Use -Clinker-plugin-lto flag during Wasm build
#358
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From: Original wasm size: 68.6K, Optimized: 31.9K To: Original wasm size: 67.2K, Optimized: 31.0K
src/cmd/build.rs
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| @@ -249,7 +249,7 @@ fn exec_cargo_for_wasm_target( | |||
| // Currently will override user defined RUSTFLAGS from .cargo/config. See https://github.com/paritytech/cargo-contract/issues/98. | |||
| std::env::set_var( | |||
| "RUSTFLAGS", | |||
| "-C link-arg=-zstack-size=65536 -C link-arg=--import-memory", | |||
| "-C link-arg=-zstack-size=65536 -C link-arg=--import-memory -Clto -Clinker-plugin-lto", | |||
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I believe the -Clto will override the release profile which we automatically append/merge to the contract's Cargo.toml. See https://github.com/paritytech/cargo-contract/blob/a8c8589798c05468b41e8125b6c5c3c1194178b6/src/workspace/profile.rs#L22.
I think we might still need to pass Clinker-plugin-lto directly as an argument, but AFAIU it seems dependent upon -Clto which is configurable from the [profile.release]
The philosophy we have followed so far is that we should provide sensible defaults for these values, but also allow the user to override them, because the same hardcoded flags might now always produce the optimal contract size for all contracts.
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What do you think if we will add it automatically here if lto is on?=)
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Clinker-plugin-lto is not a profile setting https://doc.rust-lang.org/cargo/reference/profiles.html.
What effect does just having Clto on its own have on the size?
Anyway if this flag is providing such big gains, and doesn't harm any of the other Lto options then we can possibly hardcode it.
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For example that contract takes space:
Without -Clto and -Clinker-plugin-lto: Original wasm size: 100.5K, Optimized: 47.9K
With -Clto: Original wasm size: 68.6K, Optimized: 31.9K
With -Clto and -Clinker-plugin-lto: Original wasm size: 67.2K, Optimized: 31.0K
I tried it on contracts from that folder and it causes a positive effect for all of them(but all of them has a heavy logic, except reentrancy. For reentrancy it causes a low impact there).
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I did measurements for reentrancy. Also, I removed explicit -Clto because it causes a compilation error if it is disabled or not aplieable. I tested compiler will use -Clinker-plugin-lto if he can.
flipper:
Original wasm size: 38.9K, Optimized: 12.5K
Original wasm size: 24.4K, Optimized: 4.5K
Original wasm size: 24.1K, Optimized: 4.2K
flip_on_me:
Original wasm size: 33.8K, Optimized: 10.2K
Original wasm size: 21.5K, Optimized: 2.6K
Original wasm size: 21.2K, Optimized: 2.3K
| @@ -249,7 +249,7 @@ fn exec_cargo_for_wasm_target( | |||
| // Currently will override user defined RUSTFLAGS from .cargo/config. See https://github.com/paritytech/cargo-contract/issues/98. | |||
| std::env::set_var( | |||
| "RUSTFLAGS", | |||
| "-C link-arg=-zstack-size=65536 -C link-arg=--import-memory", | |||
| "-C link-arg=-zstack-size=65536 -C link-arg=--import-memory -Clinker-plugin-lto", | |||
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If this just does nothing with other lto settings then should be fine.
Yea, I saw that issue(I tried to increase the stack size in one moment xDD). I think it is not part of this PR=) |
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Do I need to do something to get this PR approved? Or it is okey?=) |
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Can you confirm that with different LTO settings (via |
Yes, the compiler ignores that flag if the Without the |
Of course, hence the default. But we still want to provide the flexibility where possible. |
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Have you removed the events to get |
Nope, it is only with use-ink/ink#1017 =) |
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Ah I forgot, could you add this PR to the Unreleased section of CHANGELOG.md in a quick follow up? |
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#364 done=) |
With use-ink/ink#1016 and use-ink/ink#1017 it takes Original wasm size: 31.1K, Optimized: 8.8K(8828) |
-Clinker-plugin-ltoreduced the size of my contractFrom:
Original wasm size: 68.6K, Optimized: 31.9K
To:
Original wasm size: 67.2K, Optimized: 31.0K