Support for MIPS in architecture independent files....

src/mips/simulator-mips.h

Index: src/mips/simulator-mips.h
===================================================================
--- src/mips/simulator-mips.h	(revision 0)
+++ src/mips/simulator-mips.h	(revision 0)
@@ -0,0 +1,236 @@
+// Declares a Simulator for MIPS instructions if we are not generating a native
+// MIPS binary. This Simulator allows us to run and debug MIPS code generation on
+// regular desktop machines.
+// V8 calls into generated code by "calling" the CALL_GENERATED_CODE macro,
+// which will start execution in the Simulator or forwards to the real entry
+// on a MIPS HW platform.
+
+#ifndef V8_MIPS_SIMULATOR_MIPS_H_
+#define V8_MIPS_SIMULATOR_MIPS_H_
+
+#include	"allocation.h"
+
+#if defined(__mips)
+
+// When running without a simulator we call the entry directly.
+#define CALL_GENERATED_CODE(entry, p0, p1, p2, p3, p4) \
+  entry(p0, p1, p2, p3, p4);
+
+// TODO TOCHECK: Is this the same on MIPS ?
+// The stack limit beyond which we will throw stack overflow errors in
+// generated code. Because generated code on arm uses the C stack, we
+// just use the C stack limit.
+class SimulatorStack : public v8::internal::AllStatic {
+ public:
+  static inline uintptr_t JsLimitFromCLimit(uintptr_t c_limit) {
+    return c_limit;
+  }
+};
+
+// Calculated the stack limit beyond which we will throw stack overflow errors.
+// This macro must be called from a C++ method. It relies on being able to take
+// the address of "this" to get a value on the current execution stack and then
+// calculates the stack limit based on that value.
+// NOTE: The check for overflow is not safe as there is no guarantee that the
+// running thread has its stack in all memory up to address 0x00000000.
+#define GENERATED_CODE_STACK_LIMIT(limit) \
+  (reinterpret_cast<uintptr_t>(this) >= limit ? \
+      reinterpret_cast<uintptr_t>(this) - limit : 0)
+
+// Call the generated regexp code directly. The entry function pointer should
+// expect seven int/pointer sized arguments and return an int.
+#define CALL_GENERATED_REGEXP_CODE(entry, p0, p1, p2, p3, p4, p5, p6) \
+  entry(p0, p1, p2, p3, p4, p5, p6)
+
+
+#else   // #if defined(__mips)
+
+//  printf("Giving control to MIPS simulator.\n");
+//  asm("break");
+// When running with the simulator transition into simulated execution at this
+// point.
+#define CALL_GENERATED_CODE(entry, p0, p1, p2, p3, p4) \
+  reinterpret_cast<Object*>( \
+      assembler::mips::Simulator::current()->Call(FUNCTION_ADDR(entry), 5, \
+                                                  p0, p1, p2, p3, p4))
+
+#define CALL_GENERATED_REGEXP_CODE(entry, p0, p1, p2, p3, p4, p5, p6) \
+  assembler::mips::Simulator::current()->Call( \
+    FUNCTION_ADDR(entry), 7, p0, p1, p2, p3, p4, p5, p6)
+
+
+namespace assembler {
+namespace mips {
+
+class Simulator {
+ public:
+  friend class Debugger;
+
+  // Registers are declared in order. See SMRL chapter 2.
+  enum Register {
+    no_reg = -1,
+    zero_reg = 0, 
+    at, 
+    v0, v1, 
+    a0, a1, a2, a3, 
+    t0, t1, t2, t3, t4, t5, t6, t7, 
+    s0, s1, s2, s3, s4, s5, s6, s7, 
+    t8, t9, 
+    k0, k1, 
+    gp, 
+    sp, 
+    s8, 
+    ra, 
+    // HI, LO, and pc
+    HI,
+    LO,
+    pc, 
+    num_registers,
+    // aliases
+    fp = s8
+  };
+
+  // Coprocessor registers.
+  // Generated code will always use doubles. So we will only use even registers.
+  enum CRegister {
+    f0, f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11,
+    f12, f13, f14, f15,   // f12 and f14 are arguments CRegisters
+    f16, f17, f18, f19, f20, f21, f22, f23, f24, f25,
+    f26, f27, f28, f29, f30, f31, 
+    num_Cregisters
+  };
+
+  Simulator();
+  ~Simulator();
+
+  // The currently executing Simulator instance. Potentially there can be one
+  // for each native thread.
