use relative jump

include/pocketpy/codeobject.h

@@ -17,6 +17,15 @@ enum Opcode: uint8_t {
 struct Bytecode{
     uint8_t op;
     uint16_t arg;
+
+    void set_signed_arg(int arg){
+        if(arg < INT16_MIN || arg > INT16_MAX) throw std::runtime_error("byte.arg overflow");
+        this->arg = (int16_t)arg;
+    }
+
+    bool is_forward_jump() const{
+        return op >= OP_JUMP_FORWARD && op <= OP_LOOP_BREAK;
+    }
 };
 
 enum class CodeBlockType {

include/pocketpy/expr.h

@@ -93,7 +93,7 @@ struct CodeEmitContext{
     std::set<Str> global_names;
     CodeEmitContext(VM* vm, CodeObject_ co, int level): vm(vm), co(co), level(level) {}
 
-    int curr_block_i = 0;
+    int curr_iblock = 0;
     bool is_compiling_class = false;
     int base_stack_size = 0;
 

include/pocketpy/opcodes.h

@@ -87,8 +87,7 @@ OPCODE(IS_OP)
 OPCODE(IS_NOT_OP)
 OPCODE(CONTAINS_OP)
 /**************************/
-OPCODE(JUMP_ABSOLUTE)
-OPCODE(JUMP_ABSOLUTE_TOP)
+OPCODE(JUMP_FORWARD)
 OPCODE(POP_JUMP_IF_FALSE)
 OPCODE(POP_JUMP_IF_TRUE)
 OPCODE(JUMP_IF_TRUE_OR_POP)
@@ -96,6 +95,8 @@ OPCODE(JUMP_IF_FALSE_OR_POP)
 OPCODE(SHORTCUT_IF_FALSE_OR_POP)
 OPCODE(LOOP_CONTINUE)
 OPCODE(LOOP_BREAK)
+/***/
+OPCODE(JUMP_ABSOLUTE_TOP)
 OPCODE(GOTO)
 /**************************/
 OPCODE(FSTRING_EVAL)

include/pocketpy/vm.h

@@ -407,6 +407,7 @@ public:
     PyVar _t(PyVar obj){ return _all_types[_tp(obj)].obj; }
     PyVar _t(Type type){ return _all_types[type].obj; }
 
+    // equivalent to `obj == NotImplemented` but faster
     static bool is_not_implemented(PyVar obj){ return obj.type == tp_not_implemented; }
 #endif
 

src/ceval.cpp

@@ -95,7 +95,8 @@ bool VM::py_ge(PyVar _0, PyVar _1){
 #endif
 
 #define DISPATCH() { frame->_ip++; goto __NEXT_STEP; }
-#define DISPATCH_JUMP(__target) { frame->_ip=co_codes+__target; goto __NEXT_STEP; }
+#define DISPATCH_JUMP(__offset) { frame->_ip+=__offset; goto __NEXT_STEP; }
+#define DISPATCH_JUMP_ABSOLUTE(__target) { frame->_ip=co_codes+__target; goto __NEXT_STEP; }
 
