Programming_interface update

docs/understand/programming_interface.rst

@@ -6,24 +6,23 @@
 Programming interface
 *******************************************************************************
 
-The programming interface document will focus on the C/C++ HIP runtime API and the usage of this API. The runtime API provides C and C++ functions for event, stream,  device and memory managements, etc. The HIP runtime on AMD platform uses the Common Language Runtimes (CLR), while on NVIDIA platform HIP runtime is only a thin layer over the CUDA runtime.
+The programming interface document will focus on the HIP runtime API. The runtime API provides C and C++ functions for event, stream,  device and memory managements, etc. The HIP runtime on AMD platform uses the Common Language Runtimes (CLR), while on NVIDIA platform HIP runtime is only a thin layer over the CUDA runtime.
 
-- **CLR**
-  CLR contains source codes for AMD's compute languages runtimes: ``HIP`` and ``OpenCL™``. CLR includes the implementation of ``HIP`` language on the AMD platform `hipamd <https://github.com/ROCm/clr/tree/develop/hipamd>`_ and the Radeon Open Compute Common Language Runtime (rocclr), which is a virtual device interface, that HIP runtimes interact with different backends. (CLR also include the implementation of `OpenCL <https://github.com/ROCm/clr/tree/develop/opencl>`_)
-- **CUDA runtime**
-  CUDA runtime is built over the CUDA driver API (lower-level C API). For further information about the CUDA driver and runtime API, check the :doc:`hip:how-to/hip_porting_driver_api`. On non-AMD platform, HIP runtime determines, if CUDA is available and can be used. If available, HIP_PLATFORM is set to ``nvidia`` and underneath CUDA path is used.
+- **CLR** contains source codes for AMD's compute languages runtimes: ``HIP`` and ``OpenCL™``. CLR includes the implementation of ``HIP`` language on the AMD platform `hipamd <https://github.com/ROCm/clr/tree/develop/hipamd>`_ and the Radeon Open Compute Common Language Runtime (rocclr), which is a virtual device interface, that HIP runtimes interact with different backends. (CLR also include the implementation of `OpenCL <https://github.com/ROCm/clr/tree/develop/opencl>`_)
+- **CUDA runtime** is built over the CUDA driver API (lower-level C API). For further information about the CUDA driver and runtime API, check the :doc:`hip:how-to/hip_porting_driver_api`. On non-AMD platform, HIP runtime determines, if CUDA is available and can be used. If available, HIP_PLATFORM is set to ``nvidia`` and underneath CUDA path is used.
 
 HIP compilers
 =============
 
-The HIP runtime API and HIP C++ extensions are available with HIP compilers. On AMD platform ROCm currently provides two compiler interfaces: ``hipcc`` and ``amdclang++``. The ``hipcc`` command-line interface aims to provide a more familiar user interface to users who are experienced in CUDA but relatively new to the ROCm/HIP development environment. On the other hand, ``amdclang++`` provides a user interface identical to the clang++ compiler. (For further details, check `llvm <llvm-project-docs:index>`_). On NVIDIA platform HIP invoke the locally installed ``NVCC`` compiler.
+The HIP runtime API and HIP C++ extensions are available with HIP compilers. On AMD platform ROCm currently provides two compiler interfaces: ``hipcc`` and ``amdclang++``. The ``hipcc`` command-line interface aims to provide a more familiar user interface to users who are experienced in CUDA but relatively new to the ROCm/HIP development environment. On the other hand, ``amdclang++`` provides a user interface identical to the clang++ compiler. (For further details, check `llvm <llvm-project-docs:index>`_). On NVIDIA platform ``hipcc`` invoke the locally installed ``NVCC`` compiler.
+
+``NVCC`` and ``HIP-Clang`` target different architectures and use different code object formats: ``NVCC`` is ``cubin`` or ``ptx`` files, while the ``HIP-Clang`` path is the ``hsaco`` format.
 
 For compiler options, check the `GPU compiler option page <https://rocm.docs.amd.com/en/docs-5.2.3/reference/rocmcc/rocmcc.html#amd-gpu-compilation>`_.
 
 HIP compilation workflow
 ------------------------
 
-
 For example of compiling from command line, check the :ref:` SAXPY tutorial compiling <compiling_on_the_command_line>`.
 
 HIP versioning