Move closure shims into the descriptor #1065
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Currently closure shims are communicated to JS at runtime, although at runtime the same constant value is always passed to JS! More pressing, however, work in rustwasm#1002 requires knowledge of closure descriptor indices at `wasm-bindgen` time which is not currently known. Since the closure descriptor shims and such are already constant values, this commit moves the descriptor function indices into the *descriptor* for a closure/function pointer. This way we can learn about these values at `wasm-bindgen` time instead of only knowing them at runtime. This should have no semantic change on users of `wasm-bindgen`, although some closure invocations may be slightly speedier because there's less arguments being transferred over the boundary. Overall though this will help rustwasm#1002 as the closure shims that the Rust compiler generates may not be the exact ones we hand out to JS, but rather wrappers around them which do `anyref` business things.
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fitzgen
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Nov 29, 2018
| } else { | ||
| // ... otherwise we're injecting a number of new imports, so offset | ||
| // everything. | ||
| idx + info.code_idx_to_descriptor.len() as u32 |
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This particular change is just code motion / reformatting, right?
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Ah yes indeed!
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Currently closure shims are communicated to JS at runtime, although at
runtime the same constant value is always passed to JS! More pressing,
however, work in #1002 requires knowledge of closure descriptor indices
at
wasm-bindgentime which is not currently known.Since the closure descriptor shims and such are already constant values,
this commit moves the descriptor function indices into the descriptor
for a closure/function pointer. This way we can learn about these values
at
wasm-bindgentime instead of only knowing them at runtime.This should have no semantic change on users of
wasm-bindgen, althoughsome closure invocations may be slightly speedier because there's less
arguments being transferred over the boundary. Overall though this will
help #1002 as the closure shims that the Rust compiler generates may not
be the exact ones we hand out to JS, but rather wrappers around them
which do
anyrefbusiness things.