// Copyright 2012 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_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_
#define V8_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_

#include "src/macro-assembler.h"
#include "src/regexp/regexp-macro-assembler.h"
#include "src/x64/assembler-x64.h"
#include "src/zone/zone-chunk-list.h"

namespace v8 {
namespace internal {

#ifndef V8_INTERPRETED_REGEXP

class RegExpMacroAssemblerX64: public NativeRegExpMacroAssembler {
 public:
  RegExpMacroAssemblerX64(Isolate* isolate, Zone* zone, Mode mode,
                          int registers_to_save);
  ~RegExpMacroAssemblerX64() override;
  int stack_limit_slack() override;
  void AdvanceCurrentPosition(int by) override;
  void AdvanceRegister(int reg, int by) override;
  void Backtrack() override;
  void Bind(Label* label) override;
  void CheckAtStart(Label* on_at_start) override;
  void CheckCharacter(uint32_t c, Label* on_equal) override;
  void CheckCharacterAfterAnd(uint32_t c, uint32_t mask,
                              Label* on_equal) override;
  void CheckCharacterGT(uc16 limit, Label* on_greater) override;
  void CheckCharacterLT(uc16 limit, Label* on_less) override;
  // A "greedy loop" is a loop that is both greedy and with a simple
  // body. It has a particularly simple implementation.
  void CheckGreedyLoop(Label* on_tos_equals_current_position) override;
  void CheckNotAtStart(int cp_offset, Label* on_not_at_start) override;
  void CheckNotBackReference(int start_reg, bool read_backward,
                             Label* on_no_match) override;
  void CheckNotBackReferenceIgnoreCase(int start_reg, bool read_backward,
                                       bool unicode,
                                       Label* on_no_match) override;
  void CheckNotCharacter(uint32_t c, Label* on_not_equal) override;
  void CheckNotCharacterAfterAnd(uint32_t c, uint32_t mask,
                                 Label* on_not_equal) override;
  void CheckNotCharacterAfterMinusAnd(uc16 c, uc16 minus, uc16 mask,
                                      Label* on_not_equal) override;
  void CheckCharacterInRange(uc16 from, uc16 to, Label* on_in_range) override;
  void CheckCharacterNotInRange(uc16 from, uc16 to,
                                Label* on_not_in_range) override;
  void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) override;

  // Checks whether the given offset from the current position is before
  // the end of the string.
  void CheckPosition(int cp_offset, Label* on_outside_input) override;
  bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match) override;
  void Fail() override;
  Handle<HeapObject> GetCode(Handle<String> source) override;
  void GoTo(Label* label) override;
  void IfRegisterGE(int reg, int comparand, Label* if_ge) override;
  void IfRegisterLT(int reg, int comparand, Label* if_lt) override;
  void IfRegisterEqPos(int reg, Label* if_eq) override;
  IrregexpImplementation Implementation() override;
  void LoadCurrentCharacter(int cp_offset, Label* on_end_of_input,
                            bool check_bounds = true,
                            int characters = 1) override;
  void PopCurrentPosition() override;
  void PopRegister(int register_index) override;
  void PushBacktrack(Label* label) override;
  void PushCurrentPosition() override;
  void PushRegister(int register_index,
                    StackCheckFlag check_stack_limit) override;
  void ReadCurrentPositionFromRegister(int reg) override;
  void ReadStackPointerFromRegister(int reg) override;
  void SetCurrentPositionFromEnd(int by) override;
  void SetRegister(int register_index, int to) override;
  bool Succeed() override;
  void WriteCurrentPositionToRegister(int reg, int cp_offset) override;
  void ClearRegisters(int reg_from, int reg_to) override;
  void WriteStackPointerToRegister(int reg) override;

  // Called from RegExp if the stack-guard is triggered.
  // If the code object is relocated, the return address is fixed before
  // returning.
  // {raw_code} is an Address because this is called via ExternalReference.
  static int CheckStackGuardState(Address* return_address, Address raw_code,
                                  Address re_frame);

 private:
  // Offsets from rbp of function parameters and stored registers.
  static const int kFramePointer = 0;
  // Above the frame pointer - function parameters and return address.
  static const int kReturn_eip = kFramePointer + kRegisterSize;
  static const int kFrameAlign = kReturn_eip + kRegisterSize;

#ifdef _WIN64
  // Parameters (first four passed as registers, but with room on stack).
  // In Microsoft 64-bit Calling Convention, there is room on the callers
  // stack (before the return address) to spill parameter registers. We
  // use this space to store the register passed parameters.
  static const int kInputString = kFrameAlign;
  // StartIndex is passed as 32 bit int.
  static const int kStartIndex = kInputString + kRegisterSize;
  static const int kInputStart = kStartIndex + kRegisterSize;
  static const int kInputEnd = kInputStart + kRegisterSize;
  static const int kRegisterOutput = kInputEnd + kRegisterSize;
  // For the case of global regular expression, we have room to store at least
  // one set of capture results.  For the case of non-global regexp, we ignore
  // this value. NumOutputRegisters is passed as 32-bit value.  The upper
  // 32 bit of this 64-bit stack slot may contain garbage.
  static const int kNumOutputRegisters = kRegisterOutput + kRegisterSize;
  static const int kStackHighEnd = kNumOutputRegisters + kRegisterSize;
  // DirectCall is passed as 32 bit int (values 0 or 1).
  static const int kDirectCall = kStackHighEnd + kRegisterSize;
  static const int kIsolate = kDirectCall + kRegisterSize;
#else
  // In AMD64 ABI Calling Convention, the first six integer parameters
  // are passed as registers, and caller must allocate space on the stack
  // if it wants them stored. We push the parameters after the frame pointer.
  static const int kInputString = kFramePointer - kRegisterSize;
  static const int kStartIndex = kInputString - kRegisterSize;
  static const int kInputStart = kStartIndex - kRegisterSize;
  static const int kInputEnd = kInputStart - kRegisterSize;
  static const int kRegisterOutput = kInputEnd - kRegisterSize;

