[Interpreter] Basic flow control.

src/interpreter/bytecode-array-builder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 BytecodeArrayBuilder::BytecodeArrayBuilder(Isolate* isolate, Zone* zone)
     : isolate_(isolate),
       bytecodes_(zone),
       bytecode_generated_(false),
       constants_map_(isolate->heap(), zone),
       constants_(zone),
+      forward_labels_(zone),
+      bound_labels_(zone),
       parameter_count_(-1),
       local_register_count_(-1),
       temporary_register_count_(0),
       temporary_register_next_(0) {}
 
 
 void BytecodeArrayBuilder::set_locals_count(int number_of_locals) {
   local_register_count_ = number_of_locals;
   temporary_register_next_ = local_register_count_;
 }
@@ skipping 42 matching lines @@
   }
 
   Handle<BytecodeArray> output =
       factory->NewBytecodeArray(bytecode_size, &bytecodes_.front(), frame_size,
                                 parameter_count_, constant_pool);
   bytecode_generated_ = true;
   return output;
 }
 
 
-BytecodeArrayBuilder& BytecodeArrayBuilder::BinaryOperation(Token::Value binop,
+template <size_t N>
+void BytecodeArrayBuilder::RawOutputAt(ZoneVector<uint8_t>::iterator pos,
+                                       uint8_t(&bytes)[N]) {
+  DCHECK_EQ(Bytecodes::NumberOfOperands(Bytecodes::FromByte(bytes[0])), N - 1);
+  for (int i = 1; i < static_cast<int>(N); i++) {
+    DCHECK(OperandIsValid(Bytecodes::FromByte(bytes[0]), i - 1, bytes[i]));
+  }
+
+  if (bytecodes()->end() == pos) {

[rmcilroy, 2015/09/18 10:42:23]

I'm not keen on having the Output operators do patching automatically based on
position. I think Output should always push to the end of the bytecode array
(like it did previously) and there should be a special Patch function for
patching a given bytecode - that way we can also verify that we are performing a
valid patch (i.e., the previous bytecode is the same size as the patching
bytecode, etc). Given that this is likely only going to be used for forward
branches I think it makes sense to make it more special to avoid accidental
misuse.

[oth, 2015/09/23 10:46:55]

Done.

+    bytecodes()->insert(pos, bytes, bytes + N);
+  } else {
+    std::copy(bytes, bytes + N, pos);
+  }
+}
+
+
+void BytecodeArrayBuilder::Output(const ZoneVector<uint8_t>::iterator& pos,
+                                  Bytecode bytecode, uint8_t operand0) {
+  uint8_t bytes[] = {Bytecodes::ToByte(bytecode), operand0};
+  RawOutputAt(pos, bytes);
+}
+
+
+void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0,
+                                  uint8_t operand1, uint8_t operand2) {
+  uint8_t bytes[] = {Bytecodes::ToByte(bytecode), operand0, operand1, operand2};
+  RawOutputAt(bytecodes()->end(), bytes);
+}
+
+
+void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0,
+                                  uint8_t operand1) {
+  uint8_t bytes[] = {Bytecodes::ToByte(bytecode), operand0, operand1};
+  RawOutputAt(bytecodes()->end(), bytes);
+}
+
+
+void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0) {
+  uint8_t bytes[] = {Bytecodes::ToByte(bytecode), operand0};
+  RawOutputAt(bytecodes()->end(), bytes);
+}
+
+
+void BytecodeArrayBuilder::Output(Bytecode bytecode) {
+  uint8_t bytes[] = {Bytecodes::ToByte(bytecode)};
+  RawOutputAt(bytecodes()->end(), bytes);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::BinaryOperation(Token::Value op,
                                                             Register reg) {
-  Output(BytecodeForBinaryOperation(binop), reg.ToOperand());
+  Output(BytecodeForBinaryOperation(op), reg.ToOperand());
   return *this;
 }
 
