VM basics (#5)

Co-authored-by: Andre Wagner <WagnerAndre@JohnDeere.com>
Reviewed-on: https://192.168.5.48/andre/tyche/pulls/5

CMakeLists.txt

@@ -59,15 +59,15 @@ FetchContent_MakeAvailable(googletest)
 #
 
 add_library(lib${PROJECT_NAME} SHARED
-        src/bytecode/bytearray.hh
-        src/bytecode/bytearray.cc
+        src/common/overloaded.hh
+        src/common/bytearray.hh
+        src/common/bytearray.cc
         src/bytecode/bytecode.cc
         src/bytecode/bytecode.hh
         src/bytecode/bytecodeprototype.hh
-        src/common/overloaded.hh
+        src/bytecode/constant.hh
         src/vm/code.cc
         src/vm/code.hh
-        src/bytecode/constant.hh
         src/vm/instruction.hh
         src/vm/instruction.cc
         src/vm/value.cc
@@ -75,6 +75,11 @@ add_library(lib${PROJECT_NAME} SHARED
         src/vm/stack.cc
         src/vm/stack.hh
         src/vm/vm_exceptions.hh
+        src/vm/vm.cc
+        src/vm/vm.hh
+        src/vm/expr.cc
+        src/vm/expr.hh
+        src/vm/location.hh
 )
 
 target_compile_options(lib${PROJECT_NAME} PRIVATE ${warnings})

TODO.md

@@ -25,9 +25,12 @@ After some additional development:
       - [x] Output bytecode format
   - [x] Value object
   - [x] Stack object
-  - [ ] External interface
-  - [ ] Code execution (except functions)
-  - [ ] Functions
+  - [x] External interface
+  - [x] Code execution (except functions)
+  - [x] Functions
+  - [x] Print stack
+
+- [ ] Assembler
 
 After some additional development:
 - [ ] Bytecode loader

src/bytecode/bytecode.cc

@@ -1,7 +1,7 @@
 #include "bytecode.hh"
 #include "../common/overloaded.hh"
 
-namespace tyche {
+namespace tyche::bc {
 
 Bytecode::Bytecode(ByteArray ba)
     : byte_array_(std::move(ba))

src/bytecode/bytecode.hh

@@ -1,10 +1,10 @@
 #ifndef TYCHE_BYTECODE_HH
 #define TYCHE_BYTECODE_HH
 
-#include "bytearray.hh"
+#include "../common/bytearray.hh"
 #include "bytecodeprototype.hh"
 
-namespace tyche {
+namespace tyche::bc {
 
 class Bytecode {
 public:

src/bytecode/bytecodeprototype.hh

@@ -6,9 +6,9 @@
 #include <variant>
 #include <vector>
 #include "constant.hh"
-#include "bytearray.hh"
+#include "../common/bytearray.hh"
 
-namespace tyche {
+namespace tyche::bc {
 
 struct BytecodePrototype {
     struct Function {

src/bytecode/constant.hh

@@ -4,7 +4,7 @@
 #include <string>
 #include <variant>
 
-namespace tyche {
+namespace tyche::bc {
 
 using ConstantValue = std::variant<float, std::string>;
 

src/bytecode/tests.cc

@@ -3,11 +3,12 @@
 #include <cstring>
 #include <functional>
 
-#include "bytearray.hh"
+#include "../common/bytearray.hh"
 #include "bytecodeprototype.hh"
 #include "bytecode.hh"
 
 using namespace tyche;
+using namespace tyche::bc;
 
