Hard Crash on OS X and Linux (but somewhat environment dependent)

Stefan Marr java at stefan-marr.de
Wed Dec 10 11:22:35 UTC 2014


Hi Gilles:

> On 10 Dec 2014, at 11:53, Gilles Duboscq <duboscq at ssw.jku.at> wrote:
> 
> I see a lot of unsafeCast calls where the last argument is true. That
> sounds dangerous.
> Are you sure your casts really *always* hold? Regardless of
> control-flow? This argument should be the condition under which that
> cast is safe, which is usually a condition that you have already
> checked in the control-flow that leads to the cast.

I am not sure what you mean with ‘always’.
I use most of those casts to get rid of some of the null-checks I saw in IGV.

Below is a patch that adds the assertions corresponding to the unsafeCasts.

They do not trigger. Does that satisfy your definition of ‘always’?

Best regards
Stefan

diff --git a/src/som/interpreter/SArguments.java b/src/som/interpreter/SArguments.java
index 64d5cd7..4ccc53e 100644
--- a/src/som/interpreter/SArguments.java
+++ b/src/som/interpreter/SArguments.java
@@ -8,10 +8,12 @@ public final class SArguments {
   private static final int RCVR_IDX = 0;
 
   private static Object[] args(final Frame frame) {
+    assert frame.getArguments() != null;
     return CompilerDirectives.unsafeCast(frame.getArguments(), Object[].class, true, true);
   }
 
   public static Object arg(final Frame frame, final int index) {
+    assert args(frame)[index] != null;
     return CompilerDirectives.unsafeCast(args(frame)[index], Object.class, true, true);
   }
 
diff --git a/src/som/interpreter/nodes/ContextualNode.java b/src/som/interpreter/nodes/ContextualNode.java
index ec83e48..84535aa 100644
--- a/src/som/interpreter/nodes/ContextualNode.java
+++ b/src/som/interpreter/nodes/ContextualNode.java
@@ -62,14 +62,18 @@ public abstract class ContextualNode extends ExpressionNode {
     int i = contextLevel - 1;
 
     while (i > 0) {
-      self = CompilerDirectives.unsafeCast(self.getOuterSelf(), SBlock.class, true, true);
+      Object b = self.getOuterSelf();
+      assert b instanceof SBlock && b != null;
+      self = CompilerDirectives.unsafeCast(b, SBlock.class, true, true);
       i--;
     }
     return self.getContext();
   }
 
   private SBlock getLocalSelf(final VirtualFrame frame) {
-    return CompilerDirectives.unsafeCast(FrameUtil.getObjectSafe(frame, localSelf), SBlock.class, true, true);
+    Object b = FrameUtil.getObjectSafe(frame, localSelf);
+    assert b instanceof SBlock && b != null;
+    return CompilerDirectives.unsafeCast(b, SBlock.class, true, true);
   }
 
   @ExplodeLoop
@@ -77,6 +81,7 @@ public abstract class ContextualNode extends ExpressionNode {
     Object self = getLocalSelf(frame);
     int i = contextLevel;
     while (i > 0) {
+      assert self instanceof SBlock && self != null;
       SBlock block = CompilerDirectives.unsafeCast(self, SBlock.class, true, true);
       self = block.getOuterSelf();
       i--;
diff --git a/src/som/interpreter/nodes/FieldNode.java b/src/som/interpreter/nodes/FieldNode.java
index 4077baa..98a4a4b 100644
--- a/src/som/interpreter/nodes/FieldNode.java
+++ b/src/som/interpreter/nodes/FieldNode.java
@@ -81,6 +81,7 @@ public abstract class FieldNode extends ExpressionNode {
     @Override
     public Object doPreEvaluated(final VirtualFrame frame,
         final Object[] arguments) {
+      assert arguments[0] != null && arguments[0] instanceof SObject;
       return executeEvaluated(CompilerDirectives.unsafeCast(
           arguments[0], SObject.class, true, true));
     }
@@ -134,6 +135,8 @@ public abstract class FieldNode extends ExpressionNode {
     @Override
     public final Object doPreEvaluated(final VirtualFrame frame,
         final Object[] arguments) {
+      assert arguments[0] != null && arguments[0] instanceof SObject;
+      assert arguments[1] != null;
       return executeEvaluated(frame,
           CompilerDirectives.unsafeCast(arguments[0], SObject.class, true, true),
           CompilerDirectives.unsafeCast(arguments[1],  Object.class, true, true));
diff --git a/src/som/interpreter/nodes/LocalVariableNode.java b/src/som/interpreter/nodes/LocalVariableNode.java
index 6102aa2..e49bea1 100644
--- a/src/som/interpreter/nodes/LocalVariableNode.java
+++ b/src/som/interpreter/nodes/LocalVariableNode.java
@@ -72,7 +72,9 @@ public abstract class LocalVariableNode extends ExpressionNode {
 
