}

	// Construct a build list with a minimal set of roots.
	// This may remove or downgrade modules in altMods.
	reqs := &mvsReqs{roots: keep}
	min, err := mvs.Req(mainModule, rootPaths, reqs)
	if err != nil {
		return nil, err
	}
	buildList, err := mvs.BuildList([]module.Version{mainModule}, reqs)
	if err != nil {
		return nil, err
	}

	// Check if modules in altMods were downgraded but not removed.

		})
	}
}

// removeDups removes duplicate replace directives.
//
// Later replace directives take priority.
//
// require directives are not de-duplicated. That's left up to higher-level
// logic (MVS).
//
// retract directives are not de-duplicated since comments are
// meaningful, and versions may be retracted multiple times.
func (f *WorkFile) removeDups() {
	removeDups(f.Syntax, nil, &f.Replace)

		}
		return

	}

	// MOVx sym, Ry becomes MOVD symtoc, REGTMP; MOVx (REGTMP), Ry
	// MOVx Ry, sym becomes MOVD symtoc, REGTMP; MOVx Ry, (REGTMP)
	// An addition may be inserted between the two MOVs if there is an offset.

	q := obj.Appendp(p, c.newprog)
	q.As = AMOVD
	q.From.Type = obj.TYPE_MEM
	q.From.Sym = symtoc
	q.From.Name = obj.NAME_TOCREF
	q.To.Type = obj.TYPE_REG
	q.To.Reg = REGTMP

			toolchain = m.Version
			continue
		}
		list = append(list, &modfile.Require{
			Mod:      m,
			Indirect: !requirements.direct[m.Path],
		})
	}

	// Update go line.
	// Every MVS graph we consider should have go as a root,
	// and toolchain is either implied by the go line or explicitly a root.
	if goVersion == "" {
		base.Fatalf("go: internal error: missing go root module in WriteGoMod")
	}

	// Version is usually a semantic version in canonical form.
	// There are three exceptions to this general rule.
	// First, the top-level target of a build has no specific version
	// and uses Version = "".
	// Second, during MVS calculations the version "none" is used
	// to represent the decision to take no version of a given module.
	// Third, filesystem paths found in "replace" directives are
	// represented by a path with an empty version.

	"cmd/go/internal/base"
	"cmd/go/internal/cfg"
	"cmd/go/internal/fsys"
	"cmd/go/internal/gover"
	"cmd/go/internal/imports"
	"cmd/go/internal/modfetch"
	"cmd/go/internal/modindex"
	"cmd/go/internal/mvs"
	"cmd/go/internal/par"
	"cmd/go/internal/search"
	"cmd/go/internal/str"

	"golang.org/x/mod/module"
)

// loaded is the most recently-used package loader.
// It holds details about individual packages.

//
// Earlier exclude directives take priority.
//
// Later replace directives take priority.
//
// require directives are not de-duplicated. That's left up to higher-level
// logic (MVS).
//
// retract directives are not de-duplicated since comments are
// meaningful, and versions may be retracted multiple times.
func (f *File) removeDups() {
	removeDups(f.Syntax, &f.Exclude, &f.Replace)
}

	{AMOVH, C_ZREG, C_NONE, C_NONE, C_ZREG, C_NONE, 45, 4, 0, 0, 0}, /* also MOVHU */
	{AMOVW, C_ZREG, C_NONE, C_NONE, C_ZREG, C_NONE, 45, 4, 0, 0, 0}, /* also MOVWU */
	/* TODO: MVN C_SHIFT */

	/* MOVs that become MOVK/MOVN/MOVZ/ADD/SUB/OR */
	{AMOVW, C_MBCON, C_NONE, C_NONE, C_ZREG, C_NONE, 32, 4, 0, 0, 0},
	{AMOVD, C_MBCON, C_NONE, C_NONE, C_ZREG, C_NONE, 32, 4, 0, 0, 0},