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Wasm: bump default stack size to 128K #2026

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Merged
merged 1 commit into from
Nov 21, 2025
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Merged

Wasm: bump default stack size to 128K #2026

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6 changes: 6 additions & 0 deletions Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -166,6 +166,12 @@ extension WebAssemblyToolchain {
commandLine.appendFlag(.Xlinker)
commandLine.appendFlag("--table-base=\(SWIFT_ABI_WASM32_LEAST_VALID_POINTER)")

// Set slightly higher than the default (64K) stack size so that basic
// workflows like Swift Testing can run within this limited stack space.
let SWIFT_WASM_DEFAULT_STACK_SIZE = 1024 * 128
commandLine.appendFlag(.Xlinker)
commandLine.appendFlag("--stack-size=\(SWIFT_WASM_DEFAULT_STACK_SIZE)")

// Delegate to Clang for sanitizers. It will figure out the correct linker
// options.
if linkerOutputType == .executable && !sanitizers.isEmpty {
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1 change: 1 addition & 0 deletions Tests/SwiftDriverTests/SwiftDriverTests.swift
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Expand Up @@ -2766,6 +2766,7 @@ final class SwiftDriverTests: XCTestCase {
XCTAssertTrue(cmd.contains(.responseFilePath(.absolute(path.appending(components: "wasi", "static-executable-args.lnk")))))
XCTAssertTrue(cmd.contains(subsequence: [.flag("-Xlinker"), .flag("--global-base=4096")]))
XCTAssertTrue(cmd.contains(subsequence: [.flag("-Xlinker"), .flag("--table-base=4096")]))
XCTAssertTrue(cmd.contains(subsequence: [.flag("-Xlinker"), .flag("--stack-size=\(128 * 1024)")]))
XCTAssertTrue(cmd.contains(.flag("-O3")))
XCTAssertEqual(linkJob.outputs[0].file, try toPath("Test"))

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