text: // 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.
  
  #include "src/v8.h"
  
  #include "src/codegen.h"
  #include "src/deoptimizer.h"
  #include "src/full-codegen.h"
  #include "src/safepoint-table.h"
  
  namespace v8 {
  namespace internal {
  
  const int Deoptimizer::table_entry_size_ = 8;
  
  
  int Deoptimizer::patch_size() {
    const int kCallInstructionSizeInWords = 3;
    return kCallInstructionSizeInWords * Assembler::kInstrSize;
  }
  
  
  void Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(Handle<Code> code) {
    // Empty because there is no need for relocation information for the code
    // patching in Deoptimizer::PatchCodeForDeoptimization below.
  }
  
  
  void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
    Address code_start_address = code->instruction_start();
    // Invalidate the relocation information, as it will become invalid by the
    // code patching below, and is not needed any more.
    code->InvalidateRelocation();
  
    if (FLAG_zap_code_space) {
      // Fail hard and early if we enter this code object again.
      byte* pointer = code->FindCodeAgeSequence();
      if (pointer != NULL) {
        pointer += kNoCodeAgeSequenceLength;
      } else {
        pointer = code->instruction_start();
      }
      CodePatcher patcher(pointer, 1);
      patcher.masm()->bkpt(0);
  
      DeoptimizationInputData* data =
          DeoptimizationInputData::cast(code->deoptimization_data());
      int osr_offset = data->OsrPcOffset()->value();
      if (osr_offset > 0) {
        CodePatcher osr_patcher(code->instruction_start() + osr_offset, 1);
        osr_patcher.masm()->bkpt(0);
      }
    }
  
    DeoptimizationInputData* deopt_data =
        DeoptimizationInputData::cast(code->deoptimization_data());
  #ifdef DEBUG
    Address prev_call_address = NULL;
  #endif
    // For each LLazyBailout instruction insert a call to the corresponding
    // deoptimization entry.
    for (int i = 0; i < deopt_data->DeoptCount(); i++) {
      if (deopt_data->Pc(i)->value() == -1) continue;
      Address call_address = code_start_address + deopt_data->Pc(i)->value();
      Address deopt_entry = GetDeoptimizationEntry(isolate, i, LAZY);
      // We need calls to have a predictable size in the unoptimized code, but
      // this is optimized code, so we don't have to have a predictable size.
      int call_size_in_bytes =
          MacroAssembler::CallSizeNotPredictableCodeSize(isolate,
                                                         deopt_entry,
                                                         RelocInfo::NONE32);
      int call_size_in_words = call_size_in_bytes / Assembler::kInstrSize;
      DCHECK(call_size_in_bytes % Assembler::kInstrSize == 0);
      DCHECK(call_size_in_bytes <= patch_size());
      CodePatcher patcher(call_address, call_size_in_words);
      patcher.masm()->Call(deopt_entry, RelocInfo::NONE32);
      DCHECK(prev_call_address == NULL ||
             call_address >= prev_call_address + patch_size());
      DCHECK(call_address + patch_size() <= code->instruction_end());
  #ifdef DEBUG
      prev_call_address = call_address;
  #endif
    }
  }
  
  
  void Deoptimizer::FillInputFrame(Address tos, JavaScriptFrame* frame) {
    // Set the register values. The values are not important as there are no
    // callee saved registers in JavaScript frames, so all registers are
    // spilled. Registers fp and sp are set to the correct values though.
  
    for (int i = 0; i < Register::kNumRegisters; i++) {
      input_->SetRegister(i, i * 4);
    }
    input_->SetRegister(sp.code(), reinterpret_cast<intptr_t>(frame->sp()));
    input_->SetRegister(fp.code(), reinterpret_cast<intptr_t>(frame->fp()));
    for (int i = 0; i < DoubleRegister::NumAllocatableRegisters(); i++) {
      input_->SetDoubleRegister(i, 0.0);
    }
  
    // Fill the frame content from the actual data on the frame.
    for (unsigned i = 0; i < input_->GetFrameSize(); i += kPointerSize) {
      input_->SetFrameSlot(i, Memory::uint32_at(tos + i));
    }
  }
  
  
  void Deoptimizer::SetPlatformCompiledStubRegisters(
      FrameDescription* output_frame, CodeStubDescriptor* descriptor) {
    ApiFunction function(descriptor->deoptimization_handler());
    ExternalReference xref(&function, ExternalReference::BUILTIN_CALL, isolate_);
    intptr_t handler = reinterpret_cast<intptr_t>(xref.address());
    int params = descriptor->GetHandlerParameterCount();
    output_frame->SetRegister(r0.code(), params);
    output_frame->SetRegister(r1.code(), handler);
  }
  
  
  void Deoptimizer::CopyDoubleRegisters(FrameDescription* output_frame) {
    for (int i = 0; i < DwVfpRegister::kMaxNumRegisters; ++i) {
      double double_value = input_->GetDoubleRegister(i);
      output_frame->SetDoubleRegister(i, double_value);
    }
  }
  
  
  bool Deoptimizer::HasAlignmentPadding(JSFunction* function) {
    // There is no dynamic alignment padding on ARM in the input frame.
    return false;
  }
  
