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blake2: add Cargo feature to optimize for code size. #440

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merged 1 commit into from
Dec 16, 2022

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Dirbaio
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@Dirbaio Dirbaio commented Dec 9, 2022

The implementation uses some inline(always) to force inline the round and quarter_round functions for performance. This PR adds an opt-in Cargo feature to disable them, to allow optimizing for size instead.

Building for thumbv6m-none-eabi:

  • size_opt disabled: 5772 bytes
  • size_opt enabled: 2372 bytes

This saves 3.4kb of code size, which is 60%.

I'm trying to use blake2 on a microcontroller with 32kb of Flash memory (where the code is stored), so saving 3.4kb is quite substantial.

@@ -25,3 +25,4 @@ reset = [] # Enable reset functionality
simd = []
simd_opt = ["simd"]
simd_asm = ["simd_opt"]
size_opt = [] # Optimize for code size. Removes some `inline(always)`
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Could you add a new line here?

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Oops, done!

@newpavlov
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Thank you! I will release it shortly.

@newpavlov newpavlov merged commit f8b2eab into RustCrypto:master Dec 16, 2022
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2 participants