diff options
Diffstat (limited to 'doc/languages-frameworks/emscripten.section.md')
| -rw-r--r-- | doc/languages-frameworks/emscripten.section.md | 297 |
1 files changed, 141 insertions, 156 deletions
diff --git a/doc/languages-frameworks/emscripten.section.md b/doc/languages-frameworks/emscripten.section.md index 5f93dd5ff31..20d358f2e9e 100644 --- a/doc/languages-frameworks/emscripten.section.md +++ b/doc/languages-frameworks/emscripten.section.md @@ -2,168 +2,159 @@ [Emscripten](https://github.com/kripken/emscripten): An LLVM-to-JavaScript Compiler -This section of the manual covers how to use `emscripten` in nixpkgs. +If you want to work with `emcc`, `emconfigure` and `emmake` as you are used to from Ubuntu and similar distributions, -Minimal requirements: - -* nix -* nixpkgs - -Modes of use of `emscripten`: - -* **Imperative usage** (on the command line): - - If you want to work with `emcc`, `emconfigure` and `emmake` as you are used to from Ubuntu and similar distributions you can use these commands: - - * `nix-env -f "<nixpkgs>" -iA emscripten` - * `nix-shell -p emscripten` - -* **Declarative usage**: - - This mode is far more power full since this makes use of `nix` for dependency management of emscripten libraries and targets by using the `mkDerivation` which is implemented by `pkgs.emscriptenStdenv` and `pkgs.buildEmscriptenPackage`. The source for the packages is in `pkgs/top-level/emscripten-packages.nix` and the abstraction behind it in `pkgs/development/em-modules/generic/default.nix`. From the root of the nixpkgs repository: - * build and install all packages: - * `nix-env -iA emscriptenPackages` - - * dev-shell for zlib implementation hacking: - * `nix-shell -A emscriptenPackages.zlib` - -## Imperative usage {#imperative-usage} +```console +nix-shell -p emscripten +``` A few things to note: * `export EMCC_DEBUG=2` is nice for debugging -* `~/.emscripten`, the build artifact cache sometimes creates issues and needs to be removed from time to time +* The build artifact cache in `~/.emscripten` sometimes creates issues and needs to be removed from time to time -## Declarative usage {#declarative-usage} +## Examples {#declarative-usage} Let's see two different examples from `pkgs/top-level/emscripten-packages.nix`: * `pkgs.zlib.override` * `pkgs.buildEmscriptenPackage` -Both are interesting concepts. - -A special requirement of the `pkgs.buildEmscriptenPackage` is the `doCheck = true` is a default meaning that each emscriptenPackage requires a `checkPhase` implemented. - -* Use `export EMCC_DEBUG=2` from within a emscriptenPackage's `phase` to get more detailed debug output what is going wrong. -* ~/.emscripten cache is requiring us to set `HOME=$TMPDIR` in individual phases. This makes compilation slower but also makes it more deterministic. - -### Usage 1: pkgs.zlib.override {#usage-1-pkgs.zlib.override} - -This example uses `zlib` from nixpkgs but instead of compiling **C** to **ELF** it compiles **C** to **JS** since we were using `pkgs.zlib.override` and changed stdenv to `pkgs.emscriptenStdenv`. A few adaptions and hacks were set in place to make it working. One advantage is that when `pkgs.zlib` is updated, it will automatically update this package as well. However, this can also be the downside... - -See the `zlib` example: - - zlib = (pkgs.zlib.override { - stdenv = pkgs.emscriptenStdenv; - }).overrideAttrs - (old: rec { - buildInputs = old.buildInputs ++ [ pkg-config ]; - # we need to reset this setting! - env = (old.env or { }) // { NIX_CFLAGS_COMPILE = ""; }; - configurePhase = '' - # FIXME: Some tests require writing at $HOME - HOME=$TMPDIR - runHook preConfigure - - #export EMCC_DEBUG=2 - emconfigure ./configure --prefix=$out --shared - - runHook postConfigure - ''; - dontStrip = true; - outputs = [ "out" ]; - buildPhase = '' - emmake make - ''; - installPhase = '' - emmake make install - ''; - checkPhase = '' - echo "================= testing zlib using node =================" - - echo "Compiling a custom test" - set -x - emcc -O2 -s EMULATE_FUNCTION_POINTER_CASTS=1 test/example.c -DZ_SOLO \ - libz.so.