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<title>llvm-project.git/lldb/source/Target/ThreadList.cpp, branch main</title>
<subtitle>Unnamed repository; edit this file 'description' to name the repository.
</subtitle>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/'/>
<entry>
<title>Reapply "[lldb] Implement basic support for reverse-continue (#125242)" (again) (#128156)</title>
<updated>2025-03-17T15:06:25+00:00</updated>
<author>
<name>Pavel Labath</name>
<email>pavel@labath.sk</email>
</author>
<published>2025-03-17T15:06:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=1b237198dc9d308c6d589e01637ec7496b48b3e0'/>
<id>1b237198dc9d308c6d589e01637ec7496b48b3e0</id>
<content type='text'>
This reverts commit
https://github.com/llvm/llvm-project/commit/87b7f63a117c340a6d9ca47959335fd7ef6c7ad2,
reapplying

https://github.com/llvm/llvm-project/commit/7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b
with a small (and probably temporary)
change to generate more debug info to help with diagnosing buildbot
issues.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit
https://github.com/llvm/llvm-project/commit/87b7f63a117c340a6d9ca47959335fd7ef6c7ad2,
reapplying

https://github.com/llvm/llvm-project/commit/7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b
with a small (and probably temporary)
change to generate more debug info to help with diagnosing buildbot
issues.</pre>
</div>
</content>
</entry>
<entry>
<title>[lldb] Implement bidirectional access for backing&lt;-&gt;backed thread relationship (#125300)</title>
<updated>2025-02-03T21:40:57+00:00</updated>
<author>
<name>Felipe de Azevedo Piovezan</name>
<email>fpiovezan@apple.com</email>
</author>
<published>2025-02-03T21:40:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=90a51a443a2fc900e514279fa6ea8882c48b10fa'/>
<id>90a51a443a2fc900e514279fa6ea8882c48b10fa</id>
<content type='text'>
This enables finding the backed thread from the backing thread without
going through the thread list, and it will be useful for subsequent
commits.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This enables finding the backed thread from the backing thread without
going through the thread list, and it will be useful for subsequent
commits.</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "Reland "[lldb] Implement basic support for reverse-continue" (#125242)"</title>
<updated>2025-01-31T21:11:20+00:00</updated>
<author>
<name>Adrian Prantl</name>
<email>aprantl@apple.com</email>
</author>
<published>2025-01-31T21:11:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=87b7f63a117c340a6d9ca47959335fd7ef6c7ad2'/>
<id>87b7f63a117c340a6d9ca47959335fd7ef6c7ad2</id>
<content type='text'>
This reverts commit 7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b.

Breaking green dragon:

https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/as-lldb-cmake/19569/testReport/junit/lldb-api/functionalities_reverse-execution/TestReverseContinueWatchpoints_py/
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b.

Breaking green dragon:

https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/as-lldb-cmake/19569/testReport/junit/lldb-api/functionalities_reverse-execution/TestReverseContinueWatchpoints_py/
</pre>
</div>
</content>
</entry>
<entry>
<title>Reland "[lldb] Implement basic support for reverse-continue" (#125242)</title>
<updated>2025-01-31T15:56:33+00:00</updated>
<author>
<name>David Spickett</name>
<email>david.spickett@linaro.org</email>
</author>
<published>2025-01-31T15:56:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b'/>
<id>7e66cf74fb4e6a103f923e34700a7b6f20ac2a9b</id>
<content type='text'>
This reverts commit a774de807e56c1147d4630bfec3110c11d41776e.

This is the same changes as last time, plus:
* We load the binary into the target object so that on Windows, we can
resolve the locations of the functions.
* We now assert that each required breakpoint has at least 1 location,
to prevent an issue like that in the future.
* We are less strict about the unsupported error message, because it
prints "error: windows" on Windows instead of "error: gdb-remote".</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit a774de807e56c1147d4630bfec3110c11d41776e.

