From 63b82238bbe54643c63a8693299d6a9f4c0b0358 Mon Sep 17 00:00:00 2001
From: bjorn3 <bjorn3@users.noreply.github.com>
Date: Wed, 24 Jul 2019 13:16:36 +0200
Subject: [PATCH] Implement 128bit checked add and sub

---
 example/mini_core.rs   | 27 ---------------------------
 example/std_example.rs |  3 +++
 src/codegen_i128.rs    | 16 ++++++++++++++--
 3 files changed, 17 insertions(+), 29 deletions(-)

diff --git a/example/mini_core.rs b/example/mini_core.rs
index fa47831b648..221cdb3e863 100644
--- a/example/mini_core.rs
+++ b/example/mini_core.rs
@@ -44,12 +44,10 @@ unsafe impl Copy for u8 {}
 unsafe impl Copy for u16 {}
 unsafe impl Copy for u32 {}
 unsafe impl Copy for u64 {}
-unsafe impl Copy for u128 {}
 unsafe impl Copy for usize {}
 unsafe impl Copy for i8 {}
 unsafe impl Copy for i16 {}
 unsafe impl Copy for i32 {}
-unsafe impl Copy for i128 {}
 unsafe impl Copy for isize {}
 unsafe impl Copy for char {}
 unsafe impl<'a, T: ?Sized> Copy for &'a T {}
@@ -146,22 +144,6 @@ impl Add for usize {
     }
 }
 
-impl Add for u128 {
-    type Output = Self;
-
-    fn add(self, rhs: Self) -> Self {
-        self + rhs
-    }
-}
-
-impl Add for i128 {
-    type Output = Self;
-
-    fn add(self, rhs: Self) -> Self {
-        self + rhs
-    }
-}
-
 #[lang = "sub"]
 pub trait Sub<RHS = Self> {
     type Output;
@@ -286,15 +268,6 @@ impl PartialEq for i32 {
     }
 }
 
-impl PartialEq for i128 {
-    fn eq(&self, other: &i128) -> bool {
-        (*self) == (*other)
-    }
-    fn ne(&self, other: &i128) -> bool {
-        (*self) != (*other)
-    }
-}
-
 impl PartialEq for isize {
     fn eq(&self, other: &isize) -> bool {
         (*self) == (*other)
diff --git a/example/std_example.rs b/example/std_example.rs
index 9e9a7a67e05..f9fc1f2cde3 100644
--- a/example/std_example.rs
+++ b/example/std_example.rs
@@ -23,6 +23,9 @@ fn main() {
     checked_div_u128(0u128, 2u128);
     assert_eq!(1u128 + 2, 3);
 
+    // overflow panic
+    // 0xFEDCBA987654321123456789ABCDEFu128 + 0xFEDCBA987654321123456789ABCDEFu128;
+
     println!("{}", 0b100010000000000000000000000000000u128 >> 10);
     println!("{}", 0xFEDCBA987654321123456789ABCDEFu128 >> 64);
     println!("{} >> 64 == {}", 0xFEDCBA987654321123456789ABCDEFu128 as i128, 0xFEDCBA987654321123456789ABCDEFu128 as i128 >> 64);
diff --git a/src/codegen_i128.rs b/src/codegen_i128.rs
index 76d0fcb301e..9cd6bc8c786 100644
--- a/src/codegen_i128.rs
+++ b/src/codegen_i128.rs
@@ -23,8 +23,20 @@ pub fn maybe_codegen<'a, 'tcx>(
             assert!(!checked);
             return None;
         }
-        BinOp::Add | BinOp::Sub => {
-            return None; // FIXME implement checked versions
+        BinOp::Add | BinOp::Sub if !checked => return None,
+        BinOp::Add => {
+            return Some(if is_signed {
+                fx.easy_call("__rust_i128_addo", &[lhs, rhs], out_ty)
+            } else {
+                fx.easy_call("__rust_u128_addo", &[lhs, rhs], out_ty)
+            })
+        }
+        BinOp::Sub => {
+            return Some(if is_signed {
+                fx.easy_call("__rust_i128_subo", &[lhs, rhs], out_ty)
+            } else {
+                fx.easy_call("__rust_u128_subo", &[lhs, rhs], out_ty)
+            })
         }
         BinOp::Offset => unreachable!("offset should only be used on pointers, not 128bit ints"),
         BinOp::Mul => {