[vlc-devel] [PATCH v2 15/17] apple: build: build gas-preprocessor for armv7

[Martin Storsjö]

On Wed, 29 Apr 2020, Alexandre Janniaux wrote:

> ffmpeg cannot build without gas-preprocessor on armv7 for iOS.
> ---
> extras/package/apple/build.sh | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)

That doesn't seem right to me - it should definitely be buildable without 
it - I just tried with latest ffmpeg master.

The last nontrivial features that ffmpeg's arm asm used were implemented 
in Clang 5 (corresponding to Xcode 9.3). After that, ffmpeg's arm assembly 
happened to use a few minor features that Clang doesn't support (or which 
it does support, but not when targeting Darwin). Depending on what version 
of ffmpeg you build, you might need to backport the following commits:

ab05d3934de8e932dbd77979a687e6598e67535c
3a7b4ae62c798edbd82bcd8fef863c74ed2acd4a
f33f728470434a9981a53d7560d67657b93d1e26
6660bc034d212dc8fb01715d6bf3a6d3866e9715
5f83935de4ef1e32d22f90016b9ddebc1e56153f

If it still fails after making sure you have those fixes, please let me 
know what errors you are getting.

So with modern Clang versions, you should never really need 
gas-preprocessor for ios targets any longer - with minor touchups to the 
assembly in some cases. (So the only modern target that really needs 
gas-preprocessor is MSVC toolchains with armasm/armasm64.)

// Martin