cmd/compile: rename ssa.Type's Elem method to ElemType

I would like to add a

    func (t *Type) Elem() *Type

method to package gc, but that would collide with the existing

    func (t *Type) Elem() ssa.Type

method needed to make *gc.Type implement ssa.Type.  Because the latter
is much less widely used right now than the former will be, this CL
renames it to ElemType.

Longer term, hopefully gc and ssa will share a common Type interface,
and ElemType can go away.

Change-Id: I270008515dc4c01ef531cf715637a924659c4735
Reviewed-on: https://go-review.googlesource.com/20546
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -1953,7 +1953,7 @@ func (s *state) expr(n *Node) *ssa.Value {
 		for !data.Type.IsPtr() {
 			switch {
 			case data.Type.IsArray():
-				data = s.newValue1I(ssa.OpArrayIndex, data.Type.Elem(), 0, data)
+				data = s.newValue1I(ssa.OpArrayIndex, data.Type.ElemType(), 0, data)
 			case data.Type.IsStruct():
 				for i := data.Type.NumFields() - 1; i >= 0; i-- {
 					f := data.Type.FieldType(i)

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

@@ -584,8 +584,12 @@ func (t *Type) IsInterface() bool {
 	return t.Etype == TINTER
 }
 
-func (t *Type) Elem() ssa.Type {
+func (t *Type) ElemType() ssa.Type {
-	return t.Type
+	switch t.Etype {
+	case TARRAY, TPTR32, TPTR64:
+		return t.Type
+	}
+	panic(fmt.Sprintf("ElemType on invalid type %v", t))
 }
 func (t *Type) PtrTo() ssa.Type {
 	return Ptrto(t)

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

@@ -88,7 +88,7 @@ func dse(f *Func) {
 					v.SetArgs1(v.Args[2])
 				} else {
 					// zero addr mem
-					sz := v.Args[0].Type.Elem().Size()
+					sz := v.Args[0].Type.ElemType().Size()
 					if v.AuxInt != sz {
 						f.Fatalf("mismatched zero/store sizes: %d and %d [%s]",
 							v.AuxInt, sz, v.LongString())

src/cmd/compile/internal/ssa/gen/generic.rules

@@ -417,8 +417,8 @@
 // indexing operations
 // Note: bounds check has already been done
 (ArrayIndex <t> [0] (Load ptr mem)) -> @v.Args[0].Block (Load <t> ptr mem)
-(PtrIndex <t> ptr idx) && config.PtrSize == 4 -> (AddPtr ptr (Mul32 <config.fe.TypeInt()> idx (Const32 <config.fe.TypeInt()> [t.Elem().Size()])))
+(PtrIndex <t> ptr idx) && config.PtrSize == 4 -> (AddPtr ptr (Mul32 <config.fe.TypeInt()> idx (Const32 <config.fe.TypeInt()> [t.ElemType().Size()])))
-(PtrIndex <t> ptr idx) && config.PtrSize == 8 -> (AddPtr ptr (Mul64 <config.fe.TypeInt()> idx (Const64 <config.fe.TypeInt()> [t.Elem().Size()])))
+(PtrIndex <t> ptr idx) && config.PtrSize == 8 -> (AddPtr ptr (Mul64 <config.fe.TypeInt()> idx (Const64 <config.fe.TypeInt()> [t.ElemType().Size()])))
 
 // struct operations
 (StructSelect (StructMake1 x)) -> x

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

@@ -5325,7 +5325,7 @@ func rewriteValuegeneric_OpPtrIndex(v *Value, config *Config) bool {
 	_ = b
 	// match: (PtrIndex <t> ptr idx)
 	// cond: config.PtrSize == 4
-	// result: (AddPtr ptr (Mul32 <config.fe.TypeInt()> idx (Const32 <config.fe.TypeInt()> [t.Elem().Size()])))
+	// result: (AddPtr ptr (Mul32 <config.fe.TypeInt()> idx (Const32 <config.fe.TypeInt()> [t.ElemType().Size()])))
 	for {
 		t := v.Type
 		ptr := v.Args[0]
@@ -5338,14 +5338,14 @@ func rewriteValuegeneric_OpPtrIndex(v *Value, config *Config) bool {
 		v0 := b.NewValue0(v.Line, OpMul32, config.fe.TypeInt())
 		v0.AddArg(idx)
 		v1 := b.NewValue0(v.Line, OpConst32, config.fe.TypeInt())
-		v1.AuxInt = t.Elem().Size()
+		v1.AuxInt = t.ElemType().Size()
 		v0.AddArg(v1)
 		v.AddArg(v0)
 		return true
 	}
 	// match: (PtrIndex <t> ptr idx)
 	// cond: config.PtrSize == 8
-	// result: (AddPtr ptr (Mul64 <config.fe.TypeInt()> idx (Const64 <config.fe.TypeInt()> [t.Elem().Size()])))
+	// result: (AddPtr ptr (Mul64 <config.fe.TypeInt()> idx (Const64 <config.fe.TypeInt()> [t.ElemType().Size()])))
 	for {
 		t := v.Type
 		ptr := v.Args[0]
@@ -5358,7 +5358,7 @@ func rewriteValuegeneric_OpPtrIndex(v *Value, config *Config) bool {
 		v0 := b.NewValue0(v.Line, OpMul64, config.fe.TypeInt())
 		v0.AddArg(idx)
 		v1 := b.NewValue0(v.Line, OpConst64, config.fe.TypeInt())
-		v1.AuxInt = t.Elem().Size()
+		v1.AuxInt = t.ElemType().Size()
 		v0.AddArg(v1)
 		v.AddArg(v0)
 		return true

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

@@ -28,8 +28,8 @@ type Type interface {
 	IsFlags() bool
 	IsVoid() bool
 
-	Elem() Type  // given []T or *T or [n]T, return T
+	ElemType() Type // given []T or *T or [n]T, return T
-	PtrTo() Type // given T, return *T
+	PtrTo() Type    // given T, return *T
 
 	NumFields() int64       // # of fields of a struct
 	FieldType(i int64) Type // type of ith field of the struct
@@ -71,7 +71,7 @@ func (t *CompilerType) IsFlags() bool          { return t.Flags }
 func (t *CompilerType) IsVoid() bool           { return t.Void }
 func (t *CompilerType) String() string         { return t.Name }
 func (t *CompilerType) SimpleString() string   { return t.Name }
-func (t *CompilerType) Elem() Type             { panic("not implemented") }
+func (t *CompilerType) ElemType() Type         { panic("not implemented") }
 func (t *CompilerType) PtrTo() Type            { panic("not implemented") }
 func (t *CompilerType) NumFields() int64       { panic("not implemented") }
 func (t *CompilerType) FieldType(i int64) Type { panic("not implemented") }

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

@@ -42,7 +42,7 @@ func (t *TypeImpl) IsFlags() bool          { return false }
 func (t *TypeImpl) IsVoid() bool           { return false }
 func (t *TypeImpl) String() string         { return t.Name }
 func (t *TypeImpl) SimpleString() string   { return t.Name }
-func (t *TypeImpl) Elem() Type             { return t.Elem_ }
+func (t *TypeImpl) ElemType() Type         { return t.Elem_ }
 func (t *TypeImpl) PtrTo() Type            { panic("not implemented") }
 func (t *TypeImpl) NumFields() int64       { panic("not implemented") }
 func (t *TypeImpl) FieldType(i int64) Type { panic("not implemented") }