The wasm-ld linker. This the linker from the LLVM project. The external assembler llvm-mc is optional, since commit bc76487b878e59133ce3c2cc19ebb13f9a9826ea, in which, the internal assembler and object writer was enabled.
LLVM 11.0 is known to work. Development was done, using the Fedora packages llvm-11.0.0-1.fc33.x86_64 and lld-11.0.0-1.fc33.x86_64. Initial tests on MacOS used llvm-11 installed with MacPorts (https://www.macports.org) and according symlinks in /opt/local/bin (wasm32-wasi-llvm-mc -> llvm-mc-mp-11 and wasm32-embedded-llvm-mc -> llvm-mc-mp-11).
LLVM 12.0.1 also works.
The wasm-ld is part of package lld-12. fpc searches for the tool wasm32-wasi-wasm-ld or wasm-ld depending on the -XP flag you use (see /etc/fpc.cfg):
apt install lld-12 ln -sf /usr/lib/llvm-12/bin/wasm-ld ~/bin/wasm32-wasi-wasm-ld
Note: This assumes you have a $HOME/bin directory and it is in PATH.
If you need the external assembler, install the package llvm-12 and set a symlink:
apt install llvm-12 ln -sf /usr/lib/llvm-12/bin/llvm-mc ~/bin/wasm32-wasi-llvm-mc
Obtaining the compiler sources
The WebAssembly target was merged into FPC SVN trunk in r48955 on 2021-03-14. Since then, Free Pascal has moved to GitLab, so now it's now included in the git 'main' branch.
Get the sources:
git clone https://gitlab.com/freepascal.org/fpc/source.git fpc
enter the directory:
WASI - The WebAssembly System Interface
WASI is a modular system interface for WebAssembly. It allows creating portable and secure programs that can run in a sandboxed command-line environment or in the browser. See the WASI website for more information.
To build the compiler for the WASI target:
make all OS_TARGET=wasi CPU_TARGET=wasm32 BINUTILSPREFIX= OPT="-O-" PP=fpc
The following units have been ported for the WASI target:
- wasiapi - interface for the WASI API
Additionally, these units compile, but are not yet fully functional and/or tested very well:
See WebAssembly/Roadmap for details.
Compiled WASI binaries work with wasmtime version 0.23.0 or in the browser by opening:
and drag and dropping the .wasm binary directly into the browser window.
The Embedded target is primarily used for embedded systems (not a browser), without an operating system. However, it also happens to be a perfect fit for creating WebAssembly modules that don't use any particular operating system-like API.
make all OS_TARGET=embedded CPU_TARGET=wasm32 BINUTILSPREFIX= OPT="-O-" PP=fpc
Using the compiler
By default /etc/fpc.cfg contains a -XP$FPCTARGET- flag, so fpc searches for wasm32-wasi-wasm-ld. If you want to search for wasm-ld instead adapt your fpc.cfg :
If your fpc.cfg has
#IFDEF FPC_CROSSCOMPILING #IFDEF NEEDCROSSBINUTILS -XP$FPCTARGET- #ENDIF #ENDIF
Enclose it in #IFNDEF CPUWASM32 :
#IFDEF FPC_CROSSCOMPILING #IFDEF NEEDCROSSBINUTILS #ifndef cpuwasm32 -XP$FPCTARGET- #endif #ENDIF #ENDIF
Otherwise, you have to create symlinks wasm32-wasi-llvm-mc to llvm-mc, and wasm32-wasi-wasm-ld to wasm-ld.