_SIGFPE:     {_SigPanic + _SigUnblock, "SIGFPE: floating-point exception"},
	_SIGKILL:    {0, "SIGKILL: kill"},
	_SIGUSR1:    {_SigNotify, "SIGUSR1: user-defined signal 1"},
	_SIGSEGV:    {_SigPanic + _SigUnblock, "SIGSEGV: segmentation violation"},
	_SIGUSR2:    {_SigNotify, "SIGUSR2: user-defined signal 2"},
	_SIGPIPE:    {_SigNotify, "SIGPIPE: write to broken pipe"},
	_SIGALRM:    {_SigNotify, "SIGALRM: alarm clock"},

	SIGABRT   = Signal(3)
	SIGILL    = Signal(4)
	SIGPOLL   = Signal(5)
	SIGURG    = Signal(6)
	SIGSTOP   = Signal(7)
	SIGFPE    = Signal(8)
	SIGKILL   = Signal(9)
	SIGBUS    = Signal(10)
	SIGSEGV   = Signal(11)
	SIGSYS    = Signal(12)
	SIGPIPE   = Signal(13)
	SIGALRM   = Signal(14)
	SIGTERM   = Signal(15)
	SIGUSR1   = Signal(16)
	SIGUSR2   = Signal(17)
	SIGABND   = Signal(18)

	SIGPWR      = syscall.Signal(0x1d)
	SIGQUIT     = syscall.Signal(0x3)
	SIGRECONFIG = syscall.Signal(0x3a)
	SIGRETRACT  = syscall.Signal(0x3d)
	SIGSAK      = syscall.Signal(0x3f)
	SIGSEGV     = syscall.Signal(0xb)
	SIGSOUND    = syscall.Signal(0x3e)
	SIGSTOP     = syscall.Signal(0x11)
	SIGSYS      = syscall.Signal(0xc)
	SIGSYSERROR = syscall.Signal(0x30)
	SIGTALRM    = syscall.Signal(0x26)

//
// This should agree with minLegalPointer in the runtime.
const minZeroPage = 4096

// faultOnLoad is true if a load to an address below minZeroPage will trigger a SIGSEGV.
var faultOnLoad = buildcfg.GOOS != "aix"

// nilcheckelim2 eliminates unnecessary nil checks.
// Runs after lowering and scheduling.
func nilcheckelim2(f *Func) {

	SIGLWP     = syscall.Signal(0x21)
	SIGPIPE    = syscall.Signal(0xd)
	SIGPOLL    = syscall.Signal(0x16)
	SIGPROF    = syscall.Signal(0x1d)
	SIGPWR     = syscall.Signal(0x13)
	SIGQUIT    = syscall.Signal(0x3)
	SIGSEGV    = syscall.Signal(0xb)
	SIGSTOP    = syscall.Signal(0x17)
	SIGSYS     = syscall.Signal(0xc)
	SIGTERM    = syscall.Signal(0xf)
	SIGTHAW    = syscall.Signal(0x23)
	SIGTRAP    = syscall.Signal(0x5)

	SIGPWR      = syscall.Signal(0x1d)
	SIGQUIT     = syscall.Signal(0x3)
	SIGRECONFIG = syscall.Signal(0x3a)
	SIGRETRACT  = syscall.Signal(0x3d)
	SIGSAK      = syscall.Signal(0x3f)
	SIGSEGV     = syscall.Signal(0xb)
	SIGSOUND    = syscall.Signal(0x3e)
	SIGSTOP     = syscall.Signal(0x11)
	SIGSYS      = syscall.Signal(0xc)
	SIGSYSERROR = syscall.Signal(0x30)
	SIGTALRM    = syscall.Signal(0x26)

	SIGIOT      = syscall.Signal(0x6)
	SIGKILL     = syscall.Signal(0x9)
	SIGPIPE     = syscall.Signal(0xd)
	SIGPROF     = syscall.Signal(0x1b)
	SIGQUIT     = syscall.Signal(0x3)
	SIGSEGV     = syscall.Signal(0xb)
	SIGSTOP     = syscall.Signal(0x11)
	SIGSYS      = syscall.Signal(0xc)
	SIGTERM     = syscall.Signal(0xf)
	SIGTHR      = syscall.Signal(0x20)
	SIGTRAP     = syscall.Signal(0x5)

	GO_ARGS
	JMP	sync∕atomic·CompareAndSwapInt64(SB)

// Generic atomic operation implementation.
// AX already contains target function.
TEXT	racecallatomic<>(SB), NOSPLIT|NOFRAME, $0-0
	// Trigger SIGSEGV early.
	MOVQ	16(SP), R12
	MOVBLZX	(R12), R13
	// Check that addr is within [arenastart, arenaend) or within [racedatastart, racedataend).
	CMPQ	R12, runtime·racearenastart(SB)
	JB	racecallatomic_data

	SIGIO     = syscall.Signal(0x17)
	SIGIOT    = syscall.Signal(0x6)
	SIGKILL   = syscall.Signal(0x9)
	SIGPIPE   = syscall.Signal(0xd)
	SIGPROF   = syscall.Signal(0x1b)
	SIGQUIT   = syscall.Signal(0x3)
	SIGSEGV   = syscall.Signal(0xb)
	SIGSTOP   = syscall.Signal(0x11)
	SIGSYS    = syscall.Signal(0xc)
	SIGTERM   = syscall.Signal(0xf)
	SIGTHR    = syscall.Signal(0x20)
	SIGTRAP   = syscall.Signal(0x5)

	SIGIO     = syscall.Signal(0x17)
	SIGIOT    = syscall.Signal(0x6)
	SIGKILL   = syscall.Signal(0x9)
	SIGPIPE   = syscall.Signal(0xd)
	SIGPROF   = syscall.Signal(0x1b)
	SIGQUIT   = syscall.Signal(0x3)
	SIGSEGV   = syscall.Signal(0xb)
	SIGSTOP   = syscall.Signal(0x11)
	SIGSYS    = syscall.Signal(0xc)
	SIGTERM   = syscall.Signal(0xf)
	SIGTHR    = syscall.Signal(0x20)
	SIGTRAP   = syscall.Signal(0x5)