text: // Copyright 2006-2008 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
  //       disclaimer in the documentation and/or other materials provided
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "v8.h"
  
  #if defined(V8_TARGET_ARCH_ARM)
  
  #include "codegen-inl.h"
  #include "debug.h"
  
  namespace v8 {
  namespace internal {
  
  #ifdef ENABLE_DEBUGGER_SUPPORT
  bool BreakLocationIterator::IsDebugBreakAtReturn() {
    return Debug::IsDebugBreakAtReturn(rinfo());
  }
  
  
  void BreakLocationIterator::SetDebugBreakAtReturn() {
    // Patch the code changing the return from JS function sequence from
    //   mov sp, fp
    //   ldmia sp!, {fp, lr}
    //   add sp, sp, #4
    //   bx lr
    // to a call to the debug break return code.
    // #if USE_BLX
    //   ldr ip, [pc, #0]
    //   blx ip
    // #else
    //   mov lr, pc
    //   ldr pc, [pc, #-4]
    // #endif
    //   <debug break return code entry point address>
    //   bktp 0
    CodePatcher patcher(rinfo()->pc(), Assembler::kJSReturnSequenceInstructions);
  #ifdef USE_BLX
    patcher.masm()->ldr(v8::internal::ip, MemOperand(v8::internal::pc, 0));
    patcher.masm()->blx(v8::internal::ip);
  #else
    patcher.masm()->mov(v8::internal::lr, v8::internal::pc);
    patcher.masm()->ldr(v8::internal::pc, MemOperand(v8::internal::pc, -4));
  #endif
    patcher.Emit(Debug::debug_break_return()->entry());
    patcher.masm()->bkpt(0);
  }
  
  
  // Restore the JS frame exit code.
  void BreakLocationIterator::ClearDebugBreakAtReturn() {
    rinfo()->PatchCode(original_rinfo()->pc(),
                       Assembler::kJSReturnSequenceInstructions);
  }
  
  
  // A debug break in the frame exit code is identified by the JS frame exit code
  // having been patched with a call instruction.
  bool Debug::IsDebugBreakAtReturn(RelocInfo* rinfo) {
    ASSERT(RelocInfo::IsJSReturn(rinfo->rmode()));
    return rinfo->IsPatchedReturnSequence();
  }
  
  
  bool BreakLocationIterator::IsDebugBreakAtSlot() {
    ASSERT(IsDebugBreakSlot());
    // Check whether the debug break slot instructions have been patched.
    return rinfo()->IsPatchedDebugBreakSlotSequence();
  }
  
  
  void BreakLocationIterator::SetDebugBreakAtSlot() {
    ASSERT(IsDebugBreakSlot());
    // Patch the code changing the debug break slot code from
    //   mov r2, r2
    //   mov r2, r2
    //   mov r2, r2
    // to a call to the debug break slot code.
    // #if USE_BLX
    //   ldr ip, [pc, #0]
    //   blx ip
    // #else
    //   mov lr, pc
    //   ldr pc, [pc, #-4]
    // #endif
    //   <debug break slot code entry point address>
    CodePatcher patcher(rinfo()->pc(), Assembler::kDebugBreakSlotInstructions);
  #ifdef USE_BLX
    patcher.masm()->ldr(v8::internal::ip, MemOperand(v8::internal::pc, 0));
    patcher.masm()->blx(v8::internal::ip);
  #else
    patcher.masm()->mov(v8::internal::lr, v8::internal::pc);
    patcher.masm()->ldr(v8::internal::pc, MemOperand(v8::internal::pc, -4));
  #endif
    patcher.Emit(Debug::debug_break_return()->entry());
  }
  
  
  void BreakLocationIterator::ClearDebugBreakAtSlot() {
    ASSERT(IsDebugBreakSlot());
    rinfo()->PatchCode(original_rinfo()->pc(),
                       Assembler::kDebugBreakSlotInstructions);
  }
  
  
  #define __ ACCESS_MASM(masm)
  
  
  static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
                                            RegList object_regs,
                                            RegList non_object_regs) {
    __ EnterInternalFrame();
  
    // Store the registers containing live values on the expression stack to
    // make sure that these are correctly updated during GC. Non object values
    // are stored as a smi causing it to be untouched by GC.
    ASSERT((object_regs & ~kJSCallerSaved) == 0);
    ASSERT((non_object_regs & ~kJSCallerSaved) == 0);
    ASSERT((object_regs & non_object_regs) == 0);
    if ((object_regs | non_object_regs) != 0) {
      for (int i = 0; i < kNumJSCallerSaved; i++) {
        int r = JSCallerSavedCode(i);
        Register reg = { r };
        if ((non_object_regs & (1 << r)) != 0) {
          if (FLAG_debug_code) {
            __ tst(reg, Operand(0xc0000000));
            __ Assert(eq, "Unable to encode value as smi");
          }
          __ mov(reg, Operand(reg, LSL, kSmiTagSize));
        }
      }
      __ stm(db_w, sp, object_regs | non_object_regs);
    }
  
  #ifdef DEBUG
    __ RecordComment("// Calling from debug break to runtime - come in - over");
  #endif
    __ mov(r0, Operand(0));  // no arguments
    __ mov(r1, Operand(ExternalReference::debug_break()));
  
