[Lldb-commits] [PATCH] D132415: [LLDB] Add data formatter for std::coroutine_handle

[Adrian Vogelsgesang via Phabricator via lldb-commits]

avogelsgesang created this revision.
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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
reveals 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 new 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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132415

Files:
  clang/docs/tools/clang-formatted-files.txt
  lldb/packages/Python/lldbsuite/test/lldbtest.py
  lldb/source/Plugins/Language/CPlusPlus/CMakeLists.txt
  lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
  lldb/source/Plugins/Language/CPlusPlus/Coroutines.cpp
  lldb/source/Plugins/Language/CPlusPlus/Coroutines.h
  lldb/source/Plugins/Language/CPlusPlus/LibCxx.h
  lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/Makefile
  lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py
  lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/main.cpp

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