 TEST(ByteArray, ByteArray)
 {

src/vm/code.cc

@@ -2,14 +2,51 @@
 #include "../common/overloaded.hh"
 #include "instruction.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
-void Code::import_bytecode(ByteArray incoming)
+FunctionId Code::import_bytecode(ByteArray incoming)
 {
-    Bytecode bc(std::move(incoming));
+    bc::Bytecode bc(std::move(incoming));
     // TODO - adjust function calls, constants
 
     bytecode_ = std::move(bc);
+
+    return 0;  // TODO
+}
+
+Operation Code::operation(Location const& location) const
+{
+    Instruction inst = (Instruction) bytecode_.get_code_byte(location.function_id, location.pc);
+    OperandType opet = instruction_operand_type(inst);
+
+    switch (opet) {
+        case OperandType::NoOperand:
+            return {
+                .instruction = inst,
+                .operator_ = 0,
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 1 },
+            };
+        case OperandType::Int8:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int8(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 2 },
+            };
+        case OperandType::Int16:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int16(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 3 },
+            };
+        case OperandType::Int32:
+            return {
+                .instruction = inst,
+                .operator_ = bytecode_.get_code_int32(location.function_id, location.pc + 1),
+                .next_location = { .function_id = location.function_id, .pc = location.pc + 5 },
+            };
+    }
+
+    throw std::logic_error("Should not get here");
 }
 
 std::string Code::disassemble() const

src/vm/code.hh

@@ -1,18 +1,30 @@
 #ifndef TYCHE_CODE_HH
 #define TYCHE_CODE_HH
 
+#include "instruction.hh"
+#include "location.hh"
+#include "value.hh"
 #include "../bytecode/bytecode.hh"
 
-namespace tyche {
+namespace tyche::vm {
+
+struct Operation
+{
+    Instruction instruction;
+    int32_t     operator_;
+    Location    next_location;
+};
 
 class Code {
 public:
-    void import_bytecode(ByteArray incoming);
+    FunctionId import_bytecode(ByteArray incoming);
 
     [[nodiscard]] std::string disassemble() const;
 
+    [[nodiscard]] Operation operation(Location const& location) const;
+
 private:
-    Bytecode bytecode_;
+    bc::Bytecode bytecode_;
 };
 
 } // tyche

src/vm/expr.cc

@@ -0,0 +1,18 @@
+#include "expr.hh"
+
+#include "vm_exceptions.hh"
+
+namespace tyche::vm {
+
+Value binary_operation(Value const& a, Value const& b, BinaryOperationType op)
+{
+    // TODO - this is temporary code
+
+    if (a.type() == Type::Integer && b.type() == Type::Integer && op == BinaryOperationType::Sum) {
+        return Value::CreateInteger(a.as_integer() + b.as_integer());
+    } else {
+        throw VMInvalidOperation(op, a.type(), b.type());
+    }
+}
+
+}

src/vm/expr.hh

@@ -0,0 +1,12 @@
+#ifndef TYCHE_EXPR_HH
+#define TYCHE_EXPR_HH
+#include "value.hh"
+
+namespace tyche::vm {
+
+enum class BinaryOperationType { Sum };
+
+Value binary_operation(Value const& a, Value const& b, BinaryOperationType op);
+
+}
+#endif //TYCHE_EXPR_HH

src/vm/instruction.cc

@@ -1,6 +1,6 @@
 #include "instruction.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
 std::pair<std::string, size_t> debug_instruction(Instruction inst, int oper)
 {
@@ -98,30 +98,48 @@ std::pair<std::string, size_t> debug_instruction(Instruction inst, int oper)
             out = "???";
     }
 
-    if ((uint8_t) inst < 0xa0)
+    OperandType operands = instruction_operand_type(inst);
+
+    if (operands == OperandType::NoOperand)
         return { out, 1 };
 
     out += " " + std::to_string(oper);
-    if ((uint8_t) inst >= 0xe0)
+    if (operands == OperandType::Int32)
         return { out, 5 };
-    else if ((uint8_t) inst >= 0xc0)
+    if (operands == OperandType::Int16)
         return { out, 3 };
-    else
+
     return { out, 2 };
 }
 
-std::pair<std::string, size_t> debug_instruction(Bytecode const& bt, uint32_t function_id, uint32_t addr)
+std::pair<std::string, size_t> debug_instruction(bc::Bytecode const& bt, uint32_t function_id, uint32_t addr)
 {
     auto inst = (Instruction) bt.get_code_byte(function_id, addr);
 