     @Specialization(guards = "isInitialized", rewriteOn = {FrameSlotTypeException.class})
     public final Object doObject(final VirtualFrame frame) throws FrameSlotTypeException {
-      return CompilerDirectives.unsafeCast(frame.getObject(slot),
+      Object o = frame.getObject(slot);
+      assert o != null;
+      return CompilerDirectives.unsafeCast(o,
           Object.class, true, true);
     }
 
diff --git a/src/som/interpreter/nodes/NonLocalVariableNode.java b/src/som/interpreter/nodes/NonLocalVariableNode.java
index a7cd432..76230fd 100644
--- a/src/som/interpreter/nodes/NonLocalVariableNode.java
+++ b/src/som/interpreter/nodes/NonLocalVariableNode.java
@@ -60,8 +60,10 @@ public abstract class NonLocalVariableNode extends ContextualNode {
 
     @Specialization(guards = "isInitialized", rewriteOn = {FrameSlotTypeException.class})
     public final Object doObject(final VirtualFrame frame) throws FrameSlotTypeException {
+      Object o = determineContext(frame).getObject(slot);
+      assert o != null;
       return CompilerDirectives.unsafeCast(
-          determineContext(frame).getObject(slot), Object.class, true, true);
+          o, Object.class, true, true);
     }
 
 //    @Generic
diff --git a/src/som/interpreter/nodes/dispatch/CachedBlockDispatchNode.java b/src/som/interpreter/nodes/dispatch/CachedBlockDispatchNode.java
index 381552a..a6ca011 100644
--- a/src/som/interpreter/nodes/dispatch/CachedBlockDispatchNode.java
+++ b/src/som/interpreter/nodes/dispatch/CachedBlockDispatchNode.java
@@ -20,6 +20,7 @@ public final class CachedBlockDispatchNode extends AbstractCachedDispatchNode {
 
   @Override
   public Object executeDispatch(final VirtualFrame frame, final Object[] arguments) {
+    assert arguments[0] instanceof SBlock;
     SBlock rcvr = CompilerDirectives.unsafeCast(arguments[0], SBlock.class, true, true);
     if (rcvr.getMethod() == cachedSomMethod) {
       return cachedMethod.call(frame, arguments);
diff --git a/src/som/interpreter/nodes/dispatch/CachedDispatchSObjectCheckNode.java b/src/som/interpreter/nodes/dispatch/CachedDispatchSObjectCheckNode.java
index 0eb9492..49b80f9 100644
--- a/src/som/interpreter/nodes/dispatch/CachedDispatchSObjectCheckNode.java
+++ b/src/som/interpreter/nodes/dispatch/CachedDispatchSObjectCheckNode.java
@@ -22,6 +22,7 @@ public final class CachedDispatchSObjectCheckNode extends AbstractCachedDispatch
   @Override
   public Object executeDispatch(
       final VirtualFrame frame, final Object[] arguments) {
+    assert arguments[0] instanceof SObject;
     SObject rcvr = CompilerDirectives.unsafeCast(arguments[0], SObject.class, true, true);
     if (rcvr.getSOMClass() == expectedClass) {
       return cachedMethod.call(frame, arguments);
diff --git a/src/som/interpreter/nodes/dispatch/CachedDispatchSimpleCheckNode.java b/src/som/interpreter/nodes/dispatch/CachedDispatchSimpleCheckNode.java
index f86e3f5..29f82a2 100644
--- a/src/som/interpreter/nodes/dispatch/CachedDispatchSimpleCheckNode.java
+++ b/src/som/interpreter/nodes/dispatch/CachedDispatchSimpleCheckNode.java
@@ -20,6 +20,7 @@ public final class CachedDispatchSimpleCheckNode extends AbstractCachedDispatchN
   @Override
   public Object executeDispatch(final VirtualFrame frame,
       final Object[] arguments) {
+    assert arguments[0] != null;
     Object rcvr = CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true);
     if (rcvr.getClass() == expectedClass) {
       return cachedMethod.call(frame, arguments);
diff --git a/src/som/interpreter/nodes/dispatch/CachedDnuSObjectCheckNode.java b/src/som/interpreter/nodes/dispatch/CachedDnuSObjectCheckNode.java
index b5a9836..27bbc4c 100644
--- a/src/som/interpreter/nodes/dispatch/CachedDnuSObjectCheckNode.java
+++ b/src/som/interpreter/nodes/dispatch/CachedDnuSObjectCheckNode.java
@@ -27,6 +27,7 @@ public final class CachedDnuSObjectCheckNode extends AbstractCachedDispatchNode
 
   @Override
   public Object executeDispatch(final VirtualFrame frame, final Object[] arguments) {
+    assert arguments[0] instanceof SObject;
     SObject rcvr = CompilerDirectives.unsafeCast(arguments[0], SObject.class, true, true);
 
     if (rcvr.getSOMClass() == expectedClass) {
diff --git a/src/som/interpreter/nodes/dispatch/GenericBlockDispatchNode.java b/src/som/interpreter/nodes/dispatch/GenericBlockDispatchNode.java
index 64b5e6c..4ba9693 100644
--- a/src/som/interpreter/nodes/dispatch/GenericBlockDispatchNode.java
+++ b/src/som/interpreter/nodes/dispatch/GenericBlockDispatchNode.java
@@ -14,6 +14,7 @@ public final class GenericBlockDispatchNode extends AbstractDispatchNode {
   @Override
   public Object executeDispatch(final VirtualFrame frame,
       final Object[] arguments) {
+    assert arguments[0] instanceof SBlock;
     SBlock rcvr = CompilerDirectives.unsafeCast(arguments[0], SBlock.class, true, true);
     return call.call(frame, rcvr.getMethod().getCallTarget(), arguments);
   }
diff --git a/src/som/interpreter/nodes/dispatch/GenericDispatchNode.java b/src/som/interpreter/nodes/dispatch/GenericDispatchNode.java
index b429795..331f946 100644
--- a/src/som/interpreter/nodes/dispatch/GenericDispatchNode.java
+++ b/src/som/interpreter/nodes/dispatch/GenericDispatchNode.java
@@ -24,6 +24,7 @@ public final class GenericDispatchNode extends AbstractDispatchWithLookupNode {
   @Override
   public Object executeDispatch(
       final VirtualFrame frame, final Object[] arguments) {
+    assert arguments[0] != null;
     Object rcvr = CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true);
     SInvokable method = lookupMethod(rcvr);
     if (method != null) {
diff --git a/src/som/interpreter/nodes/dispatch/SObjectCheckDispatchNode.java b/src/som/interpreter/nodes/dispatch/SObjectCheckDispatchNode.java
index 2d9106c..0ea1afc 100644
--- a/src/som/interpreter/nodes/dispatch/SObjectCheckDispatchNode.java
+++ b/src/som/interpreter/nodes/dispatch/SObjectCheckDispatchNode.java
@@ -24,6 +24,7 @@ public final class SObjectCheckDispatchNode extends AbstractDispatchNode {
   @Override
   public Object executeDispatch(
       final VirtualFrame frame, final Object[] arguments) {
+    assert arguments[0] != null;
     Object rcvr = CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true);
     if (rcvr instanceof SObject) {
       return nextInCache.executeDispatch(frame, arguments);
diff --git a/src/som/interpreter/nodes/nary/BinaryExpressionNode.java b/src/som/interpreter/nodes/nary/BinaryExpressionNode.java
index a5a3f96..3b5eee7 100644
--- a/src/som/interpreter/nodes/nary/BinaryExpressionNode.java
+++ b/src/som/interpreter/nodes/nary/BinaryExpressionNode.java
@@ -29,6 +29,8 @@ public abstract class BinaryExpressionNode extends ExpressionNode
   @Override
   public final Object doPreEvaluated(final VirtualFrame frame,
       final Object[] arguments) {
+    assert arguments[0] != null;
+    assert arguments[1] != null;
     return executeEvaluated(frame,
         CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true),
         CompilerDirectives.unsafeCast(arguments[1], Object.class, true, true));
diff --git a/src/som/interpreter/nodes/nary/TernaryExpressionNode.java b/src/som/interpreter/nodes/nary/TernaryExpressionNode.java
