[lldb] Only send "posix" error codes through the gdb-remote protocol

The other side has no way of telling which namespace do these codes
belong to, so mashing them all together is not very helpful.

[lldb] Only send "posix" error codes through the gdb-remote protocol

The other side has no way of telling which namespace do these codes
belong to, so mashing them all together is not very helpful.

I'm mainly doing this to simplify some code in a pending patch
<https://github.com/llvm/llvm-project/pull/106774/files#r1752628604>,
and I've picked the posix error category semi-randomly. If we wanted to
be serious about assigning meaning to these error codes, we should
create a special error category for "gdb errors".

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Revert "[lldb] Only send "posix" error codes through the gdb-remote protocol"

This reverts commit a7c174502aef45b2d33291129cce10c085fef944.

[lldb] Only send "posix" error codes through the gdb-remote protocol

The other side has no way of telling which namespace do these codes
belong to, so mashing them all together is not very helpful.

[lldb] Only send "posix" error codes through the gdb-remote protocol

The other side has no way of telling which namespace do these codes
belong to, so mashing them all together is not very helpful.

I'm mainly doing this to simplify some code in a pending patch
<https://github.com/llvm/llvm-project/pull/106774/files#r1752628604>,
and I've picked the posix error category semi-randomly. If we wanted to
be serious about assigning meaning to these error codes, we should
create a special error category for "gdb errors".

show more ...

[lldb] Turn lldb_private::Status into a value type. (#106163)

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
ant

[lldb] Turn lldb_private::Status into a value type. (#106163)

This patch removes all of the Set.* methods from Status.

This cleanup is part of a series of patches that make it harder use the
anti-pattern of keeping a long-lives Status object around and updating
it while dropping any errors it contains on the floor.

This patch is largely NFC, the more interesting next steps this enables
is to:
1. remove Status.Clear()
2. assert that Status::operator=() never overwrites an error
3. remove Status::operator=()

Note that step (2) will bring 90% of the benefits for users, and step
(3) will dramatically clean up the error handling code in various
places. In the end my goal is to convert all APIs that are of the form

` ResultTy DoFoo(Status& error)
`
to

` llvm::Expected<ResultTy> DoFoo()
`
How to read this patch?

The interesting changes are in Status.h and Status.cpp, all other
changes are mostly

` perl -pi -e 's/\.SetErrorString/ = Status::FromErrorString/g' $(git
grep -l SetErrorString lldb/source)
`
plus the occasional manual cleanup.

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[lldb/Utility] Introduce UnimplementedError

This is essentially a replacement for the PacketUnimplementedError
previously present in the gdb-remote server code.

The reason I am introducing a generi

[lldb/Utility] Introduce UnimplementedError

This is essentially a replacement for the PacketUnimplementedError
previously present in the gdb-remote server code.

The reason I am introducing a generic error is because I wanted the
native process classes to be able to signal that they do not support
some functionality. They could not use PacketUnimplementedError as they
are independent of a specific transport protocol. Putting the error
class in the the native process code was also not ideal because the
gdb-remote code is also used for lldb-server's platform mode, which does
not (should not) know how to debug individual processes.

I'm putting it under Utility, as I think it can be generally useful for
notifying about unsupported/unimplemented functionality (and in
particular, for programatically testing whether something is
unsupported).

Differential Revision: https://reviews.llvm.org/D89121

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[lldb][NFC] Fix all formatting errors in .cpp file headers

Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp ----------------------------------------

[lldb][NFC] Fix all formatting errors in .cpp file headers

Summary:
A *.cpp file header in LLDB (and in LLDB) should like this:
```
//===-- TestUtilities.cpp -------------------------------------------------===//
```
However in LLDB most of our source files have arbitrary changes to this format and
these changes are spreading through LLDB as folks usually just use the existing
source files as templates for their new files (most notably the unnecessary
editor language indicator `-*- C++ -*-` is spreading and in every review
someone is pointing out that this is wrong, resulting in people pointing out that this
is done in the same way in other files).

This patch removes most of these inconsistencies including the editor language indicators,
all the different missing/additional '-' characters, files that center the file name, missing
trailing `===//` (mostly caused by clang-format breaking the line).

Reviewers: aprantl, espindola, jfb, shafik, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: dexonsmith, wuzish, emaste, sdardis, nemanjai, kbarton, MaskRay, atanasyan, arphaman, jfb, abidh, jsji, JDevlieghere, usaxena95, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D73258

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Create a generic handler for Xfer packets

Summary:
This is the first of a few patches I have to improve the performance of dynamic module loading on Android.

In this first diff I'll describe the co

Create a generic handler for Xfer packets

Summary:
This is the first of a few patches I have to improve the performance of dynamic module loading on Android.

In this first diff I'll describe the context of my main motivation and will then link to it in the other diffs to avoid repeating myself.

## Motivation
I have a few scenarios where opening a specific feature on an Android app takes around 40s when lldb is attached to it. The reason for that is because 40 modules are dynamicly loaded at that point in time and each one of them is taking ~1s.

## The problem
To learn about new modules we have a breakpoint on a linker function that is called twice whenever a module is loaded. One time just before it's loaded (so lldb can check which modules are loaded) and another right after it's loaded (so lldb can check again which ones are loaded and calculate the diference).
It's figuring out which modules are loaded that is taking quite some time. This is currently done by traversing the linked list of loaded shared libraries that the linker maintains in memory. Each item in the linked list requires its own `x` packet sent to the gdb server (this is android so the network also plays a part). In my scenario there are 400+ loaded libraries and even though we read 0x800 worth of bytes at a time we still make ~180 requests that end up taking 150-200ms.
We also do this twice, once before the module is loaded (state = eAdd) and another right after (state = eConsistent) which easly adds up to ~400ms per module.

## A solution

**Implement `xfer:libraries-svr4` in lldb-server:**
I noticed in the code that loads the new modules that it had support for the `xfer:libraries-svr4` packet (added ~4 years ago to support the ds2 debug server) but we didn't support it in lldb-server. This single packet returns an xml list of all the loaded modules by the process. The advantage is that there's no more need to make 180 requests to read the linked list. Additionally this new requests takes around 10ms.

**More efficient usage of the `xfer:libraries-svr4` packet in lldb:**
When `xfer:libraries-svr4` is available the Process class has a `LoadModules` function that requests this packet and then loads or unloads modules based on the current list of loaded modules by the process.
This is the function that is used by the DYLDRendezvous class to get the list of loaded modules before and after the module is loaded. However, this is really not needed since the LoadModules function already loaded or unloaded the modules accordingly. I changed this strategy to call LoadModules only once (after the process has loaded the module).

**Bugs**
I found a few issues in lldb while implementing this and have submitted independent patches for them.

I tried to devide this into multiple logical patches to make it easier to review and discuss.

## Tests

I wanted to put these set of diffs up before having all the tests up and running to start having them reviewed from a techical point of view. I'm also having some trouble making the tests running on linux so I need more time to make that happen.

# This diff

The `xfer` packages follow the same protocol, they are requested with `xfer:<object>:<read|write>:<annex>:<offset,length>` and a return that starts with `l` or `m` depending if the offset and length covers the entire data or not. Before implementing the `xfer:libraries-svr4` I refactored the `xfer:auxv` to generically handle xfer packets so we can easly add new ones.

The overall structure of the function ends up being:
* Parse the packet into its components: object, offset etc.
* Depending on the object do its own logic to generate the data.
* Return the data based on its size, the requested offset and length.

Reviewers: clayborg, xiaobai, labath

Reviewed By: labath

Subscribers: mgorny, krytarowski, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D62499

llvm-svn: 362982

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