cmd/compile: split TSLICE into separate Type kind

Instead of using TARRAY for both arrays and slices, create a new
TSLICE kind to handle slices.

Also, get rid of the "DDDArray" distinction. While kinda ugly, it
seems likely we'll need to defer evaluating the constant bounds
expressions for golang.org/issue/13890.

Passes toolstash/buildall.

Change-Id: I8e45d4900e7df3a04cce59428ec8b38035d3cc3a
Reviewed-on: https://go-review.googlesource.com/22329
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -127,11 +127,10 @@ func algtype1(t *Type) (AlgKind, *Type) {
 		}
 		return AINTER, nil
 
-	case TARRAY:
-		if t.IsSlice() {
-			return ANOEQ, t
-		}
+	case TSLICE:
+		return ANOEQ, t
 
+	case TARRAY:
 		a, bad := algtype1(t.Elem())
 		switch a {
 		case AMEM:
@@ -219,10 +218,6 @@ func genhash(sym *Sym, t *Type) {
 		Fatalf("genhash %v", t)
 
 	case TARRAY:
-		if t.IsSlice() {
-			Fatalf("genhash %v", t)
-		}
-
 		// An array of pure memory would be handled by the
 		// standard algorithm, so the element type must not be
 		// pure memory.
@@ -399,10 +394,6 @@ func geneq(sym *Sym, t *Type) {
 		Fatalf("geneq %v", t)
 
 	case TARRAY:
-		if t.IsSlice() {
-			Fatalf("geneq %v", t)
-		}
-
 		// An array of pure memory would be handled by the
 		// standard memequal, so the element type must not be
 		// pure memory. Even if we unrolled the range loop,

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

@@ -238,29 +238,31 @@ func dowidth(t *Type) {
 		if t.Elem() == nil {
 			break
 		}
-		if t.IsArray() {
-			dowidth(t.Elem())
-			if t.Elem().Width != 0 {
-				cap := (uint64(Thearch.MAXWIDTH) - 1) / uint64(t.Elem().Width)
-				if uint64(t.NumElem()) > cap {
-					Yyerror("type %v larger than address space", Tconv(t, FmtLong))
-				}
-			}
-
-			w = t.NumElem() * t.Elem().Width
-			t.Align = t.Elem().Align
-		} else if t.IsSlice() {
-			w = int64(sizeof_Array)
-			checkwidth(t.Elem())
-			t.Align = uint8(Widthptr)
-		} else if t.isDDDArray() {
+		if t.isDDDArray() {
 			if !t.Broke {
 				Yyerror("use of [...] array outside of array literal")
 				t.Broke = true
 			}
-		} else {
-			Fatalf("dowidth %v", t) // probably [...]T
+			break
+		}
+
+		dowidth(t.Elem())
+		if t.Elem().Width != 0 {
+			cap := (uint64(Thearch.MAXWIDTH) - 1) / uint64(t.Elem().Width)
+			if uint64(t.NumElem()) > cap {
+				Yyerror("type %v larger than address space", Tconv(t, FmtLong))
+			}
 		}
+		w = t.NumElem() * t.Elem().Width
+		t.Align = t.Elem().Align
+
+	case TSLICE:
+		if t.Elem() == nil {
+			break
+		}
+		w = int64(sizeof_Array)
+		checkwidth(t.Elem())
+		t.Align = uint8(Widthptr)
 
 	case TSTRUCT:
 		if t.IsFuncArgStruct() {

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

@@ -629,12 +629,12 @@ func (p *exporter) typ(t *Type) {
 		if t.isDDDArray() {
 			Fatalf("array bounds should be known at export time: %v", t)
 		}
-		if t.IsArray() {
-			p.tag(arrayTag)
-			p.int64(t.NumElem())
-		} else {
-			p.tag(sliceTag)
-		}
+		p.tag(arrayTag)
+		p.int64(t.NumElem())
+		p.typ(t.Elem())
+
+	case TSLICE:
+		p.tag(sliceTag)
 		p.typ(t.Elem())
 
 	case TDDDFIELD:

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

@@ -369,18 +369,16 @@ func (p *importer) typ() *Type {
 
 		dclcontext = savedContext
 
-	case arrayTag, sliceTag:
+	case arrayTag:
 		t = p.newtyp(TARRAY)
-		var bound int64
-		if i == arrayTag {
-			bound = p.int64()
-		}
+		bound := p.int64()
 		elem := p.typ()
-		if i == arrayTag {
-			t.Extra = &ArrayType{Elem: elem, Bound: bound}
-		} else {
-			t.Extra = SliceType{Elem: elem}
-		}
+		t.Extra = &ArrayType{Elem: elem, Bound: bound}
+
+	case sliceTag:
+		t = p.newtyp(TSLICE)
+		elem := p.typ()
+		t.Extra = SliceType{Elem: elem}
 
 	case dddTag:
 		t = p.newtyp(TDDDFIELD)

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

@@ -284,16 +284,15 @@ func convlit1(n *Node, t *Type, explicit bool, reuse canReuseNode) *Node {
 			return n
 
 		case TARRAY:
-			if !t.IsSlice() {
-				goto bad
-			}
+			goto bad
 
 		case TPTR32,
 			TPTR64,
 			TINTER,
 			TMAP,
 			TCHAN,
 			TFUNC,
+			TSLICE,
 			TUNSAFEPTR:
 			break
 

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

@@ -203,7 +203,7 @@ func reexportdep(n *Node) {
 		t := n.Type
 
 		switch t.Etype {
-		case TARRAY, TCHAN, TPTR32, TPTR64:
+		case TARRAY, TCHAN, TPTR32, TPTR64, TSLICE:
 			if t.Sym == nil {
 				t = t.Elem()
 			}
@@ -303,7 +303,7 @@ func dumpexporttype(t *Type) {
 	case TMAP:
 		dumpexporttype(t.Val())
 		dumpexporttype(t.Key())
-	case TARRAY, TCHAN, TPTR32, TPTR64:
+	case TARRAY, TCHAN, TPTR32, TPTR64, TSLICE:
 		dumpexporttype(t.Elem())
 	}
 