-    if ((uint8_t) inst >= 0xe0)
-        return debug_instruction(inst, bt.get_code_int32(function_id, addr + 1));
-    else if ((uint8_t) inst >= 0xc0)
-        return debug_instruction(inst, bt.get_code_int16(function_id, addr + 1));
-    else if ((uint8_t) inst >= 0xa0)
-        return debug_instruction(inst, bt.get_code_int8(function_id, addr + 1));
-
+    switch (instruction_operand_type(inst)) {
+        case OperandType::NoOperand:
             return debug_instruction(inst);
+        case OperandType::Int8:
+            return debug_instruction(inst, bt.get_code_int8(function_id, addr + 1));
+        case OperandType::Int16:
+            return debug_instruction(inst, bt.get_code_int16(function_id, addr + 1));
+        case OperandType::Int32:
+            return debug_instruction(inst, bt.get_code_int32(function_id, addr + 1));
+        default:
+    }
+
+    return { "???", 1 };
+}
+
+OperandType instruction_operand_type(Instruction inst)
+{
+    if ((uint8_t) inst >= 0xe0)
+        return OperandType::Int32;
+    if ((uint8_t) inst >= 0xc0)
+        return OperandType::Int16;
+    if ((uint8_t) inst >= 0xa0)
+        return OperandType::Int8;
+    return OperandType::NoOperand;
 }
 
 }

src/vm/instruction.hh

@@ -7,7 +7,7 @@
 
 #include "../bytecode/bytecode.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
 enum class Instruction : uint8_t {
 
@@ -96,7 +96,10 @@ enum class Instruction : uint8_t {
 };
 
 std::pair<std::string, size_t> debug_instruction(Instruction inst, int oper=0);
-std::pair<std::string, size_t> debug_instruction(Bytecode const& bt, uint32_t function_id, uint32_t addr);
+std::pair<std::string, size_t> debug_instruction(bc::Bytecode const& bt, uint32_t function_id, uint32_t addr);
+
+enum class OperandType { NoOperand, Int8, Int16, Int32 };
+OperandType instruction_operand_type(Instruction instruction);
 
 }
 

src/vm/location.hh

@@ -0,0 +1,16 @@
+#ifndef TYCHE_LOCATION_HH
+#define TYCHE_LOCATION_HH
+
+#include <cstdint>
+
+namespace tyche::vm {
+
+struct Location
+{
+    uint32_t function_id;
+    uint32_t pc;
+};
+
+}
+
+#endif //TYCHE_LOCATION_HH

src/vm/stack.cc

@@ -2,7 +2,7 @@
 
 #include "vm_exceptions.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
 Stack::Stack()
 {
@@ -16,7 +16,7 @@ void Stack::push(Value const& value)
 
 Value Stack::pop()
 {
-    if (stack_.size() <= fps_.size())
+    if (stack_.size() <= fps_.top())
         throw VMStackUnderflow();
 
     Value v = stack_.back();
@@ -58,4 +58,15 @@ void Stack::pop_fp()
     fps_.pop();
 }
 
+std::string Stack::debug() const
+{
+    if (stack_.empty())
+        return "empty";
+
+    std::string out;
+    for (size_t i = 0; i < stack_.size(); ++i)
+        out += "[" + stack_.at(i).to_string() + "] ";
+    return out;
+}
+
 } // tyche

src/vm/stack.hh

@@ -6,7 +6,7 @@
 
 #include "value.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
 class Stack {
 public:
@@ -21,6 +21,10 @@ public:
     void push_fp();
     void pop_fp();
 
+    [[nodiscard]] size_t fp_level() const { return fps_.size(); }
+
+    [[nodiscard]] std::string debug() const;
+
 private:
     std::vector<Value> stack_;
     std::stack<size_t> fps_;

src/vm/tests.cc

@@ -1,12 +1,15 @@
 #include "gtest/gtest.h"
 
