macro-assembler-ia32.cc.svn-base

Google浏览器V8内核代码

  fcompp();
  push(eax);
  fnstsw_ax();
  sahf();
  pop(eax);
}


void MacroAssembler::EnterInternalFrame() {
  int type = StackFrame::INTERNAL;

  push(ebp);
  mov(ebp, Operand(esp));
  push(esi);
  push(Immediate(Smi::FromInt(type)));
  push(Immediate(0));  // Push an empty code cache slot.
}


void MacroAssembler::LeaveInternalFrame() {
  if (FLAG_debug_code) {
    StackFrame::Type type = StackFrame::INTERNAL;
    cmp(Operand(ebp, StandardFrameConstants::kMarkerOffset),
        Immediate(Smi::FromInt(type)));
    Check(equal, "stack frame types must match");
  }
  leave();
}


void MacroAssembler::EnterExitFrame(StackFrame::Type type) {
  ASSERT(type == StackFrame::EXIT || type == StackFrame::EXIT_DEBUG);

  // Setup the frame structure on the stack.
  ASSERT(ExitFrameConstants::kPPDisplacement == +2 * kPointerSize);
  ASSERT(ExitFrameConstants::kCallerPCOffset == +1 * kPointerSize);
  ASSERT(ExitFrameConstants::kCallerFPOffset ==  0 * kPointerSize);
  push(ebp);
  mov(ebp, Operand(esp));

  // Reserve room for entry stack pointer and push the debug marker.
  ASSERT(ExitFrameConstants::kSPOffset  == -1 * kPointerSize);
  push(Immediate(0));  // saved entry sp, patched before call
  push(Immediate(type == StackFrame::EXIT_DEBUG ? 1 : 0));

  // Save the frame pointer and the context in top.
  ExternalReference c_entry_fp_address(Top::k_c_entry_fp_address);
  ExternalReference context_address(Top::k_context_address);
  mov(Operand::StaticVariable(c_entry_fp_address), ebp);
  mov(Operand::StaticVariable(context_address), esi);

  // Setup argc and argv in callee-saved registers.
  int offset = StandardFrameConstants::kCallerSPOffset - kPointerSize;
  mov(edi, Operand(eax));
  lea(esi, Operand(ebp, eax, times_4, offset));

  // Save the state of all registers to the stack from the memory
  // location. This is needed to allow nested break points.
  if (type == StackFrame::EXIT_DEBUG) {
    // TODO(1243899): This should be symmetric to
    // CopyRegistersFromStackToMemory() but it isn't! esp is assumed
    // correct here, but computed for the other call. Very error
    // prone! FIX THIS.  Actually there are deeper problems with
    // register saving than this asymmetry (see the bug report
    // associated with this issue).
    PushRegistersFromMemory(kJSCallerSaved);
  }

  // Reserve space for two arguments: argc and argv.
  sub(Operand(esp), Immediate(2 * kPointerSize));

  // Get the required frame alignment for the OS.
  static const int kFrameAlignment = OS::ActivationFrameAlignment();
  if (kFrameAlignment > 0) {
    ASSERT(IsPowerOf2(kFrameAlignment));
    and_(esp, -kFrameAlignment);
  }

  // Patch the saved entry sp.
  mov(Operand(ebp, ExitFrameConstants::kSPOffset), esp);
}


void MacroAssembler::LeaveExitFrame(StackFrame::Type type) {
  // Restore the memory copy of the registers by digging them out from
  // the stack. This is needed to allow nested break points.
  if (type == StackFrame::EXIT_DEBUG) {
    // It's okay to clobber register ebx below because we don't need
    // the function pointer after this.
    const int kCallerSavedSize = kNumJSCallerSaved * kPointerSize;
    int kOffset = ExitFrameConstants::kDebugMarkOffset - kCallerSavedSize;
    lea(ebx, Operand(ebp, kOffset));
    CopyRegistersFromStackToMemory(ebx, ecx, kJSCallerSaved);
  }

