These examples show when a Go implementation can use that instruction:
</p>

<pre>
// FMA allowed for computing r, because x*y is not explicitly rounded:
r  = x*y + z
r  = z;   r += x*y
t  = x*y; r = t + z
*p = x*y; r = *p + z
r  = x*y + float64(z)

// FMA disallowed for computing r, because it would omit rounding of x*y:
r  = float64(x*y) + z
r  = z; r += float64(x*y)
t  = float64(x*y); r = t + z

as C.stdout, or functions such as C.putchar.

If the import of "C" is immediately preceded by a comment, that
comment, called the preamble, is used as a header when compiling
the C parts of the package. For example:

	// #include <stdio.h>
	// #include <errno.h>
	import "C"

The preamble may contain any C code, including function and variable

These examples show when a Go implementation can use that instruction:
</p>

<pre>
// FMA allowed for computing r, because x*y is not explicitly rounded:
r  = x*y + z
r  = z;   r += x*y
t  = x*y; r = t + z
*p = x*y; r = *p + z
r  = x*y + float64(z)

// FMA disallowed for computing r, because it would omit rounding of x*y:
r  = float64(x*y) + z
r  = z; r += float64(x*y)
t  = float64(x*y); r = t + z

	TypeXHeader = 'x'

	// Type 'g' is used by the PAX format to store key-value records that
	// are relevant to all subsequent files.
	// This package only supports parsing and composing such headers,
	// but does not currently support persisting the global state across files.
	TypeXGlobalHeader = 'g'

	// Type 'S' indicates a sparse file in the GNU format.
	TypeGNUSparse = 'S'

controlling whether `panic(nil)` is allowed;
it defaults to `panicnil=0`, making `panic(nil)` a run-time error.
Using `panicnil=1` restores the behavior of Go 1.20 and earlier.

When compiling a work module or workspace that declares
an older Go version, the Go toolchain amends its defaults
to match that older Go version as closely as possible.
For example, when a Go 1.21 toolchain compiles a program,

the value in the form of a `Handle[T]`.
Two `Handle[T]` are equal if and only if the values used to produce the
handles are equal, allowing programs to deduplicate values and reduce
their memory footprint.
Comparing two `Handle[T]` values is efficient, reducing down to a simple

	fmt.Printf("%s\n", clone)
	clone[0] = 'd'
	fmt.Printf("%s\n", b)
	fmt.Printf("%s\n", clone)
	// Output:
	// abc
	// abc
	// dbc
}

func ExampleCompare() {
	// Interpret Compare's result by comparing it to zero.
	var a, b []byte
	if bytes.Compare(a, b) < 0 {
		// a less b
	}
	if bytes.Compare(a, b) <= 0 {
		// a less or equal b
	}
	if bytes.Compare(a, b) > 0 {
		// a greater b
	}

<p>
For garbage collection to run correctly, the runtime must know the
location of pointers in all global data and in most stack frames.
The Go compiler emits this information when compiling Go source files,
but assembly programs must define it explicitly.
</p>

<p>
A data symbol marked with the <code>NOPTR</code> flag (see above)
is treated as containing no pointers to runtime-allocated data.

// A nil argument is equivalent to an empty slice.
func Equal(a, b []byte) bool {
	// Neither cmd/compile nor gccgo allocates for these string conversions.
	return string(a) == string(b)
}

// Compare returns an integer comparing two byte slices lexicographically.
// The result will be 0 if a == b, -1 if a < b, and +1 if a > b.
// A nil argument is equivalent to an empty slice.
func Compare(a, b []byte) int {
	return bytealg.Compare(a, b)
}

	if tok == '>' {
		isStatic = true
	} else if tok == scanner.Ident {
		abistr := p.get(scanner.Ident).String()
		if !p.allowABI {
			if issueError {
				p.errorf("ABI selector only permitted when compiling runtime, reference was to %q", name)
			}
		} else {
			theabi, valid := obj.ParseABI(abistr)
			if !valid {
				if issueError {
					p.errorf("malformed ABI selector %q in reference to %q",