index 9d4fb29..0d91e42 100644
--- a/src/som/interpreter/nodes/nary/TernaryExpressionNode.java
+++ b/src/som/interpreter/nodes/nary/TernaryExpressionNode.java
@@ -29,6 +29,9 @@ public abstract class TernaryExpressionNode extends ExpressionNode
   @Override
   public final Object doPreEvaluated(final VirtualFrame frame,
       final Object[] arguments) {
+    assert arguments[0] != null;
+    assert arguments[1] != null;
+    assert arguments[2] != null;
     return executeEvaluated(frame,
         CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true),
         CompilerDirectives.unsafeCast(arguments[1], Object.class, true, true),
diff --git a/src/som/interpreter/nodes/nary/UnaryExpressionNode.java b/src/som/interpreter/nodes/nary/UnaryExpressionNode.java
index 7344d33..a7844a2 100644
--- a/src/som/interpreter/nodes/nary/UnaryExpressionNode.java
+++ b/src/som/interpreter/nodes/nary/UnaryExpressionNode.java
@@ -25,6 +25,7 @@ public abstract class UnaryExpressionNode extends ExpressionNode
   @Override
   public final Object doPreEvaluated(final VirtualFrame frame,
       final Object[] arguments) {
+    assert arguments[0] != null;
     return executeEvaluated(frame,
         CompilerDirectives.unsafeCast(arguments[0], Object.class, true, true));
   }
diff --git a/src/som/primitives/reflection/AbstractSymbolDispatch.java b/src/som/primitives/reflection/AbstractSymbolDispatch.java
index df92632..f0e79a8 100644
--- a/src/som/primitives/reflection/AbstractSymbolDispatch.java
+++ b/src/som/primitives/reflection/AbstractSymbolDispatch.java
@@ -94,6 +94,7 @@ public abstract class AbstractSymbolDispatch extends Node implements DispatchCha
       if (this.selector == selector) {
         Object[] arguments = SArguments.createSArgumentsArrayFrom(receiver, argsArr);
 
+        assert cachedSend instanceof PreevaluatedExpression;
         PreevaluatedExpression realCachedSend = CompilerDirectives.unsafeCast(cachedSend, PreevaluatedExpression.class, true);
         return realCachedSend.doPreEvaluated(frame, arguments);
       } else {
diff --git a/src/som/vmobjects/SArray.java b/src/som/vmobjects/SArray.java
index c3dee89..36ac1d7 100644
--- a/src/som/vmobjects/SArray.java
+++ b/src/som/vmobjects/SArray.java
@@ -21,6 +21,7 @@ public final class SArray {
   public static Object get(final Object[] arr, final long idx) {
     assert idx >= 0;
     assert idx < arr.length;
+    assert arr[(int) idx] != null;
     return CompilerDirectives.unsafeCast(arr[(int) idx], Object.class, true, true);
   }
 
diff --git a/src/som/vmobjects/SObject.java b/src/som/vmobjects/SObject.java
index c95bc80..dd1e883 100644
--- a/src/som/vmobjects/SObject.java
+++ b/src/som/vmobjects/SObject.java
@@ -106,10 +106,12 @@ public class SObject extends SAbstractObject {
   }
 
   public final long[] getExtendedPrimFields() {
+    assert extensionPrimFields instanceof long[];
     return CompilerDirectives.unsafeCast(extensionPrimFields, long[].class, true, true);
   }
 
   public final Object[] getExtensionObjFields() {
+    assert extensionObjFields instanceof Object[];
     return CompilerDirectives.unsafeCast(extensionObjFields, Object[].class, true, true);
   }
 
