`Synchronization.Mutex` fails to JIT-link TLS primitives in Immediate mode on Linux

[kateinoigakukun]

Description

The use of TLS in Mutex implementation on Linux seems to break LLVM's JIT linker?

swift/stdlib/public/Synchronization/Mutex/LinuxImpl.swift

Line 68 in 8c9f291

let selfId = _swift_stdlib_gettid()

Reproduction

import Synchronization

func takeMutex(_ m: borrowing Mutex<Int>) {
    m.withLock { $0 = 0 }
}

And execute it in the immediate mode

$ swift check.swift

Stack dump

# On x86_64 Linux
JIT session error: In check-jitted-objectbuffer: Unsupported x86-64 relocation type R_X86_64_TLSLD
Failed to materialize symbols: { (main, { $s5check9takeMutexyy15Synchronization0C0VySiGF, $s15Synchronization5MutexVAARi_zrlE8withLockyqd__qd__xzYuqd_0_YKYTXEqd_0_YKs5ErrorRd_0_Ri_d__r0_lF6$deferL_yysAERd_0_Ri_zRi_d__r_0_lF, main }) }

# On aarch64 Linux
JIT session error: Symbols not found: [ __tlsdesc_resolver, __aarch64_cas4_acq, __aarch64_cas4_rel ]
Failed to materialize symbols: { (main, { main, $s4main9takeMutexyy15Synchronization0C0VySiGF, $s15Synchronization5MutexVAARi_zrlE8withLockyqd__qd__xzYuqd_0_YKYTXEqd_0_YKs5ErrorRd_0_Ri_d__r0_lF6$deferL_yysAERd_0_Ri_zRi_d__r_0_lF }) }

Expected behavior

Successfully link and execute

Environment

swift-DEVELOPMENT-SNAPSHOT-2025-09-23-a

Additional information

No response