cs := "你好世界, hello world. 你好世界, hello world. 你好世界, hello world."
	for k := 1; k <= 2048; k <<= 4 {
		for j := 1; j <= 64; j <<= 1 {
			b.Run(fmt.Sprintf("%d:%d", k, j), func(b *testing.B) {
				for i := 0; i < b.N; i++ {
					LastIndexAny(x[:k], cs[:j])
				}
			})
		}
	}
}

func BenchmarkTrimASCII(b *testing.B) {
	cs := "0123456789abcdef"
	for k := 1; k <= 4096; k <<= 4 {

	// #include <stdlib.h>
	//
	// static void myprint(char* s) {
	//   printf("%s\n", s);
	// }
	import "C"
	import "unsafe"

	func main() {
		cs := C.CString("Hello from stdio")
		C.myprint(cs)
		C.free(unsafe.Pointer(cs))
	}

A few special functions convert between Go and C types
by making copies of the data. In pseudo-Go definitions:

	// Go string to C string

	"S":  arm.C_SBIT,
	"W":  arm.C_WBIT,
	"P":  arm.C_PBIT,
	"PW": arm.C_WBIT | arm.C_PBIT,
	"WP": arm.C_WBIT | arm.C_PBIT,
}

var armSCOND = map[string]uint8{
	"EQ":  arm.C_SCOND_EQ,
	"NE":  arm.C_SCOND_NE,
	"CS":  arm.C_SCOND_HS,
	"HS":  arm.C_SCOND_HS,
	"CC":  arm.C_SCOND_LO,
	"LO":  arm.C_SCOND_LO,
	"MI":  arm.C_SCOND_MI,
	"PL":  arm.C_SCOND_PL,
	"VS":  arm.C_SCOND_VS,
	"VC":  arm.C_SCOND_VC,
	"HI":  arm.C_SCOND_HI,

			arm64SpecialOperand[opd.String()] = opd
		}

		// Handle some special cases.
		specialMapping := map[string]arm64.SpecialOperand{
			// The internal representation of CS(CC) and HS(LO) are the same.
			"CS": arm64.SPOP_HS,
			"CC": arm64.SPOP_LO,
		}
		for s, opd := range specialMapping {
			arm64SpecialOperand[s] = opd
		}
	}
	if opd, ok := arm64SpecialOperand[name]; ok {
		return opd
	}