  // Get the return address from the stack and restore the frame pointer.
  mov(ecx, Operand(ebp, 1 * kPointerSize));
  mov(ebp, Operand(ebp, 0 * kPointerSize));

  // Pop the arguments and the receiver from the caller stack.
  lea(esp, Operand(esi, 1 * kPointerSize));

  // Restore current context from top and clear it in debug mode.
  ExternalReference context_address(Top::k_context_address);
  mov(esi, Operand::StaticVariable(context_address));
  if (kDebug) {
    mov(Operand::StaticVariable(context_address), Immediate(0));
  }

  // Push the return address to get ready to return.
  push(ecx);

  // Clear the top frame.
  ExternalReference c_entry_fp_address(Top::k_c_entry_fp_address);
  mov(Operand::StaticVariable(c_entry_fp_address), Immediate(0));
}


void MacroAssembler::PushTryHandler(CodeLocation try_location,
                                    HandlerType type) {
  ASSERT(StackHandlerConstants::kSize == 6 * kPointerSize);  // adjust this code
  // The pc (return address) is already on TOS.
  if (try_location == IN_JAVASCRIPT) {
    if (type == TRY_CATCH_HANDLER) {
      push(Immediate(StackHandler::TRY_CATCH));
    } else {
      push(Immediate(StackHandler::TRY_FINALLY));
    }
    push(Immediate(Smi::FromInt(StackHandler::kCodeNotPresent)));
    push(ebp);
    push(edi);
  } else {
    ASSERT(try_location == IN_JS_ENTRY);
    // The parameter pointer is meaningless here and ebp does not
    // point to a JS frame. So we save NULL for both pp and ebp. We
    // expect the code throwing an exception to check ebp before
    // dereferencing it to restore the context.
    push(Immediate(StackHandler::ENTRY));
    push(Immediate(Smi::FromInt(StackHandler::kCodeNotPresent)));
    push(Immediate(0));  // NULL frame pointer
    push(Immediate(0));  // NULL parameter pointer
  }
  // Cached TOS.
  mov(eax, Operand::StaticVariable(ExternalReference(Top::k_handler_address)));
  // Link this handler.
  mov(Operand::StaticVariable(ExternalReference(Top::k_handler_address)), esp);
}


Register MacroAssembler::CheckMaps(JSObject* object, Register object_reg,
                                   JSObject* holder, Register holder_reg,
                                   Register scratch,
                                   Label* miss) {
  // Make sure there's no overlap between scratch and the other
  // registers.
  ASSERT(!scratch.is(object_reg) && !scratch.is(holder_reg));

  // Keep track of the current object in register reg.
  Register reg = object_reg;
  int depth = 1;

  // Check the maps in the prototype chain.
  // Traverse the prototype chain from the object and do map checks.
  while (object != holder) {
    depth++;

    // Only global objects and objects that do not require access
    // checks are allowed in stubs.
    ASSERT(object->IsJSGlobalObject() || !object->IsAccessCheckNeeded());

    JSObject* prototype = JSObject::cast(object->GetPrototype());
    if (Heap::InNewSpace(prototype)) {
      // Get the map of the current object.
      mov(scratch, FieldOperand(reg, HeapObject::kMapOffset));
      cmp(Operand(scratch), Immediate(Handle<Map>(object->map())));
      // Branch on the result of the map check.
      j(not_equal, miss, not_taken);
      // Check access rights to the global object.  This has to happen
      // after the map check so that we know that the object is
      // actually a global object.
      if (object->IsJSGlobalObject()) {
        CheckAccessGlobal(reg, scratch, miss);
        // Restore scratch register to be the map of the object.  We
        // load the prototype from the map in the scratch register.
        mov(scratch, FieldOperand(reg, HeapObject::kMapOffset));
      }
      // The prototype is in new space; we cannot store a reference
      // to it in the code. Load it from the map.
      reg = holder_reg;  // from now the object is in holder_reg
      mov(reg, FieldOperand(scratch, Map::kPrototypeOffset));
    } else {
      // Check the map of the current object.
      cmp(FieldOperand(reg, HeapObject::kMapOffset),
          Immediate(Handle<Map>(object->map())));
      // Branch on the result of the map check.
      j(not_equal, miss, not_taken);
      // Check access rights to the global object.  This has to happen
      // after the map check so that we know that the object is
      // actually a global object.
      if (object->IsJSGlobalObject()) {
        CheckAccessGlobal(reg, scratch, miss);
      }
      // The prototype is in old space; load it directly.
      reg = holder_reg;  // from now the object is in holder_reg
      mov(reg, Handle<JSObject>(prototype));
    }

