Fix recursive issues for large Regions GC heap enumeration

src/SOS/Strike/sos.cpp

@@ -586,10 +586,10 @@ namespace sos
         mCurrObj = mStart < TO_TADDR(mSegment.mem) ? TO_TADDR(mSegment.mem) : mStart;
         mSegmentEnd = TO_TADDR(mSegment.highAllocMark);
 
-        CheckSegmentRange();
+        TryAlignToObjectInRange();
     }
 
-    bool ObjectIterator::NextSegment()
+    bool ObjectIterator::TryMoveNextSegment()
     {
         if (mCurrHeap >= mNumHeaps)
         {
@@ -648,16 +648,29 @@ namespace sos
         mLastObj = 0;
         mCurrObj = mStart < TO_TADDR(mSegment.mem) ? TO_TADDR(mSegment.mem) : mStart;
         mSegmentEnd = TO_TADDR(mSegment.highAllocMark);
-        return CheckSegmentRange();
+        return true;
     }
 
-    bool ObjectIterator::CheckSegmentRange()
+    bool ObjectIterator::TryMoveToObjectInNextSegmentInRange()
     {
-        CheckInterrupt();
+        if (TryMoveNextSegment())
+        {
+            return TryAlignToObjectInRange();
+        }
 
+        return false;
+    }
+
+    bool ObjectIterator::TryAlignToObjectInRange()
+    {
         while (!MemOverlap(mStart, mEnd, TO_TADDR(mSegment.mem), mSegmentEnd))
-            if (!NextSegment())
+        {
+            CheckInterrupt();
+            if (!TryMoveNextSegment())
+            {
                 return false;
+            }
+        }
 
         // At this point we know that the current segment contains objects in
         // the correct range.  However, there's no telling if the user gave us
@@ -724,7 +737,7 @@ namespace sos
         }
         catch(const sos::Exception &)
         {
-            NextSegment();
+            TryMoveToObjectInNextSegmentInRange();
         }
     }
 
@@ -773,7 +786,9 @@ namespace sos
         }
 
         if (mCurrObj > mEnd || mCurrObj >= mSegmentEnd)
-            NextSegment();
+        {
+            TryMoveToObjectInNextSegmentInRange();
+        }
     }
 
     SyncBlkIterator::SyncBlkIterator()

src/SOS/Strike/sos.h

@@ -627,8 +627,27 @@ namespace sos
         void BuildError(__out_ecount(count) char *out, size_t count, const char *format, ...) const;
 
         void AssertSanity() const;
-        bool NextSegment();
-        bool CheckSegmentRange();
+
+        /*
+            This function moves to the next segment/region without checking any restrictions
+            on the range. Returns true if it was able to move to a new segment/region.
+        */
+        bool TryMoveNextSegment();
+
+        /*
+            Aligns the iterator to the object that falls in the requested range, moving to 
+            the next segment/region as necessary. The iterator state doesn't change if the
+            current object already lies in the requested range. Returns true if aligning
+            to such an object was possible.
+        */
+        bool TryAlignToObjectInRange();
+
+        /*
+            Moves to the next segment/region that contains an object in the requested
+            range and align it to such object. This operation always moves the iterator.
+            Returns false if no such move was possible.
+        */
+        bool TryMoveToObjectInNextSegmentInRange();
         void MoveToNextObject();
 
     private:

src/SOS/Strike/strike.cpp

@@ -11039,6 +11039,7 @@ DECLARE_API(GCWhere)
         }
     }
 
+    DWORD heapIdx = 0;
     if (!IsServerBuild())
     {
         DacpGcHeapDetails heapDetails;
@@ -11048,13 +11049,7 @@ DECLARE_API(GCWhere)
             return Status;
         }
 
-        if (GCObjInHeap(taddrObj, heapDetails, trngSeg, gen, allocCtx, bLarge))
-        {
-            ExtOut("Address   " WIN64_8SPACES " Gen   Heap   segment   " WIN64_8SPACES " begin     " WIN64_8SPACES " allocated  " WIN64_8SPACES " size\n");
-            ExtOut("%p   %d     %2d     %p   %p   %p    0x%x(%d)\n",
-                SOS_PTR(taddrObj), gen, 0, SOS_PTR(trngSeg.segAddr), SOS_PTR(trngSeg.start), SOS_PTR(trngSeg.end), size, size);
-            bFound = TRUE;
-        }
+        bFound = GCObjInHeap(taddrObj, heapDetails, trngSeg, gen, allocCtx, bLarge);
     }
     else
     {
@@ -11080,31 +11075,30 @@ DECLARE_API(GCWhere)
             return Status;
         }
 
-        for (DWORD n = 0; n < dwNHeaps; n ++)
+        for (heapIdx = 0; heapIdx < dwNHeaps && !bFound; heapIdx++)
         {
             DacpGcHeapDetails dacHeapDetails;
-            if (dacHeapDetails.Request(g_sos, heapAddrs[n]) != S_OK)
+            if (dacHeapDetails.Request(g_sos, heapAddrs[heapIdx]) != S_OK)
             {
                 ExtOut("Error requesting details\n");
                 return Status;
             }
 
-            GCHeapDetails heapDetails(dacHeapDetails, heapAddrs[n]);
-            if (GCObjInHeap(taddrObj, heapDetails, trngSeg, gen, allocCtx, bLarge))
-            {
-                ExtOut("Address " WIN64_8SPACES " Gen Heap segment " WIN64_8SPACES " begin   " WIN64_8SPACES " allocated" WIN64_8SPACES " size\n");
-                ExtOut("%p   %d     %2d     %p   %p   %p    0x%x(%d)\n",
-                    SOS_PTR(taddrObj), gen, n, SOS_PTR(trngSeg.segAddr), SOS_PTR(trngSeg.start), SOS_PTR(trngSeg.end), size, size);
-                bFound = TRUE;
-                break;
-            }
+            GCHeapDetails heapDetails(dacHeapDetails, heapAddrs[heapIdx]);
+            bFound = GCObjInHeap(taddrObj, heapDetails, trngSeg, gen, allocCtx, bLarge);
         }
     }
 
     if (!bFound)
     {
         ExtOut("Address %#p not found in the managed heap.\n", SOS_PTR(taddrObj));
     }
+    else
+    {
+        ExtOut("Address " WIN64_8SPACES " Gen Heap segment " WIN64_8SPACES " begin   " WIN64_8SPACES " allocated" WIN64_8SPACES " size\n");
+        ExtOut("%p   %d     %2d     %p   %p   %p    0x%x(%d)\n",
+            SOS_PTR(taddrObj), gen, heapIdx, SOS_PTR(trngSeg.segAddr), SOS_PTR(trngSeg.start), SOS_PTR(trngSeg.end), size, size);
+    }
 
     return Status;
 }