Support importing memory in the main module in wit-component - #2599
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This commit updates the `wit-component` componentization process to support inputs where memory is imported as opposed to requiring memory to be exported. When this is the case it avoids the need for many shims in the "shim module" generated by wit-component which means that lowered functions can be directly imported into the main module. This in turn can lead to possible speedups since less indirection is necessary when going out to the host. This support is on-by-default and activated by detecting when memory is imported into the module. Actually generating a module that imports memory requires custom compiler flags, such as `-Clink-arg=--import-memory` in Rust, and this behavior continues to be off-by-default. In the meantime though my intention here is that this can provide a low-overhead opportunity to manually generate components with fewer shims when doing performance analysis. Internal refactorings as part of this commit revealed a preexisting issue with tests related to the `link` command where a library expected to be able to import another library's WIT functions. This only worked in some situations however, such as when strings weren't present, so the tests were updated to have the right WIT available at all times.
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This commit updates the
wit-componentcomponentization process tosupport inputs where memory is imported as opposed to requiring memory
to be exported. When this is the case it avoids the need for many shims
in the "shim module" generated by wit-component which means that lowered
functions can be directly imported into the main module. This in turn
can lead to possible speedups since less indirection is necessary when
going out to the host.
This support is on-by-default and activated by detecting when memory is
imported into the module. Actually generating a module that imports
memory requires custom compiler flags, such as
-Clink-arg=--import-memoryin Rust, and this behavior continues to beoff-by-default. In the meantime though my intention here is that this
can provide a low-overhead opportunity to manually generate components
with fewer shims when doing performance analysis.
Internal refactorings as part of this commit revealed a preexisting
issue with tests related to the
linkcommand where a library expectedto be able to import another library's WIT functions. This only worked
in some situations however, such as when strings weren't present, so the
tests were updated to have the right WIT available at all times.