src/interpreter/interpreter-assembler.h

// 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.

#ifndef V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_
#define V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_

#include "src/codegen/code-stub-assembler.h"
#include "src/common/globals.h"
#include "src/interpreter/bytecode-register.h"
#include "src/interpreter/bytecodes.h"
#include "src/objects/bytecode-array.h"
#include "src/runtime/runtime.h"

namespace v8 {
namespace internal {
namespace interpreter {

class V8_EXPORT_PRIVATE InterpreterAssembler : public CodeStubAssembler {
 public:
  InterpreterAssembler(compiler::CodeAssemblerState* state, Bytecode bytecode,
                       OperandScale operand_scale);
  ~InterpreterAssembler();
  InterpreterAssembler(const InterpreterAssembler&) = delete;
  InterpreterAssembler& operator=(const InterpreterAssembler&) = delete;

  // Returns the 32-bit unsigned count immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<Uint32T> BytecodeOperandCount(int operand_index);
  // Returns the 32-bit unsigned flag for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<Uint32T> BytecodeOperandFlag8(int operand_index);
  // Returns the 32-bit unsigned 2-byte flag for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<Uint32T> BytecodeOperandFlag16(int operand_index);
  // Returns the 32-bit zero-extended index immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<Uint32T> BytecodeOperandIdxInt32(int operand_index);
  // Returns the word zero-extended index immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<UintPtrT> BytecodeOperandIdx(int operand_index);
  // Returns the smi index immediate for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<Smi> BytecodeOperandIdxSmi(int operand_index);
  // Returns the TaggedIndex immediate for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<TaggedIndex> BytecodeOperandIdxTaggedIndex(int operand_index);
  // Returns the 32-bit unsigned immediate for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<Uint32T> BytecodeOperandUImm(int operand_index);
  // Returns the word-size unsigned immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<UintPtrT> BytecodeOperandUImmWord(int operand_index);
  // Returns the unsigned smi immediate for bytecode operand |operand_index| in
  // the current bytecode.
  TNode<Smi> BytecodeOperandUImmSmi(int operand_index);
  // Returns the 32-bit signed immediate for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<Int32T> BytecodeOperandImm(int operand_index);
  // Returns the word-size signed immediate for bytecode operand |operand_index|
  // in the current bytecode.
  TNode<IntPtrT> BytecodeOperandImmIntPtr(int operand_index);
  // Returns the smi immediate for bytecode operand |operand_index| in the
  // current bytecode.
  TNode<Smi> BytecodeOperandImmSmi(int operand_index);
  // Returns the 32-bit unsigned runtime id immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<Uint32T> BytecodeOperandRuntimeId(int operand_index);
  // Returns the word zero-extended native context index immediate for bytecode
  // operand |operand_index| in the current bytecode.
  TNode<UintPtrT> BytecodeOperandNativeContextIndex(int operand_index);
  // Returns the 32-bit unsigned intrinsic id immediate for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<Uint32T> BytecodeOperandIntrinsicId(int operand_index);
  // Accumulator.
  TNode<Object> GetAccumulator();
  void SetAccumulator(TNode<Object> value);
  void ClobberAccumulator(TNode<Object> clobber_value);

  // Context.
  TNode<Context> GetContext();
  void SetContext(TNode<Context> value);

  // Context at |depth| in the context chain starting at |context|.
  TNode<Context> GetContextAtDepth(TNode<Context> context,
                                   TNode<Uint32T> depth);

  // A RegListNodePair provides an abstraction over lists of registers.
  class RegListNodePair {
   public:
    RegListNodePair(TNode<IntPtrT> base_reg_location, TNode<Word32T> reg_count)
        : base_reg_location_(base_reg_location), reg_count_(reg_count) {}

    TNode<Word32T> reg_count() const { return reg_count_; }
    TNode<IntPtrT> base_reg_location() const { return base_reg_location_; }

   private:
    TNode<IntPtrT> base_reg_location_;
    TNode<Word32T> reg_count_;
  };

  // Backup/restore register file to/from a fixed array of the correct length.
  // There is an asymmetry between suspend/export and resume/import.
  // - Suspend copies arguments and registers to the generator.
  // - Resume copies only the registers from the generator, the arguments
  //   are copied by the ResumeGenerator trampoline.
  TNode<FixedArray> ExportParametersAndRegisterFile(
      TNode<FixedArray> array, const RegListNodePair& registers);
  TNode<FixedArray> ImportRegisterFile(TNode<FixedArray> array,
                                       const RegListNodePair& registers);

