Slowly trying to add function calls, cases for RETURN and CALL

bytecode_interpreter.cpp

@@ -17,6 +17,7 @@ enum Operation: U16{
   BC_LOAD_CONSTANT,
   BC_STORE_CONSTANT,
   BC_CALL,
+  BC_CALL_RETURN,
   BC_LOAD_FROM_MEMORY64,
   BC_LOAD_FROM_MEMORY32,
   BC_LOAD_FROM_MEMORY16,
@@ -79,6 +80,7 @@ const char *op_name[] = {
   "BC_LOAD_CONSTANT",
   "BC_STORE_CONSTANT",
   "BC_CALL",
+  "BC_CALL_RETURN",
   "BC_LOAD_FROM_MEMORY64",
   "BC_LOAD_FROM_MEMORY32",
   "BC_LOAD_FROM_MEMORY16",
@@ -181,18 +183,20 @@ struct Instruction{
 
 struct Call_Frame{
   Call_Frame *previous_call;
-  Register_Index first_register;
+  Instruction *saved_instruction_pointer;
+  Register_Index first_register_index_in_window;
+  Register_Index register_where_you_write_return_value;
 };
 
 struct Bc{
   U32 dis; // @debug_ids
 
-  U64 *stack_bottom;
+  U8 *stack_bottom;
-  U64 *stack_pointer;
+  U8 *stack_pointer;
-  U64 *stack_top;
+  U8 *stack_top;
 
   Call_Frame *top_call;
-  Register_Index first_register_index_in_window;
+
   Array<Register> registers;
   Array<Register_Index> used_registers;
   Array<Register_Index> free_registers;
@@ -274,13 +278,13 @@ new_instruction(Bc *b, Token *pos){
   return i;
 }
 
-// function void
+function void
-// emit_call(Bc *b, Token *pos, Register_Index register_with_call_address, Register_Index register_with_last_argument){
+emit_call(Bc *b, Token *pos, Register_Index register_with_call_address, Register_Index register_with_last_argument){
-//   auto i              = new_instruction(b, pos);
+  auto i              = new_instruction(b, pos);
-//   i->operation        = BC_CALL;
+  i->operation        = BC_CALL;
-//   i->index_a          = register_with_call_address;
+  i->index_a          = register_with_call_address;
-//   i->index_b          = register_with_last_argument;
+  i->index_b          = register_with_last_argument;
-// }
+}
 
 function void
 emit_load_constant_f64(Bc *b, Token *pos, Register_Index dst, F64 constant){
@@ -356,15 +360,36 @@ emit_end(Bc *b){
   i->operation        = BC_END_OF_INSTRUCTIONS;
 }
 
+#define R(x) (b->registers[b->top_call->first_register_index_in_window + (x)]) // Get register
+#define bc_stack_push(b, T) (T *)bc__stack_push(b, sizeof(T))
+
+function U8 *
+bc__stack_push(Bc *b, U64 size){
+  U8 *result = (U8 *)b->stack_pointer;
+  b->stack_pointer += size;
+  assert(b->stack_pointer < b->stack_top);
+  return result;
+}
+
+function Call_Frame *
+bc_push_call_frame(Bc *b, Register_Index function_address_register){
+  auto call = bc_stack_push(b, Call_Frame);
+  call->first_register_index_in_window = function_address_register + 1;
+  call->register_where_you_write_return_value = function_address_register;
+  call->previous_call = b->top_call;
+  call->saved_instruction_pointer = 0;
+
+  b->top_call = call;
+  return call;
+}
+
 function void
 run_bytecode_interp(Bc *b){
-  // Setup registers
   b->instruction_pointer = (Instruction *)b->instructions.memory.data;
-  b->stack_pointer = b->stack_bottom = (U64 *)b->stack.memory.data;
+  b->stack_pointer = b->stack_bottom = b->stack.memory.data;
-  b->stack_top = (U64 *)(b->stack.memory.data + b->stack.len);
+  b->stack_top = (b->stack.memory.data + b->stack.len);
-  b->first_register_index_in_window = 0;
+  bc_push_call_frame(b, 0);
 
-#define R(x) (b->registers[b->first_register_index_in_window + (x)]) // Get register
   for(;;){
     Instruction *instr = b->instruction_pointer++;
 
@@ -372,7 +397,7 @@ run_bytecode_interp(Bc *b){
     print_token_line(instr->debug_pos);
     assert_msg(b->stack_pointer < b->stack_top, "Bytecode stack overflow");
     assert_msg(b->stack_pointer >= b->stack_bottom, "Bytecode stack underflow");
-    assert_msg(b->first_register_index_in_window < b->registers.cap, "Bytecode interpreter bug, register pointer is pointing over last possible register");
+    assert_msg(b->top_call->first_register_index_in_window < b->registers.cap, "Bytecode interpreter bug, register pointer is pointing over last possible register");
 #endif
 
     bc_log("i%u[0x%llx] %s ", instr->di, instr, op_name[instr->operation]);
@@ -380,7 +405,8 @@ run_bytecode_interp(Bc *b){
       invalid_default_case;
 
       case BC_PUSH_STACK:{
-        U64 *stack = b->stack_pointer++;
+        U64 *stack = (U64 *)b->stack_pointer;
+        b->stack_pointer += sizeof(U64);
 
         U64 src = R(instr->index_a).u64;
         bc_log("r%u(src) [0x%llx|%lld|%f]", instr->index_a, src, src, src);
@@ -388,15 +414,12 @@ run_bytecode_interp(Bc *b){
       }break;
 
       case BC_POP_STACK:{
-        U64 *stack = --b->stack_pointer;
+        b->stack_pointer -= sizeof(U64);
+        U64 *stack = (U64 *)b->stack_pointer;
         bc_log("r%u(dst) [0x%llx|%lld|%f]", instr->index_c, *stack, *stack, *stack);
         R(instr->index_c).u64 = *stack;
       }break;
 
-      case BC_END_OF_INSTRUCTIONS:{
-        goto end_of_program;
-      }break;
-
       case BC_LOAD_CONSTANT: {
         R(instr->index_c) = instr->constant;
 #if BC_LOG
@@ -410,6 +433,25 @@ run_bytecode_interp(Bc *b){
 #endif
       }break;
 
+      case BC_CALL:{
+        Register_Index register_with_call_address = instr->index_a;
+        // Register_Index register_with_last_argument = instr->index_b;
+        Call_Frame *call = bc_push_call_frame(b, register_with_call_address);
+        call->saved_instruction_pointer = b->instruction_pointer;
+        b->instruction_pointer = (Instruction *)R(register_with_call_address).pointer;
+      }break;
+
+      case BC_CALL_RETURN:{
+        Call_Frame *call = b->top_call;
+        Call_Frame *prev = call->previous_call;
+        assert(prev);
+
+        b->top_call = prev;
+      }break;
+
+      case BC_END_OF_INSTRUCTIONS:{
+        goto end_of_program;
+      }break;
 //
 // *Begin* of switch_cases generated using code_generating_script.py
 //

code_generating_script.py

@@ -14,6 +14,10 @@ def should_skip(T, op):
     and op != "GT" and op != "LT" and op != "GTE" and op != "LTE":
       return True
 
+# This function inserts generated code into the specified file
+# it requires a specific comment to be triggered.
+# Lossing data would be terrible so we also backup that file
+# in case something bad happens
 def update_file(filename, comment_name, data_to_write):
   begin = f"""//
 // *Begin* of {comment_name} generated using code_generating_script.py
@@ -55,13 +59,15 @@ def update_file(filename, comment_name, data_to_write):
 
 if True:
   result = ""
-  enum_members = []
+  enum_members = [
-  enum_members.append("BC_END_OF_INSTRUCTIONS")
+    "BC_END_OF_INSTRUCTIONS",
-  enum_members.append("BC_POP_STACK")
+    "BC_POP_STACK",
-  enum_members.append("BC_PUSH_STACK")
+    "BC_PUSH_STACK",
-  enum_members.append("BC_LOAD_CONSTANT")
+    "BC_LOAD_CONSTANT",
-  enum_members.append("BC_STORE_CONSTANT")
+    "BC_STORE_CONSTANT",
-  enum_members.append("BC_CALL")
+    "BC_CALL",
+    "BC_CALL_RETURN",
+  ]
 
   load_store = ["LOAD_FROM_MEMORY", "STORE_TO_MEMORY"]
   for op in load_store: