[WASM] Implement thin-to-thick semantic for WebAssembly #186
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Resolve #30
This IRGen change enables us to call
thin-to-thick
ed functions safely on WebAssembly runtime.For example, the following SIL uses
thin_to_thick_function
instruction to transform thin function (which means there is no context argument in the last of arguments list) to thick function.On x86_64 architecture, that SIL is transformed into the following LLVM IR
On x86_64, the trailing
swiftself
is put inr13
register, so it's OK that there is a difference of trailingswiftself
parameter between callee and calling signature.But this IR is invalid on WebAssembly because WebAssembly runtime validation spec requires they should be same signature when calling function indirectly.
So I changed to emit a thunk function to match these function signatures like the following LLVM IR.
$s16closureToConvertTu
just proxy forwards the invocation to actual function which is come from trailing context pointer.This change makes some failing test cases with optimization passed without indirect function call error.