[dev.regabi] cmd/compile: add ir.Closure, ir.ClosureRead

Closures are another reference to Funcs,
and it cleans up the code quite a bit to be clear about types.

OCLOSUREVAR is renamed to OCLOSUREREAD to make
clearer that it is unrelated to the list Func.ClosureVars.

Passes buildall w/ toolstash -cmp.

Change-Id: Id0d28df2d4d6e9954e34df7a39ea226995eee937
Reviewed-on: https://go-review.googlesource.com/c/go/+/274098
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -23,8 +23,7 @@ func (p *noder) funcLit(expr *syntax.FuncLit) ir.Node {
 	fn.Nname.Ntype = xtype
 	fn.Nname.Defn = fn
 
-	clo := p.nod(expr, ir.OCLOSURE, nil, nil)
+	clo := ir.NewClosureExpr(p.pos(expr), fn)
-	clo.SetFunc(fn)
 	fn.ClosureType = ntype
 	fn.OClosure = clo
 
@@ -285,21 +284,19 @@ func transformclosure(fn *ir.Func) {
 		offset := int64(Widthptr)
 		for _, v := range fn.ClosureVars {
 			// cv refers to the field inside of closure OSTRUCTLIT.
-			cv := ir.Nod(ir.OCLOSUREVAR, nil, nil)
+			typ := v.Type()
-
-			cv.SetType(v.Type())
 			if !v.Byval() {
-				cv.SetType(types.NewPtr(v.Type()))
+				typ = types.NewPtr(typ)
 			}
-			offset = Rnd(offset, int64(cv.Type().Align))
+			offset = Rnd(offset, int64(typ.Align))
-			cv.SetOffset(offset)
+			cr := ir.NewClosureRead(typ, offset)
-			offset += cv.Type().Width
+			offset += typ.Width
 
 			if v.Byval() && v.Type().Width <= int64(2*Widthptr) {
 				// If it is a small variable captured by value, downgrade it to PAUTO.
 				v.SetClass(ir.PAUTO)
 				fn.Dcl = append(fn.Dcl, v)
-				body = append(body, ir.Nod(ir.OAS, v, cv))
+				body = append(body, ir.Nod(ir.OAS, v, cr))
 			} else {
 				// Declare variable holding addresses taken from closure
 				// and initialize in entry prologue.
@@ -310,10 +307,11 @@ func transformclosure(fn *ir.Func) {
 				addr.Curfn = fn
 				fn.Dcl = append(fn.Dcl, addr)
 				v.Heapaddr = addr
+				var src ir.Node = cr
 				if v.Byval() {
-					cv = ir.Nod(ir.OADDR, cv, nil)
+					src = ir.Nod(ir.OADDR, cr, nil)
 				}
-				body = append(body, ir.Nod(ir.OAS, addr, cv))
+				body = append(body, ir.Nod(ir.OAS, addr, src))
 			}
 		}
 
@@ -473,21 +471,17 @@ func makepartialcall(dot ir.Node, t0 *types.Type, meth *types.Sym) *ir.Func {
 	tfn.Type().SetPkg(t0.Pkg())
 
 	// Declare and initialize variable holding receiver.
-
+	cr := ir.NewClosureRead(rcvrtype, Rnd(int64(Widthptr), int64(rcvrtype.Align)))
-	cv := ir.Nod(ir.OCLOSUREVAR, nil, nil)
-	cv.SetType(rcvrtype)
-	cv.SetOffset(Rnd(int64(Widthptr), int64(cv.Type().Align)))
-
 	ptr := NewName(lookup(".this"))
 	declare(ptr, ir.PAUTO)
 	ptr.SetUsed(true)
 	var body []ir.Node
 	if rcvrtype.IsPtr() || rcvrtype.IsInterface() {
 		ptr.SetType(rcvrtype)
-		body = append(body, ir.Nod(ir.OAS, ptr, cv))
+		body = append(body, ir.Nod(ir.OAS, ptr, cr))
 	} else {
 		ptr.SetType(types.NewPtr(rcvrtype))
-		body = append(body, ir.Nod(ir.OAS, ptr, ir.Nod(ir.OADDR, cv, nil)))
+		body = append(body, ir.Nod(ir.OAS, ptr, ir.Nod(ir.OADDR, cr, nil)))
 	}
 
 	call := ir.Nod(ir.OCALL, nodSym(ir.OXDOT, ptr, meth), nil)

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

@@ -486,7 +486,7 @@ func (e *Escape) exprSkipInit(k EscHole, n ir.Node) {
 	default:
 		base.Fatalf("unexpected expr: %v", n)
 
-	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OCLOSUREVAR, ir.OTYPE, ir.OMETHEXPR:
+	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OCLOSUREREAD, ir.OTYPE, ir.OMETHEXPR:
 		// nop
 
 	case ir.ONAME:
@@ -1718,7 +1718,7 @@ func mayAffectMemory(n ir.Node) bool {
 	// We're ignoring things like division by zero, index out of range,
 	// and nil pointer dereference here.
 	switch n.Op() {
-	case ir.ONAME, ir.OCLOSUREVAR, ir.OLITERAL, ir.ONIL:
+	case ir.ONAME, ir.OCLOSUREREAD, ir.OLITERAL, ir.ONIL:
 		return false
 
 	// Left+Right group.