 #include "../bytecode/bytecodeprototype.hh"
-#include "../bytecode/bytearray.hh"
+#include "../common/bytearray.hh"
 #include "../bytecode/bytecode.hh"
 #include "code.hh"
 #include "stack.hh"
+#include "vm.hh"
 
 using namespace tyche;
+using namespace tyche::bc;
+using namespace tyche::vm;
 
 TEST(Code, ImportSingleAndDebug)
 {
@@ -68,6 +71,27 @@ TEST(Stack, FramePointer)
     ASSERT_EQ(stack.at(-2).as_integer(), 10);
 }
 
+TEST(VM, BasicCode)
+{
+    // code (2+3)
+    BytecodePrototype bp;
+    bp.functions.emplace_back(0, 0);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::PushInt8);
+    bp.functions.at(0).code.append_int8(2);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::PushInt8);
+    bp.functions.at(0).code.append_int8(3);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::Sum);
+    bp.functions.at(0).code.append_byte((uint8_t) Instruction::Return);
+    ByteArray ba = Bytecode::generate(bp);
+
+    VM vm;
+    vm.load_bytecode(std::move(ba));
+    vm.call(0);
+
+    int32_t result = vm.to_integer(-1);
+    ASSERT_EQ(result, 5);
+}
+
 int main(int argc, char** argv)
 {
     testing::InitGoogleTest(&argc, argv);

src/vm/value.cc

@@ -2,7 +2,7 @@
 
 #include "../common/overloaded.hh"
 
-namespace tyche {
+namespace tyche::vm {
 
 Type Value::type() const
 {
@@ -11,6 +11,18 @@ Type Value::type() const
         [](int32_t)            { return Type::Integer; },
         [](float)              { return Type::Float; },
         [](std::string const&) { return Type::String; },
+        [](Function const&)    { return Type::Function; },
+    }, value_);
+}
+
+std::string Value::to_string() const
+{
+    return std::visit(overloaded {
+        [](std::monostate)       { return std::string("nil"); },
+        [](int32_t i)            { return std::to_string(i); },
+        [](float f)              { return std::to_string(f); },
+        [](std::string const& s) { return s; },
+        [](Function const& f)    { return "@" + std::to_string(f.f_id); }
     }, value_);
 }
 

src/vm/value.hh

@@ -4,14 +4,19 @@
 #include <string>
 #include <variant>
 
-namespace tyche {
+namespace tyche::vm {
+
+using FunctionId = uint32_t;
 
 enum class Type : uint8_t
 {
     Nil = 0, Integer, Float, String, Array, Table, Function, NativePointer,
 };
 
+
 class Value {
+    struct Function { FunctionId f_id; };
+
 public:
     Value() : value_(std::monostate()) {}
 
@@ -19,15 +24,19 @@ public:
     static Value CreateInteger(int32_t v) { return Value(v); }
     static Value CreateFloat(float f) { return Value(f); }
     static Value CreateString(std::string const& str) { return Value(str); }
+    static Value CreateFunctionId(FunctionId f_id) { return Value(Function { f_id }); }
 
     [[nodiscard]] Type type() const;
 
     [[nodiscard]] int32_t     as_integer() const     { return std::get<int32_t>(value_); }
     [[nodiscard]] float       as_float() const       { return std::get<float>(value_); }
     [[nodiscard]] std::string as_string() const      { return std::get<std::string>(value_); }
+    [[nodiscard]] FunctionId  as_function_id() const { return std::get<Function>(value_).f_id; }
+
+    [[nodiscard]] std::string to_string() const;
 
 private:
-    using Internal = std::variant<std::monostate, int32_t, float, std::string>;
+    using Internal = std::variant<std::monostate, int32_t, float, std::string, Function>;
     Internal value_;
 
