Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)

Change GetNumChildren()/CalculateNumChildren() methods return
llvm::Expected

This is an NFC change that does no

Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)

Change GetNumChildren()/CalculateNumChildren() methods return
llvm::Expected

This is an NFC change that does not yet add any error handling or change
any code to return any errors.

This is the second big change in the patch series started with
https://github.com/llvm/llvm-project/pull/83501

A follow-up PR will wire up error handling.

show more ...

Revert "Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)"

This reverts commit 99118c809367d518ffe4de60c16da953744b68b9.

Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)

Change GetNumChildren()/CalculateNumChildren() methods return
llvm::Expected

This is an NFC change that does

Change GetNumChildren()/CalculateNumChildren() methods return llvm::Expected (#84219)

Change GetNumChildren()/CalculateNumChildren() methods return
llvm::Expected

This is an NFC change that does not yet add any error handling or change
any code to return any errors.

This is the second big change in the patch series started with
https://github.com/llvm/llvm-project/pull/83501

A follow-up PR will wire up error handling.

show more ...

Change GetChildAtIndex to take a uint32_t

Change the return type of SyntheticFrontend::CalculateNumChildren to int32_t

This way it is consistent with ValueObject and TypeSystem.

[lldb][TypeSynthetic][NFC] Make SyntheticChildrenFrontend::Update() return an enum (#80167)

This patch changes the return value of
`SyntheticChildrenFrontend::Update` to a scoped enum that aims to

[lldb][TypeSynthetic][NFC] Make SyntheticChildrenFrontend::Update() return an enum (#80167)

This patch changes the return value of
`SyntheticChildrenFrontend::Update` to a scoped enum that aims to
describe what the return value means.

show more ...

[lldb] Default can_create to true in GetChildAtIndex (NFC)

Existing callers of `GetChildAtIndex` pass true for can_create. This change
makes true the default value, callers don't have to pass an opa

[lldb] Default can_create to true in GetChildAtIndex (NFC)

Existing callers of `GetChildAtIndex` pass true for can_create. This change
makes true the default value, callers don't have to pass an opaque true.

See also D151966 for the same change to `GetChildMemberWithName`.

Differential Revision: https://reviews.llvm.org/D152031

show more ...

[LLDB] Fix assertion failure by removing `CopyType` in `std::coroutine_handle` pretty printer

The pretty printer for `std::coroutine_handle` was running into
> Assertion failed: (target_ctx != sourc

[LLDB] Fix assertion failure by removing `CopyType` in `std::coroutine_handle` pretty printer

The pretty printer for `std::coroutine_handle` was running into
> Assertion failed: (target_ctx != source_ctx && "Can't import into itself")
from ClangASTImporter.h, line 270.

This commit fixes the issue by removing the `CopyType` call from the
pretty printer. While this call was necessary in the past, it seems to
be no longer required, at least all test cases are still passing. Maybe
something changed in the meantime around the handling of `TypesystemClang`
instances. I don't quite understand why `CopyType` was necessary earlier.

I am not sure how to add a regression test for this, though. It seems
the issue is already triggered by the exising `TestCoroutineHandle.py`,
but API tests seem to ignore all violations of `lldbassert` and still
report the test as "passed", even if assertions were triggered

Differential Revision: https://reviews.llvm.org/D143127

show more ...

[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer

So far, the pretty printer for `std::coroutine_handle` internally
dereferenced the contained frame pointer displayed th

[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer

So far, the pretty printer for `std::coroutine_handle` internally
dereferenced the contained frame pointer displayed the `promise`
as a sub-value. As noticed in https://reviews.llvm.org/D132624
by @labath, this can lead to an endless loop in lldb during printing
if the coroutine frame pointers form a cycle.

This commit breaks the cycle by exposing the `promise` as a pointer
type instead of a value type. The depth to which the `frame variable`
and the `expression` commands dereference those pointers can be
controlled using the `--ptr-depth` argument.

Differential Revision: https://reviews.llvm.org/D132815

show more ...

Revert "[LLDB] Recognize `std::noop_coroutine()` in `std::coroutine_handle` pretty printer"

This reverts commit 4346318f5c700f4e85f866610fb8328fc429319b.

This test case is failing on macOS, reverti

Revert "[LLDB] Recognize `std::noop_coroutine()` in `std::coroutine_handle` pretty printer"

This reverts commit 4346318f5c700f4e85f866610fb8328fc429319b.

This test case is failing on macOS, reverting until it can be
looked at more closely to unblock the macOS CI bots.

```
File "/Volumes/work/llvm/llvm-project/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py", line 121, in test_libcpp
self.do_test(USE_LIBCPP)
File "/Volumes/work/llvm/llvm-project/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py", line 45, in do_test
self.expect_expr("noop_hdl",
File "/Volumes/work/llvm/llvm-project/lldb/packages/Python/lldbsuite/test/lldbtest.py", line 2441, in expect_expr
value_check.check_value(self, eval_result, str(eval_result))
File "/Volumes/work/llvm/llvm-project/lldb/packages/Python/lldbsuite/test/lldbtest.py", line 306, in check_value
test_base.assertEqual(self.expect_summary, val.GetSummary(),
AssertionError: 'noop_coroutine' != 'coro frame = 0x100004058'
- noop_coroutine+ coro frame = 0x100004058 : (std::coroutine_handle<void>) $1 = coro frame = 0x100004058 {
resume = 0x0000000100003344 (a.out`___lldb_unnamed_symbol223)
destroy = 0x0000000100003344 (a.out`___lldb_unnamed_symbol223)
}
Checking SBValue: (std::coroutine_handle<void>) $1 = coro frame = 0x100004058 {
resume = 0x0000000100003344 (a.out`___lldb_unnamed_symbol223)
destroy = 0x0000000100003344 (a.out`___lldb_unnamed_symbol223)
}
```

Those lldb_unnamed_symbols are synthetic names that ObjectFileMachO
adds to the symbol table, most often seen with stripped binaries,
based off of the function start addresses for all the functions -
if a function has no symbol name, lldb adds one of these names.
This change was originally landed via https://reviews.llvm.org/D132624

show more ...

Revert "[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer"

This reverts commit cd3091a88f7c55c90d9b5fff372ce1cdfc71948d.

This change crashes on macOS systems in
formatt

Revert "[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer"

This reverts commit cd3091a88f7c55c90d9b5fff372ce1cdfc71948d.

This change crashes on macOS systems in
formatters::StdlibCoroutineHandleSyntheticFrontEnd when
it fails to create the `ValueObjectSP promise` and calls
a method on it. The failure causes a segfault while running
TestCoroutineHandle.py on the "LLDB Incremental" CI bot,
https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/

This change originally landed via https://reviews.llvm.org/D132815

show more ...

[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer

So far, the pretty printer for `std::coroutine_handle` internally
dereferenced the contained frame pointer displayed th

[LLDB] Do not dereference promise pointer in `coroutine_handle` pretty printer

So far, the pretty printer for `std::coroutine_handle` internally
dereferenced the contained frame pointer displayed the `promise`
as a sub-value. As noticed in https://reviews.llvm.org/D132624
by @labath, this can lead to an endless loop in lldb during printing
if the coroutine frame pointers form a cycle.

This commit breaks the cycle by exposing the `promise` as a pointer
type instead of a value type. The depth to which the `frame variable`
and the `expression` commands dereference those pointers can be
controlled using the `--ptr-depth` argument.

Differential Revision: https://reviews.llvm.org/D132815

show more ...

[LLDB] Recognize `std::noop_coroutine()` in `std::coroutine_handle` pretty printer

With this commit, the `std::coroutine_handle` pretty printer now
recognizes `std::noop_coroutine()` handles. For no

[LLDB] Recognize `std::noop_coroutine()` in `std::coroutine_handle` pretty printer

With this commit, the `std::coroutine_handle` pretty printer now
recognizes `std::noop_coroutine()` handles. For noop coroutine handles,
we identify use the summary string `noop_coroutine` and we don't print
children

Instead of
```
(std::coroutine_handle<void>) $3 = coro frame = 0x555555559058 {
resume = 0x00005555555564f0 (a.out`std::__1::coroutine_handle<std::__1::noop_coroutine_promise>::__noop_coroutine_frame_ty_::__dummy_resume_destroy_func() at noop_coroutine_handle.h:79)
destroy = 0x00005555555564f0 (a.out`std::__1::coroutine_handle<std::__1::noop_coroutine_promise>::__noop_coroutine_frame_ty_::__dummy_resume_destroy_func() at noop_coroutine_handle.h:79)
}
```

we now print

```
(std::coroutine_handle<void>) $3 = noop_coroutine
```

Differential Revision: https://reviews.llvm.org/D132735

show more ...

