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Using the compiler

Daniel Wirtz edited this page Feb 22, 2019 · 6 revisions

Similar to TypeScript's tsc compiling to JavaScript, AssemblyScript's asc compiles to WebAssembly:

SYNTAX
  asc [entryFile ...] [options]

EXAMPLES
  asc hello.ts
  asc hello.ts -b hello.wasm -t hello.wat
  asc hello1.ts hello2.ts -b -O > hello.wasm

OPTIONS
  --version, -v         Prints just the compiler's version and exits.
  --help, -h            Prints this message and exits.
  --optimize, -O        Optimizes the module. Also has the usual shorthands:

                         -O     Uses defaults. Equivalent to -O2s
                         -O0    Equivalent to --optimizeLevel 0
                         -O1    Equivalent to --optimizeLevel 1
                         -O2    Equivalent to --optimizeLevel 2
                         -O3    Equivalent to --optimizeLevel 3
                         -Oz    Equivalent to -O but with --shrinkLevel 2
                         -O3s   Equivalent to -O3 with --shrinkLevel 1 etc.

  --optimizeLevel       How much to focus on optimizing code. [0-3]
  --shrinkLevel         How much to focus on shrinking code size. [0-2, s=1, z=2]
  --validate, -c        Validates the module using Binaryen. Exits if invalid.
  --baseDir             Specifies the base directory of input and output files.
  --outFile, -o         Specifies the output file. File extension indicates format.
  --binaryFile, -b      Specifies the binary output file (.wasm).
  --textFile, -t        Specifies the text output file (.wat).
  --asmjsFile, -a       Specifies the asm.js output file (.js).
  --idlFile, -i         Specifies the WebIDL output file (.webidl).
  --tsdFile, -d         Specifies the TypeScript definition output file (.d.ts).
  --sourceMap           Enables source map generation. Optionally takes the URL
                        used to reference the source map from the binary file.
  --debug               Enables debug information in emitted binaries.
  --noAssert            Replaces assertions with just their value without trapping.
  --noEmit              Performs compilation as usual but does not emit code.
  --importMemory        Imports the memory instance provided by the embedder.
  --sharedMemory        Declare memory as shared by settings the max shared memory.
  --memoryBase          Sets the start offset of compiler-generated static memory.
  --importTable         Imports the function table instance provided by the embedder.
  --noLib               Does not include the shipped standard library.
  --lib                 Adds one or multiple paths to custom library components and
                        uses exports of all top-level files at this path as globals.
  --use, -u             Aliases a global object under another name, e.g., to switch
                        the default 'Math' implementation used: --use Math=JSMath
  --trapMode            Sets the trap mode to use.

                         allow  Allow trapping operations. This is the default.
                         clamp  Replace trapping operations with clamping semantics.
                         js     Replace trapping operations with JS semantics.

  --runPasses           Specifies additional Binaryen passes to run after other
                        optimizations, if any. See: Binaryen/src/passes/pass.cpp
  --enable              Enables additional (experimental) WebAssembly features.

                         sign-extension  Enables sign-extension operations
                         mutable-global  Enables mutable global imports and exports
                         bulk-memory     Enables bulk memory operations
                         simd            Enables SIMD types and operations.
                         threads         Enables threading and atomic operations.

  --transform           Specifies the path to a custom transform to 'require'.
  --measure             Prints measuring information on I/O and compile times.
  --noColors            Disables terminal colors.

The compiler API can also be used programmatically. It accepts the same options as the CLI but also lets you override stdout and stderr and/or provide a callback:

const asc = require("assemblyscript/cli/asc");
asc.main([
  "myModule.ts",
  "--binaryFile", "myModule.wasm",
  "--optimize",
  "--sourceMap",
  "--measure"
], {
  stdout: process.stdout,
  stderr: process.stderr
}, function(err) {
  if (err)
    throw err;
  ...
});

Available command line options can also be obtained programmatically:

const options = require("assemblyscript/cli/asc.json");
...

You can also compile a source string directly, for example in a browser environment:

const { binary, text, stdout, stderr } = asc.compileString(`...`, { optimize: 2 });
...
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