This is the same changes as last time, plus:
* We load the binary into the target object so that on Windows, we can
resolve the locations of the functions.
* We now assert that each required breakpoint has at least 1 location,
to prevent an issue like that in the future.
* We are less strict about the unsupported error message, because it
prints "error: windows" on Windows instead of "error: gdb-remote".</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "Reland "[lldb] Implement basic support for reverse-continue" (#123906)"" (#125091)</title>
<updated>2025-01-30T16:45:36+00:00</updated>
<author>
<name>David Spickett</name>
<email>david.spickett@linaro.org</email>
</author>
<published>2025-01-30T16:45:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=a774de807e56c1147d4630bfec3110c11d41776e'/>
<id>a774de807e56c1147d4630bfec3110c11d41776e</id>
<content type='text'>
Reverts llvm/llvm-project#123945

Has failed on the Windows on Arm buildbot:
https://lab.llvm.org/buildbot/#/builders/141/builds/5865
```
********************
Unresolved Tests (2):
  lldb-api :: functionalities/reverse-execution/TestReverseContinueBreakpoints.py
  lldb-api :: functionalities/reverse-execution/TestReverseContinueWatchpoints.py
********************
Failed Tests (1):
  lldb-api :: functionalities/reverse-execution/TestReverseContinueNotSupported.py
```
Reverting while I reproduce locally.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Reverts llvm/llvm-project#123945

Has failed on the Windows on Arm buildbot:
https://lab.llvm.org/buildbot/#/builders/141/builds/5865
```
********************
Unresolved Tests (2):
  lldb-api :: functionalities/reverse-execution/TestReverseContinueBreakpoints.py
  lldb-api :: functionalities/reverse-execution/TestReverseContinueWatchpoints.py
********************
Failed Tests (1):
  lldb-api :: functionalities/reverse-execution/TestReverseContinueNotSupported.py
```
Reverting while I reproduce locally.</pre>
</div>
</content>
</entry>
<entry>
<title>Reland "[lldb] Implement basic support for reverse-continue" (#123906)" (#123945)</title>
<updated>2025-01-30T14:03:01+00:00</updated>
<author>
<name>David Spickett</name>
<email>david.spickett@linaro.org</email>
</author>
<published>2025-01-30T14:03:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=0caba6c8dc2f6f0da61f30c169f59d40591cddbc'/>
<id>0caba6c8dc2f6f0da61f30c169f59d40591cddbc</id>
<content type='text'>
This reverts commit 22561cfb443267905d4190f0e2a738e6b412457f and fixes
b7b9ccf44988edf49886743ae5c3cf4184db211f (#112079).

The problem is that x86_64 and Arm 32-bit have memory regions above the
stack that are readable but not writeable. First Arm:
```
(lldb) memory region --all
&lt;...&gt;
[0x00000000fffcf000-0x00000000ffff0000) rw- [stack]
[0x00000000ffff0000-0x00000000ffff1000) r-x [vectors]
[0x00000000ffff1000-0xffffffffffffffff) ---
```
Then x86_64:
```
$ cat /proc/self/maps
&lt;...&gt;
7ffdcd148000-7ffdcd16a000 rw-p 00000000 00:00 0                          [stack]
7ffdcd193000-7ffdcd196000 r--p 00000000 00:00 0                          [vvar]
7ffdcd196000-7ffdcd197000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]
```
Compare this to AArch64 where the test did pass:
```
$ cat /proc/self/maps
&lt;...&gt;
ffffb87dc000-ffffb87dd000 r--p 00000000 00:00 0                          [vvar]
ffffb87dd000-ffffb87de000 r-xp 00000000 00:00 0                          [vdso]
ffffb87de000-ffffb87e0000 r--p 0002a000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffb87e0000-ffffb87e2000 rw-p 0002c000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
fffff4216000-fffff4237000 rw-p 00000000 00:00 0                          [stack]
```
To solve this, look up the memory region of the stack pointer (using
https://lldb.llvm.org/resources/lldbgdbremote.html#qmemoryregioninfo-addr)
and constrain the read to within that region. Since we know the stack is
all readable and writeable.

