diff --git a/cl/_testcgo/sum/out.ll b/cl/_testcgo/sum/out.ll
index e69de29b..7a8cda47 100644
--- a/cl/_testcgo/sum/out.ll
+++ b/cl/_testcgo/sum/out.ll
@@ -0,0 +1,68 @@
+; ModuleID = 'main'
+source_filename = "main"
+
+%"github.com/goplus/llgo/internal/runtime.Slice" = type { ptr, i64, i64 }
+
+@"main.init$guard" = global ptr null
+@0 = private unnamed_addr constant [10 x i8] c"Hello %d\0A\00", align 1
+
+define void @main.init() {
+_llgo_0:
+  %0 = load i1, ptr @"main.init$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
+  br label %_llgo_2
+
+_llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
+  ret void
+}
+
+define void @main() {
+_llgo_0:
+  call void @main.init()
+  %0 = call ptr @"github.com/goplus/llgo/internal/runtime.Alloc"(i64 16)
+  %1 = getelementptr inbounds i64, ptr %0, i64 0
+  store i64 1, ptr %1, align 4
+  %2 = getelementptr inbounds i64, ptr %0, i64 1
+  store i64 2, ptr %2, align 4
+  %3 = getelementptr inbounds i64, ptr %0, i64 2
+  store i64 3, ptr %3, align 4
+  %4 = getelementptr inbounds i64, ptr %0, i64 3
+  store i64 4, ptr %4, align 4
+  %5 = call %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.NewSlice"(i64 4, i64 4)
+  %6 = call i64 @main.sum(%"github.com/goplus/llgo/internal/runtime.Slice" %5)
+  %7 = call i32 (ptr, ...) @printf(ptr @0, i64 %6)
+  ret void
+}
+
+define i64 @main.sum(%"github.com/goplus/llgo/internal/runtime.Slice" %0) {
+_llgo_0:
+  %1 = call i64 @"github.com/goplus/llgo/internal/runtime.SliceLen"(%"github.com/goplus/llgo/internal/runtime.Slice" %0)
+  br label %_llgo_1
+
+_llgo_1:                                          ; preds = %_llgo_2, %_llgo_0
+  %2 = phi i64 [ 0, %_llgo_0 ], [ %8, %_llgo_2 ]
+  %3 = phi i64 [ -1, %_llgo_0 ], [ %4, %_llgo_2 ]
+  %4 = add i64 %3, 1
+  %5 = icmp slt i64 %4, %1
+  br i1 %5, label %_llgo_2, label %_llgo_3
+
+_llgo_2:                                          ; preds = %_llgo_1
+  %6 = getelementptr inbounds i64, %"github.com/goplus/llgo/internal/runtime.Slice" %0, i64 %4
+  %7 = load i64, %"github.com/goplus/llgo/internal/runtime.Slice" %6, align 4
+  %8 = add i64 %2, %7
+  br label %_llgo_1
+
+_llgo_3:                                          ; preds = %_llgo_1
+  ret i64 %2
+}
+
+declare ptr @"github.com/goplus/llgo/internal/runtime.Alloc"(i64)
+
+declare %"github.com/goplus/llgo/internal/runtime.Slice" @"github.com/goplus/llgo/internal/runtime.NewSlice"(ptr, i64, i64)
+
+declare i32 @printf(ptr, ...)
+
+declare i64 @"github.com/goplus/llgo/internal/runtime.SliceLen"(%"github.com/goplus/llgo/internal/runtime.Slice")
diff --git a/cl/compile_test.go b/cl/compile_test.go
index 69e8c287..62f7bedb 100644
--- a/cl/compile_test.go
+++ b/cl/compile_test.go
@@ -29,7 +29,7 @@ func testCompile(t *testing.T, src, expected string) {
 }
 
 func TestFromTestcgo(t *testing.T) {
-	cltest.FromDir(t, "sum", "./_testcgo", true)
+	cltest.FromDir(t, "", "./_testcgo", true)
 }
 
 func TestFromTestdata(t *testing.T) {
diff --git a/ssa/expr.go b/ssa/expr.go
index 9ad4ee15..c9f17005 100644
--- a/ssa/expr.go
+++ b/ssa/expr.go
@@ -137,9 +137,15 @@ func (b Builder) Const(v constant.Value, typ Type) Expr {
 		case kind == types.Bool:
 			return prog.BoolVal(constant.BoolVal(v))
 		case kind >= types.Int && kind <= types.Uintptr:
-			if v, exact := constant.Uint64Val(v); exact {
-				return prog.IntVal(v, typ)
+			if v, exact := constant.Int64Val(v); exact {
+				return prog.IntVal(uint64(v), typ)
 			}
+			panic("todo")
+			/*
+				if v, exact := constant.Uint64Val(v); exact {
+					return prog.IntVal(v, typ)
+				}
+			*/
 		case kind == types.Float32 || kind == types.Float64:
 			if v, exact := constant.Float64Val(v); exact {
 				return prog.FloatVal(v, typ)
@@ -148,7 +154,7 @@ func (b Builder) Const(v constant.Value, typ Type) Expr {
 			return prog.StringVal(constant.StringVal(v))
 		}
 	}
-	panic("todo")
+	panic(fmt.Sprintf("unsupported Const: %v, %v", v, typ.t))
 }
 
 // CStr returns a c-style string constant expression.