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Commit 645f8bbc authored by David Srbecky's avatar David Srbecky
Browse files

Emit the frame for DEX PC before the frame for native PC. 

This results in more natural backtrace.

Test: ART's 137-cfi test

Change-Id: Ic472db2733a330f8dbc722887809273b77d9dfb5
parent ccb9960b

libbacktrace/UnwindStack.cpp

+21 −15
Original line number Diff line number Diff line
@@ -128,9 +128,28 @@ bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map, 
  }

  frames->resize(total_frames);

  size_t cur_frame = 0;

  for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++, cur_frame++) {

  for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++) {

    auto frame = &unwinder_frames[i];

    backtrace_frame_data_t* back_frame = &frames->at(cur_frame);



    // Inject extra 'virtual' frame that represents the dex pc data.

    // The dex pc is magic register defined in the Mterp interpreter,

    // and thus it will be restored/observed in the frame after it.

    // Adding the dex frame first here will create something like:

    //   #7 pc 006b1ba1 libartd.so  ExecuteMterpImpl+14625

    //   #8 pc 0015fa20 core.vdex   java.util.Arrays.binarySearch+8

    //   #9 pc 0039a1ef libartd.so  art::interpreter::Execute+719

    if (frame->dex_pc != 0) {

      backtrace_frame_data_t* dex_frame = &frames->at(cur_frame++);

      dex_frame->num = cur_frame;

      dex_frame->pc = frame->dex_pc;

      dex_frame->rel_pc = frame->dex_pc;

      dex_frame->sp = frame->sp;

      dex_frame->stack_size = 0;

      dex_frame->func_offset = 0;

      FillInDexFrame(stack_map, frame->dex_pc, dex_frame);

    }



    backtrace_frame_data_t* back_frame = &frames->at(cur_frame++);



    back_frame->num = cur_frame;
@@ -147,19 +166,6 @@ bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map, 
    back_frame->map.offset = frame->map_offset;

    back_frame->map.load_bias = frame->map_load_bias;

    back_frame->map.flags = frame->map_flags;



    // Inject a frame that represents the dex pc data.

    if (frame->dex_pc != 0) {

      cur_frame++;

      backtrace_frame_data_t* dex_frame = &frames->at(cur_frame);

      dex_frame->num = cur_frame;

      dex_frame->pc = frame->dex_pc;

      dex_frame->rel_pc = frame->dex_pc;

      dex_frame->sp = back_frame->sp;

      dex_frame->stack_size = 0;

      dex_frame->func_offset = 0;

      FillInDexFrame(stack_map, frame->dex_pc, dex_frame);

    }

  }



  return true;