gex/toolchain

gexcc

A C and C++ compiler for gex's wasm32 Linux target, used like gcc. It compiles with clang (--target=wasm32-unknown-linux-musl) against its own sysroot: musl with gex's wasm32 port, libgex and compiler-rt. A linked program is a position-independent wasm module in the ELF container that gexc runs. On an x86 Linux build machine the container also runs itself under gexc, so configure checks and test suites can run it like a native binary.

$ make gexcc                         # out/gexcc (GEXCC_PREFIX=DIR elsewhere)
...
out/gexcc/bin/gexcc
$ out/gexcc/bin/gexcc -O2 -o hello hello.c
$ target/x86/release/gexc run hello

make gexcc fetches musl and LLVM at their pins, then runs toolchain/gexcc/install.sh PREFIX MUSL_SRC with LLVM_SRC (C++) and busybox (the guest's /bin/sh).

Libraries are static by default. -shared writes an archive, so a build that insists on libfoo.so still links. With GEXCC_SHARED=1, -shared writes a real wasm side module instead, which gex's loader binds at run time. The debdemo repository builds Debian packages with gexcc and assembles a Debian root filesystem around them. The gexcc script's header lists its options and environment.

C++ needs libc++ built from toolchain/pins' LLVM_COMMIT of our LLVM tree (clang's version with our runtime changes). make gexcc builds it, and toolchain/gexcc/build-cxx.sh PREFIX CHECKOUT rebuilds it alone.

Windows programs

windows/ is gexcc's Windows target: MinGW-named tools (x86_64-w64-mingw32-gcc, -g++, -windres, ...) that build Windows x64 programs and DLLs as native wasm modules against 64-bit Wine's native PE side. A link writes a PE skeleton (X.exe) and its module (X.exe.wasm) beside it; Wine's loader runs the pair with no x86 code.

$ make gexcc-win                     # after make wine: out/gexcc-win
$ out/gexcc-win/bin/x86_64-w64-mingw32-gcc -O2 -mwindows -o app.exe app.c res.o -lcomctl32

make gexcc-win runs toolchain/gexcc/windows/install.sh over make wine's build tree and toolchain/gexcc/windows/build-cxx.sh for C++.

-s links a release module (the names gex does not read stripped). A dist's cores export every DLL export by default (WINE64_EXPORT_ALL=1), so such programs' calls into any of its DLLs bind; a site that ships known programs can build with WINE64_EXPORT_ALL=0 WINE64_EXPORTS=FILE, FILE listing their imports (DLL!name, one a line). windows/gexcc-win's header lists the rest.