     explicit Value(Internal const& internal) : value_(internal) {}

src/vm/vm.cc

@@ -0,0 +1,79 @@
+#include "vm.hh"
+
+#include "vm_exceptions.hh"
+#include "expr.hh"
+
+namespace tyche::vm {
+
+void VM::load_bytecode(ByteArray const& ba)
+{
+    FunctionId f_id = code_.import_bytecode(ba);
+    stack_.push(Value::CreateFunctionId(f_id));
+}
+
+void VM::call(size_t n_params)
+{
+    // TODO - parameters
+
+    Value f = stack_.pop();
+    if (f.type() != Type::Function)
+        throw VMTypeError(Type::Function, f.type());
+
+    loc_.emplace(f.as_function_id(), 0);
+    stack_.push_fp();
+    run_until_return();
+    // stack_.pop_fp();
+    loc_.pop();
+}
+
+int32_t VM::to_integer(int index) const
+{
+    Value i = stack_.at(index);
+    assert_type(i, Type::Integer);
+    return i.as_integer();
+}
+
+void VM::push_integer(int32_t value)
+{
+    stack_.push(Value::CreateInteger(value));
+}
+
+void VM::run_until_return()
+{
+    size_t level = stack_.fp_level();
+
+    while (stack_.fp_level() >= level)
+        step();
+}
+
+void VM::step()
+{
+    Operation op = code_.operation(loc_.top());
+    switch (op.instruction) {
+        case Instruction::PushInt8:
+        case Instruction::PushInt16:
+        case Instruction::PushInt32:
+            push_integer(op.operator_);
+            break;
+        case Instruction::Sum:
+            stack_.push(binary_operation(stack_.pop(), stack_.pop(), BinaryOperationType::Sum));
+            break;
+        case Instruction::Return: {
+            Value v = stack_.pop();
+            stack_.pop_fp();
+            stack_.push(v);
+            return;
+        }
+        default:
+            throw VMInvalidOpcode((uint8_t) op.instruction);
+    }
+    loc_.top() = op.next_location;
+}
+
+void VM::assert_type(Value const& val, Type type)
+{
+    if (val.type() != type)
+        throw VMTypeError(type, val.type());
+}
+
+} // tyche

src/vm/vm.hh

@@ -0,0 +1,35 @@
+#ifndef TYCHE_VM_HH
+#define TYCHE_VM_HH
+
+#include "code.hh"
+#include "location.hh"
+#include "stack.hh"
+
+namespace tyche::vm {
+
+class VM {
+public:
+    void load_bytecode(ByteArray const& ba);
+
+    void call(size_t n_params);
+
+    [[nodiscard]] int32_t to_integer(int index) const;
+
+    void push_integer(int32_t value);
+
+    [[nodiscard]] std::string debug_stack() const { return stack_.debug(); }
+
+private:
+    void run_until_return();
+    void step();
+
+    static void assert_type(Value const& val, Type type);
+
+    Stack stack_;
+    Code code_;
+    std::stack<Location> loc_;
+};
+
+} // tyche
+
+#endif //TYCHE_VM_HH

src/vm/vm_exceptions.hh

@@ -4,7 +4,9 @@
 #include <stdexcept>
 #include <string>
 
-namespace tyche {
+#include "expr.hh"
+
+namespace tyche::vm {
 
 class VMRuntimeError : public std::runtime_error
 {
@@ -24,6 +26,24 @@ public:
     explicit VMStackOutOfRange() : VMRuntimeError("Item does not exist in stack") {}
 };
 
+class VMTypeError : public VMRuntimeError
+{
+public:
+    explicit VMTypeError(Type expected, Type found) : VMRuntimeError("Type error") {}  // TODO - print types
+};
+
+class VMInvalidOpcode : public VMRuntimeError
+{
+public:
+    explicit VMInvalidOpcode(uint8_t opcode) : VMRuntimeError("Invalid opcode " + std::to_string(opcode)) {}
+};
+
+class VMInvalidOperation : public VMRuntimeError
+{
+public:
+    explicit VMInvalidOperation(BinaryOperationType op, Type type1, Type type2) : VMRuntimeError("Invalid binary operation") {}  // TODO - print types
+};
+
 }
 
 #endif //TYCHE_VM_EXCEPTIONS_HH