${old.version} -I . -o example.js - - echo "Using node to execute the test" - ${pkgs.nodejs}/bin/node ./example.js - - set +x - if [ $? -ne 0 ]; then - echo "test failed for some reason" - exit 1; - else - echo "it seems to work! very good." - fi - echo "================= /testing zlib using node =================" - ''; - - postPatch = pkgs.lib.optionalString pkgs.stdenv.isDarwin '' - substituteInPlace configure \ - --replace '/usr/bin/libtool' 'ar' \ - --replace 'AR="libtool"' 'AR="ar"' \ - --replace 'ARFLAGS="-o"' 'ARFLAGS="-r"' - ''; - }); - -### Usage 2: pkgs.buildEmscriptenPackage {#usage-2-pkgs.buildemscriptenpackage} - -This `xmlmirror` example features a emscriptenPackage which is defined completely from this context and no `pkgs.zlib.override` is used. - - xmlmirror = pkgs.buildEmscriptenPackage rec { - name = "xmlmirror"; - - buildInputs = [ pkg-config autoconf automake libtool gnumake libxml2 nodejs openjdk json_c ]; - nativeBuildInputs = [ pkg-config zlib ]; - - src = pkgs.fetchgit { - url = "https://gitlab.com/odfplugfest/xmlmirror.git"; - rev = "4fd7e86f7c9526b8f4c1733e5c8b45175860a8fd"; - hash = "sha256-i+QgY+5PYVg5pwhzcDnkfXAznBg3e8sWH2jZtixuWsk="; - }; - - configurePhase = '' - rm -f fastXmlLint.js* - # a fix for ERROR:root:For asm.js, TOTAL_MEMORY must be a multiple of 16MB, was 234217728 - # https://gitlab.com/odfplugfest/xmlmirror/issues/8 - sed -e "s/TOTAL_MEMORY=234217728/TOTAL_MEMORY=268435456/g" -i Makefile.emEnv - # https://github.com/kripken/emscripten/issues/6344 - # https://gitlab.com/odfplugfest/xmlmirror/issues/9 - sed -e "s/\$(JSONC_LDFLAGS) \$(ZLIB_LDFLAGS) \$(LIBXML20_LDFLAGS)/\$(JSONC_LDFLAGS) \$(LIBXML20_LDFLAGS) \$(ZLIB_LDFLAGS) /g" -i Makefile.emEnv - # https://gitlab.com/odfplugfest/xmlmirror/issues/11 - sed -e "s/-o fastXmlLint.js/-s EXTRA_EXPORTED_RUNTIME_METHODS='[\"ccall\", \"cwrap\"]' -o fastXmlLint.js/g" -i Makefile.emEnv - ''; - - buildPhase = '' - HOME=$TMPDIR - make -f Makefile.emEnv - ''; - - outputs = [ "out" "doc" ]; - - installPhase = '' - mkdir -p $out/share - mkdir -p $doc/share/${name} - - cp Demo* $out/share - cp -R codemirror-5.12 $out/share - cp fastXmlLint.js* $out/share - cp *.xsd $out/share - cp *.js $out/share - cp *.xhtml $out/share - cp *.html $out/share - cp *.json $out/share - cp *.rng $out/share - cp README.md $doc/share/${name} - ''; - checkPhase = '' - - ''; - }; - -### Declarative debugging {#declarative-debugging} +A special requirement of the `pkgs.buildEmscriptenPackage` is the `doCheck = true`. +This means each Emscripten package requires that a [`checkPhase`](#ssec-check-phase) is implemented. + +* Use `export EMCC_DEBUG=2` from within a phase to get more detailed debug output what is going wrong. +* The cache at `~/.emscripten` requires to set `HOME=$TMPDIR` in individual phases. + This makes compilation slower but also more deterministic. + +::: {.example #usage-1-pkgs.zlib.override} + +# Using `pkgs.zlib.override {}` + +This example uses `zlib` from Nixpkgs, but instead of compiling **C** to **ELF** it compiles **C** to **JavaScript** since we were using `pkgs.zlib.override` and changed `stdenv` to `pkgs.emscriptenStdenv`. + +A few adaptions and hacks were put in place to make it work. +One advantage is that when `pkgs.zlib` is updated, it will automatically update this package as well. + + +```nix +(pkgs.zlib.override { + stdenv = pkgs.emscriptenStdenv; +}).overrideAttrs +(old: rec { + buildInputs = old.buildInputs ++ [ pkg-config ]; + # we need to reset this setting! + env = (old.env or { }) // { NIX_CFLAGS_COMPILE = ""; }; + configurePhase = '' + # FIXME: Some tests require writing at $HOME + HOME=$TMPDIR + runHook preConfigure + + #export EMCC_DEBUG=2 + emconfigure ./configure --prefix=$out --shared + + runHook postConfigure + ''; + dontStrip = true; + outputs = [ "out" ]; + buildPhase = '' + emmake make + ''; + installPhase = '' + emmake make install + ''; + checkPhase = '' + echo "================= testing zlib using node =================" + + echo "Compiling a custom test" + set -x + emcc -O2 -s EMULATE_FUNCTION_POINTER_CASTS=1 test/example.c -DZ_SOLO \ + libz.so.${old.version} -I . -o example.js + + echo "Using node to execute the test" + ${pkgs.nodejs}/bin/node ./example.js + + set +x + if [ $? -ne 0 ]; then + echo "test failed for some reason" + exit 1; + else + echo "it seems to work! very good." + fi + echo "================= /testing zlib using node =================" + ''; + + postPatch = pkgs.lib.optionalString pkgs.stdenv.isDarwin '' + substituteInPlace configure \ + --replace '/usr/bin/libtool' 'ar' \ + --replace 'AR="libtool"' 'AR="ar"' \ + --replace 'ARFLAGS="-o"' 'ARFLAGS="-r"' + ''; +}) +``` + +:::{.example #usage-2-pkgs.buildemscriptenpackage} + +# Using `pkgs.buildEmscriptenPackage {}` + +This `xmlmirror` example features an Emscripten package that is defined completely from this context and no `pkgs.zlib.override` is used. + +```nix +pkgs.buildEmscriptenPackage rec { + name = "xmlmirror"; + + buildInputs = [ pkg-config autoconf automake libtool gnumake libxml2 nodejs openjdk json_c ]; + nativeBuildInputs = [ pkg-config zlib ]; + + src = pkgs.fetchgit { + url = "https://gitlab.com/odfplugfest/xmlmirror.git"; + rev = "4fd7e86f7c9526b8f4c1733e5c8b45175860a8fd"; + hash = "sha256-i+QgY+5PYVg5pwhzcDnkfXAznBg3e8sWH2jZtixuWsk="; + }; + + configurePhase = '' + rm -f fastXmlLint.js* + # a fix for ERROR:root:For asm.js, TOTAL_MEMORY must be a multiple of 16MB, was 234217728 + # https://gitlab.com/odfplugfest/xmlmirror/issues/8 + sed -e "s/TOTAL_MEMORY=234217728/TOTAL_MEMORY=268435456/g" -i Makefile.emEnv + # https://github.com/kripken/emscripten/issues/6344 + # https://gitlab.com/odfplugfest/xmlmirror/issues/9 + sed -e "s/\$(JSONC_LDFLAGS) \$(ZLIB_LDFLAGS) \$(LIBXML20_LDFLAGS)/\$(JSONC_LDFLAGS) \$(LIBXML20_LDFLAGS) \$(ZLIB_LDFLAGS) /g" -i Makefile.emEnv + # https://gitlab.com/odfplugfest/xmlmirror/issues/11 + sed -e "s/-o fastXmlLint.js/-s EXTRA_EXPORTED_RUNTIME_METHODS='[\"ccall\", \"cwrap\"]' -o fastXmlLint.js/g" -i Makefile.emEnv + ''; + + buildPhase = '' + HOME=$TMPDIR + make -f Makefile.emEnv + ''; + + outputs = [ "out" "doc" ]; + + installPhase = '' + mkdir -p $out/share + mkdir -p $doc/share/${name} + + cp Demo* $out/share + cp -R codemirror-5.12 $out/share + cp fastXmlLint.js* $out/share + cp *.xsd $out/share + cp *.js $out/share + cp *.xhtml $out/share + cp *.html $out/share + cp *.json $out/share + cp *.rng $out/share + cp README.md $doc/share/${name} + ''; + checkPhase = '' + + ''; +} +``` + +::: + +## Debugging {#declarative-debugging} Use `nix-shell -I nixpkgs=/some/dir/nixpkgs -A emscriptenPackages.libz` and from there you can go trough the individual steps. This makes it easy to build a good `unit test` or list the files of the project. @@ -174,9 +165,3 @@ Use `nix-shell -I nixpkgs=/some/dir/nixpkgs -A emscriptenPackages.libz` and from 5. `configurePhase` 6. `buildPhase` 7. ... happy hacking... - -## Summary {#summary} - -Using this toolchain makes it easy to leverage `nix` from NixOS, MacOSX or even Windows (WSL+ubuntu+nix). This toolchain is reproducible, behaves like the rest of the packages from nixpkgs and contains a set of well working examples to learn and adapt from. - -If in trouble, ask the maintainers. |