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

@@ -963,7 +963,7 @@ func mkinlcall(n ir.Node, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]bool)
 
 	// Handle captured variables when inlining closures.
 	if c := fn.OClosure; c != nil {
-		for _, v := range c.Func().ClosureVars {
+		for _, v := range fn.ClosureVars {
 			if v.Op() == ir.OXXX {
 				continue
 			}
@@ -973,7 +973,7 @@ func mkinlcall(n ir.Node, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]bool)
 			// NB: if we enabled inlining of functions containing OCLOSURE or refined
 			// the reassigned check via some sort of copy propagation this would most
 			// likely need to be changed to a loop to walk up to the correct Param
-			if o == nil || (o.Curfn != Curfn && o.Curfn.OClosure != Curfn) {
+			if o == nil || o.Curfn != Curfn {
 				base.Fatalf("%v: unresolvable capture %v %v\n", ir.Line(n), fn, v)
 			}
 

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

@@ -2025,7 +2025,7 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 		}
 		addr := s.addr(n)
 		return s.load(n.Type(), addr)
-	case ir.OCLOSUREVAR:
+	case ir.OCLOSUREREAD:
 		addr := s.addr(n)
 		return s.load(n.Type(), addr)
 	case ir.ONIL:
@@ -4895,7 +4895,7 @@ func (s *state) addr(n ir.Node) *ssa.Value {
 	case ir.ODOTPTR:
 		p := s.exprPtr(n.Left(), n.Bounded(), n.Pos())
 		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
-	case ir.OCLOSUREVAR:
+	case ir.OCLOSUREREAD:
 		return s.newValue1I(ssa.OpOffPtr, t, n.Offset(),
 			s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr))
 	case ir.OCONVNOP:

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

@@ -1948,7 +1948,7 @@ func typecheck1(n ir.Node, top int) (res ir.Node) {
 			n.SetType(types.NewPtr(t.Elem()))
 		}
 
-	case ir.OCLOSUREVAR:
+	case ir.OCLOSUREREAD:
 		ok |= ctxExpr
 
 	case ir.OCFUNC:
@@ -3099,7 +3099,7 @@ func islvalue(n ir.Node) bool {
 			return false
 		}
 		fallthrough
-	case ir.ODEREF, ir.ODOTPTR, ir.OCLOSUREVAR:
+	case ir.ODEREF, ir.ODOTPTR, ir.OCLOSUREREAD:
 		return true
 
 	case ir.ODOT:
@@ -3186,7 +3186,7 @@ func samesafeexpr(l ir.Node, r ir.Node) bool {
 	}
 
 	switch l.Op() {
-	case ir.ONAME, ir.OCLOSUREVAR:
+	case ir.ONAME, ir.OCLOSUREREAD:
 		return l == r
 
 	case ir.ODOT, ir.ODOTPTR:

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

@@ -555,7 +555,7 @@ opswitch:
 	case ir.ORECOVER:
 		n = mkcall("gorecover", n.Type(), init, ir.Nod(ir.OADDR, nodfp, nil))
 
-	case ir.OCLOSUREVAR, ir.OCFUNC:
+	case ir.OCLOSUREREAD, ir.OCFUNC:
 
 	case ir.OCALLINTER, ir.OCALLFUNC, ir.OCALLMETH:
 		if n.Op() == ir.OCALLINTER {

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

@@ -6,6 +6,8 @@ package ir
 
 import (
 	"cmd/compile/internal/types"
+	"cmd/internal/src"
+	"fmt"
 )
 
