diff --git a/chore/gentests/gentests.go b/chore/gentests/gentests.go
index 66f31ce2..576a2aee 100644
--- a/chore/gentests/gentests.go
+++ b/chore/gentests/gentests.go
@@ -34,6 +34,7 @@ func main() {
 	llgen.Verbose = false
 
 	llgenDir(dir + "/cl/_testlibc")
+	llgenDir(dir + "/cl/_testlibgo")
 	llgenDir(dir + "/cl/_testrt")
 	llgenDir(dir + "/cl/_testgo")
 	llgenDir(dir+"/cl/_testpy", "")
diff --git a/cl/_testlibgo/math/in.go b/cl/_testlibgo/math/in.go
new file mode 100644
index 00000000..2b07ec66
--- /dev/null
+++ b/cl/_testlibgo/math/in.go
@@ -0,0 +1,9 @@
+package main
+
+import (
+	"math/bits"
+)
+
+func main() {
+	println(bits.Len8(20))
+}
diff --git a/cl/_testlibgo/math/out.ll b/cl/_testlibgo/math/out.ll
new file mode 100644
index 00000000..ab803b48
--- /dev/null
+++ b/cl/_testlibgo/math/out.ll
@@ -0,0 +1,42 @@
+; ModuleID = 'main'
+source_filename = "main"
+
+@"main.init$guard" = global ptr null
+@__llgo_argc = global ptr null
+@__llgo_argv = global ptr null
+
+define void @main.init() {
+_llgo_0:
+  %0 = load i1, ptr @"main.init$guard", align 1
+  br i1 %0, label %_llgo_2, label %_llgo_1
+
+_llgo_1:                                          ; preds = %_llgo_0
+  store i1 true, ptr @"main.init$guard", align 1
+  call void @"math/bits.init"()
+  br label %_llgo_2
+
+_llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
+  ret void
+}
+
+define i32 @main(i32 %0, ptr %1) {
+_llgo_0:
+  store i32 %0, ptr @__llgo_argc, align 4
+  store ptr %1, ptr @__llgo_argv, align 8
+  call void @"github.com/goplus/llgo/internal/runtime.init"()
+  call void @main.init()
+  %2 = call i64 @"math/bits.Len8"(i8 20)
+  call void @"github.com/goplus/llgo/internal/runtime.PrintInt"(i64 %2)
+  call void @"github.com/goplus/llgo/internal/runtime.PrintByte"(i8 10)
+  ret i32 0
+}
+
+declare void @"math/bits.init"()
+
+declare void @"github.com/goplus/llgo/internal/runtime.init"()
+
+declare i64 @"math/bits.Len8"(i8)
+
+declare void @"github.com/goplus/llgo/internal/runtime.PrintInt"(i64)
+
+declare void @"github.com/goplus/llgo/internal/runtime.PrintByte"(i8)
diff --git a/cl/compile.go b/cl/compile.go
index 970589ce..e71609dc 100644
--- a/cl/compile.go
+++ b/cl/compile.go
@@ -192,7 +192,7 @@ func (p *context) compileMethods(pkg llssa.Package, typ types.Type) {
 // Global variable.
 func (p *context) compileGlobal(pkg llssa.Package, gbl *ssa.Global) {
 	typ := gbl.Type()
-	name, vtype := p.varName(gbl.Pkg.Pkg, gbl)
+	name, vtype, define := p.varName(gbl.Pkg.Pkg, gbl)
 	if vtype == pyVar || ignoreName(name) || checkCgo(gbl.Name()) {
 		return
 	}
@@ -200,7 +200,7 @@ func (p *context) compileGlobal(pkg llssa.Package, gbl *ssa.Global) {
 		log.Println("==> NewVar", name, typ)
 	}
 	g := pkg.NewVar(name, typ, llssa.Background(vtype))
-	if vtype == goVar {
+	if define {
 		g.Init(p.prog.Nil(g.Type))
 	}
 }
diff --git a/cl/compile_test.go b/cl/compile_test.go
index 130d6d6b..d1126f86 100644
--- a/cl/compile_test.go
+++ b/cl/compile_test.go
@@ -36,6 +36,10 @@ func TestFromTestpy(t *testing.T) {
 	cltest.FromDir(t, "", "./_testpy", false)
 }
 
+func TestFromTestlibgo(t *testing.T) {
+	cltest.FromDir(t, "", "./_testlibgo", true)
+}
+
 func TestFromTestlibc(t *testing.T) {
 	cltest.FromDir(t, "", "./_testlibc", true)
 }
diff --git a/cl/import.go b/cl/import.go
index 9b3c7831..a79144d6 100644
--- a/cl/import.go
+++ b/cl/import.go
@@ -356,24 +356,24 @@ const (
 	pyVar      = int(llssa.InPython)
 )
 
-func (p *context) varName(pkg *types.Package, v *ssa.Global) (vName string, vtype int) {
+func (p *context) varName(pkg *types.Package, v *ssa.Global) (vName string, vtype int, define bool) {
 	name := llssa.FullName(pkg, v.Name())
 	if v, ok := p.link[name]; ok {
 		if pos := strings.IndexByte(v, '.'); pos >= 0 {
 			if pos == 2 && v[0] == 'p' && v[1] == 'y' {
-				return v[3:], pyVar
+				return v[3:], pyVar, false
 			}
-			return replaceGoName(v, pos), goVar
+			return replaceGoName(v, pos), goVar, false
 		}
-		return v, cVar
+		return v, cVar, false
 	}
-	return name, goVar
+	return name, goVar, true
 }
 
 func (p *context) varOf(b llssa.Builder, v *ssa.Global) llssa.Expr {
 	pkgTypes := p.ensureLoaded(v.Pkg.Pkg)
 	pkg := p.pkg
-	name, vtype := p.varName(pkgTypes, v)
+	name, vtype, _ := p.varName(pkgTypes, v)
 	if vtype == pyVar {
 		if kind, mod := pkgKindByScope(pkgTypes.Scope()); kind == PkgPyModule {
 			return b.PyNewVar(pysymPrefix+mod, name).Expr
diff --git a/internal/runtime/panic.go b/internal/runtime/panic.go
index d252be26..1d90e032 100644
--- a/internal/runtime/panic.go
+++ b/internal/runtime/panic.go
@@ -218,6 +218,10 @@ func panicSlice3CU(x uint, y int)
 func panicSliceConvert(x int, y int)
 */
 
+var divideError error
+var overflowError error
+
+/* TODO(xsw):
 var shiftError = error(errorString("negative shift amount"))
 
 func Panicshift() {