[Mesa-dev] [PATCH 3/4] anv: Use central api generation scripts.

[Chad Versace]

On Wed 08 Aug 2018, Bas Nieuwenhuizen wrote:
> This became kind of messy as python imports cannot really look up
> parent/sibling directories. I saw some scripts use sys.path but
> that became even more messy due to import locations.
> 
> I also move the selections of the dispatch table out of the
> generation script because it is not easily shared, and generating
> it did not really win anything anyway.
> ---
>  src/intel/Android.vulkan.mk             |   9 +
>  src/intel/Makefile.vulkan.am            |  25 +-
>  src/intel/vulkan/anv_device.c           |  46 ++
>  src/intel/vulkan/anv_entrypoints_gen.py | 537 +-----------------------
>  src/intel/vulkan/anv_extensions.py      |  68 +--
>  src/intel/vulkan/anv_extensions_gen.py  | 177 +-------
>  src/intel/vulkan/meson.build            |  15 +-
>  src/vulkan/util/vk_extensions.py        |   5 +-
>  8 files changed, 98 insertions(+), 784 deletions(-)
> 
> diff --git a/src/intel/Android.vulkan.mk b/src/intel/Android.vulkan.mk


>  $(intermediates)/vulkan/anv_entrypoints.h: $(intermediates)/vulkan/dummy.c
> +	PYTHONPATH=$(MESA_TOP)/src/vulkan/util \
>  	$(VK_ENTRYPOINTS_SCRIPT) \
>  		--outdir $(dir $@) \
>  		--xml $(MESA_TOP)/src/vulkan/registry/vk.xml

Yes, modifying PYTHONPATH is messy, but it seems to me that it's the the
least-messy way.

I'm no expert on build systems, but I think it's wrong to clobber
PYTHONPATH. Instead, you should prepend the dir to PYTHONPATH.

For example, on my machine, PYTHONPATH is already set:

    $ echo $PYTHONPATH
    /usr/local/buildtools/current/sitecustomize

So, this is more correct...

   $(intermediates)/vulkan/anv_entrypoints.h: $(intermediates)/vulkan/dummy.c
   	PYTHONPATH="$(MESA_TOP)/src/vulkan/util:$${PYTHONPATH}"
   	$(VK_ENTRYPOINTS_SCRIPT) \
   		--outdir $(dir $@) \
   		--xml $(MESA_TOP)/src/vulkan/registry/vk.xml

but runs the risk of accidentally inserting $PWD into PYTHONPATH, because
Python interprets each empty path in PYTHONPATH as equivalent to $PWD.

So... perhaps it is better to modify sys.path instead of PYTHONPATH. It is
definitely safer.