64 lines
1.8 KiB
Markdown
64 lines
1.8 KiB
Markdown
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# Bazel Emscripten toolchain
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## Setup Instructions
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1. Merge the `WORKSPACE` file in with your own at the root of your bazel
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directory structure. If you don't have one, simply copy the file.
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2. Merge the `bazelrc` file in with your `.bazelrc` file at the root of your
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bazel directory structure. If you don't have one, simply copy the file and
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rename it to `.bazelrc`. (Note the `.`)
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3. Copy the `emscripten_toolchain` folder along with its contents to the root of
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your bazel directory.
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Your directory structure should look like this:
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```
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bazel_root/
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├── .bazelrc
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├── WORKSPACE
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├── emscripten_toolchain/
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│ ├── BUILD.bazel
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│ ├── builddefs.bzl
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│ ├── crosstool.bzl
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│ ├── emar.sh
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│ ├── emcc.sh
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│ ├── emcc_link.sh
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│ ├── emscripten.BUILD
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│ ├── emscripten_config
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│ ├── env.sh
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│ ├── link_wrapper.py
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│ ├── wasm_binary.py
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│ ├── wasm_cc_binary.bzl
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│ ├── wasm_rules.bzl
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├── your_project_folder/
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│ ├── your_project.file
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```
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## Building
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### Using --config=wasm
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Simply pass `--config=wasm` when building a normal `cc_binary`. The result of
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this build will be a tar archive containing any files produced by emscripten.
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### Using wasm_cc_binary
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First, write a new rule wrapping your `cc_binary`.
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```
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load("@rules_cc//cc:defs.bzl", "cc_binary")
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load("//emscripten_toolchain:wasm_rules.bzl", "wasm_cc_binary")
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cc_binary(
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name = "hello-world",
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srcs = ["hello-world.cc"],
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)
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wasm_cc_binary(
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name = "hello-world-wasm",
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cc_target = ":hello-world",
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)
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```
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Now you can run `bazel build :hello-world-wasm`. The result of this build will
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be the individual files produced by emscripten. Note that some of these files
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may be empty. This is because bazel has no concept of optional outputs for
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rules.
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