// To do that, the stack pointer must be 8-byte-aligned
// on some systems, notably FreeBSD.
// The ARM ABI says the stack pointer must be 8-byte-aligned
// on entry to any function, but only FreeBSD's C library seems to care.
// The caller was 8-byte aligned, but we push an LR.
// Declare a dummy word ($4, not $0) to make sure the
// frame is 8 bytes and stays 8-byte-aligned.
TEXT runtime·_initcgo(SB),NOSPLIT,$4

	}
}

func TestPhysPageSize(t *testing.T) {
	// Mmap fails if the address is not page aligned, so we can
	// use this to test if the page size is the true page size.
	ps := runtime.GetPhysPageSize()

	// Get a region of memory to play with. This should be page-aligned.
	b, err := runtime.Mmap(nil, 2*ps, 0, runtime.MAP_ANON|runtime.MAP_PRIVATE, -1, 0)
	if err != 0 {
		t.Fatalf("Mmap: %v", err)
	}

			// type the selector arg on some platforms.
			return
		}
		if p, ok := t.(*types.Pointer); ok {
			// Note: we assume here that the pointer p in p.foo is properly
			// aligned. We just check that foo is at a properly aligned offset.
			t = p.Elem()
		} else {
			v.checkAddr(n.X)
		}
		if t.Underlying() == t {
			v.t.Errorf("analysis can't handle unnamed type %s %v", v.fset.Position(n.Pos()), t)
		}

to a specified boundary by padding with NOOP instruction. The alignment value supported on arm64
must be a power of 2 and in the range of [8, 2048].

Examples:

	PCALIGN $16
	MOVD $2, R0          // This instruction is aligned with 16 bytes.
	PCALIGN $1024
	MOVD $3, R1          // This instruction is aligned with 1024 bytes.

}

// pages64 returns a 64-bit bitmap representing a block of 64 pages aligned
// to 64 pages. The returned block of pages is the one containing the i'th
// page in this pallocBits. Each bit represents whether the page is in-use.
func (b *pallocBits) pages64(i uint) uint64 {
	return (*pageBits)(b).block64(i)
}

// allocPages64 allocates a 64-bit block of 64 pages aligned to 64 pages according

// directio.AlignSize is defined as 0 in MacOS causing divide by 0 error.
const DirectioAlignSize = 4096

// CopyAligned - copies from reader to writer using the aligned input
// buffer, it is expected that input buffer is page aligned to
// 4K page boundaries. Without passing aligned buffer may cause
// this function to return error.
//
// This code is similar in spirit to io.Copy but it is only to be

	SUBVU	R5, R4, R7
	AND	$7, R7
	BNE	R7, out

	// if less than 8 bytes, do byte copying
	SGTU	$8, R6, R7
	BNE	R7, out

	// do one byte at a time until 8-aligned
	AND	$7, R4, R8
	BEQ	R8, words
	MOVB	(R5), R7
	ADDV	$1, R5
	MOVB	R7, (R4)
	ADDV	$1, R4
	JMP	-6(PC)

words:
	// do 8 bytes at a time if there is room
	ADDV	$-7, R9, R6 // R6 is end pointer-7

	SUBVU	R2, R1, R4
	AND	$7, R4
	BNE	R4, out

	// if less than 8 bytes, do byte copying
	SGTU	$8, R3, R4
	BNE	R4, out

	// do one byte at a time until 8-aligned
	AND	$7, R1, R5
	BEQ	R5, words
	MOVB	(R2), R4
	ADDV	$1, R2
	MOVB	R4, (R1)
	ADDV	$1, R1
	JMP	-6(PC)

words:
	// do 8 bytes at a time if there is room
	ADDV	$-7, R6, R3 // R3 is end pointer-7

// Both must be aligned to pallocChunkBytes.
//
// The caller must update p.start and p.end after calling sysGrow.
func (p *pageAlloc) sysGrow(base, limit uintptr) {
	if base%pallocChunkBytes != 0 || limit%pallocChunkBytes != 0 {
		print("runtime: base = ", hex(base), ", limit = ", hex(limit), "\n")
		throw("sysGrow bounds not aligned to pallocChunkBytes")
	}

	MOV	$8, X9
	BLT	X11, X9, check4

	// Check alignment
	AND	$7, X10, X5
	BEQZ	X5, aligned

	// Zero one byte at a time until we reach 8 byte alignment.
	SUB	X5, X9, X5
	SUB	X5, X11, X11
align:
	SUB	$1, X5
	MOVB	ZERO, 0(X10)
	ADD	$1, X10
	BNEZ	X5, align

aligned:
	// X9 already contains $8
	BLT	X11, X9, check4
	MOV	$16, X9
	BLT	X11, X9, zero8
	MOV	$32, X9