Kiss, Istvan
102 γραμμές
4.4 KiB
ReStructuredText
102 γραμμές
4.4 KiB
ReStructuredText
.. meta::
|
|
:description: Compilation workflow of the HIP compilers.
|
|
:keywords: AMD, ROCm, HIP, CUDA, HIP runtime API
|
|
|
|
.. _hip_compilers:
|
|
|
|
********************************************************************************
|
|
HIP compilers
|
|
********************************************************************************
|
|
|
|
ROCm provides the compiler driver ``hipcc``, that can be used on AMD ROCm and
|
|
NVIDIA CUDA platforms.
|
|
|
|
On ROCm, ``hipcc`` takes care of the following:
|
|
|
|
- Setting the default library and include paths for HIP
|
|
- Setting some environment variables
|
|
- Invoking the appropriate compiler - ``amdclang++``
|
|
|
|
On NVIDIA CUDA platform, ``hipcc`` takes care of invoking compiler ``nvcc``.
|
|
``amdclang++`` is based on the ``clang++`` compiler. For more
|
|
details, see the :doc:`llvm project<llvm-project:index>`.
|
|
|
|
HIP compilation workflow
|
|
================================================================================
|
|
|
|
HIP provides a flexible compilation workflow that supports both offline
|
|
compilation and runtime or just-in-time (JIT) compilation. Each approach has
|
|
advantages depending on the use case, target architecture, and performance
|
|
needs.
|
|
|
|
The offline compilation is ideal for production environments, where the
|
|
performance is critical and the target GPU architecture is known in advance.
|
|
|
|
The runtime compilation is useful in development environments or when
|
|
distributing software that must run on a wide range of hardware without the
|
|
knowledge of the GPU in advance. It provides flexibility at the cost of some
|
|
performance overhead.
|
|
|
|
Offline compilation
|
|
--------------------------------------------------------------------------------
|
|
|
|
The HIP code compilation is performed in two stages: host and device code
|
|
compilation stage.
|
|
|
|
- Device-code compilation stage: The compiled device code is embedded into the
|
|
host object file. Depending on the platform, the device code can be compiled
|
|
into assembly or binary. ``nvcc`` and ``amdclang++`` target different
|
|
architectures and use different code object formats. ``nvcc`` uses the binary
|
|
``cubin`` or the assembly PTX files, while the ``amdclang++`` path is the
|
|
binary ``hsaco`` format. On CUDA platforms, the driver compiles the PTX files
|
|
to executable code during runtime.
|
|
|
|
- Host-code compilation stage: On the host side, ``hipcc`` or ``amdclang++`` can
|
|
compile the host code in one step without other C++ compilers. On the other
|
|
hand, ``nvcc`` only replaces the ``<<<...>>>`` kernel launch syntax with the
|
|
appropriate CUDA runtime function call and the modified host code is passed to
|
|
the default host compiler.
|
|
|
|
For an example on how to compile HIP from the command line, see :ref:`SAXPY
|
|
tutorial<compiling_on_the_command_line>` .
|
|
|
|
Runtime compilation
|
|
--------------------------------------------------------------------------------
|
|
|
|
HIP allows you to compile kernels at runtime using the ``hiprtc*`` API. Kernels
|
|
are stored as a text string, which is passed to HIPRTC alongside options to
|
|
guide the compilation.
|
|
|
|
For more details, see
|
|
:doc:`HIP runtime compiler <../how-to/hip_rtc>`.
|
|
|
|
Static libraries
|
|
================================================================================
|
|
|
|
``hipcc`` supports generating two types of static libraries.
|
|
|
|
- The first type of static library only exports and launches host functions
|
|
within the same library and not the device functions. This library type offers
|
|
the ability to link with a non-hipcc compiler such as ``gcc``. Additionally,
|
|
this library type contains host objects with device code embedded as fat
|
|
binaries. This library type is generated using the flag ``--emit-static-lib``:
|
|
|
|
.. code-block:: shell
|
|
|
|
hipcc hipOptLibrary.cpp --emit-static-lib -fPIC -o libHipOptLibrary.a
|
|
gcc test.cpp -L. -lhipOptLibrary -L/path/to/hip/lib -lamdhip64 -o test.out
|
|
|
|
- The second type of static library exports device functions to be linked by
|
|
other code objects by using ``hipcc`` as the linker. This library type
|
|
contains relocatable device objects and is generated using ``ar``:
|
|
|
|
.. code-block:: shell
|
|
|
|
hipcc hipDevice.cpp -c -fgpu-rdc -o hipDevice.o
|
|
ar rcsD libHipDevice.a hipDevice.o
|
|
hipcc libHipDevice.a test.cpp -fgpu-rdc -o test.out
|
|
|
|
A full example for this can be found in the ROCm-examples, see the examples for
|
|
`static host libraries <https://github.com/ROCm/rocm-examples/tree/develop/HIP-Basic/static_host_library>`_
|
|
or `static device libraries <https://github.com/ROCm/rocm-examples/tree/develop/HIP-Basic/static_device_library>`_.
|