[dev.regabi] cmd/compile: make sure mkcall* passed non-nil init

So next CL can pass temporaries assignments for function arguments in to
init instead of CallExpr.Rargs.

Passes toolstash -cmp.

Change-Id: I2c3cb6a63e8bf9d0418052b39c1db58050f71305
Reviewed-on: https://go-review.googlesource.com/c/go/+/284893
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -26,10 +26,9 @@ func instrument(fn *ir.Func) {
 	if base.Flag.Race {
 		lno := base.Pos
 		base.Pos = src.NoXPos
-
 		if ssagen.Arch.LinkArch.Arch.Family != sys.AMD64 {
-			fn.Enter.Prepend(mkcall("racefuncenterfp", nil, nil))
-			fn.Exit.Append(mkcall("racefuncexit", nil, nil))
+			fn.Enter.Prepend(mkcallstmt("racefuncenterfp"))
+			fn.Exit.Append(mkcallstmt("racefuncexit"))
 		} else {
 
 			// nodpc is the PC of the caller as extracted by
@@ -44,8 +43,8 @@ func instrument(fn *ir.Func) {
 			nodpc.SetType(types.Types[types.TUINTPTR])
 			nodpc.SetFrameOffset(int64(-types.PtrSize))
 			fn.Dcl = append(fn.Dcl, nodpc)
-			fn.Enter.Prepend(mkcall("racefuncenter", nil, nil, nodpc))
-			fn.Exit.Append(mkcall("racefuncexit", nil, nil))
+			fn.Enter.Prepend(mkcallstmt("racefuncenter", nodpc))
+			fn.Exit.Append(mkcallstmt("racefuncexit"))
 		}
 		base.Pos = lno
 	}

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

@@ -174,12 +174,12 @@ func walkRange(nrange *ir.RangeStmt) ir.Node {
 		fn := typecheck.LookupRuntime("mapiterinit")
 
 		fn = typecheck.SubstArgTypes(fn, t.Key(), t.Elem(), th)
-		init = append(init, mkcall1(fn, nil, nil, reflectdata.TypePtr(t), ha, typecheck.NodAddr(hit)))
+		init = append(init, mkcallstmt1(fn, reflectdata.TypePtr(t), ha, typecheck.NodAddr(hit)))
 		nfor.Cond = ir.NewBinaryExpr(base.Pos, ir.ONE, ir.NewSelectorExpr(base.Pos, ir.ODOT, hit, keysym), typecheck.NodNil())
 
 		fn = typecheck.LookupRuntime("mapiternext")
 		fn = typecheck.SubstArgTypes(fn, th)
-		nfor.Post = mkcall1(fn, nil, nil, typecheck.NodAddr(hit))
+		nfor.Post = mkcallstmt1(fn, typecheck.NodAddr(hit))
 
 		key := ir.NewStarExpr(base.Pos, ir.NewSelectorExpr(base.Pos, ir.ODOT, hit, keysym))
 		if v1 == nil {
@@ -269,12 +269,14 @@ func walkRange(nrange *ir.RangeStmt) ir.Node {
 
 		// } else {
 		eif := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
-		nif.Else = []ir.Node{eif}
 
 		// hv2, hv1 = decoderune(ha, hv1)
 		eif.Lhs = []ir.Node{hv2, hv1}
 		fn := typecheck.LookupRuntime("decoderune")
-		eif.Rhs = []ir.Node{mkcall1(fn, fn.Type().Results(), nil, ha, hv1)}
+		var fnInit ir.Nodes
+		eif.Rhs = []ir.Node{mkcall1(fn, fn.Type().Results(), &fnInit, ha, hv1)}
+		fnInit.Append(eif)
+		nif.Else = fnInit
 
 		body = append(body, nif)
 
@@ -374,7 +376,7 @@ func mapClear(m ir.Node) ir.Node {
 	// instantiate mapclear(typ *type, hmap map[any]any)
 	fn := typecheck.LookupRuntime("mapclear")
 	fn = typecheck.SubstArgTypes(fn, t.Key(), t.Elem())
-	n := mkcall1(fn, nil, nil, reflectdata.TypePtr(t), m)
+	n := mkcallstmt1(fn, reflectdata.TypePtr(t), m)
 	return walkStmt(typecheck.Stmt(n))
 }
 