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Add(Register reg) {
+  return BinaryOperation(Token::Value::ADD, reg);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Subtract(Register reg) {
+  return BinaryOperation(Token::Value::SUB, reg);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Multiply(Register reg) {
+  return BinaryOperation(Token::Value::MUL, reg);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Divide(Register reg) {
+  return BinaryOperation(Token::Value::DIV, reg);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Modulo(Register reg) {
+  return BinaryOperation(Token::Value::MOD, reg);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::CompareOperation(Token::Value op,
+                                                             Register reg) {
+  Output(BytecodeForCompareOperation(op), reg.ToOperand());
+  return *this;
+}
+
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLiteral(
     v8::internal::Smi* smi) {
   int32_t raw_smi = smi->value();
   if (raw_smi == 0) {
     Output(Bytecode::kLdaZero);
   } else if (raw_smi >= -128 && raw_smi <= 127) {
     Output(Bytecode::kLdaSmi8, static_cast<uint8_t>(raw_smi));
   } else {
     LoadLiteral(Handle<Object>(smi, isolate_));
   }
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLiteral(Handle<Object> object) {
   size_t entry = GetConstantPoolEntry(object);
-  if (FitsInByteOperand(entry)) {
+  if (FitsInIdxOperand(entry)) {
     Output(Bytecode::kLdaConstant, static_cast<uint8_t>(entry));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLiteral(int value) {
+  Handle<Object> v = isolate()->factory()->NewNumberFromInt(value);
+  if (v->IsSmi()) {
+    return LoadLiteral(Smi::cast(*v));
+  } else {
+    return LoadLiteral(v);
+  }
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::LoadLiteral(double value) {
+  return LoadLiteral(isolate()->factory()->NewNumber(value));
+}
+
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadUndefined() {
   Output(Bytecode::kLdaUndefined);
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadNull() {
   Output(Bytecode::kLdaNull);
   return *this;
 }
@@ skipping 30 matching lines @@
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadNamedProperty(
     Register object, int feedback_slot, LanguageMode language_mode) {
   if (!is_sloppy(language_mode)) {
     UNIMPLEMENTED();
   }
 
-  if (FitsInByteOperand(feedback_slot)) {
+  if (FitsInIdxOperand(feedback_slot)) {
     Output(Bytecode::kLoadIC, object.ToOperand(),
            static_cast<uint8_t>(feedback_slot));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadKeyedProperty(
     Register object, int feedback_slot, LanguageMode language_mode) {
   if (!is_sloppy(language_mode)) {
     UNIMPLEMENTED();
   }
 
-  if (FitsInByteOperand(feedback_slot)) {
+  if (FitsInIdxOperand(feedback_slot)) {
     Output(Bytecode::kKeyedLoadIC, object.ToOperand(),
            static_cast<uint8_t>(feedback_slot));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::StoreNamedProperty(
     Register object, Register name, int feedback_slot,
     LanguageMode language_mode) {
   if (!is_sloppy(language_mode)) {
     UNIMPLEMENTED();
   }
 
-  if (FitsInByteOperand(feedback_slot)) {
+  if (FitsInIdxOperand(feedback_slot)) {
     Output(Bytecode::kStoreIC, object.ToOperand(), name.ToOperand(),
            static_cast<uint8_t>(feedback_slot));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::StoreKeyedProperty(
     Register object, Register key, int feedback_slot,
     LanguageMode language_mode) {
   if (!is_sloppy(language_mode)) {
     UNIMPLEMENTED();
   }
 