+  static Simulator* current();
+
+  // Accessors for register state. Reading the pc value adheres to the ARM
+  // architecture specification and is off by a 8 from the currently executing
+  // instruction.
+  void set_register(int reg, int32_t value);
+  int32_t get_register(int reg) const;
+  // Same for CRegisters
+  void set_Cregister(int creg, double value);
+  double get_Cregister(int creg) const;
+  // Get 16 high or low bits of the Cregister
+  int32_t get_CregisterHI(int creg) const;
+  int32_t get_CregisterLO(int creg) const;
+
+  // Special case of set_register and get_register to access the raw PC value.
+  void set_pc(int32_t value);
+  int32_t get_pc() const;
+
+  // Accessor to the internal simulator stack area.
+  uintptr_t StackLimit() const;
+
+  // Executes MIPS instructions until the PC reaches end_sim_pc.
+  void Execute();
+
+  // Call on program start.
+  static void Initialize();
+
+  // V8 generally calls into generated JS code with 5 parameters and into
+  // generated RegExp code with 7 parameters. This is a convenience function,
+  // which sets up the simulator state and grabs the result on return.
+  int32_t Call(byte* entry, int argument_count, ...);
+
+ private:
+  enum special_values {
+    // Known bad pc value to ensure that the simulator does not execute
+    // without being properly setup.
+    bad_ra = -1,
+    // A pc value used to signal the simulator to stop execution.  Generally
+    // the ra is set to this value on transition from native C code to
+    // simulated execution, so that the simulator can "return" to the native
+    // C code.
+    end_sim_pc = -2
+  };
+
+  // Unsupported instructions use Format to print an error and stop execution.
+  void Format(Instruction* instr, const char* format);
+
+  // Read and write memory.
+  inline uint32_t ReadBU(int32_t addr);
+  inline int32_t ReadB(int32_t addr);
+  inline void WriteB(int32_t addr, uint8_t value);
+  inline void WriteB(int32_t addr, int8_t value);
+
+  inline uint16_t ReadHU(int32_t addr, Instruction* instr);
+  inline int16_t ReadH(int32_t addr, Instruction* instr);
+  // Note: Overloaded on the sign of the value.
+  inline void WriteH(int32_t addr, uint16_t value, Instruction* instr);
+  inline void WriteH(int32_t addr, int16_t value, Instruction* instr);
+
+  inline int ReadW(int32_t addr, Instruction* instr);
+  inline void WriteW(int32_t addr, int value, Instruction* instr);
+
+  // Executing is handled based on the instruction type.
+  void DecodeType1(Instruction* instr);
+  void DecodeType3(Instruction* instr);
+  void DecodeType2(Instruction* instr);
+
+  // Executes one instruction.
+  void InstructionDecode(Instruction* instr);
+  // Execute one instruction placed in a branch delay slot.
+  void BranchDelayInstructionDecode(Instruction* instr) {
+    if(instr->isForbiddenInBranchDelay()) {
+      V8_Fatal(__FILE__, __LINE__,
+          "Eror:Unexpected %i opcode in a branch delay slot.",
+                            instr->OpcodeField());
+    }
+    InstructionDecode(instr);
+  }
+
+  enum Exception {
+    none,
+    integer_overflow, 
+    integer_underflow, 
+    num_exceptions
+  };
+  int16_t exceptions[num_exceptions];
+
+  // Exceptions
+  void SignalExceptions();
+
+  // Runtime call support.
+  static void* RedirectExternalReference(void* external_function,
+                                         bool fp_return);
+
+  // architecture state
+  // Registers
+  int32_t registers_[num_registers];
+  // Coprocessor Registers
+  double Cregisters_[num_Cregisters];
+
+  // simulator support
+  char* stack_;
+  bool pc_modified_;
+  int icount_;
+  static bool initialized_;
+
+  // registered breakpoints
+  Instruction* break_pc_;
+  Instr break_instr_;
+};
+
+} }   // namespace assembler::mips
+
+
+// The simulator has its own stack. Thus it has a different stack limit from
+// the C-based native code.  Setting the c_limit to indicate a very small
+// stack cause stack overflow errors, since the simulator ignores the input.
+// This is unlikely to be an issue in practice, though it might cause testing
+// trouble down the line.
+class SimulatorStack : public v8::internal::AllStatic {
+ public:
+  static inline uintptr_t JsLimitFromCLimit(uintptr_t c_limit) {
+    return assembler::mips::Simulator::current()->StackLimit();
+  }
+};
+
+#endif  // defined(__mips)
+
+#endif  // V8_MIPS_SIMULATOR_MIPS_H_