Reapply "[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`"

The original commit was missing a `ClangASTImporter::CopyType` call.
Original commit message:

This commit teaches t

Reapply "[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`"

The original commit was missing a `ClangASTImporter::CopyType` call.
Original commit message:

This commit teaches the `std::coroutine_handle` pretty-printer to
devirtualize type-erased promise types. This is particularly useful to
resonstruct call stacks, either of asynchronous control flow or of
recursive invocations of `std::generator`. For the example recently
introduced by https://reviews.llvm.org/D132451, printing the `__promise`
variable now shows

```
(std::__coroutine_traits_sfinae<task, void>::promise_type) __promise = {
continuation = coro frame = 0x555555562430 {
resume = 0x0000555555556310 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555556700 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
promise = {
continuation = coro frame = 0x5555555623e0 {
resume = 0x0000555555557070 (a.out`task detail::chain_fn<2>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555557460 (a.out`task detail::chain_fn<2>() at llvm-nested-example.cpp:66)
promise = {
...
}
}
result = 0
}
}
result = 0
}
```

(shortened to keep the commit message readable) instead of

```
(std::__coroutine_traits_sfinae<task, void>::promise_type) __promise = {
continuation = coro frame = 0x555555562430 {
resume = 0x0000555555556310 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555556700 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
}
result = 0
}
```

Note how the new debug output reveals the complete asynchronous call
stack: our own function resumes `chain_fn<1>` which in turn will resume
`chain_fn<2>` and so on. Thereby this change allows users of lldb to
inspect the logical coroutine call stack without using any custom debug
scripts (although the display is still a bit clumsy. It would be nicer
to also integrate this into lldb's backtrace feature, but I don't know
how to do so)

The devirtualization currently works by introspecting the function
pointed to by the `destroy` pointer. (The `resume` pointer is not worth
much, given that for the final suspend point `resume` is set to a
nullptr. We have to use the `destroy` pointer instead.) We then look
for a `__promise` variable inside the `destroy` function. This
`__promise` variable is synthetically generated by LLVM, and looking at
its type reveals the type-erased promise_type.

This approach only works for clang-generated code, though. While gcc
also adds a `_Coro_promise` variable to the `resume` function, it does
not do so for the `destroy` function. However, we can't use the `resume`
function, as it will be reset to a nullptr at the final suspension
point. For the time being, I am happy with de-virtualization only working
for clang. A follow-up commit will further improve devirtualization and
also expose the variables spilled to the coroutine frame. As part of
this, I will also revisit gcc support.

Differential Revision: https://reviews.llvm.org/D132624

show more ...

Make CompilerType safe

When a process gets restarted TypeSystem objects associated with it
may get deleted, and any CompilerType objects holding on to a
reference to that type system are a use-after

Make CompilerType safe

When a process gets restarted TypeSystem objects associated with it
may get deleted, and any CompilerType objects holding on to a
reference to that type system are a use-after-free in waiting. Because
of the SBAPI, we don't have tight control over where CompilerTypes go
and when they are used. This is particularly a problem in the Swift
plugin, where the scratch TypeSystem can be restarted while the
process is still running. The Swift plugin has a lock to prevent
abuse, but where there's a lock there can be bugs.

This patch changes CompilerType to store a std::weak_ptr<TypeSystem>.
Most of the std::weak_ptr<TypeSystem>* uglyness is hidden by
introducing a wrapper class CompilerType::WrappedTypeSystem that has a
dyn_cast_or_null() method. The only sites that need to know about the
weak pointer implementation detail are the ones that deal with
creating TypeSystems.

rdar://101505232

Differential Revision: https://reviews.llvm.org/D136650

show more ...

Revert "[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`"

This reverts commit 558db7787005348e2efaabb628ec36f1c461a741 due to
buildbot failures on ARM
* https://lab.llvm.org/b

Revert "[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`"

This reverts commit 558db7787005348e2efaabb628ec36f1c461a741 due to
buildbot failures on ARM
* https://lab.llvm.org/buildbot/#/builders/96/builds/31416
* https://lab.llvm.org/buildbot/#/builders/17/builds/30086

show more ...

