frames-arm.h

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// 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_ARM_FRAMES_ARM_H_
#define V8_ARM_FRAMES_ARM_H_
 
namespace v8 {
namespace internal {
 
 
// The ARM ABI does not specify the usage of register r9, which may be reserved
// as the static base or thread register on some platforms, in which case we
// leave it alone. Adjust the value of kR9Available accordingly:
const int kR9Available = 1;  // 1 if available to us, 0 if reserved
 
 
// Register list in load/store instructions
// Note that the bit values must match those used in actual instruction encoding
const int kNumRegs = 16;
 
 
// Caller-saved/arguments registers
const RegList kJSCallerSaved =
  1 << 0 |  // r0 a1
  1 << 1 |  // r1 a2
  1 << 2 |  // r2 a3
  1 << 3;   // r3 a4
 
const int kNumJSCallerSaved = 4;
 
// Return the code of the n-th caller-saved register available to JavaScript
// e.g. JSCallerSavedReg(0) returns r0.code() == 0
int JSCallerSavedCode(int n);
 
 
// Callee-saved registers preserved when switching from C to JavaScript
const RegList kCalleeSaved =
  1 <<  4 |  //  r4 v1
  1 <<  5 |  //  r5 v2
  1 <<  6 |  //  r6 v3
  1 <<  7 |  //  r7 v4 (cp in JavaScript code)
  1 <<  8 |  //  r8 v5 (pp in JavaScript code)
  kR9Available <<  9 |  //  r9 v6
  1 << 10 |  // r10 v7
  1 << 11;   // r11 v8 (fp in JavaScript code)
 
// When calling into C++ (only for C++ calls that can't cause a GC).
// The call code will take care of lr, fp, etc.
const RegList kCallerSaved =
  1 <<  0 |  // r0
  1 <<  1 |  // r1
  1 <<  2 |  // r2
  1 <<  3 |  // r3
  1 <<  9;   // r9
 
 
const int kNumCalleeSaved = 7 + kR9Available;
 
// Double registers d8 to d15 are callee-saved.
const int kNumDoubleCalleeSaved = 8;
 
 
// Number of registers for which space is reserved in safepoints. Must be a
// multiple of 8.
// TODO(regis): Only 8 registers may actually be sufficient. Revisit.
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.
const RegList kSafepointSavedRegisters = kJSCallerSaved | kCalleeSaved;
const int kNumSafepointSavedRegisters = kNumJSCallerSaved + kNumCalleeSaved;
 
// ----------------------------------------------------
 
 
class EntryFrameConstants : public AllStatic {
 public:
  static const int kCallerFPOffset =
      -(StandardFrameConstants::kFixedFrameSizeFromFp + kPointerSize);
};
 
 
class ExitFrameConstants : public AllStatic {
 public:
  static const int kFrameSize          = FLAG_enable_ool_constant_pool ?
                                         3 * kPointerSize : 2 * kPointerSize;
 
  static const int kConstantPoolOffset = FLAG_enable_ool_constant_pool ?
                                         -3 * kPointerSize : 0;
  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 below FP.
  static const int kCallerPCOffset = 1 * kPointerSize;
 
  // FP-relative displacement of the caller's SP.  It points just
  // below the saved PC.
  static const int kCallerSPDisplacement = 2 * 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:
  // FP-relative.
  static const int kLengthOffset = StandardFrameConstants::kExpressionsOffset;
 
  static const int kFrameSize =
      StandardFrameConstants::kFixedFrameSize + kPointerSize;
};
 
 
class ConstructFrameConstants : public AllStatic {
 public:
  // FP-relative.
  static const int kImplicitReceiverOffset = -6 * kPointerSize;
  static const int kConstructorOffset      = -5 * kPointerSize;
  static const int kLengthOffset           = -4 * kPointerSize;
  static const int kCodeOffset = StandardFrameConstants::kExpressionsOffset;
 
  static const int kFrameSize =
      StandardFrameConstants::kFixedFrameSize + 4 * kPointerSize;
};
 
 
class InternalFrameConstants : public AllStatic {
 public:
  // FP-relative.
  static const int kCodeOffset = StandardFrameConstants::kExpressionsOffset;
};
 
 
inline Object* JavaScriptFrame::function_slot_object() const {
  const int offset = JavaScriptFrameConstants::kFunctionOffset;
  return Memory::Object_at(fp() + offset);
}
 
 
inline void StackHandler::SetFp(Address slot, Address fp) {
  Memory::Address_at(slot) = fp;
}
 
 
} }  // namespace v8::internal
 
#endif  // V8_ARM_FRAMES_ARM_H_