-  if (FitsInByteOperand(feedback_slot)) {
+  if (FitsInIdxOperand(feedback_slot)) {
     Output(Bytecode::kKeyedStoreIC, object.ToOperand(), key.ToOperand(),
            static_cast<uint8_t>(feedback_slot));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::Bind(BytecodeLabel* label) {
+  auto forward_labels_iterator = forward_labels_.find(label);
+  if (forward_labels_.end() != forward_labels_iterator) {
+    // Label is forward referred to, update the referring jump instruction.
+    ZoneVector<uint8_t>::iterator it = bytecodes()->begin() + label->offset();
+    OutputJump(Bytecodes::FromByte(*it), it, bytecodes()->end());
+    forward_labels_.erase(forward_labels_iterator);
+    // Now treat as if the label will only be back referred to.
+  }
+
+  DCHECK(bound_labels_.end() == bound_labels_.find(label));
+  label->bind_to(bytecodes()->size());
+  bound_labels_.insert(label);
+  return *this;
+}
+
+
+// static
+bool BytecodeArrayBuilder::IsJumpWithSmi8Operand(Bytecode jump_bytecode) {
+  return jump_bytecode == Bytecode::kJumpSmi8 ||
+         jump_bytecode == Bytecode::kJumpIfTrueSmi8 ||
+         jump_bytecode == Bytecode::kJumpIfFalseSmi8;
+}
+
+
+// static
+Bytecode BytecodeArrayBuilder::GetJumpWithConstantOperand(
+    Bytecode jump_bytecode) {
+  switch (jump_bytecode) {
+    case Bytecode::kJumpSmi8:
+      return Bytecode::kJumpConstant;
+    case Bytecode::kJumpIfTrueSmi8:
+      return Bytecode::kJumpIfTrueConstant;
+    case Bytecode::kJumpIfFalseSmi8:
+      return Bytecode::kJumpIfFalseConstant;
+    default:
+      UNREACHABLE();
+      return Bytecode::kJumpConstant;
+  }
+}
+
+
+void BytecodeArrayBuilder::OutputJump(
+    Bytecode jump_bytecode, const ZoneVector<uint8_t>::iterator& jump_location,
+    const ZoneVector<uint8_t>::iterator& jump_target) {
+  DCHECK(IsJumpWithSmi8Operand(jump_bytecode));
+
+  int delta = static_cast<int>(jump_target - jump_location);
+  if (FitsInImm8Operand(delta)) {
+    Output(jump_location, jump_bytecode, static_cast<uint8_t>(delta));
+  } else {
+    size_t entry = GetConstantPoolEntry(handle(Smi::FromInt(delta), isolate()));
+    if (FitsInIdxOperand(entry)) {
+      jump_bytecode = GetJumpWithConstantOperand(jump_bytecode);
+      Output(jump_location, jump_bytecode, static_cast<uint8_t>(entry));
+    } else {
+      UNIMPLEMENTED();
+    }
+  }
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Jump(Bytecode jump_bytecode,
+                                                 BytecodeLabel* label) {
+  if (bound_labels_.find(label) != bound_labels_.end()) {
+    // Label has been bound already so this is a backwards jump.
+    OutputJump(jump_bytecode, bytecodes()->end(),
+               bytecodes()->begin() + label->offset());
+  } else {
+    // Label has not yet been bound so this is a forward reference
+    // that will be patched when the label is bound.
+    DCHECK(forward_labels_.find(label) == forward_labels_.end());
+    label->bind_to(bytecodes()->size());
+    forward_labels_.insert(label);
+    OutputJump(jump_bytecode, bytecodes()->end(), bytecodes()->end());
+  }
+  return *this;
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::Jump(BytecodeLabel* label) {
+  return Jump(Bytecode::kJumpSmi8, label);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::JumpIfTrue(BytecodeLabel* label) {
+  return Jump(Bytecode::kJumpIfTrueSmi8, label);
+}
+
+
+BytecodeArrayBuilder& BytecodeArrayBuilder::JumpIfFalse(BytecodeLabel* label) {
+  return Jump(Bytecode::kJumpIfFalseSmi8, label);
+}
+
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::Return() {
   Output(Bytecode::kReturn);
   return *this;
 }
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::Call(Register callable,
                                                  Register receiver,
                                                  size_t arg_count) {
-  if (FitsInByteOperand(arg_count)) {
+  if (FitsInIdxOperand(arg_count)) {
     Output(Bytecode::kCall, callable.ToOperand(), receiver.ToOperand(),
            static_cast<uint8_t>(arg_count));
   } else {
     UNIMPLEMENTED();
   }
   return *this;
 }
 
 
 size_t BytecodeArrayBuilder::GetConstantPoolEntry(Handle<Object> object) {
@@ skipping 51 matching lines @@
       } else {
         return (reg.index() >= 0 && reg.index() < temporary_register_next_);
       }
     }
   }
   UNREACHABLE();
   return false;
 }
 
 
-void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0,
-                                  uint8_t operand1, uint8_t operand2) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), 3);
-  DCHECK(OperandIsValid(bytecode, 0, operand0) &&
-         OperandIsValid(bytecode, 1, operand1) &&
-         OperandIsValid(bytecode, 2, operand2));
-  bytecodes_.push_back(Bytecodes::ToByte(bytecode));
-  bytecodes_.push_back(operand0);
-  bytecodes_.push_back(operand1);
-  bytecodes_.push_back(operand2);
-}
-
-
-void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0,
-                                  uint8_t operand1) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), 2);
-  DCHECK(OperandIsValid(bytecode, 0, operand0) &&
-         OperandIsValid(bytecode, 1, operand1));
-  bytecodes_.push_back(Bytecodes::ToByte(bytecode));
-  bytecodes_.push_back(operand0);
-  bytecodes_.push_back(operand1);
-}
-
-
-void BytecodeArrayBuilder::Output(Bytecode bytecode, uint8_t operand0) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), 1);
-  DCHECK(OperandIsValid(bytecode, 0, operand0));
-  bytecodes_.push_back(Bytecodes::ToByte(bytecode));
-  bytecodes_.push_back(operand0);
-}
-
-
-void BytecodeArrayBuilder::Output(Bytecode bytecode) {
-  DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), 0);
-  bytecodes_.push_back(Bytecodes::ToByte(bytecode));
-}
-
-
 // static
 Bytecode BytecodeArrayBuilder::BytecodeForBinaryOperation(Token::Value op) {
   switch (op) {
     case Token::Value::ADD:
       return Bytecode::kAdd;
     case Token::Value::SUB:
       return Bytecode::kSub;
     case Token::Value::MUL:
       return Bytecode::kMul;
     case Token::Value::DIV:
       return Bytecode::kDiv;
     case Token::Value::MOD:
       return Bytecode::kMod;
     default:
       UNIMPLEMENTED();
       return static_cast<Bytecode>(-1);
   }
 }
 
 
 // static
-bool BytecodeArrayBuilder::FitsInByteOperand(int value) {
+Bytecode BytecodeArrayBuilder::BytecodeForCompareOperation(Token::Value op) {
+  switch (op) {
+    case Token::Value::EQ:
+      return Bytecode::kTestEqual;
+    case Token::Value::NE:
+      return Bytecode::kTestNotEqual;
+    case Token::Value::EQ_STRICT:
+      return Bytecode::kTestEqualStrict;
+    case Token::Value::NE_STRICT:
+      return Bytecode::kTestNotEqualStrict;
+    case Token::Value::LT:
+      return Bytecode::kTestLessThan;
+    case Token::Value::GT:
+      return Bytecode::kTestGreaterThan;
+    case Token::Value::LTE:
+      return Bytecode::kTestLessThanEqual;
+    case Token::Value::GTE:
+      return Bytecode::kTestGreaterThanEqual;
+    case Token::Value::INSTANCEOF:
+      return Bytecode::kTestInstanceOf;
+    case Token::Value::IN:
+      return Bytecode::kTestIn;
+    default:
+      UNIMPLEMENTED();
+      return static_cast<Bytecode>(-1);
+  }
+}
+
+
+// static
+bool BytecodeArrayBuilder::FitsInIdxOperand(int value) {
   return 0 <= value && value <= 255;
 }
 
 
 // static
-bool BytecodeArrayBuilder::FitsInByteOperand(size_t value) {
+bool BytecodeArrayBuilder::FitsInIdxOperand(size_t value) {
   return value <= 255;
 }
 
 
+// static
+bool BytecodeArrayBuilder::FitsInImm8Operand(int value) {
+  return -128 <= value && value < 127;
+}
+
+
 TemporaryRegisterScope::TemporaryRegisterScope(BytecodeArrayBuilder* builder)
     : builder_(builder), count_(0), last_register_index_(-1) {}
 
 
 TemporaryRegisterScope::~TemporaryRegisterScope() {
   while (count_-- != 0) {
     builder_->ReturnTemporaryRegister(last_register_index_--);
   }
 }
 
 
 Register TemporaryRegisterScope::NewRegister() {
   count_++;
   last_register_index_ = builder_->BorrowTemporaryRegister();
   return Register(last_register_index_);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8