@@ -449,10 +451,10 @@ func arrayClear(loop *ir.RangeStmt, v1, v2, a ir.Node) ir.Node {
 	if a.Type().Elem().HasPointers() {
 		// memclrHasPointers(hp, hn)
 		ir.CurFunc.SetWBPos(stmt.Pos())
-		fn = mkcall("memclrHasPointers", nil, nil, hp, hn)
+		fn = mkcallstmt("memclrHasPointers", hp, hn)
 	} else {
 		// memclrNoHeapPointers(hp, hn)
-		fn = mkcall("memclrNoHeapPointers", nil, nil, hp, hn)
+		fn = mkcallstmt("memclrNoHeapPointers", hp, hn)
 	}
 
 	n.Body.Append(fn)

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

@@ -35,7 +35,7 @@ func walkSelectCases(cases []*ir.CommClause) []ir.Node {
 
 	// optimization: zero-case select
 	if ncas == 0 {
-		return []ir.Node{mkcall("block", nil, nil)}
+		return []ir.Node{mkcallstmt("block")}
 	}
 
 	// optimization: one-case select: single op.
@@ -214,7 +214,7 @@ func walkSelectCases(cases []*ir.CommClause) []ir.Node {
 		// TODO(mdempsky): There should be a cleaner way to
 		// handle this.
 		if base.Flag.Race {
-			r := mkcall("selectsetpc", nil, nil, typecheck.NodAddr(ir.NewIndexExpr(base.Pos, pcs, ir.NewInt(int64(i)))))
+			r := mkcallstmt("selectsetpc", typecheck.NodAddr(ir.NewIndexExpr(base.Pos, pcs, ir.NewInt(int64(i)))))
 			init = append(init, r)
 		}
 	}
@@ -229,7 +229,9 @@ func walkSelectCases(cases []*ir.CommClause) []ir.Node {
 	r := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
 	r.Lhs = []ir.Node{chosen, recvOK}
 	fn := typecheck.LookupRuntime("selectgo")
-	r.Rhs = []ir.Node{mkcall1(fn, fn.Type().Results(), nil, bytePtrToIndex(selv, 0), bytePtrToIndex(order, 0), pc0, ir.NewInt(int64(nsends)), ir.NewInt(int64(nrecvs)), ir.NewBool(dflt == nil))}
+	var fnInit ir.Nodes
+	r.Rhs = []ir.Node{mkcall1(fn, fn.Type().Results(), &fnInit, bytePtrToIndex(selv, 0), bytePtrToIndex(order, 0), pc0, ir.NewInt(int64(nsends)), ir.NewInt(int64(nrecvs)), ir.NewBool(dflt == nil))}
+	init = append(init, fnInit...)
 	init = append(init, typecheck.Stmt(r))
 
 	// selv and order are no longer alive after selectgo.

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

@@ -96,6 +96,9 @@ func convas(n *ir.AssignStmt, init *ir.Nodes) *ir.AssignStmt {
 var stop = errors.New("stop")
 
 func vmkcall(fn ir.Node, t *types.Type, init *ir.Nodes, va []ir.Node) *ir.CallExpr {
+	if init == nil {
+		base.Fatalf("mkcall with nil init: %v", fn)
+	}
 	if fn.Type() == nil || fn.Type().Kind() != types.TFUNC {
 		base.Fatalf("mkcall %v %v", fn, fn.Type())
 	}
@@ -115,10 +118,24 @@ func mkcall(name string, t *types.Type, init *ir.Nodes, args ...ir.Node) *ir.Cal
 	return vmkcall(typecheck.LookupRuntime(name), t, init, args)
 }
 
+func mkcallstmt(name string, args ...ir.Node) ir.Node {
+	return mkcallstmt1(typecheck.LookupRuntime(name), args...)
+}
+
 func mkcall1(fn ir.Node, t *types.Type, init *ir.Nodes, args ...ir.Node) *ir.CallExpr {
 	return vmkcall(fn, t, init, args)
 }
 
+func mkcallstmt1(fn ir.Node, args ...ir.Node) ir.Node {
+	var init ir.Nodes
+	n := vmkcall(fn, nil, &init, args)
+	if len(init) == 0 {
+		return n
+	}
+	init.Append(n)
+	return ir.NewBlockStmt(n.Pos(), init)
+}
+
 func chanfn(name string, n int, t *types.Type) ir.Node {
 	if !t.IsChan() {
 		base.Fatalf("chanfn %v", t)