// output are interpreted as UTF-8-encoded code points.
func Map(mapping func(r rune) rune, s []byte) []byte {
	// In the worst case, the slice can grow when mapped, making
	// things unpleasant. But it's so rare we barge in assuming it's
	// fine. It could also shrink but that falls out naturally.
	b := make([]byte, 0, len(s))
	for i := 0; i < len(s); {
		wid := 1
		r := rune(s[i])
		if r >= utf8.RuneSelf {

## Compiler {#compiler}

The build time overhead to building with [Profile Guided Optimization](/doc/pgo) has been reduced significantly.
Previously, large builds could see 100%+ build time increase from enabling PGO.
In Go 1.23, overhead should be in the single digit percentages.

## Assembler {#assembler}

bytes of the string.
</p>

<pre class="grammar">
append(s S, x ...T) S  // T is the element type of S
</pre>

<p>
If the capacity of <code>s</code> is not large enough to fit the additional
values, <code>append</code> allocates a new, sufficiently large underlying
array that fits both the existing slice elements and the additional values.
Otherwise, <code>append</code> re-uses the underlying array.
</p>

<pre>

type int int

// uint is an unsigned integer type that is at least 32 bits in size. It is a
// distinct type, however, and not an alias for, say, uint32.
type uint uint

// uintptr is an integer type that is large enough to hold the bit pattern of
// any pointer.
type uintptr uintptr

// byte is an alias for uint8 and is equivalent to uint8 in all ways. It is
// used, by convention, to distinguish byte values from 8-bit unsigned

	ADDW	$0x10001000, R1               // ADDW	$268439552, R1              // fb83043221001b0b
	ADDW	$0x22220000, RSP, R3          // ADDW	$572653568, RSP, R3         // 5b44a452e3433b0b

// move a large constant to a Vd.
	VMOVS	$0x80402010, V11                                      // VMOVS	$2151686160, V11
	VMOVD	$0x8040201008040201, V20                              // VMOVD	$-9205322385119247871, V20

	case scanner.Int, '(':
		p.back()
		x := int64(p.expr())
		if p.arch.Family == sys.ARM64 {
			if x >= 64 {
				p.errorf("register shift count too large: %s", str)
			}
			count = int16((x & 63) << 10)
		} else {
			if x >= 32 {
				p.errorf("register shift count too large: %s", str)
			}
			count = int16((x & 31) << 7)
		}
	default:
		p.errorf("unexpected %s in register shift", tok.String())
	}

}

func TestEndianBaseCompare(t *testing.T) {
	// This test compares byte slices that are almost identical, except one
	// difference that for some j, a[j]>b[j] and a[j+1]<b[j+1]. If the implementation
	// compares large chunks with wrong endianness, it gets wrong result.
	// no vector register is larger than 512 bytes for now
	const maxLength = 512
	a := make([]byte, maxLength)
	b := make([]byte, maxLength)

			"-fno-builtin",
		)
	}

	c = append(c, p.GccOptions...)
	c = append(c, p.gccMachine()...)
	if goos == "aix" {
		c = append(c, "-maix64")
		c = append(c, "-mcmodel=large")
	}
	// disable LTO so we get an object whose symbols we can read
	c = append(c, "-fno-lto")
	c = append(c, "-") //read input from standard input
	return c
}

type largeReader struct{}

func (largeReader) Read(p []byte) (int, error) {
	return len(p) + 1, nil
}

// Test that the scanner doesn't panic and returns ErrBadReadCount
// on a reader that returns an impossibly large count of bytes read (issue 38053).
func TestLargeReader(t *testing.T) {
	scanner := NewScanner(largeReader{})
	for scanner.Scan() {
	}
	if got, want := scanner.Err(), ErrBadReadCount; got != want {

				if !bytes.Equal(want, got) {
					t.Fatalf("incorrect result: (-got +want)\n%v", bytediff(got, want))
				}
			}
		})
	}
}

func TestPax(t *testing.T) {
	// Create an archive with a large name
	fileinfo, err := os.Stat("testdata/small.txt")
	if err != nil {
		t.Fatal(err)
	}
	hdr, err := FileInfoHeader(fileinfo, "")
	if err != nil {
		t.Fatalf("os.Stat: %v", err)
	}