diff --git a/llvm/docs/AMDGPUDwarfProposalForHeterogeneousDebugging.rst b/llvm/docs/AMDGPUDwarfProposalForHeterogeneousDebugging.rst --- a/llvm/docs/AMDGPUDwarfProposalForHeterogeneousDebugging.rst +++ b/llvm/docs/AMDGPUDwarfProposalForHeterogeneousDebugging.rst @@ -1,4 +1,4 @@ -.. _amdgpu-proposal-for-heterogeneous-debugging: +.. _amdgpu-dwarf-proposal-for-heterogeneous-debugging: ****************************************** DWARF Proposal For Heterogeneous Debugging @@ -13,9 +13,76 @@ [:ref:`DWARF `] to support heterogeneous debugging. It is not currently fully implemented and is subject to change. +.. _amdgpu-dwarf-introduction: + Introduction ============ +AMD [:ref:`AMD `] has been working on supporting heterogeneous +computing through the AMD Radeon Open Compute Platform (ROCm) [:ref:`AMD-ROCm +`]. A heterogeneous computing program can be written in a +high level language such as C++ or Fortran with OpenMP pragmas, OpenCL, or HIP +(a portable C++ programming environment for heterogeneous computing [:ref:`HIP +`]). A heterogeneous compiler and runtime allows a program to +execute on multiple devices within the same native process. Devices could +include CPUs, GPUs, DSPs, FPGAs, or other special purpose accelerators. +Currently HIP programs execute on systems with CPUs and GPUs. + +ROCm is fully open sourced and includes contributions to open source projects +such as LLVM for compilation [:ref:`LLVM `] and GDB for +debugging [:ref:`GDB `], as well as collaboration with other +third party projects such as the GCC compiler [:ref:`GCC `] +and the Perforce TotalView HPC debugger [:ref:`Perforce-TotalView +`]. + +To support debugging heterogeneous programs several features that are not +provided by current DWARF Version 5 [:ref:`DWARF `] have +been identified. This document contains a collection of proposals to address +providing those features. + +The :ref:`amdgpu-dwarf-motivation` section describes the issues that are being +addressed for heterogeneous computing. That is followed by the +:ref:`amdgpu-dwarf-proposed-changes-relative-to-dwarf-version-5` section +containing the proposed textual changes relative to the DWARF Version 5 +standard. Then there is an :ref:`amdgpu-dwarf-examples` section that links to +the AMD GPU specific usage of the features in the proposal that includes an +example. Finally, there is a :ref:`amdgpu-dwarf-references` section. There are a +number of notes included that raise open questions, or provide alternative +approaches considered. The draft proposal seeks to be general in nature and +backwards compatible with DWARF Version 5. Its goal is to be applicable to +meeting the needs of any heterogeneous system and not be vendor or architecture +specific. + +A fundamental aspect of the draft proposal is that it allows DWARF expression +location descriptions as stack elements. The draft proposal is based on DWARF +Version 5 and maintains compatibility with DWARF Version 5. After attempting +several alternatives, the current thinking is that such an addition to DWARF +Version 5 is the simplest and cleanest way to support debugging optimized GPU +code. It also appears to be generally useful and may be able to address other +reported DWARF issues, as well as being helpful in providing better optimization +support for non-GPU code. + +General feedback on this draft proposal is sought, together with suggestions on +how to clarify, simplify, or organize it before submitting it as a formal DWARF +proposal. The current draft proposal is large and may need to be split into +separate proposals before formal submission. Any suggestions on how best to do +that are appreciated. However, at the initial review stage it is believed there +is value in presenting a unified proposal as there are mutual dependencies +between the various parts that would not be as apparent if it was broken up into +separate independent proposals. + +We are in the process of modifying LLVM and GDB to support this draft proposal +which is providing experience and insights. We plan to upstream the changes to +those projects for any final form of the proposal. + +The author very much appreciates the input provided so far by many others which +has been incorporated into this current version. + +.. _amdgpu-dwarf-motivation: + +Motivation +========== + This document proposes a set of backwards compatible extensions to DWARF Version 5 [:ref:`DWARF `] for consideration of inclusion into a future DWARF Version 6 standard to support heterogeneous debugging. @@ -3753,12 +3820,16 @@ * ``DW_AT_LLVM_lanes`` ============================= ============================= +.. _amdgpu-dwarf-examples: + Examples ======== The AMD GPU specific usage of the features in the proposal, including examples, is available at :ref:`amdgpu-dwarf-debug-information`. +.. _amdgpu-dwarf-references: + References ==========