diff --git a/build.rs b/build.rs
index e2a63a6..d7f6c01 100644
--- a/build.rs
+++ b/build.rs
@@ -129,6 +129,12 @@ mod tests {
             Divsf3,
             Divdf3,
 
+            // int/add.rs
+            AddU128,
+            AddI128,
+            AddoU128,
+            AddoI128,
+
             // int/mul.rs
             Muldi3,
             Mulodi4,
@@ -154,6 +160,12 @@ mod tests {
             Lshrdi3,
             Lshrti3,
 
+            // int/sub.rs
+            SubU128,
+            SubI128,
+            SuboU128,
+            SuboI128,
+
             // int/udiv.rs
             Udivdi3,
             Udivmoddi4,
@@ -341,6 +353,242 @@ fn addsf3() {
         }
     }
 
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct AddU128 {
+        a: u128,
+        b: u128,
+        c: u128,
+    }
+
+    impl TestCase for AddU128 {
+        fn name() -> &'static str {
+            "u128_add"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_u128(rng);
+            let b = gen_u128(rng);
+            let c = a.wrapping_add(b);
+
+            Some(AddU128 { a, b, c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::add::rust_u128_add;
+
+static TEST_CASES: &[((u128, u128), u128)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn u128_add() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = rust_u128_add(a, b);
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct AddI128 {
+        a: i128,
+        b: i128,
+        c: i128,
+    }
+
+    impl TestCase for AddI128 {
+        fn name() -> &'static str {
+            "i128_add"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_i128(rng);
+            let b = gen_i128(rng);
+            let c = a.wrapping_add(b);
+
+            Some(AddI128 { a, b, c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::add::rust_i128_add;
+
+static TEST_CASES: &[((i128, i128), i128)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn i128_add() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = rust_i128_add(a, b);
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct AddoU128 {
+        a: u128,
+        b: u128,
+        c: u128,
+        d: bool,
+    }
+
+    impl TestCase for AddoU128 {
+        fn name() -> &'static str {
+            "u128_addo"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_u128(rng);
+            let b = gen_u128(rng);
+            let (c, d) = a.overflowing_add(b);
+
+            Some(AddoU128 { a, b, c, d })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), ({c}, {d})),",
+                a = self.a,
+                b = self.b,
+                c = self.c,
+                d = self.d
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::add::rust_u128_addo;
+
+static TEST_CASES: &[((u128, u128), (u128, bool))] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn u128_addo() {
+    for &((a, b), (c, d)) in TEST_CASES {
+        let (c_, d_) = rust_u128_addo(a, b);
+        assert_eq!(((a, b), (c, d)), ((a, b), (c_, d_)));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct AddoI128 {
+        a: i128,
+        b: i128,
+        c: i128,
+        d: bool,
+    }
+
+    impl TestCase for AddoI128 {
+        fn name() -> &'static str {
+            "i128_addo"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_i128(rng);
+            let b = gen_i128(rng);
+            let (c, d) = a.overflowing_add(b);
+
+            Some(AddoI128 { a, b, c, d })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), ({c}, {d})),",
+                a = self.a,
+                b = self.b,
+                c = self.c,
+                d = self.d
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::add::rust_i128_addo;
+
