Re: [PATCH 17/19] meson: Add wasm build in build scripts

[Philippe Mathieu-Daudé]

Hi Kohei,

On 16/4/25 10:14, Kohei Tokunaga wrote:
> has_int128_type is set to false on emscripten as of now to avoid errors by
> libffi. Tests are disabled on emscripten because they rely on host
> features that aren't supported by emscripten (e.g. fork and unix
> socket).
>
> Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
> ---
>   configs/meson/emscripten.txt  |  8 ++++++++
>   configure                     |  7 +++++++
>   meson.build                   | 25 ++++++++++++++++++++-----
>   meson_options.txt             |  2 +-
>   scripts/meson-buildoptions.sh |  2 +-
>   stubs/meson.build             |  4 ++++
>   6 files changed, 41 insertions(+), 7 deletions(-)
>   create mode 100644 configs/meson/emscripten.txt


> diff --git a/meson.build b/meson.build
> index 41f68d3806..c9aa5016d6 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -50,9 +50,9 @@ genh = []
>   qapi_trace_events = []
>   
>   bsd_oses = ['gnu/kfreebsd', 'freebsd', 'netbsd', 'openbsd', 'dragonfly', 'darwin']
> -supported_oses = ['windows', 'freebsd', 'netbsd', 'openbsd', 'darwin', 
> 'sunos', 'linux']
> +supported_oses = ['windows', 'freebsd', 'netbsd', 'openbsd', 'darwin', 
> 'sunos', 'linux', 'emscripten']
>   supported_cpus = ['ppc', 'ppc64', 's390x', 'riscv32', 'riscv64', 'x86', 
> 'x86_64',
> -  'arm', 'aarch64', 'loongarch64', 'mips', 'mips64', 'sparc64']
> +  'arm', 'aarch64', 'loongarch64', 'mips', 'mips64', 'sparc64', 'wasm32']
>   
>   cpu = host_machine.cpu_family()
>   
> @@ -353,6 +353,8 @@ foreach lang : all_languages
>         # endif
>         #endif''')
>       # ok
> +  elif compiler.get_id() == 'emscripten'
> +    # ok
>     else
>       error('You either need GCC v7.4 or Clang v10.0 (or XCode Clang v15.0) to 
> compile QEMU')
>     endif
> @@ -470,7 +472,10 @@ endif
>   # instead, we can't add -no-pie because it overrides -shared: the linker then
>   # tries to build an executable instead of a shared library and fails.  So
>   # don't add -no-pie anywhere and cross fingers. :(
> -if not get_option('b_pie')
> +#
> +# Emscripten doesn't support -no-pie but meson can't catch the compiler
> +# warning. So explicitly omit the flag for Emscripten.
> +if not get_option('b_pie') and host_os != 'emscripten'
>     qemu_common_flags += cc.get_supported_arguments('-fno-pie', '-no-pie')
>   endif
>   
> @@ -514,6 +519,8 @@ ucontext_probe = '''
>   supported_backends = []
>   if host_os == 'windows'
>     supported_backends += ['windows']
> +elif host_os == 'emscripten'
> +  supported_backends += ['wasm']
>   else
>     if host_os != 'darwin' and cc.links(ucontext_probe)
>       supported_backends += ['ucontext']
> @@ -2962,7 +2969,9 @@ config_host_data.set('CONFIG_ATOMIC64', cc.links('''
>       return 0;
>     }''', args: qemu_isa_flags))
>   
> -has_int128_type = cc.compiles('''
> +# has_int128_type is set to false on Emscripten to avoid errors by libffi
> +# during runtime.
> +has_int128_type = host_os != 'emscripten' and cc.compiles('''
>     __int128_t a;
>     __uint128_t b;
>     int main(void) { b = a; }''')
> @@ -3774,6 +3783,8 @@ if have_block
>     # os-win32.c does not
>     if host_os == 'windows'
>       system_ss.add(files('os-win32.c'))
> +  elif host_os == 'emscripten'
> +    blockdev_ss.add(files('os-wasm.c'))
>     else
>       blockdev_ss.add(files('os-posix.c'))
>     endif
> @@ -4456,7 +4467,11 @@ subdir('scripts')
>   subdir('tools')
>   subdir('pc-bios')
>   subdir('docs')
> -subdir('tests')
> +# Tests are disabled on emscripten because they rely on host features that 
> aren't
> +# supported by emscripten (e.g. fork and unix socket).
> +if host_os != 'emscripten'
> +  subdir('tests')
> +endif
>   if gtk.found()
>     subdir('po')
>   endif
> diff --git a/meson_options.txt b/meson_options.txt
> index 59d973bca0..45772484cc 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -34,7 +34,7 @@ option('fuzzing_engine', type : 'string', value : '',
>   option('trace_file', type: 'string', value: 'trace',
>          description: 'Trace file prefix for simple backend')
>   option('coroutine_backend', type: 'combo',
> -       choices: ['ucontext', 'sigaltstack', 'windows', 'auto'],
> +       choices: ['ucontext', 'sigaltstack', 'windows', 'wasm', 'auto'],
>          value: 'auto', description: 'coroutine backend to use')

Does wasm depend on TCI at this point (no TCG backend)? If so, should
we check TCI is enabled? (I wonder if configuring with the
--disable-tcg-interpreter option succeed).