Hi Paolo,
> > > >> has_int128_type is set to false on emscripten as of now to avoid
errors by
> > > >> libffi.
> > >
> > > What is the error here? How hard would it be to test for it?
> >
> > When has_int128_type=true, I encountered a runtime error from libffi. To
> > reproduce this, we need to actually execute a libffi call with 128-bit
> > arguments.
> >
> > > Uncaught TypeError: Cannot convert 1079505232 to a BigInt
> > > at ffi_call_js (out.js:702:37)
> > > at qemu-system-x86_64.wasm.ffi_call
(qemu-system-x86_64.wasm:0xa37712)
> > > at qemu-system-x86_64.wasm.tcg_qemu_tb_exec_tci
(qemu-system-x86_64.wasm:0x65f440)
> > > at qemu-system-x86_64.wasm.tcg_qemu_tb_exec
(qemu-system-x86_64.wasm:0x65edff)
> > > at qemu-system-x86_64.wasm.cpu_tb_exec
(qemu-system-x86_64.wasm:0x6762c0)
> > > at qemu-system-x86_64.wasm.cpu_exec_loop
(qemu-system-x86_64.wasm:0x677c84)
> > > at qemu-system-x86_64.wasm.dynCall_iii
(qemu-system-x86_64.wasm:0xab9014)
> > > at ret.<computed> (out.js:6016:24)
> > > at invoke_iii (out.js:7574:10)
> > > at qemu-system-x86_64.wasm.cpu_exec_setjmp
(qemu-system-x86_64.wasm:0x676db8)
>
> Ok, I guess a comment mentioning that it's a libffi limitation is enough.
>
> > > At least -g -O3 -pthread should not be necessary.
> >
> > Thank you for the suggestion. -sPROXY_TO_PTHREAD flag used in
c_link_args
> > always requires -pthread, even during configuration. Otherwise, emcc
returns
> > an error like:
> >
> > > emcc: error: -sPROXY_TO_PTHREAD requires -pthread to work!
> >
> > So I think -pthread needs to be included in c_link_args at minimum.
I'll try
> > to remove other flags in the next version of the series.
>
> Reading more about -sPROXY_TO_PTHREAD it seems that you need it for
> all calls to emcc, even when compiling, so it's better to leave it in
> everywhere.
>
> > > For -Wno-unused-command-line-argument what are the warnings/errors
that
> > > you are getting?
> >
> > I encountered the following error when compiling QEMU:
> >
> > > clang: error: argument unused during compilation: '-no-pie'
[-Werror,-Wunused-command-line-argument]
> >
> > It seems Emscripten doesn't support the -no-pie flag, and this wasn't
caught
> > during the configure phase. It seems that removing
> > -Wno-unused-command-line-argument would require the following change in
> > meson.build, but I'm open to better approaches.
> >
> > > -if not get_option('b_pie')
> > > +if not get_option('b_pie') and host_os != 'emscripten'
> > > qemu_common_flags += cc.get_supported_arguments('-fno-pie',
'-no-pie')
> > > endif
>
> Meson should have passed the -Werror=unused-command-line-argument flag
> when doing the above test (CLikeCompiler._has_multi_arguments ->
> has_arguments -> Compiler.compiles -> _build_wrapper ->
> build_wrapper_args -> ClangCompiler.get_compiler_check_args). It would
> be great if you can check what's wrong in this theory so perhaps meson
> can be fixed, or at least send here a meson-log.txt.
According to meson-log.txt as shown below,
-Werror=unused-command-line-argument was passed to the compiler, but it
didn't catch the warning.
> Working directory: /build/meson-private/tmp4q_5wl_9
> Code:
> extern int i;
> int i;
>
> -----------
> Command line: `/emsdk/upstream/emscripten/emcc -m32
/build/meson-private/tmp4q_5wl_9/testfile.c -o
/build/meson-private/tmp4q_5wl_9/output.o -c -D_FILE_OFFSET_BITS=64 -O0
-Werror=implicit-function-declaration -Werror=unknown-warning-option
-Werror=unused-command-line-argument -fno-pie` -> 0
> Compiler for C supports arguments -fno-pie: YES
> Running compile:
> Working directory: /build/meson-private/tmpl9yy_8gs
> Code:
> extern int i;
> int i;
>
> -----------
> Command line: `/emsdk/upstream/emscripten/emcc -m32
/build/meson-private/tmpl9yy_8gs/testfile.c -o
/build/meson-private/tmpl9yy_8gs/output.o -c -D_FILE_OFFSET_BITS=64 -O0
-Werror=implicit-function-declaration -Werror=unknown-warning-option
-Werror=unused-command-line-argument -no-pie` -> 0
> stderr:
> clang: warning: argument unused during compilation: '-no-pie'
[-Wunused-command-line-argument]
> -----------
> Compiler for C supports arguments -no-pie: YES
It seems there's a related issue thread on the Meson repository [1].
[1] https://github.com/mesonbuild/meson/issues/5355
> My suggestion is (if possible) to split out the parts of this series
> that are enough to run QEMU under TCI, and get those in as quickly as
> possible. The TCG backend can come second.
Sure, I'll try to split this patch series.
