Fix type width for pointer types

tgo.go

@@ -34,6 +34,7 @@ type Compiler struct {
 	ctx             llvm.Context
 	builder         llvm.Builder
 	machine         llvm.TargetMachine
+	targetData      llvm.TargetData
 	intType         llvm.Type
 	stringLenType   llvm.Type
 	stringType      llvm.Type
@@ -73,6 +74,7 @@ func NewCompiler(pkgName, triple string) (*Compiler, error) {
 		return nil, err
 	}
 	c.machine = target.CreateTargetMachine(triple, "", "", llvm.CodeGenLevelDefault, llvm.RelocDefault, llvm.CodeModelDefault)
+	c.targetData = c.machine.CreateTargetData()
 
 	c.mod = llvm.NewModule(pkgName)
 	c.ctx = c.mod.Context()
@@ -269,6 +271,26 @@ func (c *Compiler) getLLVMType(goType types.Type) (llvm.Type, error) {
 	}
 }
 
+func (c *Compiler) getTypeWidth(typ types.Type) (int, error) {
+	switch typ := typ.(type) {
+	case *types.Basic:
+		if typ.Kind() == types.UnsafePointer {
+			return c.targetData.PointerSize(), nil
+		}
+		llvmType, err := c.getLLVMType(typ)
+		if err != nil {
+			return 0, err
+		}
+		return llvmType.IntTypeWidth(), nil
+	case *types.Named:
+		return c.getTypeWidth(typ.Underlying())
+	case *types.Pointer:
+		return c.targetData.PointerSize(), nil
+	default:
+		return 0, errors.New("todo: type width")
+	}
+}
+
 func (c *Compiler) getInterfaceType(typ types.Type) llvm.Value {
 	if _, ok := c.itfTypeNumbers[typ]; !ok {
 		num := uint64(len(c.itfTypes))
@@ -716,7 +738,7 @@ func (c *Compiler) parseConvert(frame *Frame, expr *ssa.Convert) (llvm.Value, er
 		return value, nil
 	}
 
-	typeFrom, err := c.getLLVMType(expr.X.Type())
+	sizeFrom, err := c.getTypeWidth(expr.X.Type())
 	if err != nil {
 		return llvm.Value{}, err
 	}
@@ -724,11 +746,15 @@ func (c *Compiler) parseConvert(frame *Frame, expr *ssa.Convert) (llvm.Value, er
 	if err != nil {
 		return llvm.Value{}, err
 	}
-	sizeFrom := typeFrom.IntTypeWidth()
-	sizeTo := typeTo.IntTypeWidth()
+	sizeTo, err := c.getTypeWidth(expr.Type())
+	if err != nil {
+		return llvm.Value{}, err
+	}
 
-	if sizeFrom >= sizeTo {
-		return c.builder.CreateTruncOrBitCast(value, typeTo, ""), nil
+	if sizeFrom > sizeTo {
+		return c.builder.CreateTrunc(value, typeTo, ""), nil
+	} else if sizeFrom == sizeTo {
+		return c.builder.CreateBitCast(value, typeTo, ""), nil
 	} else { // sizeFrom < sizeTo: extend
 		switch typ := expr.X.Type().(type) { // typeFrom
 		case *types.Basic: