NumIntCast

crates/compiler/gen_dev/src/generic64/mod.rs

@@ -2716,6 +2716,28 @@ impl<
             FloatWidth::F64 => ASM::sqrt_freg64_freg64(buf, dst_reg, src_reg),
         }
     }
+
+    fn build_num_int_cast(
+        &mut self,
+        dst: &Symbol,
+        src: &Symbol,
+        source: IntWidth,
+        target: IntWidth,
+    ) {
+        let buf = &mut self.buf;
+
+        let dst_reg = self.storage_manager.claim_general_reg(buf, &dst);
+        let src_reg = self.storage_manager.load_to_general_reg(buf, &src);
+
+        if source.stack_size() == target.stack_size() {
+            match source.stack_size() {
+                8 => ASM::mov_reg64_reg64(buf, dst_reg, src_reg),
+                _ => todo!("int cast from {source:?} to {target:?}"),
+            }
+        } else {
+            todo!("int cast from {source:?} to {target:?}");
+        }
+    }
 }
 
 /// This impl block is for ir related instructions that need backend specific information.

crates/compiler/gen_dev/src/lib.rs

@@ -1141,6 +1141,19 @@ trait Backend<'a> {
                 let intrinsic = bitcode::STR_IS_EMPTY.to_string();
                 self.build_fn_call(sym, intrinsic, args, arg_layouts, ret_layout);
             }
+            LowLevel::NumIntCast => {
+                let source_width = match self.interner().get(arg_layouts[0]) {
+                    Layout::Builtin(Builtin::Int(width)) => width,
+                    _ => unreachable!(),
+                };
+
+                let target_width = match self.interner().get(*ret_layout) {
+                    Layout::Builtin(Builtin::Int(width)) => width,
+                    _ => unreachable!(),
+                };
+
+                self.build_num_int_cast(sym, &args[0], source_width, target_width)
+            }
             x => todo!("low level, {:?}", x),
         }
     }
@@ -1254,6 +1267,15 @@ trait Backend<'a> {
     /// Move a returned value into `dst`
     fn move_return_value(&mut self, dst: &Symbol, ret_layout: &InLayout<'a>);
 
+    /// build_num_abs stores the absolute value of src into dst.
+    fn build_num_int_cast(
+        &mut self,
+        dst: &Symbol,
+        src: &Symbol,
+        source: IntWidth,
+        target: IntWidth,
+    );
+
     /// build_num_abs stores the absolute value of src into dst.
     fn build_num_abs(&mut self, dst: &Symbol, src: &Symbol, layout: &InLayout<'a>);