Remove frame padding visitor and replace with explicit noop instructi…

…ons to introduce padding.
raphw · Oct 29, 2021 · cf0aba1 · cf0aba1
1 parent 91fa996
commit cf0aba1
Show file tree

Hide file tree

Showing 6 changed files with 40 additions and 370 deletions.
diff --git a/byte-buddy-dep/src/main/java/net/bytebuddy/asm/Advice.java b/byte-buddy-dep/src/main/java/net/bytebuddy/asm/Advice.java
@@ -54,7 +54,6 @@
 import net.bytebuddy.utility.JavaType;
 import net.bytebuddy.utility.OpenedClassReader;
 import net.bytebuddy.utility.visitor.ExceptionTableSensitiveMethodVisitor;
-import net.bytebuddy.utility.visitor.FramePaddingMethodVisitor;
 import net.bytebuddy.utility.visitor.LineNumberPrependingMethodVisitor;
 import net.bytebuddy.utility.visitor.StackAwareMethodVisitor;
 import org.objectweb.asm.*;
@@ -535,9 +534,9 @@ protected MethodVisitor doWrap(TypeDescription instrumentedType,
                                    Implementation.Context implementationContext,
                                    int writerFlags,
                                    int readerFlags) {
-        methodVisitor = new FramePaddingMethodVisitor(methodEnter.isPrependLineNumber()
-                ? new LineNumberPrependingMethodVisitor(methodVisitor)
-                : methodVisitor);
+        if (methodEnter.isPrependLineNumber()) {
+            methodVisitor = new LineNumberPrependingMethodVisitor(methodVisitor);
+        }
         if (!methodExit.isAlive()) {
             return new AdviceVisitor.WithoutExitAdvice(methodVisitor,
                     implementationContext,
@@ -4875,11 +4874,13 @@ protected abstract ForInstrumentedMethod resolve(MethodDescription instrumentedM
      * the local variable array must still be intact and the stack must be empty. A frame is added
      * subsequently to the post processor's execution, making it feasible to add a jump instruction to the
      * end of the method after which no further byte code instructions must be issued. This also applies
-     * to compound post processors.
+     * to compound post processors. If a post processor emits a frame as its last instruction, it should
+     * yield a <i>NOP</i> instruction to avoid that subsequent code starts with a frame.
      * </p>
      * <p>
      * <b>Important</b>: A post processor is triggered after the suppression handler. Exceptions triggered
-     * by post processing code will therefore cause those exceptions to be propagated.
+     * by post processing code will therefore cause those exceptions to be propagated unless the post
+     * processor configures explicit exception handling.
      * </p>
      */
     public interface PostProcessor {
@@ -10541,6 +10542,7 @@ protected void onAfterExceptionTable() {
             mv.visitLabel(preparationStart);
             methodSizeHandler.requireStackSize(argumentHandler.prepare(mv));
             stackMapFrameHandler.injectStartFrame(mv);
+            mv.visitInsn(Opcodes.NOP);
             onUserStart();
         }
 
@@ -13161,6 +13163,7 @@ public Size apply(MethodVisitor methodVisitor, Context implementationContext) {
                 Size size = dispatcher.apply(methodVisitor, offset, label).aggregate(stackManipulation.apply(methodVisitor, implementationContext));
                 methodVisitor.visitLabel(label);
                 stackMapFrameHandler.injectIntermediateFrame(methodVisitor, Collections.<TypeDescription>emptyList());
+                methodVisitor.visitInsn(Opcodes.NOP);
                 return size;
             }
 

diff --git a/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/TypeWriter.java b/byte-buddy-dep/src/main/java/net/bytebuddy/dynamic/scaffold/TypeWriter.java
@@ -52,7 +52,6 @@
 import net.bytebuddy.utility.CompoundList;
 import net.bytebuddy.utility.OpenedClassReader;
 import net.bytebuddy.utility.privilege.GetSystemPropertyAction;
-import net.bytebuddy.utility.visitor.FramePaddingMethodVisitor;
 import net.bytebuddy.utility.visitor.MetadataAwareClassVisitor;
 import org.objectweb.asm.*;
 import org.objectweb.asm.commons.ClassRemapper;
@@ -4406,6 +4405,7 @@ public void onFrame(int type, int localVariableLength) {
                                  */
                                 public void emitFrame(MethodVisitor methodVisitor) {
                                     methodVisitor.visitFrame(Opcodes.F_NEW, EMPTY.length, EMPTY, EMPTY.length, EMPTY);
+                                    methodVisitor.visitInsn(Opcodes.NOP);
                                 }
                             }
 
@@ -4453,6 +4453,7 @@ public void emitFrame(MethodVisitor methodVisitor) {
                                     } else {
                                         methodVisitor.visitFrame(Opcodes.F_CHOP, currentLocalVariableLength, EMPTY, EMPTY.length, EMPTY);
                                     }
+                                    methodVisitor.visitInsn(Opcodes.NOP);
                                     currentLocalVariableLength = 0;
                                 }
                             }
@@ -4604,7 +4605,7 @@ protected WithDrain(MethodVisitor methodVisitor,
                                                 AnnotationValueFilter.Factory annotationValueFilterFactory,
                                                 boolean requireFrames,
                                                 boolean expandFrames) {
-                                super(new FramePaddingMethodVisitor(methodVisitor), instrumentedType, record, annotationValueFilterFactory, requireFrames, expandFrames);
+                                super(methodVisitor, instrumentedType, record, annotationValueFilterFactory, requireFrames, expandFrames);
                                 appended = new Label();
                                 original = new Label();
                             }
@@ -5358,7 +5359,6 @@ public void visitCode() {
                                 if (!resolution.getAppendedParameters().isEmpty()
                                         && (writerFlags & ClassWriter.COMPUTE_FRAMES) == 0
                                         && implementationContext.getClassFileVersion().isAtLeast(ClassFileVersion.JAVA_V6)) {
-                                    mv = new FramePaddingMethodVisitor(mv);
                                     if ((readerFlags & ClassReader.EXPAND_FRAMES) == 0 && resolution.getAppendedParameters().size() < 4) {
                                         super.visitFrame(Opcodes.F_CHOP, resolution.getAppendedParameters().size(), EMPTY, EMPTY.length, EMPTY);
                                     } else {
@@ -5391,6 +5391,7 @@ public void visitCode() {
                                                 ? Opcodes.F_FULL
                                                 : Opcodes.F_NEW, frame.length, frame, EMPTY.length, EMPTY);
                                     }
+                                    super.visitInsn(Opcodes.NOP);
                                 }
                             } else {
                                 mv = IGNORE_METHOD;

diff --git a/byte-buddy-dep/src/main/java/net/bytebuddy/utility/visitor/FramePaddingMethodVisitor.java b/byte-buddy-dep/src/main/java/net/bytebuddy/utility/visitor/FramePaddingMethodVisitor.java