commit 797b29a897b26bf7a29939bdc188217e5ad7ae9c
author David Srbecky <dsrbecky@google.com> Thu Jan 25 22:55:49 2018 +0000
committer android-build-merger <android-build-merger@google.com> Thu Jan 25 22:55:49 2018 +0000
tree 9f5c2e0373e8de3c07ecedad10b4d56be82fa533
parent 503e7228b12d6ca23e6ad9c41149ef20625247ad
parent 257d0248bfc7a02253cfc781bf6552c4700b3f09

Merge "Emit the frame for DEX PC before the frame for native PC." am: 4a2178836e
am: 9ba37712e5

Change-Id: I8f6d12c0011efbb2e2c7c84545086b88d4d5b2b2

libbacktrace/UnwindStack.cpp

diff --git a/libbacktrace/UnwindStack.cpp b/libbacktrace/UnwindStack.cpp
index 91bcc66..c5dd45b 100644
--- a/libbacktrace/UnwindStack.cpp
+++ b/libbacktrace/UnwindStack.cpp
@@ -128,9 +128,28 @@
   }
   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 @@
     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;