  // For the case of global regular expression, we have room to store at least
  // one set of capture results.  For the case of non-global regexp, we ignore
  // this value.
  static const int kNumOutputRegisters = kRegisterOutput - kRegisterSize;
  static const int kStackHighEnd = kFrameAlign;
  static const int kDirectCall = kStackHighEnd + kRegisterSize;
  static const int kIsolate = kDirectCall + kRegisterSize;
#endif

#ifdef _WIN64
  // Microsoft calling convention has three callee-saved registers
  // (that we are using). We push these after the frame pointer.
  static const int kBackup_rsi = kFramePointer - kRegisterSize;
  static const int kBackup_rdi = kBackup_rsi - kRegisterSize;
  static const int kBackup_rbx = kBackup_rdi - kRegisterSize;
  static const int kLastCalleeSaveRegister = kBackup_rbx;
#else
  // AMD64 Calling Convention has only one callee-save register that
  // we use. We push this after the frame pointer (and after the
  // parameters).
  static const int kBackup_rbx = kNumOutputRegisters - kRegisterSize;
  static const int kLastCalleeSaveRegister = kBackup_rbx;
#endif

  static const int kSuccessfulCaptures =
      kLastCalleeSaveRegister - kSystemPointerSize;
  // When adding local variables remember to push space for them in
  // the frame in GetCode.
  static const int kStringStartMinusOne =
      kSuccessfulCaptures - kSystemPointerSize;

  // First register address. Following registers are below it on the stack.
  static const int kRegisterZero = kStringStartMinusOne - kSystemPointerSize;

  // Initial size of code buffer.
  static const int kRegExpCodeSize = 1024;

  // Load a number of characters at the given offset from the
  // current position, into the current-character register.
  void LoadCurrentCharacterUnchecked(int cp_offset, int character_count);

  // Check whether preemption has been requested.
  void CheckPreemption();

  // Check whether we are exceeding the stack limit on the backtrack stack.
  void CheckStackLimit();

  // Generate a call to CheckStackGuardState.
  void CallCheckStackGuardState();

  // The rbp-relative location of a regexp register.
  Operand register_location(int register_index);

  // The register containing the current character after LoadCurrentCharacter.
  inline Register current_character() { return rdx; }

  // The register containing the backtrack stack top. Provides a meaningful
  // name to the register.
  inline Register backtrack_stackpointer() { return rcx; }

  // The registers containing a self pointer to this code's Code object.
  inline Register code_object_pointer() { return r8; }

  // Byte size of chars in the string to match (decided by the Mode argument)
  inline int char_size() { return static_cast<int>(mode_); }

  // Equivalent to a conditional branch to the label, unless the label
  // is nullptr, in which case it is a conditional Backtrack.
  void BranchOrBacktrack(Condition condition, Label* to);

  void MarkPositionForCodeRelativeFixup() {
    code_relative_fixup_positions_.push_back(masm_.pc_offset());
  }

  void FixupCodeRelativePositions();

  // Call and return internally in the generated code in a way that
  // is GC-safe (i.e., doesn't leave absolute code addresses on the stack)
  inline void SafeCall(Label* to);
  inline void SafeCallTarget(Label* label);
  inline void SafeReturn();

  // Pushes the value of a register on the backtrack stack. Decrements the
  // stack pointer (rcx) by a word size and stores the register's value there.
  inline void Push(Register source);

  // Pushes a value on the backtrack stack. Decrements the stack pointer (rcx)
  // by a word size and stores the value there.
  inline void Push(Immediate value);

  // Pushes the Code object relative offset of a label on the backtrack stack
  // (i.e., a backtrack target). Decrements the stack pointer (rcx)
  // by a word size and stores the value there.
  inline void Push(Label* label);

  // Pops a value from the backtrack stack. Reads the word at the stack pointer
  // (rcx) and increments it by a word size.
  inline void Pop(Register target);

  // Drops the top value from the backtrack stack without reading it.
  // Increments the stack pointer (rcx) by a word size.
  inline void Drop();

  inline void ReadPositionFromRegister(Register dst, int reg);

  Isolate* isolate() const { return masm_.isolate(); }

  MacroAssembler masm_;
  NoRootArrayScope no_root_array_scope_;

  ZoneChunkList<int> code_relative_fixup_positions_;

  // Which mode to generate code for (LATIN1 or UC16).
  Mode mode_;

  // One greater than maximal register index actually used.
  int num_registers_;

  // Number of registers to output at the end (the saved registers
  // are always 0..num_saved_registers_-1)
  int num_saved_registers_;

  // Labels used internally.
  Label entry_label_;
  Label start_label_;
  Label success_label_;
  Label backtrack_label_;
  Label exit_label_;
  Label check_preempt_label_;
  Label stack_overflow_label_;
};

#endif  // V8_INTERPRETED_REGEXP

}  // namespace internal
}  // namespace v8

#endif  // V8_REGEXP_X64_REGEXP_MACRO_ASSEMBLER_X64_H_