[FEA]: Debugger pretty-printers: cuda::annotated_ptr #10100

[iakshayubale]

Description

This PR adds comprehensive debugger pretty-printer support for cuda::annotated_ptr<_Tp, _Property> types to libcudacxx, enabling developers to inspect pointer values and access properties in both GDB and LLDB debuggers with enhanced readability.

Changes

GDB Pretty-Printer (libcudacxx/share/libcudacxx/gdb/annotated_ptr.py)

• Type detector that identifies cuda::annotated_ptr types by examining template arguments
• Printer class that extracts template arguments (_Tp and _Property)
• Safe access to the __repr member containing the wrapped pointer value
• Null pointer handling that displays "nullptr" instead of "0x0"
• Exception-based error handling: gracefully falls back to type-only display on read failures
• Output format: cuda::annotated_ptr<Type, Property> -> 0xaddress
• ABI namespace stripping for clean type name display

LLDB Pretty-Printer (libcudacxx/share/libcudacxx/lldb/annotated_ptr.py)

• Regex-based type detection requiring exactly 2 template arguments
• Safe member access using LLDB SBValue API (GetChildMemberWithName, GetValueAsUnsigned)
• Robust null pointer detection: distinguishes between real null pointers (value = 0) and read errors
• Graceful degradation: falls back to type-only description when pointer value cannot be read
• Exception handling for edge cases (missing fields, invalid pointers)
• Identical output format to GDB for consistency across debuggers
• Integration with LLDB's type summary system

Test Suite (libcudacxx/test/debugging/annotated_ptr/)

• C++ test source with 3 inspection scenarios covering different access properties:
  • streaming_annotated_int with cuda::access_property::streaming
  • persisting_annotated_int with cuda::access_property::persisting
  • global_annotated_float with cuda::access_property::global
  • streaming_annotated_int with nullptr to validate null pointer handling
• Const-correct test data: all test storage declared const to follow CCCL coding guidelines
• Keep-for-debugger breakpoint hooks using inline assembly
• CMake integration using standard libcudacxx_add_pretty_printer_test macro
• Expected output validation files for both GDB and LLDB

Registrations

• Updated libcudacxx/share/libcudacxx/gdb/__init__.py to import and register the new pretty-printer
• Updated libcudacxx/share/libcudacxx/lldb/__init__.py to import and register the new formatter
• Updated libcudacxx/test/debugging/CMakeLists.txt to include annotated_ptr tests in the test suite

Closes #10100

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between b3f7119 and 3f6d208.

📒 Files selected for processing (1)

• libcudacxx/share/libcudacxx/gdb/annotated_ptr.py

🚧 Files skipped from review as they are similar to previous changes (1)

• libcudacxx/share/libcudacxx/gdb/annotated_ptr.py

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📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Added debugger pretty-printer support for cuda::annotated_ptr in both GDB and LLDB.
  • Annotated pointers now show the annotated type plus access property, and render the wrapped pointer as an address or nullptr.

• Tests

  • Added debugging coverage for annotated pointers, including streaming, persisting, global, and nullptr cases, with expected output verified for both GDB and LLDB.

Walkthrough

Added GDB and LLDB pretty-printers for cuda::annotated_ptr, registered them through existing debugger entry points, and added CUDA debugging tests covering streaming, persisting, global, and null pointer cases with expected output fixtures.

Changes

annotated_ptr debugging support

Layer / File(s)	Summary
GDB annotated_ptr printer libcudacxx/share/libcudacxx/gdb/...	Recognizes cuda::annotated_ptr, removes ABI namespaces from displayed types, formats pointer addresses or nullptr, and registers the printer.
LLDB annotated_ptr formatter libcudacxx/share/libcudacxx/lldb/...	Recognizes annotated pointer types, reads the non-synthetic __repr value, formats summaries, and registers the callbacks.
Debugger test coverage libcudacxx/test/debugging/...	Adds streaming, persisting, global, and null pointer test cases with GDB and LLDB expected output.

Assessment against linked issues

Objective	Addressed	Explanation
Implement GDB and LLDB pretty-printers under the specified libcudacxx/share/libcudacxx/<debugger>/annotated_ptr.py paths [#10100]	✅
Add exhaustive debugging tests under libcudacxx/test/debugging/annotated_ptr [#10100]	✅

Possibly related PRs

• NVIDIA/cccl#10229: Updates the same GDB and LLDB registration tuples for another pretty-printer module.

Suggested reviewers: wmaxey

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (2)

libcudacxx/test/debugging/annotated_ptr/source.cu (2)

42-44: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

suggestion: Resolve the constness of the test storage. These locals are never assigned after initialization; if the cuda::annotated_ptr<int/float> constructors accept const pointees, declare them const. Otherwise, document why mutable storage is required rather than silently violating the repository rule.

As per coding guidelines, all variables that are not modified must be declared const.

Source: Coding guidelines

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41-56: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

suggestion: Add a null-pointer case to this debugger test matrix. Both printers have a dedicated nullptr path, but the current source only constructs non-null pointers, so regressions there will not be caught. Add the corresponding case in libcudacxx/test/debugging/annotated_ptr/CMakeLists.txt and both expected fixtures.

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 16d578af-bd9e-450c-bb12-40cc5a546ad6

📥 Commits

Reviewing files that changed from the base of the PR and between 45b8bb9 and 4c689b3.

📒 Files selected for processing (9)

• libcudacxx/share/libcudacxx/gdb/__init__.py
• libcudacxx/share/libcudacxx/gdb/annotated_ptr.py
• libcudacxx/share/libcudacxx/lldb/__init__.py
• libcudacxx/share/libcudacxx/lldb/annotated_ptr.py
• libcudacxx/test/debugging/CMakeLists.txt
• libcudacxx/test/debugging/annotated_ptr/CMakeLists.txt
• libcudacxx/test/debugging/annotated_ptr/gdb.expected
• libcudacxx/test/debugging/annotated_ptr/lldb.expected
• libcudacxx/test/debugging/annotated_ptr/source.cu

[iakshayubale]

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