  
  #define __ masm()->
  
  // This code tries to be close to ia32 code so that any changes can be
  // easily ported.
  void Deoptimizer::EntryGenerator::Generate() {
    GeneratePrologue();
  
    // Save all general purpose registers before messing with them.
    const int kNumberOfRegisters = Register::kNumRegisters;
  
    // Everything but pc, lr and ip which will be saved but not restored.
    RegList restored_regs = kJSCallerSaved | kCalleeSaved | ip.bit();
  
    const int kDoubleRegsSize =
        kDoubleSize * DwVfpRegister::kMaxNumAllocatableRegisters;
  
    // Save all allocatable VFP registers before messing with them.
    DCHECK(kDoubleRegZero.code() == 14);
    DCHECK(kScratchDoubleReg.code() == 15);
  
    // Check CPU flags for number of registers, setting the Z condition flag.
    __ CheckFor32DRegs(ip);
  
    // Push registers d0-d13, and possibly d16-d31, on the stack.
    // If d16-d31 are not pushed, decrease the stack pointer instead.
    __ vstm(db_w, sp, d16, d31, ne);
    __ sub(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);
    __ vstm(db_w, sp, d0, d13);
  
    // Push all 16 registers (needed to populate FrameDescription::registers_).
    // TODO(1588) Note that using pc with stm is deprecated, so we should perhaps
    // handle this a bit differently.
    __ stm(db_w, sp, restored_regs  | sp.bit() | lr.bit() | pc.bit());
  
    __ mov(ip, Operand(ExternalReference(Isolate::kCEntryFPAddress, isolate())));
    __ str(fp, MemOperand(ip));
  
    const int kSavedRegistersAreaSize =
        (kNumberOfRegisters * kPointerSize) + kDoubleRegsSize;
  
    // Get the bailout id from the stack.
    __ ldr(r2, MemOperand(sp, kSavedRegistersAreaSize));
  
    // Get the address of the location in the code object (r3) (return
    // address for lazy deoptimization) and compute the fp-to-sp delta in
    // register r4.
    __ mov(r3, lr);
    // Correct one word for bailout id.
    __ add(r4, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
    __ sub(r4, fp, r4);
  
    // Allocate a new deoptimizer object.
    // Pass four arguments in r0 to r3 and fifth argument on stack.
    __ PrepareCallCFunction(6, r5);
    __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
    __ mov(r1, Operand(type()));  // bailout type,
    // r2: bailout id already loaded.
    // r3: code address or 0 already loaded.
    __ str(r4, MemOperand(sp, 0 * kPointerSize));  // Fp-to-sp delta.
    __ mov(r5, Operand(ExternalReference::isolate_address(isolate())));
    __ str(r5, MemOperand(sp, 1 * kPointerSize));  // Isolate.
    // Call Deoptimizer::New().
    {
      AllowExternalCallThatCantCauseGC scope(masm());
      __ CallCFunction(ExternalReference::new_deoptimizer_function(isolate()), 6);
    }
  
    // Preserve "deoptimizer" object in register r0 and get the input
    // frame descriptor pointer to r1 (deoptimizer->input_);
    __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
  
    // Copy core registers into FrameDescription::registers_[kNumRegisters].
    DCHECK(Register::kNumRegisters == kNumberOfRegisters);
    for (int i = 0; i < kNumberOfRegisters; i++) {
      int offset = (i * kPointerSize) + FrameDescription::registers_offset();
      __ ldr(r2, MemOperand(sp, i * kPointerSize));
      __ str(r2, MemOperand(r1, offset));
    }
  
    // Copy VFP registers to
    // double_registers_[DoubleRegister::kMaxNumAllocatableRegisters]
    int double_regs_offset = FrameDescription::double_registers_offset();
    for (int i = 0; i < DwVfpRegister::kMaxNumAllocatableRegisters; ++i) {
      int dst_offset = i * kDoubleSize + double_regs_offset;
      int src_offset = i * kDoubleSize + kNumberOfRegisters * kPointerSize;
      __ vldr(d0, sp, src_offset);
      __ vstr(d0, r1, dst_offset);
    }
  
    // Remove the bailout id and the saved registers from the stack.
    __ add(sp, sp, Operand(kSavedRegistersAreaSize + (1 * kPointerSize)));
  
    // Compute a pointer to the unwinding limit in register r2; that is
    // the first stack slot not part of the input frame.
    __ ldr(r2, MemOperand(r1, FrameDescription::frame_size_offset()));
    __ add(r2, r2, sp);
  
