cmd/compile/internal/gc: remove Node.IsStatic field

We can immediately emit static assignment data rather than queueing
them up to be processed during SSA building.

Passes toolstash -cmp.

Change-Id: I8bcea4b72eafb0cc0b849cd93e9cde9d84f30d5e
Reviewed-on: https://go-review.googlesource.com/37024
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

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

@@ -335,10 +335,6 @@ func (n *Node) jconv(s fmt.State, flag FmtFlag) {
 		fmt.Fprintf(s, " tc(%d)", n.Typecheck)
 	}
 
-	if c == 0 && n.IsStatic {
-		fmt.Fprint(s, " static")
-	}
-
 	if n.Isddd {
 		fmt.Fprintf(s, " isddd(%v)", n.Isddd)
 	}

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

@@ -751,19 +751,15 @@ func fixedlit(ctxt initContext, kind initKind, n *Node, var_ *Node, init *Nodes)
 		a = typecheck(a, Etop)
 		switch kind {
 		case initKindStatic:
-			a = walkexpr(a, init) // add any assignments in r to top
-			if a.Op != OAS {
-				Fatalf("fixedlit: not as, is %v", a)
-			}
-			a.IsStatic = true
+			genAsStatic(a)
 		case initKindDynamic, initKindLocalCode:
 			a = orderstmtinplace(a)
 			a = walkstmt(a)
+			init.Append(a)
 		default:
 			Fatalf("fixedlit: bad kind %d", kind)
 		}
 
-		init.Append(a)
 	}
 }
 
@@ -780,12 +776,22 @@ func slicelit(ctxt initContext, n *Node, var_ *Node, init *Nodes) {
 		fixedlit(ctxt, initKindDynamic, n, vstat, init)
 
 		// copy static to slice
-		a := nod(OSLICE, vstat, nil)
+		var_ = typecheck(var_, Erv|Easgn)
+		var nam Node
+		if !stataddr(&nam, var_) || nam.Class != PEXTERN {
+			Fatalf("slicelit: %v", var_)
+		}
+
+		var v Node
+		nodconst(&v, Types[TINT], t.NumElem())
+
+		nam.Xoffset += int64(array_array)
+		gdata(&nam, nod(OADDR, vstat, nil), Widthptr)
+		nam.Xoffset += int64(array_nel) - int64(array_array)
+		gdata(&nam, &v, Widthint)
+		nam.Xoffset += int64(array_cap) - int64(array_nel)
+		gdata(&nam, &v, Widthint)
 
-		a = nod(OAS, var_, a)
-		a = typecheck(a, Etop)
-		a.IsStatic = true
-		init.Append(a)
 		return
 	}
 
@@ -964,18 +970,14 @@ func maplit(n *Node, m *Node, init *Nodes) {
 				lhs := nod(OINDEX, vstatk, nodintconst(b))
 				as := nod(OAS, lhs, index)
 				as = typecheck(as, Etop)
-				as = walkexpr(as, init)
-				as.IsStatic = true
-				init.Append(as)
+				genAsStatic(as)
 
 				// build vstatv[b] = value
 				setlineno(value)
 				lhs = nod(OINDEX, vstatv, nodintconst(b))
 				as = nod(OAS, lhs, value)
 				as = typecheck(as, Etop)
-				as = walkexpr(as, init)
-				as.IsStatic = true
-				init.Append(as)
+				genAsStatic(as)
 
 				b++
 			}
@@ -1344,69 +1346,15 @@ func isvaluelit(n *Node) bool {
 	return n.Op == OARRAYLIT || n.Op == OSTRUCTLIT
 }
 
-func genAsInitNoCheck(n *Node) bool {
-	nr := n.Right
-	nl := n.Left
-	if nr == nil {
+func genAsStatic(as *Node) {
 	var nam Node
-		return stataddr(&nam, nl) && nam.Class == PEXTERN
-	}
-
-	if nr.Type == nil || !eqtype(nl.Type, nr.Type) {
-		return false
-	}
-
-	var nam Node
-	if !stataddr(&nam, nl) || nam.Class != PEXTERN {
-		return false
-	}
-
-	switch nr.Op {
-	default:
-		return false
-
-	case OCONVNOP:
-		nr = nr.Left
-		if nr == nil || nr.Op != OSLICEARR {
-			return false
-		}
-		fallthrough
-
-	case OSLICEARR:
-		low, high, _ := nr.SliceBounds()
-		if low != nil || high != nil {
-			return false
-		}
-		nr = nr.Left
-		if nr == nil || nr.Op != OADDR {
-			return false
-		}
-		ptr := nr
-		nr = nr.Left
-		if nr == nil || nr.Op != ONAME {
-			return false
+	if !stataddr(&nam, as.Left) || nam.Class != PEXTERN {
+		Fatalf("genAsStatic: lhs %v", as.Left)
 	}
 
-		// nr is the array being converted to a slice
-		if nr.Type == nil || !nr.Type.IsArray() {
-			return false
+	if as.Right.Op != OLITERAL {
+		Fatalf("genAsStatic: rhs %v", as.Right)
 	}
 
-		nam.Xoffset += int64(array_array)
-		gdata(&nam, ptr, Widthptr)
-
-		nam.Xoffset += int64(array_nel) - int64(array_array)
-		var nod1 Node
-		nodconst(&nod1, Types[TINT], nr.Type.NumElem())
-		gdata(&nam, &nod1, Widthint)
-
-		nam.Xoffset += int64(array_cap) - int64(array_nel)
-		gdata(&nam, &nod1, Widthint)
-
-		return true
-
-	case OLITERAL:
-		gdata(&nam, nr, int(nr.Type.Width))
-		return true
-	}
+	gdata(&nam, as.Right, int(as.Right.Type.Width))
 }

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

@@ -630,15 +630,6 @@ func (s *state) stmt(n *Node) {
 		b.AddEdgeTo(lab.target)
 
 	case OAS:
-		// Generate static data rather than code, if possible.
-		if n.IsStatic {
-			if !genAsInitNoCheck(n) {
-				Dump("\ngen_as_init", n)
-				Fatalf("gen_as_init couldn't generate static data")
-			}
-			return
-		}
-
 		if n.Left == n.Right && n.Left.Op == ONAME {
 			// An x=x assignment. No point in doing anything
 			// here. In addition, skipping this assignment

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

@@ -65,7 +65,6 @@ type Node struct {
 	Walkdef   uint8 // tracks state during typecheckdef; 2 == loop detected
 	Typecheck uint8 // tracks state during typechecking; 2 == loop detected
 	Local     bool  // type created in this file (see also Type.Local); TODO(gri): move this into flags
-	IsStatic  bool  // whether this Node will be converted to purely static data
 	Initorder uint8
 	Used      bool // for variable/label declared and not used error
 	Isddd     bool // is the argument variadic

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

@@ -145,9 +145,6 @@ func walkstmt(n *Node) *Node {
 	if n == nil {
 		return n
 	}
-	if n.IsStatic { // don't walk, generated by anylit.
-		return n
-	}
 
 	setlineno(n)
 
@@ -720,9 +717,7 @@ opswitch:
 		}
 
 		if n.Left != nil && n.Right != nil {
-			static := n.IsStatic
 			n = convas(n, init)
-			n.IsStatic = static
 		}
 
 	case OAS2: