Zero-initialize uninitialized variables in JIT

Added logic to zero-initialize variables when no explicit initializer is provided. Introduced a gen_zero function to handle zeroing memory, and added a test case to verify zero-initialization behavior.

Author: wtholliday

src/jit.rs

@@ -394,6 +394,8 @@ impl<'a> FunctionTranslator<'a> {
                 if let Some(init_id) = init {
                     let init_value = self.translate_expr(*init_id, decl, decls);
                     self.gen_copy(*ty, addr, init_value, decls);
+                } else {
+                    self.gen_zero(*ty, addr, decls);
                 }
 
                 self.builder.ins().iconst(I32, 0)
@@ -519,6 +521,20 @@ impl<'a> FunctionTranslator<'a> {
         }
     }
 
+    fn gen_zero(
+        &mut self,
+        t: crate::TypeID,
+        dst: Value,
+        decls: &crate::DeclTable,
+    ) {
+        let size = t.size(decls) as u32;
+        let zero = self.builder.ins().iconst(I8, 0);
+        // Store zero byte-by-byte for the size of the type
+        for offset in 0..size {
+            self.builder.ins().store(MemFlags::new(), zero, dst, offset as i32);
+        }
+    }
+
     fn gen_eq(
         &mut self,
         t: crate::TypeID,

tests/cases/zero_init.lyte

@@ -0,0 +1,10 @@
+// args: --c
+// expected stdout:
+// compilation successful
+
+assert(cond: bool) → void
+
+main {
+    var i: i32
+    assert(i == 0)
+}