((NE|EQ) (TESTL (SHLL (MOVLconst [1]) x) y)) => ((ULT|UGE) (BTL x y))
((NE|EQ) (TESTQ (SHLQ (MOVQconst [1]) x) y)) => ((ULT|UGE) (BTQ x y))
((NE|EQ) (TESTLconst [c] x)) && isUint32PowerOfTwo(int64(c))
    => ((ULT|UGE) (BTLconst [int8(log32(c))] x))
((NE|EQ) (TESTQconst [c] x)) && isUint64PowerOfTwo(int64(c))
    => ((ULT|UGE) (BTQconst [int8(log32(c))] x))
((NE|EQ) (TESTQ (MOVQconst [c]) x)) && isUint64PowerOfTwo(c)

	MOVQ	SI, _rt0_amd64_lib_argv<>(SB)

	// Synchronous initialization.
	CALL	runtime·libpreinit(SB)

	// Create a new thread to finish Go runtime initialization.
	MOVQ	_cgo_sys_thread_create(SB), AX
	TESTQ	AX, AX
	JZ	nocgo

	// We're calling back to C.
	// Align stack per ELF ABI requirements.
	MOVQ	SP, BX  // Callee-save in C ABI
	ANDQ	$~15, SP
	MOVQ	$_rt0_amd64_lib_go(SB), DI
	MOVQ	$0, SI
	CALL	AX

//		}
//		// Use addr.
//		...
//	}
//
// nosplit because it is used during write barriers and must not be preempted.
//
//go:nosplit
func (tp typePointers) nextFast() (typePointers, uintptr) {
	// TESTQ/JEQ
	if tp.mask == 0 {
		return tp, 0
	}
	// BSFQ
	var i int
	if goarch.PtrSize == 8 {
		i = sys.TrailingZeros64(uint64(tp.mask))
	} else {
		i = sys.TrailingZeros32(uint32(tp.mask))
	}