meson: Convert the 'neon' option into a feature

Easier to express things, now that runtime is a no-op.

meson.build

@@ -135,9 +135,7 @@ if host_machine.cpu_family() == 'arm'
     have_neon = true
   endif
 endif
-if cc.compiles('''#ifndef __aarch64__
-#error no aarch64 arch
-#endif''')
+if host_machine.cpu_family() == 'aarch64'
   have_arm64 = true
   have_neon = true
   arch_cflags += ['-DWEBRTC_ARCH_ARM64']
@@ -165,23 +163,9 @@ if ['x86', 'x86_64'].contains(host_machine.cpu_family())
   endif
 endif
 
-neon_opt = get_option('neon')
-if neon_opt == 'auto'
-  if have_arm64
-    neon_opt = 'yes'
-  elif have_neon
-    neon_opt = 'runtime'
-  else
-    neon_opt = 'no'
-  endif
-endif
-if neon_opt != 'no' and not have_neon
-  error('Compiler or architecture does not support NEON')
-endif
-if neon_opt == 'runtime'
-  warning('webrtc cannot check NEON support at runtime, will build without NEON')
-endif
-if neon_opt == 'yes'
+neon_opt = get_option('neon').require(have_neon)
+
+if neon_opt.enabled()
   arch_cflags += ['-DWEBRTC_HAS_NEON']
   if not have_arm64
     arch_cflags += ['-mfpu=neon']

meson_options.txt

@@ -1,8 +1,8 @@
 option('gnustl', type: 'feature',
        value: 'auto',
        description: 'Use gnustl for a c++ library implementation (only used on Android)')
-option('neon', type: 'combo',
-       choices: ['auto', 'yes', 'runtime', 'no'],
+option('neon', type: 'feature',
+       value: 'auto',
        description: 'Enable NEON optimisations')
 option('inline-sse', type: 'boolean',
        value: true,

webrtc/common_audio/meson.build

@@ -112,7 +112,7 @@ if have_armv7
   ]
 endif
 
-if neon_opt == 'yes'
+if neon_opt.enabled()
   common_audio_sources += [
     'fir_filter_neon.cc',
     'resampler/sinc_resampler_neon.cc',

webrtc/modules/audio_processing/meson.build

@@ -180,7 +180,7 @@ else
   ]
 endif
 
-if neon_opt == 'yes'
+if neon_opt.enabled()
   webrtc_audio_processing_sources += [
     'aecm/aecm_core_neon.cc',
   ]

webrtc/third_party/pffft/meson.build

@@ -4,11 +4,7 @@ pffft_sources = [
 
 pffft_cflags = [ '-D_GNU_SOURCE' ]
 
-if neon_opt == 'runtime'
-  warning('pffft cannot check NEON support at runtime, will build without NEON')
-endif
-
-if not have_inline_sse or (have_arm and neon_opt != 'yes') or (have_mips and host_machine.endian() == 'little') or have_mips64
+if not have_inline_sse or (have_arm and not neon_opt.enabled()) or (have_mips and host_machine.endian() == 'little') or have_mips64
   pffft_cflags += [ '-DPFFFT_SIMD_DISABLE' ]
 endif