+static TEST_CASES: &[((i128, i128), (i128, bool))] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn i128_addo() {
+    for &((a, b), (c, d)) in TEST_CASES {
+        let (c_, d_) = rust_i128_addo(a, b);
+        assert_eq!(((a, b), (c, d)), ((a, b), (c_, d_)));
+    }
+}
+"
+        }
+    }
+
     #[derive(Eq, Hash, PartialEq)]
     pub struct Ashldi3 {
         a: u64,
@@ -3229,6 +3477,242 @@ fn subsf3() {
         }
     }
 
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct SubU128 {
+        a: u128,
+        b: u128,
+        c: u128,
+    }
+
+    impl TestCase for SubU128 {
+        fn name() -> &'static str {
+            "u128_sub"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_u128(rng);
+            let b = gen_u128(rng);
+            let c = a.wrapping_sub(b);
+
+            Some(SubU128 { a, b, c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::sub::rust_u128_sub;
+
+static TEST_CASES: &[((u128, u128), u128)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn u128_sub() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = rust_u128_sub(a, b);
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct SubI128 {
+        a: i128,
+        b: i128,
+        c: i128,
+    }
+
+    impl TestCase for SubI128 {
+        fn name() -> &'static str {
+            "i128_sub"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_i128(rng);
+            let b = gen_i128(rng);
+            let c = a.wrapping_sub(b);
+
+            Some(SubI128 { a, b, c })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), {c}),",
+                a = self.a,
+                b = self.b,
+                c = self.c
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::sub::rust_i128_sub;
+
+static TEST_CASES: &[((i128, i128), i128)] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn i128_sub() {
+    for &((a, b), c) in TEST_CASES {
+        let c_ = rust_i128_sub(a, b);
+        assert_eq!(((a, b), c), ((a, b), c_));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct SuboU128 {
+        a: u128,
+        b: u128,
+        c: u128,
+        d: bool,
+    }
+
+    impl TestCase for SuboU128 {
+        fn name() -> &'static str {
+            "u128_subo"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_u128(rng);
+            let b = gen_u128(rng);
+            let (c, d) = a.overflowing_sub(b);
+
+            Some(SuboU128 { a, b, c, d })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), ({c}, {d})),",
+                a = self.a,
+                b = self.b,
+                c = self.c,
+                d = self.d
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::sub::rust_u128_subo;
+
+static TEST_CASES: &[((u128, u128), (u128, bool))] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn u128_subo() {
+    for &((a, b), (c, d)) in TEST_CASES {
+        let (c_, d_) = rust_u128_subo(a, b);
+        assert_eq!(((a, b), (c, d)), ((a, b), (c_, d_)));
+    }
+}
+"
+        }
+    }
+
+    #[derive(Eq, Hash, PartialEq)]
+    pub struct SuboI128 {
+        a: i128,
+        b: i128,
+        c: i128,
+        d: bool,
+    }
+
+    impl TestCase for SuboI128 {
+        fn name() -> &'static str {
+            "i128_subo"
+        }
+
+        fn generate<R>(rng: &mut R) -> Option<Self>
+        where
+            R: Rng,
+            Self: Sized,
+        {
+            let a = gen_i128(rng);
+            let b = gen_i128(rng);
+            let (c, d) = a.overflowing_sub(b);
+
+            Some(SuboI128 { a, b, c, d })
+        }
+
+        fn to_string(&self, buffer: &mut String) {
+            writeln!(
+                buffer,
+                "(({a}, {b}), ({c}, {d})),",
+                a = self.a,
+                b = self.b,
+                c = self.c,
