frames-mips.h

// Copyright 2011 the V8 project authors. All rights reserved.
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#ifndef V8_MIPS_FRAMES_MIPS_H_
#define V8_MIPS_FRAMES_MIPS_H_


namespace v8 {
namespace internal {

// Register lists.
// Note that the bit values must match those used in actual instruction
// encoding.
static const int kNumRegs = 32;

static const RegList kJSCallerSaved =
  1 << 2 |  // v0
  1 << 4 |  // a0
  1 << 5 |  // a1
  1 << 6 |  // a2
  1 << 7;   // a3

static const int kNumJSCallerSaved = 5;


// Return the code of the n-th caller-saved register available to JavaScript
// e.g. JSCallerSavedReg(0) returns a0.code() == 4.
int JSCallerSavedCode(int n);


// Callee-saved registers preserved when switching from C to JavaScript.
static const RegList kCalleeSaved =
  // Saved temporaries.
  1 << 16 | 1 << 17 | 1 << 18 | 1 << 19 |
  1 << 20 | 1 << 21 | 1 << 22 | 1 << 23 |
  // gp, sp, fp.
  1 << 28 | 1 << 29 | 1 << 30;

static const int kNumCalleeSaved = 11;


// Number of registers for which space is reserved in safepoints. Must be a
// multiple of 8.
// TODO(mips): Only 8 registers may actually be sufficient. Revisit.
static const int kNumSafepointRegisters = 16;

// Define the list of registers actually saved at safepoints.
// Note that the number of saved registers may be smaller than the reserved
// space, i.e. kNumSafepointSavedRegisters <= kNumSafepointRegisters.
static const RegList kSafepointSavedRegisters = kJSCallerSaved | kCalleeSaved;
static const int kNumSafepointSavedRegisters =
    kNumJSCallerSaved + kNumCalleeSaved;

typedef Object* JSCallerSavedBuffer[kNumJSCallerSaved];

static const int kUndefIndex = -1;
// Map with indexes on stack that corresponds to codes of saved registers.
static const int kSafepointRegisterStackIndexMap[kNumRegs] = {
  kUndefIndex,
  kUndefIndex,
  0,  // v0
  kUndefIndex,
  1,  // a0
  2,  // a1
  3,  // a2
  4,  // a3
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  5,  // Saved temporaries.
  6,
  7,
  8,
  9,
  10,
  11,
  12,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  kUndefIndex,
  13,  // gp
  14,  // sp
  15,  // fp
  kUndefIndex
};


// ----------------------------------------------------

class StackHandlerConstants : public AllStatic {
 public:
  static const int kNextOffset  = 0 * kPointerSize;
  static const int kStateOffset = 1 * kPointerSize;
  static const int kFPOffset    = 2 * kPointerSize;
  static const int kPCOffset    = 3 * kPointerSize;

  static const int kSize = kPCOffset + kPointerSize;
};


class EntryFrameConstants : public AllStatic {
 public:
  static const int kCallerFPOffset      = -3 * kPointerSize;
};


class ExitFrameConstants : public AllStatic {
 public:
  // See some explanation in MacroAssembler::EnterExitFrame.
  // This marks the top of the extra allocated stack space.
  static const int kStackSpaceOffset = -3 * kPointerSize;

  static const int kCodeOffset = -2 * kPointerSize;

  static const int kSPOffset = -1 * kPointerSize;

  // The caller fields are below the frame pointer on the stack.
  static const int kCallerFPOffset = +0 * kPointerSize;
  // The calling JS function is between FP and PC.
  static const int kCallerPCOffset = +1 * kPointerSize;

  // MIPS-specific: a pointer to the old sp to avoid unnecessary calculations.
  static const int kCallerSPOffset = +2 * kPointerSize;

  // FP-relative displacement of the caller's SP.
  static const int kCallerSPDisplacement = +2 * kPointerSize;
};


class StandardFrameConstants : public AllStatic {
 public:
  static const int kExpressionsOffset = -3 * kPointerSize;
  static const int kMarkerOffset      = -2 * kPointerSize;
  static const int kContextOffset     = -1 * kPointerSize;
  static const int kCallerFPOffset    =  0 * kPointerSize;
  static const int kCallerPCOffset    = +1 * kPointerSize;
  static const int kCallerSPOffset    = +2 * kPointerSize;

  // Size of the MIPS 4 32-bit argument slots.
  // This is just an alias with a shorter name. Use it from now on.
  static const int kRArgsSlotsSize = 4 * kPointerSize;
  static const int kRegularArgsSlotsSize = kRArgsSlotsSize;

  // C/C++ argument slots size.
  static const int kCArgSlotCount = 4;
  static const int kCArgsSlotsSize = kCArgSlotCount * kPointerSize;
  // JS argument slots size.
  static const int kJSArgsSlotsSize = 0 * kPointerSize;
  // Assembly builtins argument slots size.
  static const int kBArgsSlotsSize = 0 * kPointerSize;
};


class JavaScriptFrameConstants : public AllStatic {
 public:
  // FP-relative.
  static const int kLocal0Offset = StandardFrameConstants::kExpressionsOffset;
  static const int kLastParameterOffset = +2 * kPointerSize;
  static const int kFunctionOffset = StandardFrameConstants::kMarkerOffset;

  // Caller SP-relative.
  static const int kParam0Offset   = -2 * kPointerSize;
  static const int kReceiverOffset = -1 * kPointerSize;
};


class ArgumentsAdaptorFrameConstants : public AllStatic {
 public:
  static const int kLengthOffset = StandardFrameConstants::kExpressionsOffset;
};


class InternalFrameConstants : public AllStatic {
 public:
  static const int kCodeOffset = StandardFrameConstants::kExpressionsOffset;
};


inline Object* JavaScriptFrame::function_slot_object() const {
  const int offset = JavaScriptFrameConstants::kFunctionOffset;
  return Memory::Object_at(fp() + offset);
}


} }  // namespace v8::internal

#endif