Add option to enable pulley support for pre-compilation and runtime of modules and components by dblnz · Pull Request #358 · hyperlight-dev/hyperlight-wasm

dblnz · 2026-02-04T13:58:11Z

This PR adds an option to enable pulley interpreter instead of the default cranelift for wasmtime.

To use pulley one needs to:

Precompile the module/component for pulley64 target. It can be done using hyperlight-wasm-aot compile --pulley command
Enable the pulley feature for hyperlight-wasm to build the wasm_runtime with pulley feature that correctly sets the config.target("pulley64") for the Config passed to the wasmtime Engine .

Copilot

Pull request overview

This PR adds support for the Pulley interpreter as an alternative to Cranelift for WebAssembly compilation and execution in Hyperlight. Pulley is an interpreted execution mode for WebAssembly that can be enabled at both AOT compilation time and runtime.

Changes:

Added --pulley flag to the AOT compilation tool to target the pulley64 architecture
Added pulley feature flag to enable pulley runtime support in the wasm_runtime and hyperlight_wasm crates
Added Justfile recipes to build and test modules/components with pulley support

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/wasm_runtime/src/module.rs	Configures wasmtime engine to use pulley64 target when pulley feature is enabled
src/wasm_runtime/src/component.rs	Configures wasmtime engine to use pulley64 target when pulley feature is enabled for component model
src/wasm_runtime/build.rs	Adds cfg alias for pulley feature flag
src/wasm_runtime/Cargo.toml	Adds pulley feature that enables wasmtime's pulley support
src/hyperlight_wasm_aot/src/main.rs	Adds --pulley command-line flag and logic to compile for pulley64 target
src/hyperlight_wasm_aot/Cargo.toml	Unconditionally enables pulley feature in wasmtime since AOT tool needs both targets
src/hyperlight_wasm/build.rs	Propagates pulley feature flag to wasm_runtime build
src/hyperlight_wasm/Cargo.toml	Adds pulley feature flag
Justfile	Adds recipes to build and test pulley-compiled modules and components

Comments suppressed due to low confidence (1)

src/hyperlight_wasm_aot/src/main.rs:194

When compiling for the pulley target with debug enabled, the code still calls config.cranelift_opt_level(OptLevel::None). Since pulley is an interpreter that doesn't use Cranelift, this setting may be ignored or could potentially cause issues. Consider wrapping Cranelift-specific configuration in a conditional check to only apply when not using pulley (e.g., if !pulley { config.cranelift_opt_level(OptLevel::None); }).

    if debug {
        config.debug_info(true);
        config.cranelift_opt_level(OptLevel::None);

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src/wasm_runtime/src/module.rs

src/wasm_runtime/src/component.rs

src/hyperlight_wasm_aot/src/main.rs

Justfile

Signed-off-by: Doru Blânzeanu <dblnz@pm.me>

simongdavies

one small comment about version checking

simongdavies · 2026-02-04T15:41:53Z

src/hyperlight_wasm_aot/src/main.rs

            // load the file into wasmtime, check that it is aot compiled and extract the version of wasmtime used to compile it from its metadata
            let bytes = std::fs::read(&file).unwrap();
-            let config = get_config(debug, false);
+            let config = get_config(debug, false, false);


I think this means that the version number check does not work with pulley compiled files, not sure if this is what we want? Wonder if we can detect the type by parsing the file?

I added a --pulley option for check-wasmtime-version command.
There isn't an intended way to use the Engine to verify whether the file is targeted for Pulley or not.
We could parse the files, but it doesn't look good 😄
If you really think that is something we should do, I can open up an issue and take that on at a later time

I think it would be nice to have but since its not immediately available that's probably find. I would assume wasmtime checks this somewhere when running so at the very least the user would get an error when trying to run the wrongly compiled version?

We could parse the files, but it doesn't look good 😄

It looks like it is very simple to check, as it's just the elf header: e_machine == ET_RISCV and e_flags contains wasmtime_environ::obj::EF_WASMTIME_PULLEY64. Apparently other crates like wasmtime-objdump also check this, so I imagine it's safe to use.

src/hyperlight_wasm_aot/src/main.rs

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

src/hyperlight_wasm_aot/src/main.rs:202

When compiling for pulley64 target with debug enabled, the code sets cranelift_opt_level(OptLevel::None) which is specific to the Cranelift compiler. This may cause unexpected behavior or errors when using the pulley interpreter. Consider conditionally applying this setting only when not using pulley, or verify that this setting is safely ignored by pulley.

    if debug {
        config.debug_info(true);
        config.cranelift_opt_level(OptLevel::None);

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Copilot · 2026-02-04T16:53:05Z

src/wasm_runtime/src/component.rs

+        .map_err(|_| {
+            HyperlightGuestError::new(
+                ErrorCode::GuestError,
+                "Failed to set wasmtime target: pulley64".to_string(),
+            )
+        })
+        .unwrap();


The map_err followed by .unwrap() is redundant. Since this function doesn't return a Result, the custom error created by map_err will never be used. Consider either removing the map_err and keeping just .unwrap() to match the pattern on line 124, or provide a more descriptive panic message using .expect("Failed to set wasmtime target: pulley64").