    // Unwind the stack down to - but not including - the unwinding
    // limit and copy the contents of the activation frame to the input
    // frame description.
    __ add(r3,  r1, Operand(FrameDescription::frame_content_offset()));
    Label pop_loop;
    Label pop_loop_header;
    __ b(&pop_loop_header);
    __ bind(&pop_loop);
    __ pop(r4);
    __ str(r4, MemOperand(r3, 0));
    __ add(r3, r3, Operand(sizeof(uint32_t)));
    __ bind(&pop_loop_header);
    __ cmp(r2, sp);
    __ b(ne, &pop_loop);
  
    // Compute the output frame in the deoptimizer.
    __ push(r0);  // Preserve deoptimizer object across call.
    // r0: deoptimizer object; r1: scratch.
    __ PrepareCallCFunction(1, r1);
    // Call Deoptimizer::ComputeOutputFrames().
    {
      AllowExternalCallThatCantCauseGC scope(masm());
      __ CallCFunction(
          ExternalReference::compute_output_frames_function(isolate()), 1);
    }
    __ pop(r0);  // Restore deoptimizer object (class Deoptimizer).
  
    // Replace the current (input) frame with the output frames.
    Label outer_push_loop, inner_push_loop,
        outer_loop_header, inner_loop_header;
    // Outer loop state: r4 = current "FrameDescription** output_",
    // r1 = one past the last FrameDescription**.
    __ ldr(r1, MemOperand(r0, Deoptimizer::output_count_offset()));
    __ ldr(r4, MemOperand(r0, Deoptimizer::output_offset()));  // r4 is output_.
    __ add(r1, r4, Operand(r1, LSL, 2));
    __ jmp(&outer_loop_header);
    __ bind(&outer_push_loop);
    // Inner loop state: r2 = current FrameDescription*, r3 = loop index.
    __ ldr(r2, MemOperand(r4, 0));  // output_[ix]
    __ ldr(r3, MemOperand(r2, FrameDescription::frame_size_offset()));
    __ jmp(&inner_loop_header);
    __ bind(&inner_push_loop);
    __ sub(r3, r3, Operand(sizeof(uint32_t)));
    __ add(r6, r2, Operand(r3));
    __ ldr(r6, MemOperand(r6, FrameDescription::frame_content_offset()));
    __ push(r6);
    __ bind(&inner_loop_header);
    __ cmp(r3, Operand::Zero());
    __ b(ne, &inner_push_loop);  // test for gt?
    __ add(r4, r4, Operand(kPointerSize));
    __ bind(&outer_loop_header);
    __ cmp(r4, r1);
    __ b(lt, &outer_push_loop);
  
    // Check CPU flags for number of registers, setting the Z condition flag.
    __ CheckFor32DRegs(ip);
  
    __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
    int src_offset = FrameDescription::double_registers_offset();
    for (int i = 0; i < DwVfpRegister::kMaxNumRegisters; ++i) {
      if (i == kDoubleRegZero.code()) continue;
      if (i == kScratchDoubleReg.code()) continue;
  
      const DwVfpRegister reg = DwVfpRegister::from_code(i);
      __ vldr(reg, r1, src_offset, i < 16 ? al : ne);
      src_offset += kDoubleSize;
    }
  
    // Push state, pc, and continuation from the last output frame.
    __ ldr(r6, MemOperand(r2, FrameDescription::state_offset()));
    __ push(r6);
    __ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
    __ push(r6);
    __ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
    __ push(r6);
  
    // Push the registers from the last output frame.
    for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
      int offset = (i * kPointerSize) + FrameDescription::registers_offset();
      __ ldr(r6, MemOperand(r2, offset));
      __ push(r6);
    }
  
    // Restore the registers from the stack.
    __ ldm(ia_w, sp, restored_regs);  // all but pc registers.
    __ pop(ip);  // remove sp
    __ pop(ip);  // remove lr
  
    __ InitializeRootRegister();
  
    __ pop(ip);  // remove pc
    __ pop(ip);  // get continuation, leave pc on stack
    __ pop(lr);
    __ Jump(ip);
    __ stop("Unreachable.");
  }
  
  
  void Deoptimizer::TableEntryGenerator::GeneratePrologue() {
    // Create a sequence of deoptimization entries.
    // Note that registers are still live when jumping to an entry.
    Label done;
    for (int i = 0; i < count(); i++) {
      int start = masm()->pc_offset();
      USE(start);
      __ mov(ip, Operand(i));
      __ b(&done);
      DCHECK(masm()->pc_offset() - start == table_entry_size_);
    }
    __ bind(&done);
    __ push(ip);
  }
  
  
  void FrameDescription::SetCallerPc(unsigned offset, intptr_t value) {
    SetFrameSlot(offset, value);
  }
  
  
  void FrameDescription::SetCallerFp(unsigned offset, intptr_t value) {
    SetFrameSlot(offset, value);
  }
  
  
  void FrameDescription::SetCallerConstantPool(unsigned offset, intptr_t value) {
    DCHECK(FLAG_enable_ool_constant_pool);
    SetFrameSlot(offset, value);
  }
  
  
  #undef __
  
  } }  // namespace v8::internal
  