 PyVar VM::__run_top_frame(){
     Frame* frame = &callstack.top();
@@ -638,26 +639,24 @@ __NEXT_STEP:
         TOP() = VAR(static_cast<bool>((int)CAST(bool, _0) ^ byte.arg));
     } DISPATCH()
     /*****************************************/
-    case OP_JUMP_ABSOLUTE:
-        DISPATCH_JUMP(byte.arg)
-    case OP_JUMP_ABSOLUTE_TOP:
-        DISPATCH_JUMP(_CAST(int, POPX()))
+    case OP_JUMP_FORWARD:
+        DISPATCH_JUMP((int16_t)byte.arg)
     case OP_POP_JUMP_IF_FALSE:
-        if(!py_bool(POPX())) DISPATCH_JUMP(byte.arg)
+        if(!py_bool(POPX())) DISPATCH_JUMP((int16_t)byte.arg)
         DISPATCH()
     case OP_POP_JUMP_IF_TRUE:
-        if(py_bool(POPX())) DISPATCH_JUMP(byte.arg)
+        if(py_bool(POPX())) DISPATCH_JUMP((int16_t)byte.arg)
         DISPATCH()
     case OP_JUMP_IF_TRUE_OR_POP:
         if(py_bool(TOP())){
-            DISPATCH_JUMP(byte.arg)
+            DISPATCH_JUMP((int16_t)byte.arg)
         }else{
             POP();
             DISPATCH()
         }
     case OP_JUMP_IF_FALSE_OR_POP:
         if(!py_bool(TOP())){
-            DISPATCH_JUMP(byte.arg)
+            DISPATCH_JUMP((int16_t)byte.arg)
         }else{
             POP();
             DISPATCH()
@@ -666,22 +665,26 @@ __NEXT_STEP:
         if(!py_bool(TOP())){                // [b, False]
             STACK_SHRINK(2);                // []
             PUSH(vm->False);                // [False]
-            DISPATCH_JUMP(byte.arg)
+            DISPATCH_JUMP((int16_t)byte.arg)
         } else{
             POP();                          // [b]
             DISPATCH()
         }
     case OP_LOOP_CONTINUE:
-        DISPATCH_JUMP(byte.arg)
-    case OP_LOOP_BREAK:
-        frame->prepare_jump_break(&s_data, byte.arg);
-        DISPATCH_JUMP(byte.arg)
+        // just an alias of OP_JUMP_FORWARD
+        DISPATCH_JUMP((int16_t)byte.arg)
+    case OP_LOOP_BREAK: {
+        frame->prepare_jump_break(&s_data, frame->ip()+byte.arg);
+        DISPATCH_JUMP((int16_t)byte.arg)
+    }
+    case OP_JUMP_ABSOLUTE_TOP:
+        DISPATCH_JUMP_ABSOLUTE(_CAST(int, POPX()))
     case OP_GOTO: {
         StrName _name(byte.arg);
         int target = frame->co->labels.try_get_likely_found(_name);
         if(target < 0) RuntimeError(_S("label ", _name.escape(), " not found"));
         frame->prepare_jump_break(&s_data, target);
-        DISPATCH_JUMP(target)
+        DISPATCH_JUMP_ABSOLUTE(target)
     }
     /*****************************************/
     case OP_FSTRING_EVAL:{
@@ -803,7 +806,7 @@ __NEXT_STEP:
         PyVar _0 = py_next(TOP());
         if(_0 == StopIteration){
             int target = frame->prepare_loop_break(&s_data);
-            DISPATCH_JUMP(target)
+            DISPATCH_JUMP_ABSOLUTE(target)
         } else{
             PUSH(_0);
             DISPATCH()
@@ -813,7 +816,7 @@ __NEXT_STEP:
         PyVar _0 = py_next(TOP());
         if(_0 == StopIteration){
             int target = frame->prepare_loop_break(&s_data);
-            DISPATCH_JUMP(target)
+            DISPATCH_JUMP_ABSOLUTE(target)
         }else{
             frame->_locals[byte.arg] = _0;
             DISPATCH()
@@ -823,7 +826,7 @@ __NEXT_STEP:
         PyVar _0 = py_next(TOP());
         if(_0 == StopIteration){
             int target = frame->prepare_loop_break(&s_data);
-            DISPATCH_JUMP(target)
+            DISPATCH_JUMP_ABSOLUTE(target)
         }else{
             frame->f_globals().set(StrName(byte.arg), _0);
             DISPATCH()
@@ -833,7 +836,7 @@ __NEXT_STEP:
         PyVar _0 = py_next(TOP());
         if(_0 == StopIteration){
             int target = frame->prepare_loop_break(&s_data);
-            DISPATCH_JUMP(target)
+            DISPATCH_JUMP_ABSOLUTE(target)
         }else{
             PUSH(_0);
             return PY_OP_YIELD;
@@ -847,7 +850,7 @@ __NEXT_STEP:
             if(n == 0){
                 // StopIteration
                 int target = frame->prepare_loop_break(&s_data);
-                DISPATCH_JUMP(target)
+                DISPATCH_JUMP_ABSOLUTE(target)
             }else if(n == 1){
                 // UNPACK_SEQUENCE
                 __op_unpack_sequence(byte.arg);
@@ -865,7 +868,7 @@ __NEXT_STEP:
                 __op_unpack_sequence(byte.arg);
             }else{
                 int target = frame->prepare_loop_break(&s_data);
-                DISPATCH_JUMP(target)
+                DISPATCH_JUMP_ABSOLUTE(target)
             }
         }
     } DISPATCH()

src/compiler.cpp

@@ -47,17 +47,13 @@ namespace pkpy{
         if(ctx()->co->consts.size() > 65530){
             SyntaxError("maximum number of constants exceeded");
         }
-        if(codes.size() > 65530 && ctx()->co->src->mode != JSON_MODE){
-            // json mode does not contain jump instructions, so it is safe to ignore this check
-            SyntaxError("maximum number of opcodes exceeded");
-        }
         // pre-compute LOOP_BREAK and LOOP_CONTINUE
         for(int i=0; i<codes.size(); i++){
             Bytecode& bc = codes[i];
             if(bc.op == OP_LOOP_CONTINUE){
-                bc.arg = ctx()->co->blocks[bc.arg].start;
+                bc.set_signed_arg(ctx()->co->blocks[bc.arg].start - i);
             }else if(bc.op == OP_LOOP_BREAK){
-                bc.arg = ctx()->co->blocks[bc.arg].get_break_end();
+                bc.set_signed_arg(ctx()->co->blocks[bc.arg].get_break_end() - i);
             }
         }
         // pre-compute func->is_simple
@@ -655,12 +651,12 @@ __EAT_DOTS_END:
         int patch = ctx()->emit_(OP_POP_JUMP_IF_FALSE, BC_NOARG, prev().line);
         compile_block_body();
         if (match(TK("elif"))) {
-            int exit_patch = ctx()->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, prev().line);
+            int exit_patch = ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, prev().line);
             ctx()->patch_jump(patch);
             compile_if_stmt();
             ctx()->patch_jump(exit_patch);
         } else if (match(TK("else"))) {
-            int exit_patch = ctx()->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, prev().line);
+            int exit_patch = ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, prev().line);
             ctx()->patch_jump(patch);
             compile_block_body();
             ctx()->patch_jump(exit_patch);
@@ -691,7 +687,7 @@ __EAT_DOTS_END:
         EXPR_TUPLE(); ctx()->emit_expr();
         ctx()->emit_(OP_GET_ITER, BC_NOARG, BC_KEEPLINE);
         CodeBlock* block = ctx()->enter_block(CodeBlockType::FOR_LOOP);
-        int for_codei = ctx()->emit_(OP_FOR_ITER, BC_NOARG, BC_KEEPLINE);
+        int for_codei = ctx()->emit_(OP_FOR_ITER, ctx()->curr_iblock, BC_KEEPLINE);
         bool ok = vars->emit_store(ctx());
         if(!ok) SyntaxError();  // this error occurs in `vars` instead of this line, but...nevermind
         ctx()->try_merge_for_iter_store(for_codei);
@@ -710,7 +706,7 @@ __EAT_DOTS_END:
         compile_block_body();
         small_vector_2<int, 6> patches;
         patches.push_back(
-            ctx()->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, BC_KEEPLINE)
+            ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, BC_KEEPLINE)
         );
         ctx()->exit_block();
 
@@ -739,13 +735,13 @@ __EAT_DOTS_END:
                 // pop the exception 
                 ctx()->emit_(OP_POP_EXCEPTION, BC_NOARG, BC_KEEPLINE);
                 compile_block_body();
-                patches.push_back(ctx()->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, BC_KEEPLINE));
+                patches.push_back(ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, BC_KEEPLINE));
                 ctx()->patch_jump(patch);
             }while(curr().type == TK("except"));
         }
 
         if(match(TK("finally"))){
-            int patch = ctx()->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, BC_KEEPLINE);
+            int patch = ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, BC_KEEPLINE);
             finally_entry = ctx()->co->codes.size();
             compile_block_body();
             ctx()->emit_(OP_JUMP_ABSOLUTE_TOP, BC_NOARG, BC_KEEPLINE);
@@ -755,7 +751,8 @@ __EAT_DOTS_END:
         if(finally_entry != -1){
             i64 target = ctx()->co->codes.size()+2;
             ctx()->emit_(OP_LOAD_CONST, ctx()->add_const(VAR(target)), BC_KEEPLINE);
-            ctx()->emit_(OP_JUMP_ABSOLUTE, finally_entry, BC_KEEPLINE);
+            int i = ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, BC_KEEPLINE);
+            ctx()->co->codes[i].set_signed_arg(finally_entry - i);
         }
         ctx()->emit_(OP_RE_RAISE, BC_NOARG, BC_KEEPLINE);
 
@@ -764,7 +761,8 @@ __EAT_DOTS_END:
         if(finally_entry != -1){
             i64 target = ctx()->co->codes.size()+2;
             ctx()->emit_(OP_LOAD_CONST, ctx()->add_const(VAR(target)), BC_KEEPLINE);
-            ctx()->emit_(OP_JUMP_ABSOLUTE, finally_entry, BC_KEEPLINE);
+            int i = ctx()->emit_(OP_JUMP_FORWARD, BC_NOARG, BC_KEEPLINE);
+            ctx()->co->codes[i].set_signed_arg(finally_entry - i);
         }
     }
 