Suggested change

.map_err(|_| {

HyperlightGuestError::new(

ErrorCode::GuestError,

"Failed to set wasmtime target: pulley64".to_string(),

)

})

.unwrap();

.expect("Failed to set wasmtime target: pulley64");

Copilot · 2026-02-04T16:53:06Z

Justfile

+build-pulley-rust-wasm-examples target=default-target features="": (mkdir-redist target)
+    rustup target add wasm32-unknown-unknown
+    cd ./src/rust_wasm_samples && cargo build --target wasm32-unknown-unknown --profile={{ if target == "debug" {"dev"} else { target } }}
+    cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} ./src/rust_wasm_samples/target/wasm32-unknown-unknown/{{ target }}/rust_wasm_samples.wasm ./x64/{{ target }}/rust_wasm_samples.aot


The pulley-compiled binaries write to the same output path as the regular cranelift-compiled binaries (e.g., ./x64/{{ target }}/rust_wasm_samples.aot). This means running build-pulley-rust-wasm-examples will overwrite the output from build-rust-wasm-examples. Consider using distinct output paths (e.g., ./x64/{{ target }}/pulley/rust_wasm_samples.aot) to avoid accidental overwrites and allow both versions to coexist.

Copilot · 2026-02-04T16:53:06Z

Justfile

+    # we also explicitly target wasm32-unknown-unknown since cargo component might try to pull in wasi imports https://github.com/bytecodealliance/cargo-component/issues/290
+    rustup target add wasm32-unknown-unknown
+    cd ./src/component_sample && cargo component build --target wasm32-unknown-unknown --profile={{ if target == "debug" {"dev"} else { target } }}
+    cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} --component ./src/component_sample/target/wasm32-unknown-unknown/{{ target }}/component_sample.wasm ./x64/{{ target }}/component_sample.aot


The pulley-compiled component writes to the same output path as the regular cranelift-compiled component (./x64/{{ target }}/component_sample.aot). This means running build-pulley-rust-component-examples will overwrite the output from build-rust-component-examples. Consider using distinct output paths (e.g., ./x64/{{ target }}/pulley/component_sample.aot) to avoid accidental overwrites and allow both versions to coexist.

Suggested change

cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} --component ./src/component_sample/target/wasm32-unknown-unknown/{{ target }}/component_sample.wasm ./x64/{{ target }}/component_sample.aot

mkdir {{ mkdir-arg }} x64/{{ target }}/pulley

cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} --component ./src/component_sample/target/wasm32-unknown-unknown/{{ target }}/component_sample.wasm ./x64/{{ target }}/pulley/component_sample.aot

dblnz added the kind/enhancement New feature or request label Feb 4, 2026

andreiltd previously approved these changes Feb 4, 2026

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simongdavies requested a review from Copilot February 4, 2026 15:30

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dblnz added 2 commits February 4, 2026 17:51

Add option to build and run pulley pre-compiled modules or components

020de16

Signed-off-by: Doru Blânzeanu <dblnz@pm.me>

Add some tests for pulley on CI

51d839b

Signed-off-by: Doru Blânzeanu <dblnz@pm.me>

simongdavies previously approved these changes Feb 4, 2026

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dblnz dismissed stale reviews from simongdavies and andreiltd via 51d839b February 4, 2026 15:58

dblnz force-pushed the pulley-support branch from 82eb985 to 51d839b Compare February 4, 2026 15:58

dblnz requested a review from Copilot February 4, 2026 16:40

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Add option to enable pulley support for pre-compilation and runtime of modules and components#358

Add option to enable pulley support for pre-compilation and runtime of modules and components#358
dblnz wants to merge 2 commits intohyperlight-dev:mainfrom
dblnz:pulley-support

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	cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} --component ./src/component_sample/target/wasm32-unknown-unknown/{{ target }}/component_sample.wasm ./x64/{{ target }}/component_sample.aot
	mkdir {{ mkdir-arg }} x64/{{ target }}/pulley
	cargo run {{ if features =="" {''} else if features=="no-default-features" {"--no-default-features" } else {"--features " + features } }} -p hyperlight-wasm-aot compile --pulley {{ if features =~ "gdb" {"--debug"} else {""} }} --component ./src/component_sample/target/wasm32-unknown-unknown/{{ target }}/component_sample.wasm ./x64/{{ target }}/pulley/component_sample.aot

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