Cleanup the libbacktrace interface a bit.

- Change the field name load_base to load_bias (which is what it really is).
- Add a rel_pc field so that callers do not need to compute it themselves.
- Remove the BacktraceMap::GetRelativePc() since nobody should need to
  compute this themselves.

Bug: 23762183

Test: Compiles and unit tests pass (debuggerd, libbacktrace).
Change-Id: I2cb579767120adf08c407a58f3c487ee3f2b45fc

1 files changed, 5 insertions, 0 deletions

diff --git a/libbacktrace/UnwindCurrent.cpp b/libbacktrace/UnwindCurrent.cpp
index 3c509e61a..2c87fa837 100644
--- a/libbacktrace/UnwindCurrent.cpp
+++ b/libbacktrace/UnwindCurrent.cpp
@@ -133,6 +133,11 @@ bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucon
           backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
           prev->stack_size = frame->sp - prev->sp;
         }
+        if (BacktraceMap::IsValid(frame->map)) {
+          frame->rel_pc = frame->pc - frame->map.start + frame->map.load_bias;
+        } else {
+          frame->rel_pc = frame->pc;
+        }
         num_frames++;
       } else {
         num_ignore_frames--;