    CEntryStub ceb(1);
    __ CallStub(&ceb);
  
    // Restore the register values from the expression stack.
    if ((object_regs | non_object_regs) != 0) {
      __ ldm(ia_w, sp, object_regs | non_object_regs);
      for (int i = 0; i < kNumJSCallerSaved; i++) {
        int r = JSCallerSavedCode(i);
        Register reg = { r };
        if ((non_object_regs & (1 << r)) != 0) {
          __ mov(reg, Operand(reg, LSR, kSmiTagSize));
        }
        if (FLAG_debug_code &&
            (((object_regs |non_object_regs) & (1 << r)) == 0)) {
          __ mov(reg, Operand(kDebugZapValue));
        }
      }
    }
  
    __ LeaveInternalFrame();
  
    // Now that the break point has been handled, resume normal execution by
    // jumping to the target address intended by the caller and that was
    // overwritten by the address of DebugBreakXXX.
    __ mov(ip, Operand(ExternalReference(Debug_Address::AfterBreakTarget())));
    __ ldr(ip, MemOperand(ip));
    __ Jump(ip);
  }
  
  
  void Debug::GenerateLoadICDebugBreak(MacroAssembler* masm) {
    // Calling convention for IC load (from ic-arm.cc).
    // ----------- S t a t e -------------
    //  -- r2    : name
    //  -- lr    : return address
    //  -- r0    : receiver
    //  -- [sp]  : receiver
    // -----------------------------------
    // Registers r0 and r2 contain objects that need to be pushed on the
    // expression stack of the fake JS frame.
    Generate_DebugBreakCallHelper(masm, r0.bit() | r2.bit(), 0);
  }
  
  
  void Debug::GenerateStoreICDebugBreak(MacroAssembler* masm) {
    // Calling convention for IC store (from ic-arm.cc).
    // ----------- S t a t e -------------
    //  -- r0    : value
    //  -- r1    : receiver
    //  -- r2    : name
    //  -- lr    : return address
    // -----------------------------------
    // Registers r0, r1, and r2 contain objects that need to be pushed on the
    // expression stack of the fake JS frame.
    Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit(), 0);
  }
  
  
  void Debug::GenerateKeyedLoadICDebugBreak(MacroAssembler* masm) {
    // ---------- S t a t e --------------
    //  -- lr     : return address
    //  -- r0     : key
    //  -- r1     : receiver
    Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit(), 0);
  }
  
  
  void Debug::GenerateKeyedStoreICDebugBreak(MacroAssembler* masm) {
    // ---------- S t a t e --------------
    //  -- r0     : value
    //  -- r1     : key
    //  -- r2     : receiver
    //  -- lr     : return address
    Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit(), 0);
  }
  
  
  void Debug::GenerateCallICDebugBreak(MacroAssembler* masm) {
    // Calling convention for IC call (from ic-arm.cc)
    // ----------- S t a t e -------------
    //  -- r2     : name
    // -----------------------------------
    Generate_DebugBreakCallHelper(masm, r2.bit(), 0);
  }
  
  
  void Debug::GenerateConstructCallDebugBreak(MacroAssembler* masm) {
    // Calling convention for construct call (from builtins-arm.cc)
    //  -- r0     : number of arguments (not smi)
    //  -- r1     : constructor function
    Generate_DebugBreakCallHelper(masm, r1.bit(), r0.bit());
  }
  
  
  void Debug::GenerateReturnDebugBreak(MacroAssembler* masm) {
    // In places other than IC call sites it is expected that r0 is TOS which
    // is an object - this is not generally the case so this should be used with
    // care.
    Generate_DebugBreakCallHelper(masm, r0.bit(), 0);
  }
  
  
  void Debug::GenerateStubNoRegistersDebugBreak(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  No registers used on entry.
    // -----------------------------------
    Generate_DebugBreakCallHelper(masm, 0, 0);
  }
  
  
  void Debug::GenerateSlot(MacroAssembler* masm) {
    // Generate enough nop's to make space for a call instruction. Avoid emitting
    // the constant pool in the debug break slot code.
    Assembler::BlockConstPoolScope block_const_pool(masm);
    Label check_codesize;
    __ bind(&check_codesize);
    __ RecordDebugBreakSlot();
    for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
      __ nop(2);
    }
    ASSERT_EQ(Assembler::kDebugBreakSlotInstructions,
              masm->InstructionsGeneratedSince(&check_codesize));
  }
  
  
  void Debug::GenerateSlotDebugBreak(MacroAssembler* masm) {
    // In the places where a debug break slot is inserted no registers can contain
    // object pointers.
    Generate_DebugBreakCallHelper(masm, 0, 0);
  }
  
  
  void Debug::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
    masm->Abort("LiveEdit frame dropping is not supported on arm");
  }
  
  
  void Debug::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
    masm->Abort("LiveEdit frame dropping is not supported on arm");
  }
  
  const bool Debug::kFrameDropperSupported = false;
  
  #undef __
  
  
  
  #endif  // ENABLE_DEBUGGER_SUPPORT
  
  } }  // namespace v8::internal
  
  #endif  // V8_TARGET_ARCH_ARM
  