Integer add with carry instructions.

Integer addition with carry in/out/both.

src/libcretonne/ir/instructions.rs

@@ -149,6 +149,11 @@ pub enum InstructionData {
         ty: Type,
         args: [Value; 3],
     },
+    TernaryOverflow {
+        opcode: Opcode,
+        ty: Type,
+        data: Box<TernaryOverflowData>,
+    },
     InsertLane {
         opcode: Opcode,
         ty: Type,
@@ -254,6 +259,19 @@ impl Default for VariableArgs {
     }
 }
 
+/// Payload data for ternary instructions with multiple results, such as `iadd_carry`.
+#[derive(Clone, Debug)]
+pub struct TernaryOverflowData {
+    pub second_result: Value,
+    pub args: [Value; 3],
+}
+
+impl Display for TernaryOverflowData {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{}, {}, {}", self.args[0], self.args[1], self.args[2])
+    }
+}
+
 /// Payload data for jump instructions. These need to carry lists of EBB arguments that won't fit
 /// in the allowed InstructionData size.
 #[derive(Clone, Debug)]