I have also added skipIfRemote to the tests, since getting them working
in that context is too complex to be worth it.

Memory write failures now display the range they tried to write, and
register write errors will show the name of the register where possible.

The patch also includes a workaround for a an issue where the test code
could mistake an `x` response that happens to begin with an `O` for an
output packet (stdout). This workaround will not be necessary one we
start using the [new
implementation](https://discourse.llvm.org/t/rfc-fixing-incompatibilties-of-the-x-packet-w-r-t-gdb/84288)
of the `x` packet.

---------

Co-authored-by: Pavel Labath &lt;pavel@labath.sk&gt;</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 22561cfb443267905d4190f0e2a738e6b412457f and fixes
b7b9ccf44988edf49886743ae5c3cf4184db211f (#112079).

The problem is that x86_64 and Arm 32-bit have memory regions above the
stack that are readable but not writeable. First Arm:
```
(lldb) memory region --all
&lt;...&gt;
[0x00000000fffcf000-0x00000000ffff0000) rw- [stack]
[0x00000000ffff0000-0x00000000ffff1000) r-x [vectors]
[0x00000000ffff1000-0xffffffffffffffff) ---
```
Then x86_64:
```
$ cat /proc/self/maps
&lt;...&gt;
7ffdcd148000-7ffdcd16a000 rw-p 00000000 00:00 0                          [stack]
7ffdcd193000-7ffdcd196000 r--p 00000000 00:00 0                          [vvar]
7ffdcd196000-7ffdcd197000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]
```
Compare this to AArch64 where the test did pass:
```
$ cat /proc/self/maps
&lt;...&gt;
ffffb87dc000-ffffb87dd000 r--p 00000000 00:00 0                          [vvar]
ffffb87dd000-ffffb87de000 r-xp 00000000 00:00 0                          [vdso]
ffffb87de000-ffffb87e0000 r--p 0002a000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffb87e0000-ffffb87e2000 rw-p 0002c000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
fffff4216000-fffff4237000 rw-p 00000000 00:00 0                          [stack]
```
To solve this, look up the memory region of the stack pointer (using
https://lldb.llvm.org/resources/lldbgdbremote.html#qmemoryregioninfo-addr)
and constrain the read to within that region. Since we know the stack is
all readable and writeable.

I have also added skipIfRemote to the tests, since getting them working
in that context is too complex to be worth it.

Memory write failures now display the range they tried to write, and
register write errors will show the name of the register where possible.

The patch also includes a workaround for a an issue where the test code
could mistake an `x` response that happens to begin with an `O` for an
output packet (stdout). This workaround will not be necessary one we
start using the [new
implementation](https://discourse.llvm.org/t/rfc-fixing-incompatibilties-of-the-x-packet-w-r-t-gdb/84288)
of the `x` packet.

---------

Co-authored-by: Pavel Labath &lt;pavel@labath.sk&gt;</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "[lldb] Implement basic support for reverse-continue" (#123906)</title>
<updated>2025-01-22T08:43:11+00:00</updated>
<author>
<name>Pavel Labath</name>
<email>pavel@labath.sk</email>
</author>
<published>2025-01-22T08:43:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=22561cfb443267905d4190f0e2a738e6b412457f'/>
<id>22561cfb443267905d4190f0e2a738e6b412457f</id>
<content type='text'>
Reverts llvm/llvm-project#112079 due to failures on the arm bot.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Reverts llvm/llvm-project#112079 due to failures on the arm bot.</pre>
</div>
</content>
</entry>
<entry>
<title>[lldb] Implement basic support for reverse-continue (#112079)</title>
<updated>2025-01-22T07:37:17+00:00</updated>
<author>
<name>Robert O'Callahan</name>
<email>rocallahan@google.com</email>
</author>
<published>2025-01-22T07:37:17+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=b7b9ccf44988edf49886743ae5c3cf4184db211f'/>
<id>b7b9ccf44988edf49886743ae5c3cf4184db211f</id>
<content type='text'>
This commit adds support for a
`SBProcess::ContinueInDirection()` API. A user-accessible command for
this will follow in a later commit.

