gdb.base/line65535.exp
@@ -0,0 +1,28 @@
+# Copyright 2019 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/>.
+
+# This test tries to place a breakpoint on line 65535.
+# For the purpose of this test we are satisfied if the break
+# command succeeds, we will not try to actually run to that line.
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
+ return -1
+}
+
+gdb_test "break $srcfile:65535" \
+ ".*Breakpoint 1 at .*: file $srcfile, line 65535\\..*" \
+ "break at line 65535"
--
1.9.1