[GODEBUG:*]
	GODEBUG contains <suffix>
[GOEXPERIMENT:*]
	GOEXPERIMENT <suffix> is enabled
[GOOS:*]
	runtime.GOOS == <suffix>
[abscc]
	default $CC path is absolute and exists
[asan]
	GOOS/GOARCH supports -asan
[buildmode:*]
	go supports -buildmode=<suffix>
[case-sensitive]
	$WORK filesystem is case-sensitive
[cc:*]
	go env CC = <suffix> (ignoring the go/env file)
[cgo]
	host CGO_ENABLED

	flagDumpDep       = flag.Bool("dumpdep", false, "dump symbol dependency graph")
	flagRace          = flag.Bool("race", false, "enable race detector")
	flagMsan          = flag.Bool("msan", false, "enable MSan interface")
	flagAsan          = flag.Bool("asan", false, "enable ASan interface")
	flagAslr          = flag.Bool("aslr", true, "enable ASLR for buildmode=c-shared on windows")

	flagFieldTrack = flag.String("k", "", "set field tracking `symbol`")

	if race.Enabled {
		if *done > 0 {
			race.WriteRange(unsafe.Pointer(&p[0]), int(*done))
		}
		race.Acquire(unsafe.Pointer(&ioSync))
	}
	if msan.Enabled && *done > 0 {
		msan.Write(unsafe.Pointer(&p[0]), uintptr(*done))
	}
	if asan.Enabled && *done > 0 {
		asan.Write(unsafe.Pointer(&p[0]), uintptr(*done))
	}
	return err
}

func WriteFile(fd Handle, p []byte, done *uint32, overlapped *Overlapped) error {

		"run only those tests matching the regular expression; empty means to run all. "+
			"Special exception: if the string begins with '!', the match is inverted.")
	flag.BoolVar(&t.msan, "msan", false, "run in memory sanitizer builder mode")
	flag.BoolVar(&t.asan, "asan", false, "run in address sanitizer builder mode")
	flag.BoolVar(&t.json, "json", false, "report test results in JSON")

	xflagparse(-1) // any number of args
	if noRebuild {

	< runtime/internal/sys
	< internal/runtime/syscall
	< internal/runtime/atomic
	< internal/runtime/exithook
	< runtime/internal/math
	< runtime
	< sync/atomic
	< internal/race
	< internal/msan
	< internal/asan
	< internal/weak
	< sync
	< internal/bisect
	< internal/godebug
	< internal/reflectlite
	< errors
	< internal/oserror;

	cmp, internal/race, math/bits
	< iter
	< maps, slices;

		linux/ppc64le and linux/arm64 (only for 48-bit VMA).
	-msan
		enable interoperation with memory sanitizer.
		Supported only on linux/amd64, linux/arm64, linux/loong64, freebsd/amd64
		and only with Clang/LLVM as the host C compiler.
		PIE build mode will be used on all platforms except linux/amd64.
	-asan
		enable interoperation with address sanitizer.

	BuildModReason     string                  // reason -mod was set, if set by default
	BuildLinkshared    bool                    // -linkshared flag
	BuildMSan          bool                    // -msan flag
	BuildASan          bool                    // -asan flag
	BuildCover         bool                    // -cover flag
	BuildCoverMode     string                  // -covermode flag
	BuildCoverPkg      []string                // -coverpkg flag

	if cfg.BuildRace {
		deps = append(deps, "runtime/race")
	}
	// Using memory sanitizer forces an import of runtime/msan.
	if cfg.BuildMSan {
		deps = append(deps, "runtime/msan")
	}
	// Using address sanitizer forces an import of runtime/asan.
	if cfg.BuildASan {
		deps = append(deps, "runtime/asan")
	}
	// Building for coverage forces an import of runtime/coverage.

		suffixsep = "_"
		suffix = *flagInstallSuffix
	} else if *flagRace {
		suffixsep = "_"
		suffix = "race"
	} else if *flagMsan {
		suffixsep = "_"
		suffix = "msan"
	} else if *flagAsan {
		suffixsep = "_"
		suffix = "asan"
	}

	if buildcfg.GOROOT != "" {
		Lflag(ctxt, filepath.Join(buildcfg.GOROOT, "pkg", fmt.Sprintf("%s_%s%s%s", buildcfg.GOOS, buildcfg.GOARCH, suffixsep, suffix)))
	}

	They are implemented by computing the arctangent
	after appropriate range reduction.
*/

// Asin returns the arcsine, in radians, of x.
//
// Special cases are:
//
//	Asin(±0) = ±0
//	Asin(x) = NaN if x < -1 or x > 1
func Asin(x float64) float64 {
	if haveArchAsin {
		return archAsin(x)
	}
	return asin(x)
}

func asin(x float64) float64 {
	if x == 0 {
		return x // special case
	}
	sign := false