  // Loads from and stores to the interpreter register file.
  TNode<Object> LoadRegister(Register reg);
  TNode<IntPtrT> LoadAndUntagRegister(Register reg);
  TNode<Object> LoadRegisterAtOperandIndex(int operand_index);
  std::pair<TNode<Object>, TNode<Object>> LoadRegisterPairAtOperandIndex(
      int operand_index);
  void StoreRegister(TNode<Object> value, Register reg);
  void StoreRegisterAtOperandIndex(TNode<Object> value, int operand_index);
  void StoreRegisterPairAtOperandIndex(TNode<Object> value1,
                                       TNode<Object> value2, int operand_index);
  void StoreRegisterTripleAtOperandIndex(TNode<Object> value1,
                                         TNode<Object> value2,
                                         TNode<Object> value3,
                                         int operand_index);

  RegListNodePair GetRegisterListAtOperandIndex(int operand_index);
  TNode<Object> LoadRegisterFromRegisterList(const RegListNodePair& reg_list,
                                             int index);
  TNode<IntPtrT> RegisterLocationInRegisterList(const RegListNodePair& reg_list,
                                                int index);

  // Load constant at the index specified in operand |operand_index| from the
  // constant pool.
  TNode<Object> LoadConstantPoolEntryAtOperandIndex(int operand_index);
  // Load and untag constant at the index specified in operand |operand_index|
  // from the constant pool.
  TNode<IntPtrT> LoadAndUntagConstantPoolEntryAtOperandIndex(int operand_index);
  // Load constant at |index| in the constant pool.
  TNode<Object> LoadConstantPoolEntry(TNode<WordT> index);
  // Load and untag constant at |index| in the constant pool.
  TNode<IntPtrT> LoadAndUntagConstantPoolEntry(TNode<WordT> index);

  TNode<JSFunction> LoadFunctionClosure();

  // Load the FeedbackVector for the current function. The returned node could
  // be undefined.
  TNode<Union<FeedbackVector, Undefined>> LoadFeedbackVector();

  auto LoadFeedbackVectorOrUndefinedIfJitless() {
#ifndef V8_JITLESS
    return LoadFeedbackVector();
#else
    return UndefinedConstant();
#endif  // V8_JITLESS
  }

  static constexpr UpdateFeedbackMode DefaultUpdateFeedbackMode() {
#ifndef V8_JITLESS
    return UpdateFeedbackMode::kOptionalFeedback;
#else
    return UpdateFeedbackMode::kNoFeedback;
#endif  // !V8_JITLESS
  }

  // Call JSFunction or Callable |function| with |args| arguments, possibly
  // including the receiver depending on |receiver_mode|. After the call returns
  // directly dispatches to the next bytecode.
  void CallJSAndDispatch(TNode<JSAny> function, TNode<Context> context,
                         const RegListNodePair& args,
                         ConvertReceiverMode receiver_mode);

  // Call JSFunction or Callable |function| with |arg_count| arguments (not
  // including receiver) passed as |args|, possibly including the receiver
  // depending on |receiver_mode|. After the call returns directly dispatches to
  // the next bytecode.
  template <class... TArgs>
  void CallJSAndDispatch(TNode<JSAny> function, TNode<Context> context,
                         TNode<Word32T> arg_count,
                         ConvertReceiverMode receiver_mode, TArgs... args);

  // Call JSFunction or Callable |function| with |args|
  // arguments (not including receiver), and the final argument being spread.
  // After the call returns directly dispatches to the next bytecode.
  void CallJSWithSpreadAndDispatch(TNode<JSAny> function,
                                   TNode<Context> context,
                                   const RegListNodePair& args,
                                   TNode<UintPtrT> slot_id);

  // Call constructor |target| with |args| arguments (not including receiver).
  // The |new_target| is the same as the |target| for the new keyword, but
  // differs for the super keyword.
  TNode<Object> Construct(
      TNode<JSAny> target, TNode<Context> context, TNode<JSAny> new_target,
      const RegListNodePair& args, TNode<UintPtrT> slot_id,
      TNode<Union<FeedbackVector, Undefined>> maybe_feedback_vector);

  // Call constructor |target| with |args| arguments (not including
  // receiver). The last argument is always a spread. The |new_target| is the
  // same as the |target| for the new keyword, but differs for the super
  // keyword.
  TNode<Object> ConstructWithSpread(TNode<JSAny> target, TNode<Context> context,
                                    TNode<JSAny> new_target,
                                    const RegListNodePair& args,
                                    TNode<UintPtrT> slot_id);

  // Call constructor |target|, forwarding all arguments in the current JS
  // frame.
  TNode<Object> ConstructForwardAllArgs(TNode<JSAny> target,
                                        TNode<Context> context,
                                        TNode<JSAny> new_target,
                                        TNode<TaggedIndex> slot_id);

  // Call runtime function with |args| arguments.
  template <class T = Object>
  TNode<T> CallRuntimeN(TNode<Uint32T> function_id, TNode<Context> context,
                        const RegListNodePair& args, int return_count);

  // Jump forward relative to the current bytecode by the |jump_offset|.
  void Jump(TNode<IntPtrT> jump_offset);

  // Jump backward relative to the current bytecode by the |jump_offset|.
  void JumpBackward(TNode<IntPtrT> jump_offset);

  // Jump forward relative to the current bytecode by |jump_offset| if the
  // word values |lhs| and |rhs| are equal.
  void JumpIfTaggedEqual(TNode<Object> lhs, TNode<Object> rhs,
                         TNode<IntPtrT> jump_offset);

  // Jump forward relative to the current bytecode by offest specified in
  // operand |operand_index| if the word values |lhs| and |rhs| are equal.
  void JumpIfTaggedEqual(TNode<Object> lhs, TNode<Object> rhs,
                         int operand_index);

  // Jump forward relative to the current bytecode by offest specified from the
  // constant pool if the word values |lhs| and |rhs| are equal.
  // The constant's index is specified in operand |operand_index|.
  void JumpIfTaggedEqualConstant(TNode<Object> lhs, TNode<Object> rhs,
                                 int operand_index);

  // Jump forward relative to the current bytecode by |jump_offset| if the
  // word values |lhs| and |rhs| are not equal.
  void JumpIfTaggedNotEqual(TNode<Object> lhs, TNode<Object> rhs,
                            TNode<IntPtrT> jump_offset);

  // Jump forward relative to the current bytecode by offest specified in
  // operand |operand_index| if the word values |lhs| and |rhs| are not equal.
  void JumpIfTaggedNotEqual(TNode<Object> lhs, TNode<Object> rhs,
                            int operand_index);

  // Jump forward relative to the current bytecode by offest specified from the
  // constant pool if the word values |lhs| and |rhs| are not equal.
  // The constant's index is specified in operand |operand_index|.
  void JumpIfTaggedNotEqualConstant(TNode<Object> lhs, TNode<Object> rhs,
                                    int operand_index);

  // Updates the profiler interrupt budget for a return.
  void UpdateInterruptBudgetOnReturn();

  // Adjusts the interrupt budget by the provided weight. Returns the new
  // budget.
  TNode<Int32T> UpdateInterruptBudget(TNode<Int32T> weight);
  // Decrements the bytecode array's interrupt budget by a 32-bit unsigned
  // |weight| and calls Runtime::kInterrupt if counter reaches zero.
  enum StackCheckBehavior {
    kEnableStackCheck,
    kDisableStackCheck,
  };
  void DecreaseInterruptBudget(TNode<Int32T> weight,
                               StackCheckBehavior stack_check_behavior);

  TNode<Int8T> LoadOsrState(TNode<FeedbackVector> feedback_vector);

  // Dispatch to the bytecode.
  void Dispatch();

  // Dispatch bytecode as wide operand variant.
  void DispatchWide(OperandScale operand_scale);

  // Dispatch to |target_bytecode| at |new_bytecode_offset|.
  // |target_bytecode| should be equivalent to loading from the offset.
  void DispatchToBytecode(TNode<WordT> target_bytecode,
                          TNode<IntPtrT> new_bytecode_offset);

  // Dispatches to |target_bytecode| at BytecodeOffset(). Includes short-star
  // lookahead if the current bytecode_ is likely followed by a short-star
  // instruction.
  void DispatchToBytecodeWithOptionalStarLookahead(
      TNode<WordT> target_bytecode);

