We need some binary target correctness: each object file is marked with the target it was built for, and when linking, ld marks the final binary with the greater target it found on the way. With the hacks to allow building unsupported instructions on the target used by the compiler, the resulting objects end up having a bumped target, thus bumping the final binary (libxul) target, which is not expected. Using .object_arch forces the target to be downsized for the given object file, but doesn't affect the final binary target, since other object files are still targeted at whatever target is used by the compiler.
Created attachment 544967 [details] [diff] [review] Avoid bumping ARM target because of NEON code in gfx (Not convinced you are the right reviewer for this)
Comment on attachment 544967 [details] [diff] [review] Avoid bumping ARM target because of NEON code in gfx Do we need something like this for pixman as well?
pixman already has something like this.