src/arm/virtual-frame-arm.cc

// Copyright 2009 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
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//       with the distribution.
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//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
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#include "v8.h"

#include "codegen-inl.h"
#include "register-allocator-inl.h"
#include "scopes.h"

namespace v8 {
namespace internal {

// -------------------------------------------------------------------------
// VirtualFrame implementation.

#define __ ACCESS_MASM(masm())


// On entry to a function, the virtual frame already contains the
// receiver and the parameters.  All initial frame elements are in
// memory.
VirtualFrame::VirtualFrame()
    : elements_(parameter_count() + local_count() + kPreallocatedElements),
      stack_pointer_(parameter_count()) {  // 0-based index of TOS.
  for (int i = 0; i <= stack_pointer_; i++) {
    elements_.Add(FrameElement::MemoryElement(NumberInfo::kUnknown));
  }
  for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
    register_locations_[i] = kIllegalIndex;
  }
}


void VirtualFrame::SyncElementBelowStackPointer(int index) {
  UNREACHABLE();
}


void VirtualFrame::SyncElementByPushing(int index) {
  UNREACHABLE();
}


void VirtualFrame::SyncRange(int begin, int end) {
  // All elements are in memory on ARM (ie, synced).
#ifdef DEBUG
  for (int i = begin; i <= end; i++) {
    ASSERT(elements_[i].is_synced());
  }
#endif
}


void VirtualFrame::MergeTo(VirtualFrame* expected) {
  // ARM frames are currently always in memory.
  ASSERT(Equals(expected));
}


void VirtualFrame::MergeMoveRegistersToMemory(VirtualFrame* expected) {
  UNREACHABLE();
}


void VirtualFrame::MergeMoveRegistersToRegisters(VirtualFrame* expected) {
  UNREACHABLE();
}


void VirtualFrame::MergeMoveMemoryToRegisters(VirtualFrame* expected) {
  UNREACHABLE();
}


void VirtualFrame::Enter() {
  Comment cmnt(masm(), "[ Enter JS frame");

#ifdef DEBUG
  // Verify that r1 contains a JS function.  The following code relies
  // on r2 being available for use.
  if (FLAG_debug_code) {
    Label map_check, done;
    __ tst(r1, Operand(kSmiTagMask));
    __ b(ne, &map_check);
    __ stop("VirtualFrame::Enter - r1 is not a function (smi check).");
    __ bind(&map_check);
    __ CompareObjectType(r1, r2, r2, JS_FUNCTION_TYPE);
    __ b(eq, &done);
    __ stop("VirtualFrame::Enter - r1 is not a function (map check).");
    __ bind(&done);
  }
#endif  // DEBUG

  // We are about to push four values to the frame.
  Adjust(4);
  __ stm(db_w, sp, r1.bit() | cp.bit() | fp.bit() | lr.bit());
  // Adjust FP to point to saved FP.
  __ add(fp, sp, Operand(2 * kPointerSize));
  cgen()->allocator()->Unuse(r1);
  cgen()->allocator()->Unuse(lr);
}


void VirtualFrame::Exit() {
  Comment cmnt(masm(), "[ Exit JS frame");
  // Record the location of the JS exit code for patching when setting
  // break point.
  __ RecordJSReturn();

  // Drop the execution stack down to the frame pointer and restore the caller
  // frame pointer and return address.
  __ mov(sp, fp);
  __ ldm(ia_w, sp, fp.bit() | lr.bit());
}


void VirtualFrame::AllocateStackSlots() {
  int count = local_count();
  if (count > 0) {
    Comment cmnt(masm(), "[ Allocate space for locals");
    Adjust(count);
    // Initialize stack slots with 'undefined' value.
    __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
    __ LoadRoot(r2, Heap::kStackLimitRootIndex);
    if (count < kLocalVarBound) {
      // For less locals the unrolled loop is more compact.
      for (int i = 0; i < count; i++) {
        __ push(ip);
      }
    } else {
      // For more locals a loop in generated code is more compact.
      Label alloc_locals_loop;
      __ mov(r1, Operand(count));
      __ bind(&alloc_locals_loop);
      __ push(ip);
      __ sub(r1, r1, Operand(1), SetCC);
      __ b(ne, &alloc_locals_loop);
    }
  } else {
    __ LoadRoot(r2, Heap::kStackLimitRootIndex);
  }
  // Check the stack for overflow or a break request.
  // Put the lr setup instruction in the delay slot.  The kInstrSize is added
  // to the implicit 8 byte offset that always applies to operations with pc
  // and gives a return address 12 bytes down.
  masm()->add(lr, pc, Operand(Assembler::kInstrSize));
  masm()->cmp(sp, Operand(r2));
  StackCheckStub stub;
  // Call the stub if lower.
  masm()->mov(pc,
              Operand(reinterpret_cast<intptr_t>(stub.GetCode().location()),
                      RelocInfo::CODE_TARGET),
              LeaveCC,
              lo);
}