+                d = self.d
+            )
+                    .unwrap();
+        }
+
+        fn prologue() -> &'static str {
+            "
+use compiler_builtins::int::sub::rust_i128_subo;
+
+static TEST_CASES: &[((i128, i128), (i128, bool))] = &[
+"
+        }
+
+        fn epilogue() -> &'static str {
+            "
+];
+
+#[test]
+fn i128_subo() {
+    for &((a, b), (c, d)) in TEST_CASES {
+        let (c_, d_) = rust_i128_subo(a, b);
+        assert_eq!(((a, b), (c, d)), ((a, b), (c_, d_)));
+    }
+}
+"
+        }
+    }
+
     #[derive(Eq, Hash, PartialEq)]
     pub struct Mulsf3 {
         a: u32,  // f32
diff --git a/src/int/add.rs b/src/int/add.rs
index b0f7ab6..5c746c2 100644
--- a/src/int/add.rs
+++ b/src/int/add.rs
@@ -65,56 +65,3 @@ pub fn rust_u128_addo(a: u128, b: u128) -> (u128, bool) {
     let r = a.addo(b, &mut oflow);
     (r, oflow != 0)
 }
-
-#[test]
-fn test_add() {
-    assert_eq!(rust_u128_add(1, 2), 3);
-    assert_eq!(rust_u128_add(!0, 3), 2);
-    assert_eq!(rust_u128_add(1 << 63, 1 << 63), 1 << 64);
-    assert_eq!(rust_u128_add(
-        0x54009B79B43145A0_B781BF1FD491296E_u128,
-        0x6019CEECA5354210_839AB51D155FF7F3_u128),
-        0xB41A6A66596687B1_3B1C743CE9F12161_u128);
-    assert_eq!(rust_u128_add(
-        0x3AE89C3AACEE47CD_8721275248B38DDB_u128,
-        0xEFDD73C41D344744_B0842900C3352A63_u128),
-        0x2AC60FFECA228F12_37A550530BE8B83E_u128);
-
-    assert_eq!(rust_i128_add(1, 2), 3);
-    assert_eq!(rust_i128_add(-1, 3), 2);
-}
-
-#[test]
-fn test_addo() {
-    assert_eq!(rust_u128_addo(1, 2), (3, false));
-    assert_eq!(rust_u128_addo(!0, 3), (2, true));
-    assert_eq!(rust_u128_addo(1 << 63, 1 << 63), (1 << 64, false));
-    assert_eq!(rust_u128_addo(
-        0x54009B79B43145A0_B781BF1FD491296E_u128,
-        0x6019CEECA5354210_839AB51D155FF7F3_u128),
-        (0xB41A6A66596687B1_3B1C743CE9F12161_u128, false));
-    assert_eq!(rust_u128_addo(
-        0x3AE89C3AACEE47CD_8721275248B38DDB_u128,
-        0xEFDD73C41D344744_B0842900C3352A63_u128),
-        (0x2AC60FFECA228F12_37A550530BE8B83E_u128, true));
-
-    assert_eq!(rust_i128_addo(1, 2), (3, false));
-    assert_eq!(rust_i128_addo(-1, 3), (2, false));
-    assert_eq!(rust_i128_addo(1 << 63, 1 << 63), (1 << 64, false));
-    assert_eq!(rust_i128_addo(
-        0x54009B79B43145A0_B781BF1FD491296E_i128,
-        0x6019CEECA5354210_839AB51D155FF7F3_i128),
-        (-0x4BE59599A699784E_C4E38BC3160EDE9F_i128, true));
-    assert_eq!(rust_i128_addo(
-        0x3AE89C3AACEE47CD_8721275248B38DDB_i128,
-        -0x10228C3BE2CBB8BB_4F7BD6FF3CCAD59D_i128),
-        (0x2AC60FFECA228F12_37A550530BE8B83E_i128, false));
-    assert_eq!(rust_i128_addo(
-        -0x54009B79B43145A0_B781BF1FD491296E_i128,
-        -0x6019CEECA5354210_839AB51D155FF7F3_i128),
-        (0x4BE59599A699784E_C4E38BC3160EDE9F_i128, true));
-    assert_eq!(rust_i128_addo(
-        -0x3AE89C3AACEE47CD_8721275248B38DDB_i128,
-        0x10228C3BE2CBB8BB_4F7BD6FF3CCAD59D_i128),
-        (-0x2AC60FFECA228F12_37A550530BE8B83E_i128, false));
-}
\ No newline at end of file
diff --git a/src/int/sub.rs b/src/int/sub.rs
index 0b0cbf2..abcb45a 100644
--- a/src/int/sub.rs
+++ b/src/int/sub.rs
@@ -50,56 +50,3 @@ pub fn rust_u128_subo(a: u128, b: u128) -> (u128, bool) {
     let r = a.subo(b, &mut oflow);
     (r, oflow != 0)
 }
-
-#[test]
-fn test_sub() {
-    assert_eq!(rust_u128_sub(3, 2), 1);
-    assert_eq!(rust_u128_sub(2, 3), !0);
-    assert_eq!(rust_u128_sub(1 << 64, 1 << 63), 1 << 63);
-    assert_eq!(rust_u128_sub(
-        0xB41A6A66596687B1_3B1C743CE9F12161_u128,
-        0x6019CEECA5354210_839AB51D155FF7F3_u128),
-        0x54009B79B43145A0_B781BF1FD491296E_u128);