  // Abort with the given abort reason.
  void Abort(AbortReason abort_reason);
  void AbortIfWordNotEqual(TNode<WordT> lhs, TNode<WordT> rhs,
                           AbortReason abort_reason);
  // Abort if |register_count| is invalid for given register file array.
  void AbortIfRegisterCountInvalid(TNode<FixedArray> parameters_and_registers,
                                   TNode<IntPtrT> parameter_count,
                                   TNode<UintPtrT> register_count);

  // Attempts to OSR.
  enum OnStackReplacementParams {
    kBaselineCodeIsCached,
    kDefault,
  };
  void OnStackReplacement(TNode<Context> context,
                          TNode<FeedbackVector> feedback_vector,
                          TNode<IntPtrT> relative_jump,
                          TNode<Int32T> loop_depth,
                          TNode<IntPtrT> feedback_slot, TNode<Int8T> osr_state,
                          OnStackReplacementParams params);

  // The BytecodeOffset() is the offset from the ByteCodeArray pointer; to
  // translate into runtime `BytecodeOffset` (defined in utils.h as the offset
  // from the start of the bytecode section), this constant has to be applied.
  static constexpr int kFirstBytecodeOffset =
      BytecodeArray::kHeaderSize - kHeapObjectTag;

  // Returns the offset from the BytecodeArrayPointer of the current bytecode.
  TNode<IntPtrT> BytecodeOffset();

 protected:
  Bytecode bytecode() const { return bytecode_; }
  static bool TargetSupportsUnalignedAccess();

  void ToNumberOrNumeric(Object::Conversion mode);

  void StoreRegisterForShortStar(TNode<Object> value, TNode<WordT> opcode);

  // Load the bytecode at |bytecode_offset|.
  TNode<WordT> LoadBytecode(TNode<IntPtrT> bytecode_offset);

  // Load the parameter count of the current function from its BytecodeArray.
  TNode<IntPtrT> LoadParameterCountWithoutReceiver();

 private:
  // Returns a pointer to the current function's BytecodeArray object.
  TNode<BytecodeArray> BytecodeArrayTaggedPointer();

  // Returns a pointer to first entry in the interpreter dispatch table.
  TNode<ExternalReference> DispatchTablePointer();

  // Returns the accumulator value without checking whether bytecode
  // uses it. This is intended to be used only in dispatch and in
  // tracing as these need to bypass accumulator use validity checks.
  TNode<Object> GetAccumulatorUnchecked();

  // Returns the frame pointer for the interpreted frame of the function being
  // interpreted.
  TNode<RawPtrT> GetInterpretedFramePointer();

  // Operations on registers.
  TNode<IntPtrT> RegisterLocation(Register reg);
  TNode<IntPtrT> RegisterLocation(TNode<IntPtrT> reg_index);
  TNode<IntPtrT> NextRegister(TNode<IntPtrT> reg_index);
  TNode<Object> LoadRegister(TNode<IntPtrT> reg_index);
  void StoreRegister(TNode<Object> value, TNode<IntPtrT> reg_index);

  // Saves and restores interpreter bytecode offset to the interpreter stack
  // frame when performing a call.
  void CallPrologue();
  void CallEpilogue();

  // Increment the dispatch counter for the (current, next) bytecode pair.
  void TraceBytecodeDispatch(TNode<WordT> target_bytecode);

  // Traces the current bytecode by calling |function_id|.
  void TraceBytecode(Runtime::FunctionId function_id);

  // Returns the offset of register |index| relative to RegisterFilePointer().
  TNode<IntPtrT> RegisterFrameOffset(TNode<IntPtrT> index);

  // Returns the offset of an operand relative to the current bytecode offset.
  TNode<IntPtrT> OperandOffset(int operand_index);

  // Returns a value built from an sequence of bytes in the bytecode
  // array starting at |relative_offset| from the current bytecode.
  // The |result_type| determines the size and signedness.  of the
  // value read. This method should only be used on architectures that
  // do not support unaligned memory accesses.
  TNode<Word32T> BytecodeOperandReadUnaligned(int relative_offset,
                                              MachineType result_type);

