go-libwebp

Experimental translation from libwebp to Go source.
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build-wasm.sh (2283B)

      1 #!/bin/sh
      2 #
      3 # Build libwebp to a single wasm32-wasi reactor module: scalar only, because
      4 # reaching libwebp's SSE kernels on wasm needs Emscripten's compat headers
      5 # (see tools/build-wasm-emscripten.sh, which builds the shipped module).
      6 #
      7 # This is the lighter-weight toolchain and the control for comparing against
      8 # the Emscripten output. It writes a comparison artifact into bench/lib and
      9 # never touches the checked-in lib/wasm/webp/libwebp.wasm.
     10 #
     11 # Requires only `zig` (tested with 0.15.2) — no mingw, no osxcross, no ccgo.
     12 
     13 set -eux
     14 
     15 ZIG=${ZIG:-zig}
     16 HERE=$(cd "$(dirname "$0")" && pwd)
     17 SRC=$HERE/../c-lib
     18 OUT=${OUT:-$HERE/../bench/lib}/libwebp-zig-scalar.wasm
     19 mkdir -p "$(dirname "$OUT")"
     20 OBJ=$(mktemp -d)
     21 trap 'rm -rf "$OBJ"' EXIT
     22 
     23 # sharpyuv is a separate top-level library since libwebp 1.3; the encoder
     24 # links against it.
     25 #
     26 # The arch-specific dsp translation units are internally guarded by
     27 # WEBP_USE_{SSE2,NEON,MSA,...} and reduce to stubs on wasm, so the whole
     28 # directory can be compiled unconditionally.
     29 #
     30 # Note: no SIMD. Enabling libwebp's SSE2 kernels on wasm needs Emscripten's
     31 # SSE-to-simd128 compat headers, which wasi-sdk and zig do not ship; clang's
     32 # own emmintrin.h rejects non-x86 targets and zig rejects -msse2 outright.
     33 cd "$SRC"
     34 for f in src/dec/*.c src/enc/*.c src/utils/*.c src/dsp/*.c sharpyuv/*.c; do
     35     $ZIG cc -target wasm32-wasi -O3 -DNDEBUG -I"$SRC" \
     36         -c "$f" -o "$OBJ/$(echo "$f" | tr / _).o"
     37 done
     38 
     39 # A reactor exports _initialize instead of _start and stays resident.
     40 # The default 16 MiB wasm stack sets the floor on every instance's linear
     41 # memory; 1 MiB is ample for libwebp and makes instances ~6x cheaper to
     42 # create and far cheaper to pool.
     43 $ZIG cc -target wasm32-wasi -O3 -mexec-model=reactor \
     44     -Wl,--export=WebPEncodeRGBA \
     45     -Wl,--export=WebPEncodeLosslessRGBA \
     46     -Wl,--export=WebPDecodeRGBA \
     47     -Wl,--export=WebPFree \
     48     -Wl,--export=malloc \
     49     -Wl,--export=free \
     50     -Wl,--gc-sections \
     51     -Wl,-z,stack-size=1048576 \
     52     -Wl,--initial-memory=2097152 \
     53     -o "$OUT.dbg" "$OBJ"/*.o
     54 
     55 # DWARF is ~76% of the module and wazero does not use it. Keep the `name`
     56 # section: it is what turns a trap into a readable frame.
     57 python3 "$HERE/strip-wasm-debug.py" "$OUT.dbg" "$OUT"
     58 rm -f "$OUT.dbg"
     59 ls -la "$OUT"