src/expr.cpp

@@ -14,7 +14,7 @@ namespace pkpy{
     }
 
     int CodeEmitContext::get_loop() const {
-        int index = curr_block_i;
+        int index = curr_iblock;
         while(index >= 0){
             if(co->blocks[index].type == CodeBlockType::FOR_LOOP) break;
             if(co->blocks[index].type == CodeBlockType::WHILE_LOOP) break;
@@ -26,18 +26,18 @@ namespace pkpy{
     CodeBlock* CodeEmitContext::enter_block(CodeBlockType type){
         if(type==CodeBlockType::FOR_LOOP || type==CodeBlockType::CONTEXT_MANAGER) base_stack_size++;
         co->blocks.push_back(CodeBlock(
-            type, curr_block_i, base_stack_size, (int)co->codes.size()
+            type, curr_iblock, base_stack_size, (int)co->codes.size()
         ));
-        curr_block_i = co->blocks.size()-1;
-        return &co->blocks[curr_block_i];
+        curr_iblock = co->blocks.size()-1;
+        return &co->blocks[curr_iblock];
     }
 
     void CodeEmitContext::exit_block(){
-        auto curr_type = co->blocks[curr_block_i].type;
+        auto curr_type = co->blocks[curr_iblock].type;
         if(curr_type == CodeBlockType::FOR_LOOP || curr_type==CodeBlockType::CONTEXT_MANAGER) base_stack_size--;
-        co->blocks[curr_block_i].end = co->codes.size();
-        curr_block_i = co->blocks[curr_block_i].parent;
-        if(curr_block_i < 0) PK_FATAL_ERROR();
+        co->blocks[curr_iblock].end = co->codes.size();
+        curr_iblock = co->blocks[curr_iblock].parent;
+        if(curr_iblock < 0) PK_FATAL_ERROR();
 
         if(curr_type == CodeBlockType::FOR_LOOP){
             // add a no op here to make block check work
@@ -54,7 +54,7 @@ namespace pkpy{
 
     int CodeEmitContext::emit_(Opcode opcode, uint16_t arg, int line, bool is_virtual) {
         co->codes.push_back(Bytecode{(uint8_t)opcode, arg});
-        co->lines.push_back(CodeObject::LineInfo{line, is_virtual, curr_block_i});
+        co->lines.push_back(CodeObject::LineInfo{line, is_virtual, curr_iblock});
         int i = co->codes.size() - 1;
         if(line == BC_KEEPLINE){
             if(i >= 1) co->lines[i].lineno = co->lines[i-1].lineno;
@@ -97,7 +97,7 @@ namespace pkpy{
 
     void CodeEmitContext::patch_jump(int index) {
         int target = co->codes.size();
-        co->codes[index].arg = target;
+        co->codes[index].set_signed_arg(target-index);
     }
 
     bool CodeEmitContext::add_label(StrName name){
@@ -399,7 +399,8 @@ namespace pkpy{
         iter->emit_(ctx);
         ctx->emit_(OP_GET_ITER, BC_NOARG, BC_KEEPLINE);
         ctx->enter_block(CodeBlockType::FOR_LOOP);
-        int for_codei = ctx->emit_(OP_FOR_ITER, BC_NOARG, BC_KEEPLINE);
+        int curr_iblock = ctx->curr_iblock;
+        int for_codei = ctx->emit_(OP_FOR_ITER, curr_iblock, BC_KEEPLINE);
         bool ok = vars->emit_store(ctx);
         // this error occurs in `vars` instead of this line, but...nevermind
         if(!ok) throw std::runtime_error("SyntaxError");
@@ -414,7 +415,7 @@ namespace pkpy{
             expr->emit_(ctx);
             ctx->emit_(op1(), BC_NOARG, BC_KEEPLINE);
         }
-        ctx->emit_(OP_LOOP_CONTINUE, ctx->get_loop(), BC_KEEPLINE);
+        ctx->emit_(OP_LOOP_CONTINUE, curr_iblock, BC_KEEPLINE);
         ctx->exit_block();
     }
 
@@ -729,7 +730,7 @@ namespace pkpy{
         cond->emit_(ctx);
         int patch = ctx->emit_(OP_POP_JUMP_IF_FALSE, BC_NOARG, cond->line);
         true_expr->emit_(ctx);
-        int patch_2 = ctx->emit_(OP_JUMP_ABSOLUTE, BC_NOARG, true_expr->line);
+        int patch_2 = ctx->emit_(OP_JUMP_FORWARD, BC_NOARG, true_expr->line);
         ctx->patch_jump(patch);
         false_expr->emit_(ctx);
         ctx->patch_jump(patch_2);

src/vm.cpp

@@ -710,29 +710,34 @@ PyVar VM::new_module(Str name, Str package) {
     return obj;
 }
 
