41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
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Minimal Build
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=============
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{{#include ../../links.md}}
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Configuration
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-------------
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In order to compile a _minimal_ build - i.e. a build optimized for size - perhaps for `no-std` embedded targets or for
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compiling to [WASM], it is essential that the correct linker flags are used in `cargo.toml`:
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```toml
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[profile.release]
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lto = "fat" # turn on Link-Time Optimizations
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codegen-units = 1 # trade compile time with maximum optimization
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opt-level = "z" # optimize for size
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```
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Opt-Out of Features
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------------------
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Opt out of as many features as possible, if they are not needed, to reduce code size because, remember, by default
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all code is compiled in as what a script requires cannot be predicted. If a language feature is not needed,
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omitting them via special features is a prudent strategy to optimize the build for size.
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Omitting arrays ([`no_index`]) yields the most code-size savings, followed by floating-point support
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([`no_float`]), checked arithmetic/script resource limits ([`unchecked`]) and finally object maps and custom types ([`no_object`]).
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Where the usage scenario does not call for loading externally-defined modules, use [`no_module`] to save some bytes.
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Disable script-defined functions ([`no_function`]) only when the feature is not needed because code size savings is minimal.
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Use a Raw [`Engine`]
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-------------------
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[`Engine::new_raw`](#raw-engine) creates a _raw_ engine.
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A _raw_ engine supports, out of the box, only a very [restricted set](#built-in-operators) of basic arithmetic and logical operators.
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Selectively include other necessary functionalities by loading specific [packages] to minimize the footprint.
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Packages are sharable (even across threads via the [`sync`] feature), so they only have to be created once.
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