LRValue.Indirect for following pointer values.

compiler/ast/lrvalue.go

@@ -79,6 +79,38 @@ func (lrv *LRValue) BasePtrInfo() *ssa.PtrInfo {
 	return lrv.baseInfo
 }
 
+// Indirect returns LRValue for the value that lrv points to. If lrv
+// is not a pointer, Indirect returns lrv.
+func (lrv *LRValue) Indirect() *LRValue {
+	v := lrv.RValue()
+	if v.Type.Type != types.TPtr {
+		return lrv
+	}
+
+	ret := *lrv
+	ret.valueType = *lrv.valueType.ElementType
+	ret.value.PtrInfo = nil
+
+	if lrv.baseInfo.ContainerType.Type == types.TStruct {
+		ret.value.Type = types.Undefined
+
+		// Lookup struct field.
+		ret.structField = nil
+		for _, f := range lrv.baseValue.Type.Struct {
+			if f.Type.Offset == lrv.baseInfo.Offset {
+				ret.structField = &f
+			}
+		}
+		if ret.structField == nil {
+			panic("LRValue.Indirect: could not find struct field")
+		}
+	} else {
+		ret.value.Type = *lrv.value.Type.ElementType
+	}
+
+	return &ret
+}
+
 // Set sets the l-value to rv.
 func (lrv LRValue) Set(rv ssa.Value) error {
 	if !ssa.CanAssign(lrv.valueType, rv) {
@@ -123,7 +155,7 @@ func (lrv LRValue) Set(rv ssa.Value) error {
 	// The l-value and r-value types are now resolved. Let's define
 	// the variable with correct type and value information,
 	// overriding any old values.
-	lrv.block.Bindings.Define(lValue, &rv)
+	lrv.baseInfo.Bindings.Define(lValue, &rv)
 
 	return nil
 }

compiler/ast/ssagen.go

@@ -1833,7 +1833,7 @@ func (ast *Slice) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 		return nil, nil, ctx.Errorf(ast, "invalid expression")
 	}
 	expr := exprs[0]
-	elementType := expr.Deref()
+	elementType := expr.IndirectType()
 	if !elementType.Type.Array() {
 		return nil, nil, ctx.Errorf(ast, "invalid operation: cannot slice %v",
 			expr.Type.Type)
@@ -2182,6 +2182,7 @@ func (ast *Copy) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 		if err != nil {
 			return nil, nil, ctx.Error(ast.Dst, err.Error())
 		}
+		lrv = lrv.Indirect()
 		dst = lrv.RValue()
 		if !dst.Type.Type.Array() {
 			return nil, nil, ast.errf(ctx, ast.Dst, "got %v", dst.Type)
@@ -2200,6 +2201,7 @@ func (ast *Copy) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 		if err != nil {
 			return nil, nil, ctx.Error(ast.Dst, err.Error())
 		}
+		lrv = lrv.Indirect()
 		dst = lrv.RValue()
 		if !dst.Type.Type.Array() {
 			return nil, nil, ast.errf(ctx, ast.Dst, "got %v", dst.Type)
@@ -2225,12 +2227,7 @@ func (ast *Copy) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 		return nil, nil, ast.errf(ctx, ast.Src, "got multivalue %T", ast.Src)
 	}
 	src := v[0]
-	var srcType types.Info
-	if src.Type.Type == types.TPtr {
-		srcType = *src.Type.ElementType
-	} else {
-		srcType = src.Type
-	}
+	srcType := src.IndirectType()
 	if !srcType.Type.Array() {
 		return nil, nil, ast.errf(ctx, ast.Src, "got %v", src.Type)
 	}
@@ -2262,7 +2259,7 @@ func (ast *Copy) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 		block.AddInstr(ssa.NewSliceInstr(src, fromConst, toConst, tmp))
 		err := lrv.Set(tmp)
 		if err != nil {
-			return nil, nil, err
+			return nil, nil, ctx.Error(ast, err.Error())
 		}
 	} else {
 		// Src overwrites part of dst.
@@ -2285,7 +2282,7 @@ func (ast *Copy) SSA(block *ssa.Block, ctx *Codegen, gen *ssa.Generator) (
 
 		err := lrv.Set(tmp2)
 		if err != nil {
-			return nil, nil, err
+			return nil, nil, ctx.Error(ast, err.Error())
 		}
 	}
 

compiler/ssa/value.go

@@ -75,9 +75,9 @@ func (v Value) Check() {
 	}
 }
 
-// Deref returns the pointer element type of the value. For
-// non-pointer values, this returns the value type itself.
-func (v Value) Deref() types.Info {
+// IndirectType returns the type that v points to. If v is not a
+// pointer, IndirectType returns the type of v.
+func (v Value) IndirectType() types.Info {
 	if v.Type.Type == types.TPtr {
 		return *v.Type.ElementType
 	}