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

@@ -416,6 +416,7 @@ var etnames = []string{
 	TPTR64:      "PTR64",
 	TFUNC:       "FUNC",
 	TARRAY:      "ARRAY",
+	TSLICE:      "SLICE",
 	TSTRUCT:     "STRUCT",
 	TCHAN:       "CHAN",
 	TMAP:        "MAP",
@@ -587,12 +588,12 @@ func typefmt(t *Type, flag FmtFlag) string {
 		return "*" + t.Elem().String()
 
 	case TARRAY:
-		if t.IsArray() {
-			return fmt.Sprintf("[%d]%v", t.NumElem(), t.Elem())
-		}
 		if t.isDDDArray() {
 			return "[...]" + t.Elem().String()
 		}
+		return fmt.Sprintf("[%d]%v", t.NumElem(), t.Elem())
+
+	case TSLICE:
 		return "[]" + t.Elem().String()
 
 	case TCHAN:

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

@@ -1031,7 +1031,7 @@ func componentgen_wb(nr, nl *Node, wb bool) bool {
 		// Emit vardef if needed.
 		if nl.Op == ONAME {
 			switch nl.Type.Etype {
-			case TARRAY, TSTRING, TINTER, TSTRUCT:
+			case TARRAY, TSLICE, TSTRING, TINTER, TSTRUCT:
 				Gvardef(nl)
 			}
 		}
@@ -1204,13 +1204,12 @@ func visitComponents(t *Type, startOffset int64, f func(elem *Type, elemOffset i
 		return f(Ptrto(Types[TUINT8]), startOffset) &&
 			f(Types[Simtype[TUINT]], startOffset+int64(Widthptr))
 
-	case TARRAY:
-		if t.IsSlice() {
-			return f(Ptrto(t.Elem()), startOffset+int64(Array_array)) &&
-				f(Types[Simtype[TUINT]], startOffset+int64(Array_nel)) &&
-				f(Types[Simtype[TUINT]], startOffset+int64(Array_cap))
-		}
+	case TSLICE:
+		return f(Ptrto(t.Elem()), startOffset+int64(Array_array)) &&
+			f(Types[Simtype[TUINT]], startOffset+int64(Array_nel)) &&
+			f(Types[Simtype[TUINT]], startOffset+int64(Array_cap))
 
+	case TARRAY:
 		// Short-circuit [1e6]struct{}.
 		if t.Elem().Width == 0 {
 			return true

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

@@ -277,7 +277,7 @@ func gused(n *Node) {
 func Isfat(t *Type) bool {
 	if t != nil {
 		switch t.Etype {
-		case TSTRUCT, TARRAY, TSTRING,
+		case TSTRUCT, TARRAY, TSLICE, TSTRING,
 			TINTER: // maybe remove later
 			return true
 		}

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

@@ -731,7 +731,7 @@ func orderstmt(n *Node, order *Order) {
 		default:
 			Fatalf("orderstmt range %v", n.Type)
 
-		case TARRAY:
+		case TARRAY, TSLICE:
 			if n.List.Len() < 2 || isblank(n.List.Second()) {
 				// for i := range x will only use x once, to compute len(x).
 				// No need to copy it.

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

@@ -918,18 +918,17 @@ func onebitwalktype1(t *Type, xoffset *int64, bv Bvec) {
 		bvset(bv, int32(*xoffset/int64(Widthptr)+1)) // pointer in second slot
 		*xoffset += t.Width
 
+	case TSLICE:
+		// struct { byte *array; uintgo len; uintgo cap; }
+		if *xoffset&int64(Widthptr-1) != 0 {
+			Fatalf("onebitwalktype1: invalid TARRAY alignment, %v", t)
+		}
+		bvset(bv, int32(*xoffset/int64(Widthptr))) // pointer in first slot (BitsPointer)
+		*xoffset += t.Width
+
 	case TARRAY:
-		if t.IsSlice() {
-			// struct { byte *array; uintgo len; uintgo cap; }
-			if *xoffset&int64(Widthptr-1) != 0 {
-				Fatalf("onebitwalktype1: invalid TARRAY alignment, %v", t)
-			}
-			bvset(bv, int32(*xoffset/int64(Widthptr))) // pointer in first slot (BitsPointer)
-			*xoffset += t.Width
-		} else {
-			for i := int64(0); i < t.NumElem(); i++ {
-				onebitwalktype1(t.Elem(), xoffset, bv)
-			}
+		for i := int64(0); i < t.NumElem(); i++ {
+			onebitwalktype1(t.Elem(), xoffset, bv)
 		}
 
 	case TSTRUCT:

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

@@ -49,7 +49,7 @@ func typecheckrange(n *Node) {
 		Yyerror("cannot range over %v", Nconv(n.Right, FmtLong))
 		goto out
 
-	case TARRAY:
+	case TARRAY, TSLICE:
 		t1 = Types[TINT]
 		t2 = t.Elem()
 
@@ -164,7 +164,7 @@ func walkrange(n *Node) {
 	default:
 		Fatalf("walkrange")
 
-	case TARRAY:
+	case TARRAY, TSLICE:
 		if memclrrange(n, v1, v2, a) {
 			lineno = lno
 			return