Fixes #813: Only add frames if class file version supports attribute

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/ExceptionHandlers.java

@@ -1,6 +1,7 @@
 package datadog.trace.agent.tooling;
 
 import datadog.trace.bootstrap.ExceptionLogger;
+import net.bytebuddy.ClassFileVersion;
 import net.bytebuddy.asm.Advice.ExceptionHandler;
 import net.bytebuddy.implementation.Implementation;
 import net.bytebuddy.implementation.bytecode.StackManipulation;
@@ -41,6 +42,9 @@ public class ExceptionHandlers {
               final Label eatException = new Label();
               final Label handlerExit = new Label();
               
+              // Frames are only meaningful for class files in version 6 or later.
+              final boolean frames = context.getClassFileVersion().isAtLeast(ClassFileVersion.JAVA_V6);
+
               mv.visitTryCatchBlock(logStart, logEnd, eatException, "java/lang/Throwable");
 
               // stack: (top) throwable
@@ -67,13 +71,17 @@ public class ExceptionHandlers {
               // if the runtime can't reach our ExceptionHandler or logger,
               //   silently eat the exception
               mv.visitLabel(eatException);
-              mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[] {"java/lang/Throwable"});
+              if (frames) {
+                mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[] {"java/lang/Throwable"});
+              }
               mv.visitInsn(Opcodes.POP);
               // mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Throwable",
               //    "printStackTrace", "()V", false);
 
               mv.visitLabel(handlerExit);
-              mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+              if (frames) {
+                mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+              }
 
               return size;
             }

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/context/FieldBackedProvider.java

@@ -25,6 +25,7 @@ import java.util.Map;
 import java.util.Set;
 import lombok.extern.slf4j.Slf4j;
 import net.bytebuddy.ByteBuddy;
+import net.bytebuddy.ClassFileVersion;
 import net.bytebuddy.agent.builder.AgentBuilder;
 import net.bytebuddy.asm.AsmVisitorWrapper;
 import net.bytebuddy.description.field.FieldDescription;
@@ -620,6 +621,7 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
               getFieldAccessorInterface(keyClassName, contextClassName);
           private final String accessorInterfaceInternalName = accessorInterface.getInternalName();
           private final String instrumentedTypeInternalName = instrumentedType.getInternalName();
+          private final boolean frames = implementationContext.getClassFileVersion().isAtLeast(ClassFileVersion.JAVA_V6);
 
           @Override
           public MethodVisitor visitMethod(
@@ -679,7 +681,9 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
                 true);
             mv.visitInsn(Opcodes.ARETURN);
             mv.visitLabel(elseLabel);
-            mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            if (frames) {
+              mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            }
             mv.visitVarInsn(Opcodes.ALOAD, 0);
             mv.visitVarInsn(Opcodes.ALOAD, 1);
             mv.visitMethodInsn(
@@ -732,7 +736,9 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
                 true);
             mv.visitJumpInsn(Opcodes.GOTO, endLabel);
             mv.visitLabel(elseLabel);
-            mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            if (frames) {
+              mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            }
             mv.visitVarInsn(Opcodes.ALOAD, 0);
             mv.visitVarInsn(Opcodes.ALOAD, 1);
             mv.visitVarInsn(Opcodes.ALOAD, 2);
@@ -743,7 +749,9 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
                 Utils.getMethodDefinition(instrumentedType, "mapPut").getDescriptor(),
                 false);
             mv.visitLabel(endLabel);
-            mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            if (frames) {
+              mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            }
             mv.visitInsn(Opcodes.RETURN);
             mv.visitMaxs(0, 0);
             mv.visitEnd();
@@ -778,7 +786,9 @@ public class FieldBackedProvider implements InstrumentationContextProvider {
             mv.visitVarInsn(Opcodes.ALOAD, 1);
             mv.visitInsn(Opcodes.ARETURN);
             mv.visitLabel(elseLabel);
-            mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            if (frames) {
+              mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+            }
             mv.visitVarInsn(Opcodes.ALOAD, 0);
             mv.visitVarInsn(Opcodes.ALOAD, 1);
             mv.visitMethodInsn(

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/MuzzleVisitor.java

@@ -6,6 +6,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
+import net.bytebuddy.ClassFileVersion;
 import net.bytebuddy.asm.AsmVisitorWrapper;
 import net.bytebuddy.description.field.FieldDescription;
 import net.bytebuddy.description.field.FieldList;
@@ -46,15 +47,19 @@ public class MuzzleVisitor implements AsmVisitorWrapper {
       MethodList<?> methods,
       int writerFlags,
       int readerFlags) {
-    return new InsertSafetyMatcher(classVisitor);
+    return new InsertSafetyMatcher(classVisitor, implementationContext.getClassFileVersion().isAtLeast(ClassFileVersion.JAVA_V6));
   }
 
   public static class InsertSafetyMatcher extends ClassVisitor {
+    
+    private final boolean frames;
+    
     private String instrumentationClassName;
     private Instrumenter.Default instrumenter;
 
-    public InsertSafetyMatcher(ClassVisitor classVisitor) {
+    public InsertSafetyMatcher(ClassVisitor classVisitor, boolean frames) {
       super(Opcodes.ASM7, classVisitor);
+      this.frames = frames;
     }
 
     @Override
@@ -430,7 +435,9 @@ public class MuzzleVisitor implements AsmVisitorWrapper {
               "Ldatadog/trace/agent/tooling/muzzle/ReferenceMatcher;");
 
           mv.visitLabel(ret);
-          mv.visitFrame(Opcodes.F_SAME, 1, null, 0, null);
+          if (frames) {
+            mv.visitFrame(Opcodes.F_SAME, 1, null, 0, null);
+          }
           mv.visitVarInsn(Opcodes.ALOAD, 0);
           mv.visitFieldInsn(
               Opcodes.GETFIELD,