 // A miniStmt is a miniNode with extra fields common to expressions.
@@ -45,3 +47,40 @@ func (n *miniExpr) SetBounded(b bool)     { n.flags.set(miniExprBounded, b) }
 func (n *miniExpr) Init() Nodes           { return n.init }
 func (n *miniExpr) PtrInit() *Nodes       { return &n.init }
 func (n *miniExpr) SetInit(x Nodes)       { n.init = x }
+
+// A ClosureExpr is a function literal expression.
+type ClosureExpr struct {
+	miniExpr
+	fn *Func
+}
+
+func NewClosureExpr(pos src.XPos, fn *Func) *ClosureExpr {
+	n := &ClosureExpr{fn: fn}
+	n.op = OCLOSURE
+	n.pos = pos
+	return n
+}
+
+func (n *ClosureExpr) String() string                { return fmt.Sprint(n) }
+func (n *ClosureExpr) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
+func (n *ClosureExpr) RawCopy() Node                 { c := *n; return &c }
+func (n *ClosureExpr) Func() *Func                   { return n.fn }
+
+// A ClosureRead denotes reading a variable stored within a closure struct.
+type ClosureRead struct {
+	miniExpr
+	offset int64
+}
+
+func NewClosureRead(typ *types.Type, offset int64) *ClosureRead {
+	n := &ClosureRead{offset: offset}
+	n.typ = typ
+	n.op = OCLOSUREREAD
+	return n
+}
+
+func (n *ClosureRead) String() string                { return fmt.Sprint(n) }
+func (n *ClosureRead) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }
+func (n *ClosureRead) RawCopy() Node                 { c := *n; return &c }
+func (n *ClosureRead) Type() *types.Type             { return n.typ }
+func (n *ClosureRead) Offset() int64                 { return n.offset }

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

@@ -53,8 +53,8 @@ type Func struct {
 	body Nodes
 	iota int64
 
-	Nname    *Name // ONAME node
+	Nname    *Name        // ONAME node
-	OClosure Node  // OCLOSURE node
+	OClosure *ClosureExpr // OCLOSURE node
 
 	Shortname *types.Sym
 

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

@@ -601,20 +601,20 @@ const (
 	OTARRAY // []int, [8]int, [N]int or [...]int
 
 	// misc
-	ODDD        // func f(args ...int) or f(l...) or var a = [...]int{0, 1, 2}.
+	ODDD         // func f(args ...int) or f(l...) or var a = [...]int{0, 1, 2}.
-	OINLCALL    // intermediary representation of an inlined call.
+	OINLCALL     // intermediary representation of an inlined call.
-	OEFACE      // itable and data words of an empty-interface value.
+	OEFACE       // itable and data words of an empty-interface value.
-	OITAB       // itable word of an interface value.
+	OITAB        // itable word of an interface value.
-	OIDATA      // data word of an interface value in Left
+	OIDATA       // data word of an interface value in Left
-	OSPTR       // base pointer of a slice or string.
+	OSPTR        // base pointer of a slice or string.
-	OCLOSUREVAR // variable reference at beginning of closure function
+	OCLOSUREREAD // read from inside closure struct at beginning of closure function
-	OCFUNC      // reference to c function pointer (not go func value)
+	OCFUNC       // reference to c function pointer (not go func value)
-	OCHECKNIL   // emit code to ensure pointer/interface not nil
+	OCHECKNIL    // emit code to ensure pointer/interface not nil
-	OVARDEF     // variable is about to be fully initialized
+	OVARDEF      // variable is about to be fully initialized
-	OVARKILL    // variable is dead
+	OVARKILL     // variable is dead
-	OVARLIVE    // variable is alive
+	OVARLIVE     // variable is alive
-	ORESULT     // result of a function call; Xoffset is stack offset
+	ORESULT      // result of a function call; Xoffset is stack offset
-	OINLMARK    // start of an inlined body, with file/line of caller. Xoffset is an index into the inline tree.
+	OINLMARK     // start of an inlined body, with file/line of caller. Xoffset is an index into the inline tree.
 
 	// arch-specific opcodes
 	ORETJMP // return to other function
@@ -1162,8 +1162,6 @@ var okForNod = [OEND]bool{
 	OCFUNC:         true,
 	OCHECKNIL:      true,
 	OCLOSE:         true,
-	OCLOSURE:       true,
-	OCLOSUREVAR:    true,
 	OCOMPLEX:       true,
 	OCOMPLIT:       true,
 	OCONV:          true,

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

@@ -152,7 +152,7 @@ func _() {
 	_ = x[OITAB-141]
 	_ = x[OIDATA-142]
 	_ = x[OSPTR-143]
-	_ = x[OCLOSUREVAR-144]
+	_ = x[OCLOSUREREAD-144]
 	_ = x[OCFUNC-145]
 	_ = x[OCHECKNIL-146]
 	_ = x[OVARDEF-147]
@@ -165,9 +165,9 @@ func _() {
 	_ = x[OEND-154]
 }
 
