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Enable --gc-sections for WebAssembly targets #7356

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Merged
merged 2 commits into from
Feb 21, 2024
Merged

Enable --gc-sections for WebAssembly targets #7356

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cb9faa8
Enable `--gc-sections` for WebAssembly targets
kateinoigakukun Feb 21, 2024
17dc065
Add test case for linker dead stripping with release configuration
kateinoigakukun Feb 21, 2024
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9 changes: 0 additions & 9 deletions Sources/Build/BuildDescription/ProductBuildDescription.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -122,15 +122,6 @@ public final class ProductBuildDescription: SPMBuildCore.ProductBuildDescription
return ["-Xlinker", "-dead_strip"]
} else if triple.isWindows() {
return ["-Xlinker", "/OPT:REF"]
} else if triple.arch == .wasm32 {
// FIXME: wasm-ld strips data segments referenced through __start/__stop symbols
// during GC, and it removes Swift metadata sections like swift5_protocols
// We should add support of SHF_GNU_RETAIN-like flag for __attribute__((retain))
// to LLVM and wasm-ld
// This workaround is required for not only WASI but also all WebAssembly triples
// using wasm-ld (e.g. wasm32-unknown-unknown). So this branch is conditioned by
// arch == .wasm32
return []
} else {
return ["-Xlinker", "--gc-sections"]
}
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33 changes: 33 additions & 0 deletions Tests/BuildTests/CrossCompilationBuildPlanTests.swift
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Expand Up @@ -70,6 +70,39 @@ final class CrossCompilationBuildPlanTests: XCTestCase {
)
}

func testWasmTargetRelease() throws {
let pkgPath = AbsolutePath("/Pkg")

let (graph, fs, observabilityScope) = try trivialPackageGraph(pkgRootPath: pkgPath)

var parameters = mockBuildParameters(
config: .release, targetTriple: .wasi, linkerDeadStrip: true
)
parameters.linkingParameters.shouldLinkStaticSwiftStdlib = true
let result = try BuildPlanResult(plan: BuildPlan(
buildParameters: parameters,
graph: graph,
fileSystem: fs,
observabilityScope: observabilityScope
))
let buildPath = result.plan.productsBuildPath

let appBuildDescription = try result.buildProduct(for: "app")
XCTAssertEqual(
try appBuildDescription.linkArguments(),
[
result.plan.destinationBuildParameters.toolchain.swiftCompilerPath.pathString,
"-L", buildPath.pathString,
"-o", buildPath.appending(components: "app.wasm").pathString,
"-module-name", "app", "-static-stdlib", "-emit-executable",
"-Xlinker", "--gc-sections",
"@\(buildPath.appending(components: "app.product", "Objects.LinkFileList"))",
"-target", "wasm32-unknown-wasi",
"-g",
]
)
}

func testWASITarget() throws {
let pkgPath = AbsolutePath("/Pkg")

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