Manually emit stack frames in EnumValueOfRewriteRule (#33)

This is emitting uncompressed/expanded frames which will need to be computed/compressed on write, but should still be better than recomputing frames for everything.

Author: jpenilla

src/main/java/io/papermc/asm/rules/rename/EnumValueOfRewriteRule.java

@@ -66,6 +66,8 @@ public void generateMethod(final GeneratorAdapterFactory factory, final MethodCa
         methodGenerator.visitLookupSwitchInsn(lookupSwitchEndLabel, lookupSwitchKeys, labels);
         for (int i = 0; i < labels.length; i++) {
             methodGenerator.mark(labels[i]);
+            // LocalVariableSorter will insert the trailing int local for this and all following visitFrame calls; adding it manually would cause duplicate locals in the frame
+            methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 1, new Object[]{"java/lang/String"});
             // generate case
             final List<String> matchingStrings = hashToField.get(lookupSwitchKeys[i]);
             if (matchingStrings.size() == 1) {
@@ -93,11 +95,13 @@ public void generateMethod(final GeneratorAdapterFactory factory, final MethodCa
                     methodGenerator.goTo(lookupSwitchEndLabel);
                     if (nestedLabels[j] != lookupSwitchEndLabel) {
                         methodGenerator.mark(nestedLabels[j]); // mark start of next label (except last one)
+                        methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 1, new Object[]{"java/lang/String"});
                     }
                 }
             }
         }
         methodGenerator.mark(lookupSwitchEndLabel);
+        methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 1, new Object[]{"java/lang/String"});
         methodGenerator.loadLocal(tableSwitchIndexLocal);
         final Label[] tableSwitchLabels = new Label[tableSwitchIndexToRenamedField.length];
         for (int i = 0; i < tableSwitchLabels.length; i++) {
@@ -108,12 +112,15 @@ public void generateMethod(final GeneratorAdapterFactory factory, final MethodCa
         methodGenerator.visitTableSwitchInsn(0, tableSwitchIndexToRenamedField.length - 1, tableSwitchDefaultLabel, tableSwitchLabels);
         for (int i = 0; i < tableSwitchIndexToRenamedField.length; i++) {
             methodGenerator.mark(tableSwitchLabels[i]);
+            methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 1, new Object[]{"java/lang/String"});
             methodGenerator.push(tableSwitchIndexToRenamedField[i]);
             methodGenerator.goTo(tableSwitchEndLabel);
         }
         methodGenerator.mark(tableSwitchDefaultLabel);
+        methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 1, new Object[]{"java/lang/String"});
         methodGenerator.loadArg(0); // default to the passed in value
         methodGenerator.mark(tableSwitchEndLabel);
+        methodGenerator.visitFrame(Opcodes.F_NEW, 1, new Object[]{"java/lang/String"}, 2, new Object[]{"java/lang/String", "java/lang/String"});
         methodGenerator.invokeStatic(Type.getType(original.owner().descriptorString()), new Method(original.name(), original.descriptor().descriptorString()));
         methodGenerator.returnValue();
         methodGenerator.endMethod();

src/test/java/io/papermc/asm/TestUtil.java

@@ -54,9 +54,9 @@ public byte[] process(final byte[] bytes) {
             final ClassReader classReader = new ClassReader(bytes);
             final ClassWriter classWriter;
             if (this.copyFromClassReader()) {
-                classWriter = new ClassWriter(classReader, ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+                classWriter = new ClassWriter(classReader, ClassWriter.COMPUTE_MAXS);
             } else {
-                classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+                classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);
             }
             classReader.accept(this.factory.createVisitor(classWriter), 0);
             return classWriter.toByteArray();