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[System] Use a larger limit for when to use response file #2002

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Merged
merged 1 commit into from
Oct 15, 2025
Merged

[System] Use a larger limit for when to use response file #2002

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10 changes: 4 additions & 6 deletions Sources/SwiftDriver/Utilities/System.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -62,17 +62,15 @@ func quoteArgument(_ argument: String) -> String {
#if canImport(Darwin) || os(Linux) || os(Android) || os(OpenBSD) || os(FreeBSD)
// Adapted from llvm::sys::commandLineFitsWithinSystemLimits.
func commandLineFitsWithinSystemLimits(path: String, args: [String]) -> Bool {
let upperBound = sysconf(Int32(_SC_ARG_MAX))
guard upperBound != -1 else {
let systemLimit = sysconf(Int32(_SC_ARG_MAX))
guard systemLimit != -1 else {
// The system reports no limit.
return true
}
// The lower bound for ARG_MAX on a POSIX system
let lowerBound = Int(_POSIX_ARG_MAX)
// This the same baseline used by xargs.
let baseline = 128 * 1024
let posixLimit = Int(_POSIX_ARG_MAX)

var effectiveArgMax = max(min(baseline, upperBound), lowerBound)
var effectiveArgMax = max(systemLimit, posixLimit)
// Conservatively assume environment variables consume half the space.
effectiveArgMax /= 2

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4 changes: 2 additions & 2 deletions Tests/SwiftDriverTests/SwiftDriverTests.swift
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Expand Up @@ -1766,7 +1766,7 @@ final class SwiftDriverTests: XCTestCase {
}

func testUsingResponseFiles() throws {
let manyArgs = (1...20000).map { "-DTEST_\($0)" }
let manyArgs = (1...200000).map { "-DTEST_\($0)" }
// Needs response file
do {
let source = try AbsolutePath(validating: "/foo.swift")
Expand Down Expand Up @@ -1879,7 +1879,7 @@ final class SwiftDriverTests: XCTestCase {
// The jobs below often take large command lines (e.g., when passing a large number of Clang
// modules to Swift). Ensure that they don't regress in their ability to pass response files
// from the driver to the frontend.
let manyArgs = (1...20000).map { "-DTEST_\($0)" }
let manyArgs = (1...200000).map { "-DTEST_\($0)" }

// Compile + separate emit module job
do {
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