Skip samples where top function's stack frame is not setup properly

src/profile-generator.cc

 // Copyright 2012 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
@@ skipping 513 matching lines @@
     CodeTree::Locator locator;
     if (!tree_.FindGreatestLessThan(addr, &locator)) break;
     Address start2 = locator.key(), end2 = start2 + locator.value().size;
     if (start2 < end && start < end2) to_delete.Add(start2);
     addr = start2 - 1;
   }
   for (int i = 0; i < to_delete.length(); ++i) tree_.Remove(to_delete[i]);
 }
 
 
-CodeEntry* CodeMap::FindEntry(Address addr) {
+CodeEntry* CodeMap::FindEntry(Address addr, Address* start) {
   CodeTree::Locator locator;
   if (tree_.FindGreatestLessThan(addr, &locator)) {
     // locator.key() <= addr. Need to check that addr is within entry.
     const CodeEntryInfo& entry = locator.value();
-    if (addr < (locator.key() + entry.size))
+    if (addr < (locator.key() + entry.size)) {
+      if (start)
+        *start = locator.key();
       return entry.entry;
+    }
   }
   return NULL;
 }
 
 
 int CodeMap::GetSharedId(Address addr) {
   CodeTree::Locator locator;
   // For shared function entries, 'size' field is used to store their IDs.
   if (tree_.Find(addr, &locator)) {
     const CodeEntryInfo& entry = locator.value();
@@ skipping 340 matching lines @@
 
 
 void ProfileGenerator::RecordTickSample(const TickSample& sample) {
   // Allocate space for stack frames + pc + function + vm-state.
   ScopedVector<CodeEntry*> entries(sample.frames_count + 3);
   // As actual number of decoded code entries may vary, initialize
   // entries vector with NULL values.
   CodeEntry** entry = entries.start();
   memset(entry, 0, entries.length() * sizeof(*entry));
   if (sample.pc != NULL) {
-    *entry++ = code_map_.FindEntry(sample.pc);
+    Address start;
+    CodeEntry* pc_entry = code_map_.FindEntry(sample.pc, &start);
+    // If pc is in the function code before it setup stack frame or after the
+    // frame was destroyed SafeStackTraceFrameIterator incorrectly thinks that
+    // ebp cotains return address of the current function and skips caller's
+    // frame. Check for this case and just skip such samples.
+    if (pc_entry && pc_entry->frame_setup_offset() != -1) {
+      Code* code = Code::cast(HeapObject::FromAddress(start));
+      Address instruction_start = code->instruction_start();
+      // Frame setup code is at least 4 bytes.
+      if (sample.pc < instruction_start + pc_entry->frame_setup_offset() + 4)
+        return;

[loislo, 2013/04/26 13:36:56]

looks like you are skipping the other stack traces.

[yurys, 2013/04/26 13:43:51]

Yes, this is intentional, the comment above describes that.

+      Address frame_destroy = instruction_start +
+          pc_entry->frame_destroy_offset();
+      if (frame_destroy < sample.pc && sample.pc < frame_destroy + 4)
+        return;

[loislo, 2013/04/26 13:36:56]

ditto

[yurys, 2013/04/26 13:43:51]

See above.

+    }
+    *entry++ = pc_entry;

[loislo, 2013/04/26 13:36:56]

sounds like you are adding zero entry if the mapping wasn't found.

[yurys, 2013/04/26 13:43:51]

This part didn't change, it is normal case - pc could have pointed into some
stub code e.g.

 
     if (sample.has_external_callback) {
       // Don't use PC when in external callback code, as it can point
       // inside callback's code, and we will erroneously report
       // that a callback calls itself.
       *(entries.start()) = NULL;
       *entry++ = code_map_.FindEntry(sample.external_callback);
     }
 
     for (const Address* stack_pos = sample.stack,
@@ skipping 16 matching lines @@
     if (no_symbolized_entries) {
       *entry++ = EntryForVMState(sample.state);
     }
   }
 
   profiles_->AddPathToCurrentProfiles(entries);
 }
 
 
 } }  // namespace v8::internal