  // Returns zero- or sign-extended to word32 value of the operand.
  TNode<Uint8T> BytecodeOperandUnsignedByte(int operand_index);
  TNode<Int8T> BytecodeOperandSignedByte(int operand_index);
  TNode<Uint16T> BytecodeOperandUnsignedShort(int operand_index);
  TNode<Int16T> BytecodeOperandSignedShort(int operand_index);
  TNode<Uint32T> BytecodeOperandUnsignedQuad(int operand_index);
  TNode<Int32T> BytecodeOperandSignedQuad(int operand_index);

  // Returns zero- or sign-extended to word32 value of the operand of
  // given size.
  TNode<Int32T> BytecodeSignedOperand(int operand_index,
                                      OperandSize operand_size);
  TNode<Uint32T> BytecodeUnsignedOperand(int operand_index,
                                         OperandSize operand_size);

  // Returns the word-size sign-extended register index for bytecode operand
  // |operand_index| in the current bytecode.
  TNode<IntPtrT> BytecodeOperandReg(int operand_index);

  // Returns the word zero-extended index immediate for bytecode operand
  // |operand_index| in the current bytecode for use when loading a constant
  // pool element.
  TNode<UintPtrT> BytecodeOperandConstantPoolIdx(int operand_index);

  // Jump to a specific bytecode offset.
  void JumpToOffset(TNode<IntPtrT> new_bytecode_offset);

  // Jump forward relative to the current bytecode by |jump_offset| if the
  // |condition| is true. Helper function for JumpIfTaggedEqual and
  // JumpIfTaggedNotEqual.
  void JumpConditional(TNode<BoolT> condition, TNode<IntPtrT> jump_offset);

  // Jump forward relative to the current bytecode by offest specified in
  // operand |operand_index| if the |condition| is true. Helper function for
  // JumpIfTaggedEqual and JumpIfTaggedNotEqual.
  void JumpConditionalByImmediateOperand(TNode<BoolT> condition,
                                         int operand_index);

  // Jump forward relative to the current bytecode by offest specified from the
  // constant pool if the |condition| is true. The constant's index is specified
  // in operand |operand_index|. Helper function for JumpIfTaggedEqualConstant
  // and JumpIfTaggedNotEqualConstant.
  void JumpConditionalByConstantOperand(TNode<BoolT> condition,
                                        int operand_index);

  // Save the bytecode offset to the interpreter frame.
  void SaveBytecodeOffset();
  // Reload the bytecode offset from the interpreter frame.
  TNode<IntPtrT> ReloadBytecodeOffset();

  // Updates and returns BytecodeOffset() advanced by the current bytecode's
  // size. Traces the exit of the current bytecode.
  TNode<IntPtrT> Advance();

  // Updates and returns BytecodeOffset() advanced by delta bytecodes.
  // Traces the exit of the current bytecode.
  TNode<IntPtrT> Advance(int delta);
  TNode<IntPtrT> Advance(TNode<IntPtrT> delta);

  // Look ahead for short Star and inline it in a branch, including subsequent
  // dispatch. Anything after this point can assume that the following
  // instruction was not a short Star.
  void StarDispatchLookahead(TNode<WordT> target_bytecode);

  // Build code for short Star at the current BytecodeOffset() and Advance() to
  // the next dispatch offset.
  void InlineShortStar(TNode<WordT> target_bytecode);

  // Dispatch to the bytecode handler with code entry point |handler_entry|.
  void DispatchToBytecodeHandlerEntry(TNode<RawPtrT> handler_entry,
                                      TNode<IntPtrT> bytecode_offset);

  int CurrentBytecodeSize() const;

  OperandScale operand_scale() const { return operand_scale_; }

  Bytecode bytecode_;
  OperandScale operand_scale_;
  CodeStubAssembler::TVariable<RawPtrT> interpreted_frame_pointer_;
  CodeStubAssembler::TVariable<BytecodeArray> bytecode_array_;
  CodeStubAssembler::TVariable<IntPtrT> bytecode_offset_;
  CodeStubAssembler::TVariable<ExternalReference> dispatch_table_;
  CodeStubAssembler::TVariable<Object> accumulator_;
  ImplicitRegisterUse implicit_register_use_;
  bool made_call_;
  bool reloaded_frame_ptr_;
  bool bytecode_array_valid_;
};

}  // namespace interpreter
}  // namespace internal
}  // namespace v8

#endif  // V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_