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88 lines
1.8 KiB
Swift
88 lines
1.8 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift Atomics open source project
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//
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// Copyright (c) 2024 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#if arch(arm) || arch(arm64) || arch(arm64_32)
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@inline(__always)
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var _tries: Int {
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100
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}
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#if arch(arm)
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// The following are acceptable operands to the aarch64 hint intrinsic from
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// 'llvm-project/llvm/lib/Target/ARM/ARMInstrInfo.td':
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//
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// `nop` = 0
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// `yield` = 1
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// `wfe` = 2
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// `wfi` = 3
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// `sev` = 4
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// `sevl` = 5
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//
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// There are others, but for the sake of spin loops, we only care about 'wfe'.
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@_extern(c, "llvm.arm.hint")
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func _hint(_: UInt32)
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#else
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// The following are acceptable operands to the aarch64 hint intrinsic from
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// 'llvm-project/llvm/lib/Target/AArch64/AArch64InstrInfo.td':
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//
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// `nop` = 0
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// `yield` = 1
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// `wfe` = 2
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// `wfi` = 3
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// `sev` = 4
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// `sevl` = 5
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//
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// There are others, but for the sake of spin loops, we only care about 'wfe'.
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@_extern(c, "llvm.aarch64.hint")
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func _hint(_: UInt32)
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#endif
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@inline(__always)
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func _wfe() {
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_hint(2)
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}
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#elseif arch(i386) || arch(x86_64)
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@inline(__always)
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var _tries: Int {
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1000
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}
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@_extern(c, "llvm.x86.sse2.pause")
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func _pause()
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#else
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@inline(__always)
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var _tries: Int {
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100
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}
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#endif
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@inline(__always)
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func _spinLoopHint() {
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#if arch(arm) || arch(arm64) || arch(arm64_32)
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_wfe()
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#elseif arch(i386) || arch(x86_64)
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_pause()
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#else
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// Just do a nop on architectures we don't know about.
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#endif
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}
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