@@ -207,6 +209,7 @@ public class SObject extends SAbstractObject {
 
   @Override
   public final SClass getSOMClass() {
+    assert clazz instanceof SClass;
     return CompilerDirectives.unsafeCast(clazz, SClass.class, true, true);
   }
 



> 
> -Gilles
> 
> On Wed, Dec 10, 2014 at 12:15 AM, Stefan Marr <java at stefan-marr.de> wrote:
>> Hi Gilles:
>> 
>> Here the log file.
>> 
>> Best regards
>> Stefan
>> 
>> 
>> 
>> 
>> 
>>> On 10 Dec 2014, at 00:04, Gilles Duboscq <duboscq at ssw.jku.at> wrote:
>>> 
>>> Hello Stefan,
>>> 
>>> Thanks for the report.
>>> Could you send us the hs_err file as well (hs_err_pid68949.log)?
>>> 
>>> -Gilles
>>> 
>>> On Tue, Dec 9, 2014 at 11:35 PM, Stefan Marr <java at stefan-marr.de> wrote:
>>>> Hi:
>>>> 
>>>> In one of my experiments, I got a hard crash of the Graal VM.
>>>> Error below.
>>>> 
>>>> The error is somewhat dependent on either environment or for instance whether -ea and/or -esa are passed to the VM.
>>>> Though, I haven’t managed to find a way to avoid crashes reliably.
>>>> 
>>>> To reproduced, you’ll need with a little API change (see patch below) or my version of GraalVM.
>>>> 
>>>> git clone https://github.com/smarr/GraalVM.git
>>>> cd GraalVM
>>>> ./mx.sh --vm server build -p
>>>> cd ../
>>>> git clone -b mt-vs-pe/without-control-specialization https://github.com/smarr/TruffleSOM.git
>>>> cd TruffleSOM
>>>> ant
>>>> ../GraalVM/mxtool/mx --vm server vm -Xbootclasspath/a:build/classes som.vm.Universe -cp Smalltalk:Examples/Benchmarks/DeltaBlue Examples/Benchmarks/BenchmarkHarness.som  DeltaBlue  1500 0 6000
>>>> 
>>>> Best regards
>>>> Stefan
>>>> 
>>>> 
>>>> #
>>>> # A fatal error has been detected by the Java Runtime Environment:
>>>> #
>>>> #  SIGSEGV (0xb) at pc=0x000000010d601e5b, pid=68949, tid=4867
>>>> #
>>>> # JRE version: Java(TM) SE Runtime Environment (8.0_20-b26) (build 1.8.0_20-b26)
>>>> # Java VM: OpenJDK 64-Bit Server VM (25.25-b02-internal-graal-unknown-venus-2-2014-12-09_22-44-20_CET mixed mode bsd-amd64 compressed oops)
>>>> # Problematic frame:
>>>> # J 7192 Graal com.oracle.graal.truffle.OptimizedCallTarget.callRoot([Ljava/lang/Object;)Ljava/lang/Object; (191 bytes) @ 0x000000010d601e5b [0x000000010d601e20+0x3b]
>>>> #
>>>> # Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
>>>> #
>>>> # An error report file with more information is saved as:
>>>> # /Users/smarr/Projects/PostDoc/Truffle/som/hs_err_pid68949.log
>>>> Loaded disassembler from /Users/smarr/Projects/PostDoc/Truffle/graal/jdk1.8.0_20/product/jre/lib/hsdis-amd64.dylib
>>>> Compiled method (Graal)   12445 7192       4       com.oracle.graal.truffle.OptimizedCallTarget::callRoot (191 bytes)
>>>> total in heap  [0x000000010d601cd0,0x000000010d601f50] = 640
>>>> relocation     [0x000000010d601e08,0x000000010d601e20] = 24
>>>> main code      [0x000000010d601e20,0x000000010d601edd] = 189
>>>> stub code      [0x000000010d601edd,0x000000010d601ee0] = 3
>>>> oops           [0x000000010d601ee0,0x000000010d601ef8] = 24
