Store frame pointers

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 36b3177b7c02c474b058bc3f0f8f2a8c1aa5b4c1..c4b2185d757d10a6156435425b59b14404895599 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -11192,8 +11192,9 @@ static const int kFrameDetailsLocalCountIndex = 4;
 static const int kFrameDetailsSourcePositionIndex = 5;
 static const int kFrameDetailsConstructCallIndex = 6;
 static const int kFrameDetailsAtReturnIndex = 7;
-static const int kFrameDetailsFlagsIndex = 8;
-static const int kFrameDetailsFirstDynamicIndex = 9;
+static const int kFrameDetailsFramePointerIndex = 8;
+static const int kFrameDetailsFlagsIndex = 9;
+static const int kFrameDetailsFirstDynamicIndex = 10;
 
 
 static SaveContext* FindSavedContextForFrame(Isolate* isolate,
@@ -11220,7 +11221,8 @@ static SaveContext* FindSavedContextForFrame(Isolate* isolate,
 // 5: Source position
 // 6: Constructor call
 // 7: Is at return
-// 8: Flags
+// 8: Frame pointer
+// 9: Flags
 // Arguments name, value
 // Locals name, value
 // Return value if any
@@ -11405,6 +11407,17 @@ RUNTIME_FUNCTION(Runtime_GetFrameDetails) {
   // Add the at return information.
   details->set(kFrameDetailsAtReturnIndex, heap->ToBoolean(at_return));
 
+  // No memory address will actually be larger than 2^48 on a current x64
+  // machine but we truncate to 53 bits to future proof this method. Users
+  // should not care about the exact frame pointer values only the
+  // order of frame pointers. Truncating to 53 bits will still generate the
+  // correct ordering with very high probability.
+  uintptr_t frame_pointer =
+      reinterpret_cast<uintptr_t>(it.frame()->UnpaddedFP()) &
+      ((static_cast<uintptr_t>(1)<<53) - 1);

[hausner, 2014/09/05 18:08:36]

How about building the mask as a const uint64_t value in a separate statement?
Also, what happens when you shift by 53 if you run on 32bit hardware? Can you
omit this address mangling (with ifdefs) when run on a 32bit platform?

+  details->set(kFrameDetailsFramePointerIndex,
+      *isolate->factory()->NewNumber(static_cast<double>(frame_pointer)));
+
   // Add flags to indicate information on whether this frame is
   //   bit 0: invoked in the debugger context.
   //   bit 1: optimized frame.