Thanks Evgeny for this minimal Example! AALOAD is a perfect hint.
I added it to our FramesTest and indeed it fails. I'll investigate.
Cheers,
-marc
On 2017-09-19 14:56, Evgeny Mandrikov wrote:
> Sorry, forgot to attach file, here it is.
>
> On Tuesday, September 19, 2017 at 2:53:28 PM UTC+2, Evgeny Mandrikov wrote:
>
>> Hi Marc,
>>
>> FYI:
>>
>> I tried to instrument class from this thread by JaCoCo 0.6.4, where we had
>> FrameTracker and got ClassCastException in it at line
>> https://github.com/jacoco/jacoco/blob/v0.6.4/org.jacoco.core/src/org/jacoco/core/internal/instr/FrameTracker.java#L253
>> [1] ("java.lang.Integer cannot be cast to java.lang.String"), i.e. during
>> processing of AALOAD instruction.
>>
>> We replaced our FrameTracker by ASM's AnalyzerAdapter that has another
>> implementation for AALOAD -
>> https://gitlab.ow2.org/asm/asm/blob/ASM_5_2/src/org/objectweb/asm/commons/AnalyzerAdapter.java#L665
>> [2]
>>
>> None of our existing tests touches else-branch of this implementation, while
>> it is touched by class from this thread. So I tried to build smaller example
>> that will also touch this line - you'll find it in attachment:
>>
>> * as said above - target class is not a reduction of class from this thread
>> * and actually code of target class has no sense
>> * however target class doesn't pass our FramesTest
>> * and test demonstrates pretty similar VerifyError ("Type 'java/lang/Object'
>> is not assignable to null") when executed with JDK 8u131
>> * to trigger VerifyError, target class must first be read and written back
>> by ASM ClassWriter.COMPUTE_FRAMES - this reflects statement that class from
>> this thread is a result of instrumentation by another tool, and this is what
>> happens in FramesTest
>>
>> Hope this simplifies hunting of root cause and together we'll finally find
>> it (hopefully not in our code :D)
>
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Links:
------
[1]
https://github.com/jacoco/jacoco/blob/v0.6.4/org.jacoco.core/src/org/jacoco/core/internal/instr/FrameTracker.java#L253
[2]
https://gitlab.ow2.org/asm/asm/blob/ASM_5_2/src/org/objectweb/asm/commons/AnalyzerAdapter.java#L665
[3]
https://groups.google.com/d/msgid/jacoco/34c8ae23-d518-43c7-8c87-951fe6b550a9%40googlegroups.com?utm_medium=email&utm_source=footer
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package org.jacoco.core.test;
import org.jacoco.core.instr.Instrumenter;
import org.jacoco.core.runtime.IRuntime;
import org.jacoco.core.runtime.SystemPropertiesRuntime;
import org.junit.Test;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
public class IssueTest {
public static class Target {
private static boolean b() {
return false;
}
public static void fun() {
Object[] a = null;
for (Object o : a) {
if (b()) {
b();
}
}
}
}
@Test
public void test() throws Exception {
final ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
new ClassReader(Target.class.getName()).accept(cw, 0);
final byte[] bytes = cw.toByteArray();
new TargetLoader().add(Target.class.getName(), bytes)
.getDeclaredMethods();
final IRuntime runtime = new SystemPropertiesRuntime();
final Instrumenter instrumenter = new Instrumenter(runtime);
final byte[] instrumented = instrumenter.instrument(bytes,
Target.class.getName());
new TargetLoader().add(Target.class.getName(), instrumented)
.getDeclaredMethods();
}
}
