Merge pull request llvm#160 from AMD-Lightning-Internal/amd/dev/harkgill/update-environment-variable-docs

Add documentation on HIPCC_COMPILE_FLAGS_APPEND and HIPCC_LINK_FLAGS_…

Author: harkgill-amd

amd/hipcc/docs/env.rst

@@ -18,3 +18,17 @@ The environment variable ``HIP_PLATFORM`` can be used to specify ``amd`` or ``nv
 Additional environment variable controls:
 
 * ``CUDA_PATH``       : Path to the CUDA SDK. The default is ``/usr/local/cuda``. This is only used for NVIDIA platforms.
+* ``HIPCC_COMPILE_FLAGS_APPEND``       : Append extra flags as compilation options to ``hipcc``.
+* ``HIPCC_LINK_FLAGS_APPEND``       : Append extra flags as linking options to ``hipcc``.
+* ``HIPCC_VERBOSE``  : Outputs detailed information on subcommands executed during compilation.
+
+  - ``HIPCC_VERBOSE = 1``: Displays the command to ``clang++`` or ``nvcc`` with all options (`hipcc-cmd`).
+  - ``HIPCC_VERBOSE = 2``: Displays all relevant environment variables and their values.
+  - ``HIPCC_VERBOSE = 4``: Displays only the arguments passed to the ``hipcc`` command (`hipcc_args`).
+  - ``HIPCC_VERBOSE = 5``: Displays both the command to ``clang++`` or ``nvcc`` and ``hipcc`` arguments (`hipcc-cmd` and `hipcc-args`).
+  - ``HIPCC_VERBOSE = 6``: Displays all relevant environment variables and their values, along with the arguments to the ``hipcc`` command.
+  - ``HIPCC_VERBOSE = 7``: Displays all of the above: `hipcc-cmd`, `hipcc-args`, and environment variables.
+ 
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+