ASM Support

Build scripts of libraries try to enable all CPU optimizations possible. But some libraries do not support CPU optimizations and configure/build operations fail when asm is enabled.

Below you can see the libraries and architectures that do not support asm. Other than that all libraries are built with asm enabled.

Android

• gmp: Enabling assembly produces cannot locate symbol "__gmp_binvert_limb_table" error when library is loaded.
• gnutls, libass, xvidcore, x264: Enabling asm for x86 ABI causes text relocation errors for libavfilter.so/libavformat.so/libavcodec.so.
• libtheora: asm is disabled on LTS releases. Enabling asm causes random crashes on pre API 21 devices
• libwebp dropped support for arm-v7a architecture (armeabi-v7a without NEON) with release 1.0.2.
• x265: Assembly compilation fails for arm64-v8a architecture. It is possible to build arm-v7a, arm-v7a-neon and x86 with assembly enabled but all three ABIs include relocation errors. Additionally, assembly on x86-64 causes linking errors.

iOS / tvOS

• gmp: Enabling assembly on armv7, armv7s, arm64 and arm64e architectures causes configure to fail with configure: error: cannot determine how to define a 32-bit word.
• libjpeg-turbo: Build fails on i386 architecture with error: symbol '.no_avx2' undefined error.
• xvidcore: Build fails for i386 architecture when asm is enabled. ffmpeg crashes when asm is enabled on x86-64 architecture.
• x265: Assembly compilation fails for arm64 and arm64e architectures.