//
// Even though the Go tar Reader and the BSD tar utility can handle entries
// with arbitrary offsets and lengths, the GNU tar utility can only handle
// offsets and lengths that are multiples of blockSize.
func alignSparseEntries(src []sparseEntry, size int64) []sparseEntry {
	dst := src[:0]
	for _, s := range src {
		pos, end := s.Offset, s.endOffset()

		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 (p *Parser) register(name string, prefix rune) (r1, r2 int16, scale int8, ok bool) {
	// R1 or R(1) R1:R2 R1,R2 R1+R2, or R1*scale.
	r1, ok = p.registerReference(name)
	if !ok {
		return

https://golang.org/doc/articles/c_go_cgo.html.

CFLAGS, CPPFLAGS, CXXFLAGS, FFLAGS and LDFLAGS may be defined with pseudo
#cgo directives within these comments to tweak the behavior of the C, C++
or Fortran compiler. Values defined in multiple directives are concatenated
together. The directive can include a list of build constraints limiting its
effect to systems satisfying one of the constraints

		m := fileLineRE.FindStringSubmatch(line)
		if m == nil {
			t.Errorf("unexpected error: %v", line)
			continue
		}
		fileline := m[1]
		if errors[fileline] != "" && errors[fileline] != line {
			t.Errorf("multiple errors on %s:\n\t%s\n\t%s", fileline, errors[fileline], line)
			continue
		}
		errors[fileline] = line
	}

	// Reconstruct expected errors by independently "parsing" the input.

		p.firstProg = prog
	} else {
		p.lastProg.Link = prog
	}
	p.lastProg = prog
	if doLabel {
		p.pc++
		for _, label := range p.pendingLabels {
			if p.labels[label] != nil {
				p.errorf("label %q multiply defined", label)
				return
			}
			p.labels[label] = prog
		}
		p.pendingLabels = p.pendingLabels[0:0]
	}
	prog.Pc = p.pc
	if *flags.Debug {
		fmt.Println(p.lineNum, prog)
	}
	if testOut != nil {