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Doug Gregor
736efe4bfa
When the embedded stdlib's target triple matches the new
SWIFT_EMBEDDED_INTERFACE_LTO_TRIPLE_REGEX (empty by default), build it
under `CodeGenerationModel=interface` with LLVM LTO. The resulting
`libswiftCore.a` contains real bitcode rather than the empty stubs
produced for the default Inlinable model, so clients reference its
strong external definitions instead of re-emitting `linkonce_odr`
copies of every stdlib function. C/C++ sources in the embedded
libraries are compiled with `-flto=` to match, so the linker sees a
coherent set of bitcode inputs.
Compiler:
`SILFunction::hasValidLinkageForFragileRef` accepts
`isNeverEmitIntoClient()` callees so a serialized caller in another
module can reference an interface-mode body in libswiftCore.a by
name. The linker resolves the call to the owning module's
definition.
Stdlib:
Promote `writeChars` (the embedded stdout helper used by
`EmbeddedPrint`'s `print` overloads and `_Stdout.write`) to
`@usableFromInline internal` so the SIL Linker can pull the body
into generic specializations like `print<Int>` emitted into client
code.
Test infrastructure:
* `SWIFT_EMBEDDED_INTERFACE_LTO_TRIPLE_REGEX` is plumbed into lit via
`lit.site.cfg.in`; `test/lit.cfg` derives the
`embedded_stdlib_default_codegen` / `embedded_stdlib_interface_lto`
feature globally so any test can `REQUIRES:`, `UNSUPPORTED:`, or
`%if` against it.
* Tests that verify default-mode contract (`dependencies-*`,
`exclusivity_runtime`, `throw-trap-stdlib`,
`concurrency-non-symbols`, `concurrency-deleted-method`) now
`REQUIRES: embedded_stdlib_default_codegen`.
* `SILOptimizer/devirt_deinits.swift` gates its embedded RUN line
with `%if embedded_stdlib_default_codegen %{ ... %}` because that
line doesn't link against `libswiftCore.a`.
* Add an interface-mode RUN line to `extern_c_body_in_other_module`
and a new `extern_c_thunk_no_interface_model` test covering
interface-mode-specific behavior around `@_extern(c)` and
`@_silgen_name` thunks.