[dev.typeparams] cmd/compile: add morestack arg spilling code on ARM64

Spill arg registers before calling morestack, and reload after.

Change-Id: I09404def321b8f935d5e8836a46ccae8256d0d55
Reviewed-on: https://go-review.googlesource.com/c/go/+/322853
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

src/cmd/compile/internal/arm64/ssa.go

@@ -162,7 +162,16 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 		p.From.Reg = v.Args[0].Reg()
 		ssagen.AddrAuto(&p.To, v)
 	case ssa.OpArgIntReg, ssa.OpArgFloatReg:
-		// TODO: generate morestack spill code
+		// The assembler needs to wrap the entry safepoint/stack growth code with spill/unspill
+		// The loop only runs once.
+		for _, a := range v.Block.Func.RegArgs {
+			// Pass the spill/unspill information along to the assembler, offset by size of
+			// the saved LR slot.
+			addr := ssagen.SpillSlotAddr(a, arm64.REGSP, base.Ctxt.FixedFrameSize())
+			s.FuncInfo().AddSpill(
+				obj.RegSpill{Reg: a.Reg, Addr: addr, Unspill: loadByType(a.Type), Spill: storeByType(a.Type)})
+		}
+		v.Block.Func.RegArgs = nil
 		ssagen.CheckArgReg(v)
 	case ssa.OpARM64ADD,
 		ssa.OpARM64SUB,

src/cmd/compile/internal/ssagen/ssa.go

@@ -650,7 +650,6 @@ func buildssa(fn *ir.Func, worker int) *ssa.Func {
 	// it mimics the behavior of the former ABI (everything stored) and because it's not 100%
 	// clear if naming conventions are respected in autogenerated code.
 	// TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
-	// TODO non-amd64 architectures have link registers etc that may require adjustment here.
 	for _, p := range params.InParams() {
 		typs, offs := p.RegisterTypesAndOffsets()
 		for i, t := range typs {

src/cmd/internal/obj/arm64/obj7.go

@@ -161,17 +161,20 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
 	pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
 
+	if q != nil {
+		q.To.SetTarget(pcdata)
+	}
+	bls.To.SetTarget(pcdata)
+
+	spill := c.cursym.Func().SpillRegisterArgs(pcdata, c.newprog)
+
 	// MOV	LR, R3
-	movlr := obj.Appendp(pcdata, c.newprog)
+	movlr := obj.Appendp(spill, c.newprog)
 	movlr.As = AMOVD
 	movlr.From.Type = obj.TYPE_REG
 	movlr.From.Reg = REGLINK
 	movlr.To.Type = obj.TYPE_REG
 	movlr.To.Reg = REG_R3
-	if q != nil {
-		q.To.SetTarget(movlr)
-	}
-	bls.To.SetTarget(movlr)
 
 	debug := movlr
 	if false {
@@ -196,7 +199,8 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
 	}
 	call.To.Sym = c.ctxt.Lookup(morestack)
 
-	pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
+	unspill := c.cursym.Func().UnspillRegisterArgs(call, c.newprog)
+	pcdata = c.ctxt.EndUnsafePoint(unspill, c.newprog, -1)
 
 	// B	start
 	jmp := obj.Appendp(pcdata, c.newprog)