[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`

This commit teaches the `std::coroutine_handle` pretty-printer to
devirtualize type-erased promise types. This is particularly

[LLDB] Devirtualize coroutine promise types for `std::coroutine_handle`

This commit teaches the `std::coroutine_handle` pretty-printer to
devirtualize type-erased promise types. This is particularly useful to
resonstruct call stacks, either of asynchronous control flow or of
recursive invocations of `std::generator`. For the example recently
introduced by https://reviews.llvm.org/D132451, printing the `__promise`
variable now shows

```
(std::__coroutine_traits_sfinae<task, void>::promise_type) __promise = {
continuation = coro frame = 0x555555562430 {
resume = 0x0000555555556310 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555556700 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
promise = {
continuation = coro frame = 0x5555555623e0 {
resume = 0x0000555555557070 (a.out`task detail::chain_fn<2>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555557460 (a.out`task detail::chain_fn<2>() at llvm-nested-example.cpp:66)
promise = {
...
}
}
result = 0
}
}
result = 0
}
```

(shortened to keep the commit message readable) instead of

```
(std::__coroutine_traits_sfinae<task, void>::promise_type) __promise = {
continuation = coro frame = 0x555555562430 {
resume = 0x0000555555556310 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
destroy = 0x0000555555556700 (a.out`task detail::chain_fn<1>() at llvm-nested-example.cpp:66)
}
result = 0
}
```

Note how the new debug output reveals the complete asynchronous call
stack: our own function resumes `chain_fn<1>` which in turn will resume
`chain_fn<2>` and so on. Thereby this change allows users of lldb to
inspect the logical coroutine call stack without using any custom debug
scripts (although the display is still a bit clumsy. It would be nicer
to also integrate this into lldb's backtrace feature, but I don't know
how to do so)

The devirtualization currently works by introspecting the function
pointed to by the `destroy` pointer. (The `resume` pointer is not worth
much, given that for the final suspend point `resume` is set to a
nullptr. We have to use the `destroy` pointer instead.) We then look
for a `__promise` variable inside the `destroy` function. This
`__promise` variable is synthetically generated by LLVM, and looking at
its type reveals the type-erased promise_type.

This approach only works for clang-generated code, though. While gcc
also adds a `_Coro_promise` variable to the `resume` function, it does
not do so for the `destroy` function. However, we can't use the `resume`
function, as it will be reset to a nullptr at the final suspension
point. For the time being, I am happy with de-virtualization only working
for clang. A follow-up commit will further improve devirtualization and
also expose the variables spilled to the coroutine frame. As part of
this, I will also revisit gcc support.

Differential Revision: https://reviews.llvm.org/D132624

show more ...

[LLDB] Add data formatter for std::coroutine_handle

This patch adds a formatter for `std::coroutine_handle`, both for libc++
and libstdc++. For the type-erased `coroutine_handle<>`, it shows the
`re

[LLDB] Add data formatter for std::coroutine_handle

This patch adds a formatter for `std::coroutine_handle`, both for libc++
and libstdc++. For the type-erased `coroutine_handle<>`, it shows the
`resume` and `destroy` function pointers. For a non-type-erased
`coroutine_handle<promise_type>` it also shows the `promise` value.

With this change, executing the `v t` command on the example from
https://clang.llvm.org/docs/DebuggingCoroutines.html now outputs

```
(task) t = {
handle = coro frame = 0x55555555b2a0 {
resume = 0x0000555555555a10 (a.out`coro_task(int, int) at llvm-example.cpp:36)
destroy = 0x0000555555556090 (a.out`coro_task(int, int) at llvm-example.cpp:36)
}
}
```

instead of just

```
(task) t = {
handle = {
__handle_ = 0x55555555b2a0
}
}
```

Note, how the symbols for the `resume` and `destroy` function pointer
reveal which coroutine is stored inside the `std::coroutine_handle`.
A follow-up commit will use this fact to infer the coroutine's promise
type and the representation of its internal coroutine state based on
the `resume` and `destroy` pointers.

The same formatter is used for both libc++ and libstdc++. It would
also work for MSVC's standard library, however it is not registered
for MSVC, given that lldb does not provide pretty printers for other
MSVC types, either.

The formatter is in a newly added `Coroutines.{h,cpp}` file because there
does not seem to be an already existing place where we could share
formatters across libc++ and libstdc++. Also, I expect this code to grow
as we improve debugging experience for coroutines further.

**Testing**

* Added API test

Differential Revision: https://reviews.llvm.org/D132415

show more ...