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feat: Linker #87

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@george-cosma george-cosma commented Sep 19, 2024

Pull Request Overview

This pull request adds a "Lookup table" linker. See #83 first.

Basically, after each time a new module is added we attempt to create a "lookup table". This lookup table translate the imported functions from each module to the exported local function in the already-existing modules.

Resumability is kept by passing all module-specific details (like the wasm binary, the readers, function types, store, etc.) to the interpreter_loop::run function. These details have been compiled into a structure called ExecutionInfo.

Also of note, I split the "FunctionInstance" structure into two variants - local and imported, for clarity sake. This comes with the needed modification to the validation process and store-creation process.

Testing Strategy

This pull request was tested by writing a new test, and tested against the existing tests.

Formatting

  • Ran cargo fmt
  • Ran cargo check
  • Ran cargo build
  • Ran cargo doc
  • Ran nix fmt

Github Issue

This pull request closes #83

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george-cosma commented Sep 24, 2024

Blocked on #88

@george-cosma george-cosma force-pushed the dev/george-linker branch 3 times, most recently from 737c1a5 to 9e29849 Compare September 26, 2024 13:24
@george-cosma george-cosma marked this pull request as ready for review September 26, 2024 13:27
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codecov bot commented Sep 26, 2024

Codecov Report

Attention: Patch coverage is 90.76087% with 34 lines in your changes missing coverage. Please review.

Files with missing lines Patch % Lines
src/execution/interpreter_loop.rs 91.20% 11 Missing ⚠️
src/execution/mod.rs 90.75% 3 Missing and 8 partials ⚠️
src/validation/mod.rs 81.57% 7 Missing ⚠️
src/execution/lut.rs 94.00% 2 Missing and 1 partial ⚠️
src/core/error.rs 0.00% 2 Missing ⚠️
Files with missing lines Coverage Δ
src/execution/execution_info.rs 100.00% <100.00%> (ø)
src/execution/store.rs 76.66% <100.00%> (+23.33%) ⬆️
src/execution/value_stack.rs 78.78% <100.00%> (+0.66%) ⬆️
src/validation/code.rs 71.42% <100.00%> (-1.07%) ⬇️
src/core/error.rs 30.88% <0.00%> (-5.49%) ⬇️
src/execution/lut.rs 94.00% <94.00%> (ø)
src/validation/mod.rs 76.51% <81.57%> (+0.23%) ⬆️
src/execution/interpreter_loop.rs 96.58% <91.20%> (-0.47%) ⬇️
src/execution/mod.rs 93.60% <90.75%> (+2.37%) ⬆️

Comment on lines +33 to +42
// TODO: what do we want to do if there is a missing import/export pair? Currently we fail the entire
// operation. Should it be a RuntimeError if said missing pair is called?
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As per internal discussion, "better safe than sorry"

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// TODO: how do we handle the start function, if we don't have a LUT yet?
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If a module has a start function, this function will error out if we attempt to run "start" if there are any unmet imports, even if they are not used in "start" itself.

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Running an example where we have an import and it's not met in wasm-interp leads to the same error: invalid import. I think this is the safe way to go about it.
(wasm-interp actually errors out even if we don't run any of the code:

(module
  (import "console" "log" (func $log (param i32)))
  (func $dummy
    i32.const 0
    drop 
  )
;;   (start $dummy)
)

)

src/execution/mod.rs Outdated Show resolved Hide resolved
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Signed-off-by: George Cosma <[email protected]>
@@ -288,20 +357,30 @@ where
let (module_idx, func_idx) =
self.get_indicies(&function_ref.module_name, &function_ref.function_name)?;

if module_idx != function_ref.module_index || func_idx != function_ref.function_index {
// TODO: should we return a different error here?
if module_idx != function_ref.module_index {
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Maybe just one if statement here with both conditions combined?

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The reason I wanted to split them off was to be able to discern which reference is wrong - the module or the function. This was done to conform to the two errors: ModuleNotFound and FunctionNotFound. However, it would also be valid to say there should be a 3rd error type to indicate a stale or incorrect reference

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I see, that makes sense. I also agree on the 3rd error type for an incorrect reference.

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The never-ending Linker problem
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