feat(parser,ir,backend): Fully support func params and disable r0-r3 alloc temporarily

src/backend/generator.rs

@@ -15,6 +15,7 @@ pub struct Generator {
 
 const DEFAULT_VAR_ALIGN: usize = 4;
 
+const ARG_REGS: [Register; 4] = [REG_R0, REG_R1, REG_R2, REG_R3];
 fn load_variable(variable: Variable, reg_allocator: &mut RegisterAllocator, var_index_to_stack_offset: &BTreeMap<usize, usize>, instrs: &mut Vec<ARMInstr>) -> RegisterAlloc {
     match variable.var_type {
         VariableType::Global => {
@@ -27,8 +28,14 @@ fn load_variable(variable: Variable, reg_allocator: &mut RegisterAllocator, var_
             // }
             var_alloc
         },
-        VariableType::ParamTemp => {
-            todo!()
+        VariableType::ParamTemp(param_index) => {
+            if param_index < ARG_REGS.len() {
+                let reg = ARG_REGS[param_index];
+                let var_alloc = reg_allocator.alloc_reg(reg).expect("Ran out of registers");
+                var_alloc
+            } else {
+                todo!("More than 4 parameters not supported yet");
+            }
         },
         _ => {
             let stack_offset = var_index_to_stack_offset.get(&variable.index).expect("Variable not declared");
@@ -48,7 +55,7 @@ fn save_variable(variable: Variable, reg: Register, reg_allocator: &mut Register
             instrs.push(LoadPseudoInstr::new(address_alloc.reg, format!("global_var_{}", variable.index)));
             instrs.push(StoreInstr::new(reg, address_alloc.reg, None));
         },
-        VariableType::ParamTemp => {
+        VariableType::ParamTemp(_) => {
             todo!()
         },
         _ => {
@@ -199,7 +206,6 @@ impl Generator {
         if args.len() > 4 {
             todo!("More than 4 arguments not supported yet");
         }
-        const ARG_REGS: [Register; 4] = [REG_R0, REG_R1, REG_R2, REG_R3];
         let mut arg_reg_allocs = Vec::new();
         for (i, arg) in args.into_iter().enumerate() {
             arg_reg_allocs.push(self.register_allocator.alloc_reg(ARG_REGS[i]).expect("Ran out of registers"));