matching the new flags. To disallow flags that would otherwise be allowed,
set CGO_CFLAGS_DISALLOW to a regular expression matching arguments
that must be disallowed. In both cases the regular expression must match
a full argument: to allow -mfoo=bar, use CGO_CFLAGS_ALLOW='-mfoo.*',
not just CGO_CFLAGS_ALLOW='-mfoo'. Similarly named variables control
the allowed CPPFLAGS, CXXFLAGS, FFLAGS, and LDFLAGS.

	SUBV	$9531, R16	// 6210dac5
	SUBV	$-9531, R13	// 61ad253b
	SUBVU	$9531, R16	// 6610dac5

//	LMUL rreg ',' rreg
//	{
//		outcode(int($1), &$2, 0, &$4);
//	}
	MUL	R19, R8		// 01130018
	MULU	R21, R13	// 01b50019
	MULV	R19, R8		// 0113001c
	MULVU	R21, R13	// 01b5001d

//	LDIV rreg ',' rreg
//	{
//		outcode(int($1), &$2, 0, &$4);
//	}
	DIV	R18, R22	// 02d2001a
	DIVU	R14, R9		// 012e001b

// If fi describes a directory, a slash is appended to the name.
//
// Since fs.FileInfo's Name method only returns the base name of
// the file it describes, it may be necessary to modify Header.Name
// to provide the full path name of the file.
//
// If fi implements [FileInfoNames]
// Header.Gname and Header.Uname
// are provided by the methods of the interface.
func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error) {

		// or space is needed.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			// Guarantee no overflow in the multiplication below.
			const maxInt = int(^uint(0) >> 1)
			if len(s.buf) >= s.maxTokenSize || len(s.buf) > maxInt/2 {

// fs.FileInfo.
// Because fs.FileInfo's Name method returns only the base name of
// the file it describes, it may be necessary to modify the Name field
// of the returned header to provide the full path name of the file.
// If compression is desired, callers should set the FileHeader.Method
// field; it is unset by default.
func FileInfoHeader(fi fs.FileInfo) (*FileHeader, error) {
	size := fi.Size()

---
title: "Go, Backwards Compatibility, and GODEBUG"
layout: article
---

<!--
This document is kept in the Go repo, not x/website,
because it documents the full list of known GODEBUG settings,
which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.

that assembly programming is a fraught endeavor.
(Exception: the <code>g</code> register renaming on ARM.)
</p>

<p>
In Go object files and binaries, the full name of a symbol is the
package path followed by a period and the symbol name:
<code>fmt.Printf</code> or <code>math/rand.Int</code>.
Because the assembler's parser treats period and slash as punctuation,

// given ASCII character in the set. The 128-bits of the lower 16 bytes,
// starting with the least-significant bit of the lowest word to the
// most-significant bit of the highest word, map to the full range of all
// 128 ASCII characters. The 128-bits of the upper 16 bytes will be zeroed,
// ensuring that any non-ASCII character will be reported as not in the set.
// This allocates a total of 32 bytes even though the upper half

		return 0, false
	}
	r, ok := p.arch.RegisterNumber(name, int16(num))
	if !ok {
		p.errorf("illegal register %s(%d)", name, r)
		return 0, false
	}
	return r, true
}

// register parses a full register reference where there is no symbol present (as in 4(R0) or R(10) but not sym(SB))
// including forms involving multiple registers such as R1:R2.

func (b *Reader) ReadBytes(delim byte) ([]byte, error) {
	full, frag, n, err := b.collectFragments(delim)
	// Allocate new buffer to hold the full pieces and the fragment.
	buf := make([]byte, n)
	n = 0
	// Copy full pieces and fragment in.
	for i := range full {
		n += copy(buf[n:], full[i])
	}
	copy(buf[n:], frag)
	return buf, err
}