build.sh

#!/bin/sh -ex

WASI_SDK=wasi-sdk-25.0-x86_64-linux
WASI_SDK_URL=https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-25/wasi-sdk-25.0-x86_64-linux.tar.gz
if ! [ -d ${WASI_SDK} ]; then curl -L ${WASI_SDK_URL} | tar xzf -; fi

# This script does a lot of really awful things to Yosys to make the WASM artifact smaller.
# This improves startup latency and reduces download size.

cat >yosys-src/Makefile.conf <<END
export PATH := $(pwd)/${WASI_SDK}/bin:${PATH}
WASI_SYSROOT := $(pwd)/${WASI_SDK}/share/wasi-sysroot

CONFIG := wasi
PREFIX := /

ENABLE_TCL := 0
ENABLE_ABC := 0
ENABLE_GLOB := 0
ENABLE_PLUGINS := 0
ENABLE_READLINE := 0
ENABLE_EDITLINE := 0
ENABLE_VERIFIC := 0
ENABLE_COVER := 0
ENABLE_LIBYOSYS := 0
ENABLE_PROTOBUF := 0
ENABLE_ZLIB := 0

CXXFLAGS += -D_WASI_EMULATED_PROCESS_CLOCKS -flto
LDFLAGS += -lwasi-emulated-process-clocks -flto -Wl,--strip-all
END

cat >yosys-src/frontends/verilog/preproc_stub.cc <<END
#include "preproc.h"

YOSYS_NAMESPACE_BEGIN

struct define_body_t {};

define_map_t::define_map_t() {}
define_map_t::~define_map_t() {}
void define_map_t::clear() {}

YOSYS_NAMESPACE_END
END

cat >yosys-src/passes/cmds/design_stub.cc <<END
#include "kernel/yosys.h"

YOSYS_NAMESPACE_BEGIN

std::map<std::string, RTLIL::Design*> saved_designs;
std::vector<RTLIL::Design*> pushed_designs;

YOSYS_NAMESPACE_END
END

YOSYS_PYPI_VER=$(python3 setup.py --version)
YOSYS_GIT_REV=$(git -C yosys-src rev-parse --short HEAD | tr -d '\n')
YOSYS_VER_STR='Amaranth Yosys $(YOSYS_VER) '"(PyPI ver ${YOSYS_PYPI_VER}, git sha1 ${YOSYS_GIT_REV})"
YOSYS_OBJS="\
kernel/version_${YOSYS_GIT_REV}.cc \
kernel/driver.o \
kernel/json.o \
kernel/register.o \
kernel/rtlil.o \
kernel/log.o \
kernel/calc.o \
kernel/mem.o \
kernel/ff.o \
kernel/fmt.o \
kernel/scopeinfo.o \
kernel/cellaigs.o \
kernel/satgen.o \
kernel/qcsat.o \
kernel/yosys.o \
libs/bigint/BigInteger.o \
libs/bigint/BigUnsigned.o \
libs/sha1/sha1.o \
libs/json11/json11.o \
libs/ezsat/ezsat.o \
libs/ezsat/ezminisat.o \
libs/minisat/Options.o \
libs/minisat/SimpSolver.o \
libs/minisat/Solver.o \
libs/minisat/System.o \
frontends/ast/ast.o \
frontends/ast/simplify.o \
frontends/rtlil/rtlil_parser.tab.o \
frontends/rtlil/rtlil_lexer.o \
frontends/rtlil/rtlil_frontend.o \
frontends/verilog/preproc_stub.o \
frontends/verilog/const2ast.o \
passes/hierarchy/hierarchy.o \
passes/hierarchy/uniquify.o \
passes/hierarchy/submod.o \
passes/proc/proc.o \
passes/proc/proc_prune.o \
passes/proc/proc_clean.o \
passes/proc/proc_rmdead.o \
passes/proc/proc_init.o \
passes/proc/proc_arst.o \
passes/proc/proc_memwr.o \
passes/proc/proc_mux.o \
passes/proc/proc_dlatch.o \
passes/proc/proc_dff.o \
passes/proc/proc_rom.o \
passes/opt/opt.o \
passes/opt/opt_merge.o \
passes/opt/opt_mem.o \
passes/opt/opt_mem_feedback.o \
passes/opt/opt_mem_priority.o \
passes/opt/opt_mem_widen.o \
passes/opt/opt_muxtree.o \
passes/opt/opt_reduce.o \
passes/opt/opt_dff.o \
passes/opt/opt_share.o \
passes/opt/opt_clean.o \
passes/opt/opt_expr.o \
passes/opt/share.o \
passes/opt/wreduce.o \
passes/opt/opt_demorgan.o \
passes/opt/rmports.o \
passes/opt/opt_lut.o \
passes/opt/opt_lut_ins.o \
passes/opt/opt_ffinv.o \
passes/opt/pmux2shiftx.o \
passes/opt/muxpack.o \
passes/cmds/plugin.o \
passes/cmds/design_stub.o \
passes/cmds/select.o \
passes/cmds/delete.o \
passes/cmds/clean_zerowidth.o \
passes/memory/memory_collect.o \
passes/techmap/attrmap.o \
passes/techmap/flatten.o \
passes/techmap/bmuxmap.o \
passes/techmap/demuxmap.o \
passes/techmap/simplemap.o \
backends/rtlil/rtlil_backend.o \
backends/cxxrtl/cxxrtl_backend.o \
backends/verilog/verilog_backend.o \
backends/json/json.o \
"
make -C yosys-src GIT_REV="${YOSYS_GIT_REV}" YOSYS_VER_STR="${YOSYS_VER_STR}" OBJS="${YOSYS_OBJS}" PRETTY=0 CXX="ccache clang"

cp yosys-src/yosys.wasm amaranth_yosys/
rm -rf amaranth_yosys/share
mkdir -p amaranth_yosys/share/include/backends/cxxrtl
cp -r yosys-src/share/include/backends/cxxrtl/runtime amaranth_yosys/share/include/backends/cxxrtl/