cmd/compile/internal/gc: add s390x support

Allows instructions with a From3 field to be used in regopt so
long as From3 represents a constant. This is needed because the
storage-to-storage instructions on s390x place the length of the
data into From3.

Change-Id: I12cd32d4f997baf2fe97937bb7d45bbf716dfcb5
Reviewed-on: https://go-review.googlesource.com/20875Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/cgen.go

@@ -247,7 +247,7 @@ func cgen_wb(n, res *Node, wb bool) {
 		return
 	}
 
-	if Ctxt.Arch.InFamily(sys.AMD64, sys.I386) && n.Addable {
+	if Ctxt.Arch.InFamily(sys.AMD64, sys.I386, sys.S390X) && n.Addable {
 		Thearch.Gmove(n, res)
 		return
 	}
@@ -1829,7 +1829,7 @@ func bgenx(n, res *Node, wantTrue bool, likely int, to *obj.Prog) {
 		// Some architectures might need a temporary or other help here,
 		// but they don't support direct generation of a bool value yet.
 		// We can fix that as we go.
-		mayNeedTemp := Ctxt.Arch.InFamily(sys.ARM, sys.ARM64, sys.MIPS64, sys.PPC64)
+		mayNeedTemp := Ctxt.Arch.InFamily(sys.ARM, sys.ARM64, sys.MIPS64, sys.PPC64, sys.S390X)
 
 		if genval {
 			if mayNeedTemp {

src/cmd/compile/internal/gc/gsubr.go

@@ -58,7 +58,9 @@ func Ismem(n *Node) bool {
 		return true
 
 	case OADDR:
-		return Thearch.LinkArch.InFamily(sys.AMD64, sys.PPC64) // because 6g uses PC-relative addressing; TODO(rsc): not sure why 9g too
+		// amd64 and s390x use PC relative addressing.
+		// TODO(rsc): not sure why ppc64 needs this too.
+		return Thearch.LinkArch.InFamily(sys.AMD64, sys.PPC64, sys.S390X)
 	}
 
 	return false
@@ -84,7 +86,7 @@ func Gbranch(as obj.As, t *Type, likely int) *obj.Prog {
 	p := Prog(as)
 	p.To.Type = obj.TYPE_BRANCH
 	p.To.Val = nil
-	if as != obj.AJMP && likely != 0 && Thearch.LinkArch.Family != sys.PPC64 && Thearch.LinkArch.Family != sys.ARM64 && Thearch.LinkArch.Family != sys.MIPS64 {
+	if as != obj.AJMP && likely != 0 && !Thearch.LinkArch.InFamily(sys.PPC64, sys.ARM64, sys.MIPS64, sys.S390X) {
 		p.From.Type = obj.TYPE_CONST
 		if likely > 0 {
 			p.From.Offset = 1
@@ -458,7 +460,7 @@ func Naddr(a *obj.Addr, n *Node) {
 	case OADDR:
 		Naddr(a, n.Left)
 		a.Etype = uint8(Tptr)
-		if !Thearch.LinkArch.InFamily(sys.MIPS64, sys.ARM, sys.ARM64, sys.PPC64) { // TODO(rsc): Do this even for arm, ppc64.
+		if !Thearch.LinkArch.InFamily(sys.MIPS64, sys.ARM, sys.ARM64, sys.PPC64, sys.S390X) { // TODO(rsc): Do this even for these architectures.
 			a.Width = int64(Widthptr)
 		}
 		if a.Type != obj.TYPE_MEM {

src/cmd/compile/internal/gc/pgen.go

@@ -287,7 +287,7 @@ func allocauto(ptxt *obj.Prog) {
 		if haspointers(n.Type) {
 			stkptrsize = Stksize
 		}
-		if Thearch.LinkArch.InFamily(sys.MIPS64, sys.ARM, sys.ARM64, sys.PPC64) {
+		if Thearch.LinkArch.InFamily(sys.MIPS64, sys.ARM, sys.ARM64, sys.PPC64, sys.S390X) {
 			Stksize = Rnd(Stksize, int64(Widthptr))
 		}
 		if Stksize >= 1<<31 {

src/cmd/compile/internal/gc/reg.go

@@ -1115,7 +1115,7 @@ func regopt(firstp *obj.Prog) {
 
 		// Currently we never generate three register forms.
 		// If we do, this will need to change.
-		if p.From3Type() != obj.TYPE_NONE {
+		if p.From3Type() != obj.TYPE_NONE && p.From3Type() != obj.TYPE_CONST {
 			Fatalf("regopt not implemented for from3")
 		}
 

src/cmd/compile/internal/gc/walk.go

@@ -673,7 +673,7 @@ opswitch:
 		walkexprlist(n.List.Slice(), init)
 
 		if n.Left.Op == ONAME && n.Left.Sym.Name == "Sqrt" && n.Left.Sym.Pkg.Path == "math" {
-			if Thearch.LinkArch.InFamily(sys.AMD64, sys.ARM, sys.ARM64, sys.PPC64) {
+			if Thearch.LinkArch.InFamily(sys.AMD64, sys.ARM, sys.ARM64, sys.PPC64, sys.S390X) {
 				n.Op = OSQRT
 				n.Left = n.List.First()
 				n.List.Set(nil)
@@ -3294,6 +3294,11 @@ func walkrotate(n *Node) *Node {
 	// Constants adding to width?
 	w := int(l.Type.Width * 8)
 
+	if Thearch.LinkArch.Family == sys.S390X && w != 32 && w != 64 {
+		// only supports 32-bit and 64-bit rotates
+		return n
+	}
+
 	if Smallintconst(l.Right) && Smallintconst(r.Right) {
 		sl := int(l.Right.Int64())
 		if sl >= 0 {