-static std::string _opcode_argstr(VM* vm, Bytecode byte, const CodeObject* co){
-    std::string argStr = std::to_string(byte.arg);
+static std::string _opcode_argstr(VM* vm, int i, Bytecode byte, const CodeObject* co){
+    SStream ss;
+    if(byte.is_forward_jump()){
+        std::string argStr = std::to_string((int16_t)byte.arg);
+        ss << (i64)(int16_t)byte.arg;
+        ss << " (to " << (i64)((int16_t)byte.arg + i) << ")";
+        return ss.str().str();
+    }
+    ss << (i64)byte.arg;
     switch(byte.op){
         case OP_LOAD_CONST: case OP_FORMAT_STRING: case OP_IMPORT_PATH:
-            if(vm != nullptr){
-                argStr += _S(" (", vm->py_repr(co->consts[byte.arg]), ")").sv();
-            }
+            if(vm != nullptr) ss << " (" << vm->py_repr(co->consts[byte.arg]) << ")";
             break;
         case OP_LOAD_NAME: case OP_LOAD_GLOBAL: case OP_LOAD_NONLOCAL: case OP_STORE_GLOBAL:
         case OP_LOAD_ATTR: case OP_LOAD_METHOD: case OP_STORE_ATTR: case OP_DELETE_ATTR:
         case OP_BEGIN_CLASS: case OP_GOTO:
         case OP_DELETE_GLOBAL: case OP_INC_GLOBAL: case OP_DEC_GLOBAL: case OP_STORE_CLASS_ATTR: case OP_FOR_ITER_STORE_GLOBAL:
-            argStr += _S(" (", StrName(byte.arg).sv(), ")").sv();
+            ss << " (" << StrName(byte.arg).sv() << ")";
             break;
         case OP_LOAD_FAST: case OP_STORE_FAST: case OP_DELETE_FAST: case OP_INC_FAST: case OP_DEC_FAST:
         case OP_FOR_ITER_STORE_FAST: case OP_LOAD_SUBSCR_FAST: case OP_STORE_SUBSCR_FAST:
-            argStr += _S(" (", co->varnames[byte.arg].sv(), ")").sv();
+            ss << " (" << co->varnames[byte.arg].sv() << ")";
             break;
         case OP_LOAD_FUNCTION:
-            argStr += _S(" (", co->func_decls[byte.arg]->code->name, ")").sv();
+            ss << " (" << co->func_decls[byte.arg]->code->name << ")";
             break;
     }
-    return argStr;
+    return ss.str().str();
 }
 
 Str VM::disassemble(CodeObject_ co){
@@ -742,14 +747,10 @@ Str VM::disassemble(CodeObject_ co){
     };
 
     std::vector<int> jumpTargets;
-    for(auto byte : co->codes){
-        if(byte.op == OP_JUMP_ABSOLUTE || byte.op == OP_POP_JUMP_IF_FALSE || byte.op == OP_SHORTCUT_IF_FALSE_OR_POP || byte.op == OP_LOOP_CONTINUE){
-            jumpTargets.push_back(byte.arg);
-        }
-        if(byte.op == OP_GOTO){
-            // TODO: pre-compute jump targets for OP_GOTO
-            int* target = co->labels.try_get_2_likely_found(StrName(byte.arg));
-            if(target != nullptr) jumpTargets.push_back(*target);
+    for(int i=0; i<co->codes.size(); i++){
+        Bytecode byte = co->codes[i];
+        if(byte.is_forward_jump()){
+            jumpTargets.push_back((int16_t)byte.arg + i);
         }
     }
     SStream ss;
@@ -773,11 +774,8 @@ Str VM::disassemble(CodeObject_ co){
         std::string bc_name(OP_NAMES[byte.op]);
         if(co->lines[i].is_virtual) bc_name += '*';
         ss << " " << pad(bc_name, 25) << " ";
-        // ss << pad(byte.arg == -1 ? "" : std::to_string(byte.arg), 5);
-        std::string argStr = _opcode_argstr(this, byte, co.get());
+        std::string argStr = _opcode_argstr(this, i, byte, co.get());
         ss << argStr;
-        // ss << pad(argStr, 40);      // may overflow
-        // ss << co->blocks[byte.block].type;
         if(i != co->codes.size() - 1) ss << '\n';
     }
 
@@ -835,7 +833,7 @@ void VM::__log_s_data(const char* title) {
         output.pop_back(); output.pop_back();
     }
     output.push_back(']');
-    Bytecode byte = frame->co->codes[frame->_ip];
+    Bytecode byte = *frame->_ip;
     std::cout << output << " " << OP_NAMES[byte.op] << " " << _opcode_argstr(nullptr, byte, frame->co) << std::endl;
 }
 #endif