void VirtualFrame::SaveContextRegister() {
  UNIMPLEMENTED();
}


void VirtualFrame::RestoreContextRegister() {
  UNIMPLEMENTED();
}


void VirtualFrame::PushReceiverSlotAddress() {
  UNIMPLEMENTED();
}


int VirtualFrame::InvalidateFrameSlotAt(int index) {
  UNIMPLEMENTED();
  return kIllegalIndex;
}


void VirtualFrame::TakeFrameSlotAt(int index) {
  UNIMPLEMENTED();
}


void VirtualFrame::StoreToFrameSlotAt(int index) {
  UNIMPLEMENTED();
}


void VirtualFrame::PushTryHandler(HandlerType type) {
  // Grow the expression stack by handler size less one (the return
  // address in lr is already counted by a call instruction).
  Adjust(kHandlerSize - 1);
  __ PushTryHandler(IN_JAVASCRIPT, type);
}


void VirtualFrame::CallRuntime(Runtime::Function* f, int arg_count) {
  Forget(arg_count);
  ASSERT(cgen()->HasValidEntryRegisters());
  __ CallRuntime(f, arg_count);
}


void VirtualFrame::CallRuntime(Runtime::FunctionId id, int arg_count) {
  Forget(arg_count);
  ASSERT(cgen()->HasValidEntryRegisters());
  __ CallRuntime(id, arg_count);
}


#ifdef ENABLE_DEBUGGER_SUPPORT
void VirtualFrame::DebugBreak() {
  ASSERT(cgen()->HasValidEntryRegisters());
  __ DebugBreak();
}
#endif


void VirtualFrame::InvokeBuiltin(Builtins::JavaScript id,
                                 InvokeJSFlags flags,
                                 int arg_count) {
  Forget(arg_count);
  __ InvokeBuiltin(id, flags);
}


void VirtualFrame::CallCodeObject(Handle<Code> code,
                                  RelocInfo::Mode rmode,
                                  int dropped_args) {
  switch (code->kind()) {
    case Code::CALL_IC:
    case Code::FUNCTION:
      break;
    case Code::KEYED_LOAD_IC:
    case Code::LOAD_IC:
    case Code::KEYED_STORE_IC:
    case Code::STORE_IC:
      ASSERT(dropped_args == 0);
      break;
    case Code::BUILTIN:
      ASSERT(*code == Builtins::builtin(Builtins::JSConstructCall));
      break;
    default:
      UNREACHABLE();
      break;
  }
  Forget(dropped_args);
  ASSERT(cgen()->HasValidEntryRegisters());
  __ Call(code, rmode);
}


void VirtualFrame::Drop(int count) {
  ASSERT(count >= 0);
  ASSERT(height() >= count);
  int num_virtual_elements = (element_count() - 1) - stack_pointer_;

  // Emit code to lower the stack pointer if necessary.
  if (num_virtual_elements < count) {
    int num_dropped = count - num_virtual_elements;
    stack_pointer_ -= num_dropped;
    __ add(sp, sp, Operand(num_dropped * kPointerSize));
  }

  // Discard elements from the virtual frame and free any registers.
  for (int i = 0; i < count; i++) {
    FrameElement dropped = elements_.RemoveLast();
    if (dropped.is_register()) {
      Unuse(dropped.reg());
    }
  }
}


Result VirtualFrame::Pop() {
  UNIMPLEMENTED();
  return Result();
}


void VirtualFrame::EmitPop(Register reg) {
  ASSERT(stack_pointer_ == element_count() - 1);
  stack_pointer_--;
  elements_.RemoveLast();
  __ pop(reg);
}


void VirtualFrame::EmitPush(Register reg) {
  ASSERT(stack_pointer_ == element_count() - 1);
  elements_.Add(FrameElement::MemoryElement(NumberInfo::kUnknown));
  stack_pointer_++;
  __ push(reg);
}


void VirtualFrame::EmitPushMultiple(int count, int src_regs) {
  ASSERT(stack_pointer_ == element_count() - 1);
  Adjust(count);
  __ stm(db_w, sp, src_regs);
}


#undef __

} }  // namespace v8::internal