tree 4e961806b5872443aa7b0d82e69ae469d8106114
parent 407a459d7d35c6f9d598f36e13e4c1a19142903d
author L. E. Segovia <amy@amyspark.me> 1681856135 +0000
committer James Zern <jzern@google.com> 1682534286 +0000

cmake: use assembly language support

This commit moves the asm libraries to object libraries through CMake's
ASM and ASM_NASM support. It brings the following benefits:

- we no longer need to duplicate between static and shared libraries
- Nasm objects can now be fully compiled in parallel (as they're not
  custom targets anymore)
- there's no longer the need for dummy C files to determine the linker

The ASM language support is currently unused, but it's been added since
AS_EXECUTABLE was used for both Nasm and GAS files.

For Xcode, the existing approach has to be preserved due to the
following issues:

- the Xcode generator does not recognise ASM_NASM as a valid language,
  so it does not output build rules
- even if this was fixed (with explicitFileType set to
  "sourcecode.nasm"), the default build rule in Xcode does not carry
  any of the ASM_NASM flags, nor the selected object format

These issues were already detected in [1], and I asked about them in
the CMake Discourse forum [2], to no avail yet.

Since this change relies on CMake's CheckLanguage module and ASM_NASM
language support, the minimum version has been increased to 3.9.

[1]: https://cmake.org/pipermail/cmake/2018-October/068332.html
[2]: https://discourse.cmake.org/t/building-nasm-files-with-xcode/7934

Related: aomedia:3401
Change-Id: Id0d4c8208afa403df30c0b8ab9b0809e6d67d6d8