-const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCALLPARTCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLFIELDDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNEWOBJNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECVRUNESTRSELRECVSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFMETHEXPRBLOCKBREAKCASECONTINUEDEFEREMPTYFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWTCHANTMAPTSTRUCTTINTERTFUNCTARRAYDDDINLCALLEFACEITABIDATASPTRCLOSUREVARCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKRETJMPGETGEND"
+const _Op_name = "XXXNAMENONAMETYPEPACKLITERALNILADDSUBORXORADDSTRADDRANDANDAPPENDBYTES2STRBYTES2STRTMPRUNES2STRSTR2BYTESSTR2BYTESTMPSTR2RUNESASAS2AS2DOTTYPEAS2FUNCAS2MAPRAS2RECVASOPCALLCALLFUNCCALLMETHCALLINTERCALLPARTCAPCLOSECLOSURECOMPLITMAPLITSTRUCTLITARRAYLITSLICELITPTRLITCONVCONVIFACECONVNOPCOPYDCLDCLFUNCDCLFIELDDCLCONSTDCLTYPEDELETEDOTDOTPTRDOTMETHDOTINTERXDOTDOTTYPEDOTTYPE2EQNELTLEGEGTDEREFINDEXINDEXMAPKEYSTRUCTKEYLENMAKEMAKECHANMAKEMAPMAKESLICEMAKESLICECOPYMULDIVMODLSHRSHANDANDNOTNEWNEWOBJNOTBITNOTPLUSNEGORORPANICPRINTPRINTNPARENSENDSLICESLICEARRSLICESTRSLICE3SLICE3ARRSLICEHEADERRECOVERRECVRUNESTRSELRECVSELRECV2IOTAREALIMAGCOMPLEXALIGNOFOFFSETOFSIZEOFMETHEXPRBLOCKBREAKCASECONTINUEDEFEREMPTYFALLFORFORUNTILGOTOIFLABELGORANGERETURNSELECTSWITCHTYPESWTCHANTMAPTSTRUCTTINTERTFUNCTARRAYDDDINLCALLEFACEITABIDATASPTRCLOSUREREADCFUNCCHECKNILVARDEFVARKILLVARLIVERESULTINLMARKRETJMPGETGEND"
 
-var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 126, 129, 139, 146, 153, 160, 164, 168, 176, 184, 193, 201, 204, 209, 216, 223, 229, 238, 246, 254, 260, 264, 273, 280, 284, 287, 294, 302, 310, 317, 323, 326, 332, 339, 347, 351, 358, 366, 368, 370, 372, 374, 376, 378, 383, 388, 396, 399, 408, 411, 415, 423, 430, 439, 452, 455, 458, 461, 464, 467, 470, 476, 479, 485, 488, 494, 498, 501, 505, 510, 515, 521, 526, 530, 535, 543, 551, 557, 566, 577, 584, 588, 595, 602, 610, 614, 618, 622, 629, 636, 644, 650, 658, 663, 668, 672, 680, 685, 690, 694, 697, 705, 709, 711, 716, 718, 723, 729, 735, 741, 747, 752, 756, 763, 769, 774, 780, 783, 790, 795, 799, 804, 808, 818, 823, 831, 837, 844, 851, 857, 864, 870, 874, 877}
+var _Op_index = [...]uint16{0, 3, 7, 13, 17, 21, 28, 31, 34, 37, 39, 42, 48, 52, 58, 64, 73, 85, 94, 103, 115, 124, 126, 129, 139, 146, 153, 160, 164, 168, 176, 184, 193, 201, 204, 209, 216, 223, 229, 238, 246, 254, 260, 264, 273, 280, 284, 287, 294, 302, 310, 317, 323, 326, 332, 339, 347, 351, 358, 366, 368, 370, 372, 374, 376, 378, 383, 388, 396, 399, 408, 411, 415, 423, 430, 439, 452, 455, 458, 461, 464, 467, 470, 476, 479, 485, 488, 494, 498, 501, 505, 510, 515, 521, 526, 530, 535, 543, 551, 557, 566, 577, 584, 588, 595, 602, 610, 614, 618, 622, 629, 636, 644, 650, 658, 663, 668, 672, 680, 685, 690, 694, 697, 705, 709, 711, 716, 718, 723, 729, 735, 741, 747, 752, 756, 763, 769, 774, 780, 783, 790, 795, 799, 804, 808, 819, 824, 832, 838, 845, 852, 858, 865, 871, 875, 878}
 
 func (i Op) String() string {
 	if i >= Op(len(_Op_index)-1) {

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

@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 172, 296},
+		{Func{}, 168, 288},
 		{Name{}, 128, 224},
 		{node{}, 84, 144},
 	}