8323681: SA PointerFinder code should support G1

Reviewed-by: tschatzl, kevinw

Author: plummercj

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/g1/G1CollectedHeap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -122,6 +122,17 @@ public void heapRegionIterate(HeapRegionClosure hrcl) {
         }
     }
 
+    public HeapRegion heapRegionForAddress(Address addr) {
+        Iterator<HeapRegion> iter = heapRegionIterator();
+        while (iter.hasNext()) {
+            HeapRegion hr = iter.next();
+            if (hr.isInRegion(addr)) {
+                return hr;
+            }
+        }
+        return null;
+    }
+
     public CollectedHeapName kind() {
         return CollectedHeapName.G1;
     }

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/g1/HeapRegion.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -140,6 +140,10 @@ public static long getPointerSize() {
         return pointerSize;
     }
 
+    public boolean isInRegion(Address addr) {
+        return (addr.greaterThanOrEqual(bottom()) && addr.lessThan(end()));
+    }
+
     public void printOn(PrintStream tty) {
         tty.print("Region: " + bottom() + "," + top() + "," + end());
         tty.println(":" + type.typeAnnotation() + (isPinned() ? " Pinned" : ""));

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/PointerFinder.java

@@ -27,6 +27,7 @@
 import sun.jvm.hotspot.code.*;
 import sun.jvm.hotspot.debugger.*;
 import sun.jvm.hotspot.debugger.cdbg.*;
+import sun.jvm.hotspot.gc.g1.*;
 import sun.jvm.hotspot.gc.serial.*;
 import sun.jvm.hotspot.gc.shared.*;
 import sun.jvm.hotspot.interpreter.*;
@@ -104,8 +105,7 @@ public static PointerLocation find(Address a) {
 
       // If we are using the SerialHeap, find out which generation the address is in
       if (heap instanceof SerialHeap) {
-        SerialHeap sh = (SerialHeap) heap;
-        loc.heap = heap;
+        SerialHeap sh = (SerialHeap)heap;
         for (int i = 0; i < sh.nGens(); i++) {
           Generation g = sh.getGen(i);
           if (g.isIn(a)) {
@@ -119,6 +119,18 @@ public static PointerLocation find(Address a) {
         }
       }
 
+      // If we are using the G1CollectedHeap, find out which region the address is in
+      if (heap instanceof G1CollectedHeap) {
+        G1CollectedHeap g1 = (G1CollectedHeap)heap;
+        loc.hr = g1.heapRegionForAddress(a);
+        // We don't assert that loc.hr is not null like we do for the SerialHeap. This is
+        // because heap.isIn(a) can return true if the address is anywhere in G1's mapped
+        // memory, even if that area of memory is not in use by a G1 HeapRegion. So there
+        // may in fact be no HeapRegion for the address even though it is in the heap.
+        // Leaving loc.hr == null in this case will result in PointerFinder saying that
+        // the address is "In unknown section of Java the heap", which is what we want.
+      }
+
       return loc;
     }
 

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/PointerLocation.java

@@ -28,6 +28,7 @@
 import sun.jvm.hotspot.code.*;
 import sun.jvm.hotspot.debugger.*;
 import sun.jvm.hotspot.debugger.cdbg.*;
+import sun.jvm.hotspot.gc.g1.*;
 import sun.jvm.hotspot.gc.serial.*;
 import sun.jvm.hotspot.gc.shared.*;
 import sun.jvm.hotspot.interpreter.*;
@@ -57,7 +58,8 @@ public class PointerLocation {
   ClosestSymbol nativeSymbol;
 
   CollectedHeap heap;
-  Generation gen;
+  Generation gen;  // Serial heap generation
+  HeapRegion hr;   // G1 heap region
 
   // If UseTLAB was enabled and the pointer was found in a
   // currently-active TLAB, these will be set
@@ -123,7 +125,11 @@ public boolean inOtherGen() {
   }
 
   public Generation getGeneration() {
-      return gen;
+    return gen; // SerialHeap generation
+  }
+
+  public HeapRegion getHeapRegion() {
+    return hr; // G1 heap region
   }
 
   /** This may be true if isInNewGen is also true */
@@ -278,18 +284,36 @@ public void printOn(PrintStream tty, boolean printAddress, boolean verbose) {
         } else {
           tty.format("\"%s\" %s\n", thread.getThreadName(), thread);
         }
-      } else {
-        if (isInNewGen()) {
-          tty.print("In new generation ");
-        } else if (isInOldGen()) {
-          tty.print("In old generation ");
-        } else {
-          tty.print("In unknown section of Java heap");
-        }
+      }
+      // This section provides details about where in the heap the address is located,
+      // but we only want to do that if it is not in a TLAB or if verbose requested.
+      if (!isInTLAB() || verbose) {
         if (getGeneration() != null) {
-          getGeneration().printOn(tty); // does not include "\n"
+          // Address is in SerialGC heap
+          if (isInNewGen()) {
+              tty.print("In new generation of SerialGC heap");
+          } else if (isInOldGen()) {
+              tty.print("In old generation of SerialGC heap");
+          } else {
+              tty.print("In unknown generation of SerialGC heap");
+          }
+          if (verbose) {
+              tty.print(":");
+              getGeneration().printOn(tty); // does not include "\n"
+          }
+          tty.println();
+        } else if (getHeapRegion() != null) {
+            // Address is in the G1 heap
+            if (verbose) {
+                tty.print("In G1 heap ");
+                getHeapRegion().printOn(tty); // includes "\n"
+            } else {
+                tty.println("In G1 heap region");
+            }
+        } else {
+            // Address is some other heap type that we haven't special cased yet.
+            tty.println("In unknown section of the Java heap");
         }
-        tty.println();
       }
     } else if (isInInterpreter()) {
       tty.print("In interpreter codelet: ");