    // Go to the next object in the prototype chain.
    object = prototype;
  }

  // Check the holder map.
  cmp(FieldOperand(reg, HeapObject::kMapOffset),
      Immediate(Handle<Map>(holder->map())));
  j(not_equal, miss, not_taken);

  // Log the check depth.
  LOG(IntEvent("check-maps-depth", depth));

  // Perform security check for access to the global object and return
  // the holder register.
  ASSERT(object == holder);
  ASSERT(object->IsJSGlobalObject() || !object->IsAccessCheckNeeded());
  if (object->IsJSGlobalObject()) {
    CheckAccessGlobal(reg, scratch, miss);
  }
  return reg;
}


void MacroAssembler::CheckAccessGlobal(Register holder_reg,
                                       Register scratch,
                                       Label* miss) {
  ASSERT(!holder_reg.is(scratch));

  // Load the security context.
  ExternalReference security_context =
      ExternalReference(Top::k_security_context_address);
  mov(scratch, Operand::StaticVariable(security_context));
  // When generating debug code, make sure the security context is set.
  if (FLAG_debug_code) {
    cmp(Operand(scratch), Immediate(0));
    Check(not_equal, "we should not have an empty security context");
  }
  // Load the global object of the security context.
  int offset = Context::kHeaderSize + Context::GLOBAL_INDEX * kPointerSize;
  mov(scratch, FieldOperand(scratch, offset));
  // Check that the security token in the calling global object is
  // compatible with the security token in the receiving global
  // object.
  mov(scratch, FieldOperand(scratch, JSGlobalObject::kSecurityTokenOffset));
  cmp(scratch, FieldOperand(holder_reg, JSGlobalObject::kSecurityTokenOffset));
  j(not_equal, miss, not_taken);
}


void MacroAssembler::NegativeZeroTest(Register result,
                                      Register op,
                                      Label* then_label) {
  Label ok;
  test(result, Operand(result));
  j(not_zero, &ok, taken);
  test(op, Operand(op));
  j(sign, then_label, not_taken);
  bind(&ok);
}


void MacroAssembler::NegativeZeroTest(Register result,
                                      Register op1,
                                      Register op2,
                                      Register scratch,
                                      Label* then_label) {
  Label ok;
  test(result, Operand(result));
  j(not_zero, &ok, taken);
  mov(scratch, Operand(op1));
  or_(scratch, Operand(op2));
  j(sign, then_label, not_taken);
  bind(&ok);
}


void MacroAssembler::CallStub(CodeStub* stub) {
  ASSERT(allow_stub_calls());  // calls are not allowed in some stubs
  call(stub->GetCode(), RelocInfo::CODE_TARGET);
}


void MacroAssembler::StubReturn(int argc) {
  ASSERT(argc >= 1 && generating_stub());
  ret((argc - 1) * kPointerSize);
}


void MacroAssembler::IllegalOperation() {
  push(Immediate(Factory::undefined_value()));
}


void MacroAssembler::CallRuntime(Runtime::FunctionId id, int num_arguments) {
  CallRuntime(Runtime::FunctionForId(id), num_arguments);
}


void MacroAssembler::CallRuntime(Runtime::Function* f, int num_arguments) {
  // If the expected number of arguments of the runtime function is
  // constant, we check that the actual number of arguments match the