>>>> metadata       [0x000000010d601ef8,0x000000010d601f00] = 8
>>>> scopes data    [0x000000010d601f00,0x000000010d601f18] = 24
>>>> scopes pcs     [0x000000010d601f18,0x000000010d601f48] = 48
>>>> dependencies   [0x000000010d601f48,0x000000010d601f50] = 8
>>>> Compiled method (c2)   12445 2114       4       com.oracle.graal.truffle.OptimizedCallTarget::doInvoke (6 bytes)
>>>> total in heap  [0x000000010c77b910,0x000000010c77bb58] = 584
>>>> relocation     [0x000000010c77ba48,0x000000010c77ba60] = 24
>>>> main code      [0x000000010c77ba60,0x000000010c77bac0] = 96
>>>> stub code      [0x000000010c77bac0,0x000000010c77bae8] = 40
>>>> oops           [0x000000010c77bae8,0x000000010c77baf0] = 8
>>>> metadata       [0x000000010c77baf0,0x000000010c77baf8] = 8
>>>> scopes data    [0x000000010c77baf8,0x000000010c77bb08] = 16
>>>> scopes pcs     [0x000000010c77bb08,0x000000010c77bb38] = 48
>>>> dependencies   [0x000000010c77bb38,0x000000010c77bb40] = 8
>>>> handler table  [0x000000010c77bb40,0x000000010c77bb58] = 24
>>>> 
>>>> 
>>>> diff --git a/graal/com.oracle.graal.truffle/src/com/oracle/graal/truffle/OptimizedCallTarget.java b/graal/com.oracle.graal.truffle/src/com/oracle/graal/truffle/OptimizedCallTarget.java
>>>> index 8d00194..0670fad 100644
>>>> --- a/graal/com.oracle.graal.truffle/src/com/oracle/graal/truffle/OptimizedCallTarget.java
>>>> +++ b/graal/com.oracle.graal.truffle/src/com/oracle/graal/truffle/OptimizedCallTarget.java
>>>> @@ -104,7 +104,7 @@ public class OptimizedCallTarget extends InstalledCode implements RootCallTarget
>>>>        if (root == null || !root.isCloningAllowed()) {
>>>>            return null;
>>>>        }
>>>> -        return NodeUtil.cloneNode(root);
>>>> +        return root.cloneRootNode();
>>>>    }
>>>> 
>>>>    public Assumption getNodeRewritingAssumption() {
>>>> diff --git a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/RootNode.java b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/RootNode.java
>>>> index aebf748..2552eea 100644
>>>> --- a/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/RootNode.java
>>>> +++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/nodes/RootNode.java
>>>> @@ -79,6 +79,10 @@ public abstract class RootNode extends Node {
>>>>        return false;
>>>>    }
>>>> 
>>>> +    public RootNode cloneRootNode() {
>>>> +        return NodeUtil.cloneNode(this);
>>>> +    }
>>>> +
>>>>    /**
>>>>     * Reports the execution count of a loop that is a child of this node. The optimization
>>>>     * heuristics can use the loop count to guide compilation and inlining.
>>>> 
>>>> 
>>>> 
>>>> --
>>>> Stefan Marr
>>>> INRIA Lille - Nord Europe
>>>> http://stefan-marr.de/research/
>>>> 
>>>> 
>>>> 
>> 
>> --
>> Stefan Marr
>> INRIA Lille - Nord Europe
>> http://stefan-marr.de/research/
>> 
>> 
>> 
>> 

-- 
Stefan Marr
INRIA Lille - Nord Europe
http://stefan-marr.de/research/





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