-    assert_eq!(rust_u128_sub(
-        0x2AC60FFECA228F12_37A550530BE8B83E_u128,
-        0xEFDD73C41D344744_B0842900C3352A63_u128),
-        0x3AE89C3AACEE47CD_8721275248B38DDB_u128);
-
-    assert_eq!(rust_i128_sub(3, 2), 1);
-    assert_eq!(rust_i128_sub(2, 3), -1);
-}
-
-#[test]
-fn test_subo() {
-    assert_eq!(rust_u128_subo(3, 2), (1, false));
-    assert_eq!(rust_u128_subo(2, 3), (!0, true));
-    assert_eq!(rust_u128_subo(1 << 64, 1 << 63), (1 << 63, false));
-    assert_eq!(rust_u128_subo(
-        0xB41A6A66596687B1_3B1C743CE9F12161_u128,
-        0x6019CEECA5354210_839AB51D155FF7F3_u128),
-        (0x54009B79B43145A0_B781BF1FD491296E_u128, false));
-    assert_eq!(rust_u128_subo(
-        0x2AC60FFECA228F12_37A550530BE8B83E_u128,
-        0xEFDD73C41D344744_B0842900C3352A63_u128),
-        (0x3AE89C3AACEE47CD_8721275248B38DDB_u128, true));
-
-    assert_eq!(rust_i128_subo(3, 2), (1, false));
-    assert_eq!(rust_i128_subo(2, 3), (-1, false));
-    assert_eq!(rust_i128_subo(1 << 64, 1 << 63), (1 << 63, false));
-    assert_eq!(rust_i128_subo(
-        -0x4BE59599A699784E_C4E38BC3160EDE9F_i128,
-        0x6019CEECA5354210_839AB51D155FF7F3_i128),
-        (0x54009B79B43145A0_B781BF1FD491296E_i128, true));
-    assert_eq!(rust_i128_subo(
-        0x2AC60FFECA228F12_37A550530BE8B83E_i128,
-        -0x10228C3BE2CBB8BB_4F7BD6FF3CCAD59D_i128),
-        (0x3AE89C3AACEE47CD_8721275248B38DDB_i128, false));
-    assert_eq!(rust_i128_subo(
-        0x4BE59599A699784E_C4E38BC3160EDE9F_i128,
-        -0x6019CEECA5354210_839AB51D155FF7F3_i128),
-        (-0x54009B79B43145A0_B781BF1FD491296E_i128, true));
-    assert_eq!(rust_i128_subo(
-        -0x2AC60FFECA228F12_37A550530BE8B83E_i128,
-        0x10228C3BE2CBB8BB_4F7BD6FF3CCAD59D_i128),
-        (-0x3AE89C3AACEE47CD_8721275248B38DDB_i128, false));
-}
\ No newline at end of file
diff --git a/tests/i128_add.rs b/tests/i128_add.rs
new file mode 100644
index 0000000..13af050
--- /dev/null
+++ b/tests/i128_add.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/i128_add.rs"));
diff --git a/tests/i128_addo.rs b/tests/i128_addo.rs
new file mode 100644
index 0000000..306ffac
--- /dev/null
+++ b/tests/i128_addo.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/i128_addo.rs"));
diff --git a/tests/i128_sub.rs b/tests/i128_sub.rs
new file mode 100644
index 0000000..933fe4f
--- /dev/null
+++ b/tests/i128_sub.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/i128_sub.rs"));
diff --git a/tests/i128_subo.rs b/tests/i128_subo.rs
new file mode 100644
index 0000000..0c2b67c
--- /dev/null
+++ b/tests/i128_subo.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/i128_subo.rs"));
diff --git a/tests/u128_add.rs b/tests/u128_add.rs
new file mode 100644
index 0000000..d4b8f2c
--- /dev/null
+++ b/tests/u128_add.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/u128_add.rs"));
diff --git a/tests/u128_addo.rs b/tests/u128_addo.rs
new file mode 100644
index 0000000..caff682
--- /dev/null
+++ b/tests/u128_addo.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/u128_addo.rs"));
diff --git a/tests/u128_sub.rs b/tests/u128_sub.rs
new file mode 100644
index 0000000..024266b
--- /dev/null
+++ b/tests/u128_sub.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/u128_sub.rs"));
diff --git a/tests/u128_subo.rs b/tests/u128_subo.rs
new file mode 100644
index 0000000..b3fb4b8
--- /dev/null
+++ b/tests/u128_subo.rs
@@ -0,0 +1,8 @@
+#![feature(compiler_builtins_lib)]
+#![feature(i128_type)]
+#![cfg_attr(all(target_arch = "arm",
+                not(any(target_env = "gnu", target_env = "musl")),
+                target_os = "linux",
+                test), no_std)]
+
+include!(concat!(env!("OUT_DIR"), "/u128_subo.rs"));