[dev.regabi] cmd/compile: remove CallExpr.Rargs

Instead, push the temps assignments to init. This does not pass
toolstash, since when before this, the temps were evaluated after
function callee, now we evaluate them before.

Change-Id: Icb9cb10e036925b56c1ef3eec468416a11f4932f
Reviewed-on: https://go-review.googlesource.com/c/go/+/284894
Trust: Cuong Manh Le <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>

Author: cuonglm

src/cmd/compile/internal/ir/expr.go

@@ -159,7 +159,6 @@ type CallExpr struct {
 	origNode
 	X         Node
 	Args      Nodes
-	Rargs     Nodes   // TODO(rsc): Delete.
 	KeepAlive []*Name // vars to be kept alive until call returns
 	IsDDD     bool
 	Use       CallUse

src/cmd/compile/internal/ir/node_gen.go

@@ -4492,30 +4492,8 @@ func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
 
 // intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
 func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
-	// Construct map of temps; see comments in s.call about the structure of n.
-	temps := map[ir.Node]*ssa.Value{}
-	for _, a := range n.Args {
-		if a.Op() != ir.OAS {
-			s.Fatalf("non-assignment as a temp function argument %v", a.Op())
-		}
-		a := a.(*ir.AssignStmt)
-		l, r := a.X, a.Y
-		if l.Op() != ir.ONAME {
-			s.Fatalf("non-ONAME temp function argument %v", a.Op())
-		}
-		// Evaluate and store to "temporary".
-		// Walk ensures these temporaries are dead outside of n.
-		temps[l] = s.expr(r)
-	}
-	args := make([]*ssa.Value, len(n.Rargs))
-	for i, n := range n.Rargs {
-		// Store a value to an argument slot.
-		if x, ok := temps[n]; ok {
-			// This is a previously computed temporary.
-			args[i] = x
-			continue
-		}
-		// This is an explicit value; evaluate it.
+	args := make([]*ssa.Value, len(n.Args))
+	for i, n := range n.Args {
 		args[i] = s.expr(n)
 	}
 	return args
@@ -4528,13 +4506,6 @@ func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
 // (as well as the deferBits variable), and this will enable us to run the proper
 // defer calls during panics.
 func (s *state) openDeferRecord(n *ir.CallExpr) {
-	// Do any needed expression evaluation for the args (including the
-	// receiver, if any). This may be evaluating something like 'autotmp_3 =
-	// once.mutex'. Such a statement will create a mapping in s.vars[] from
-	// the autotmp name to the evaluated SSA arg value, but won't do any
-	// stores to the stack.
-	s.stmtList(n.Args)
-
 	var args []*ssa.Value
 	var argNodes []*ir.Name
 
@@ -4567,7 +4538,7 @@ func (s *state) openDeferRecord(n *ir.CallExpr) {
 		opendefer.closureNode = opendefer.closure.Aux.(*ir.Name)
 		opendefer.rcvrNode = opendefer.rcvr.Aux.(*ir.Name)
 	}
-	for _, argn := range n.Rargs {
+	for _, argn := range n.Args {
 		var v *ssa.Value
 		if TypeOK(argn.Type()) {
 			v = s.openDeferSave(nil, argn.Type(), s.expr(argn))
@@ -4853,11 +4824,6 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 	types.CalcSize(fn.Type())
 	stksize := fn.Type().ArgWidth() // includes receiver, args, and results
 
-	// Run all assignments of temps.
-	// The temps are introduced to avoid overwriting argument
-	// slots when arguments themselves require function calls.
-	s.stmtList(n.Args)
-
 	var call *ssa.Value
 	if k == callDeferStack {
 		testLateExpansion = ssa.LateCallExpansionEnabledWithin(s.f)
@@ -4891,7 +4857,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 		// Then, store all the arguments of the defer call.
 		ft := fn.Type()
 		off := t.FieldOff(12)
-		args := n.Rargs
+		args := n.Args
 
 		// Set receiver (for interface calls). Always a pointer.
 		if rcvr != nil {
@@ -4966,7 +4932,7 @@ func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Val
 
 		// Write args.
 		t := n.X.Type()
-		args := n.Rargs
+		args := n.Args
 		if n.Op() == ir.OCALLMETH {
 			base.Fatalf("OCALLMETH missed by walkCall")
 		}

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

@@ -535,15 +535,15 @@ func walkCall1(n *ir.CallExpr, init *ir.Nodes) {
 		if mayCall(arg) {
 			// assignment of arg to Temp
 			tmp := typecheck.Temp(param.Type)
-			a := convas(ir.NewAssignStmt(base.Pos, tmp, arg), init)
+			a := convas(typecheck.Stmt(ir.NewAssignStmt(base.Pos, tmp, arg)).(*ir.AssignStmt), init)
 			tempAssigns = append(tempAssigns, a)
 			// replace arg with temp
 			args[i] = tmp
 		}
 	}
 
-	n.Args = tempAssigns
-	n.Rargs = args
+	init.Append(tempAssigns...)
+	n.Args = args
 }
 
 // walkDivMod walks an ODIV or OMOD node.