This feature depends on a gdbserver implementation (e.g. `rr`) providing
support for the `bc` and `bs` packets. `lldb-server` does not support
those packets, and there is no plan to change that. For testing
purposes, this commit adds a Python implementation of *very limited*
record-and-reverse-execute functionality, implemented as a proxy between
lldb and lldb-server in `lldbreverse.py`. This should not (and in
practice cannot) be used for anything except testing.

The tests here are quite minimal but we test that simple breakpoints and
watchpoints work as expected during reverse execution, and that
conditional breakpoints and watchpoints work when the condition calls a
function that must be executed in the forward direction.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This commit adds support for a
`SBProcess::ContinueInDirection()` API. A user-accessible command for
this will follow in a later commit.

This feature depends on a gdbserver implementation (e.g. `rr`) providing
support for the `bc` and `bs` packets. `lldb-server` does not support
those packets, and there is no plan to change that. For testing
purposes, this commit adds a Python implementation of *very limited*
record-and-reverse-execute functionality, implemented as a proxy between
lldb and lldb-server in `lldbreverse.py`. This should not (and in
practice cannot) be used for anything except testing.

The tests here are quite minimal but we test that simple breakpoints and
watchpoints work as expected during reverse execution, and that
conditional breakpoints and watchpoints work when the condition calls a
function that must be executed in the forward direction.</pre>
</div>
</content>
</entry>
<entry>
<title>Refactor `ThreadList::WillResume()` to prepare to support reverse execution (#120817)</title>
<updated>2025-01-15T21:18:25+00:00</updated>
<author>
<name>Robert O'Callahan</name>
<email>rocallahan@google.com</email>
</author>
<published>2025-01-15T21:18:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=d594d4cef7d0ba15370435aac362fe44224c1bab'/>
<id>d594d4cef7d0ba15370435aac362fe44224c1bab</id>
<content type='text'>
These changes are designed to not change any behavior, but to make it
easy to add code to choose the direction of execution after we've
identified which thread(s) to run but before we add any
`ThreadPlanStepOverBreakpoint`s. And honestly I think they make the
existing code a bit clearer.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These changes are designed to not change any behavior, but to make it
easy to add code to choose the direction of execution after we've
identified which thread(s) to run but before we add any
`ThreadPlanStepOverBreakpoint`s. And honestly I think they make the
existing code a bit clearer.</pre>
</div>
</content>
</entry>
<entry>
<title>[lldb] Fix ThreadList assignment race (#98293)</title>
<updated>2024-07-11T12:04:19+00:00</updated>
<author>
<name>Pavel Labath</name>
<email>pavel@labath.sk</email>
</author>
<published>2024-07-11T12:04:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.belthelziquor.com/llvm-project.git/commit/?id=e1bd337865fca9f455225ba37b76595d37bad213'/>
<id>e1bd337865fca9f455225ba37b76595d37bad213</id>
<content type='text'>
ThreadList uses the Process mutex to guard its state. This means its not
possible to safely modify its process member, as the member is required
to lock the mutex.

Fortunately for us, we never actually need to change the process member
(we always just juggle different kinds of thread lists belonging to the
same process).

This patch replaces the process member assignment (which is technically
a race even when it assigns the same value) with an assertion.

Since all this means that the class can never change its process member
value (and it also must be non-null at all times), I've also changed the
member type to a reference.</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
ThreadList uses the Process mutex to guard its state. This means its not
possible to safely modify its process member, as the member is required
to lock the mutex.

Fortunately for us, we never actually need to change the process member
(we always just juggle different kinds of thread lists belonging to the
same process).

This patch replaces the process member assignment (which is technically
a race even when it assigns the same value) with an assertion.

Since all this means that the class can never change its process member
value (and it also must be non-null at all times), I've also changed the
member type to a reference.</pre>
</div>
</content>
</entry>
</feed>
