Implement no_std support for SDK

[ilblackdragon]

The goal is to reduce dramatically contract size.
For example contract without std can be 5-8KB
Currently this requires to not use SDK at all.

[matklad]

I suggest profiling the memory usage first to understand what exactly is causing bloat before jumping to the solutions.

I would be surprised if std per se is a problem. My understanding is that, code-size wise, you don't pay for what you don't use in Rust/wasm. At the same time, some core functionality (formatting machinery mainly) is known to cause bloat.

The relevant tools are:

• cargo bloat
• cargo llvm-lines
• twiggy

[matklad]

Just so that the link is not lost in private communication: this post shows that removing formatting machinery from an already no_std crates leads to 92% reduction in size: https://jamesmunns.com/blog/fmt-unreasonably-expensive/.

[ilblackdragon]

I have profilled before and there are three major sources of bloat in wasm files: - fmt - full path and error strings in asserts and other errors - std dependencies of some libraries like serde and rand For example I have 8kb contracts for NEAR without using SDK right now when reducing it when avoid using dependencies and asserts.

…

On Tue, Jun 22, 2021 at 2:39 AM Aleksey Kladov ***@***.***> wrote: Just so that the link is not lost in private communication: this post shows that removing formatting machinery from *an already no_std* crates leads to 92% reduction in size: https://jamesmunns.com/blog/fmt-unreasonably-expensive/. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#443 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABK27WWNI5BTPLJPY6FN6TTUBK5TANCNFSM462C3ZGQ> .

-- Best regards, Illia Polosukhin

[bowenwang1996]

It would be rad if we can get the size of rust contracts down to 8kb

[ilblackdragon]

Checked - adding core::alloc::format and formatting a simple literal - +4kb, debug formatting vector - +10kb to binary size. In general any debug formatting especially on the structs will always balloon the size of the binary, so derive(Debug) should be excluded for wasm.

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On Fri, Jun 25, 2021 at 5:46 AM Bowen Wang ***@***.***> wrote: It would be rad if we can get the size of rust contracts down to 8kb — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#443 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABK27Q5MKMCETWUZOXABCLTUR3CZANCNFSM462C3ZGQ> .

-- Best regards, Illia Polosukhin

[frol]

Just for context, I want to mention that there is an experimental no-std NEAR SDK: https://github.com/austinabell/nesdie