Class transformer optimizations (#5159)

* Filter packages for deobf transformation
* Only serialize transformed class with TerminalTransformer if bytecode changed

src/main/java/net/minecraftforge/fml/common/asm/transformers/DeobfuscationTransformer.java

@@ -19,8 +19,12 @@
 
 package net.minecraftforge.fml.common.asm.transformers;
 
+import java.util.Arrays;
+
 import net.minecraft.launchwrapper.IClassNameTransformer;
 import net.minecraft.launchwrapper.IClassTransformer;
+import net.minecraft.launchwrapper.Launch;
+
 import net.minecraftforge.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper;
 import net.minecraftforge.fml.common.asm.transformers.deobf.FMLRemappingAdapter;
 
@@ -29,6 +33,22 @@ import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.commons.RemappingClassAdapter;
 
 public class DeobfuscationTransformer implements IClassTransformer, IClassNameTransformer {
+    private static final String[] EXEMPT_LIBS = new String[] {
+            "com.google.",
+            "com.mojang.",
+            "joptsimple.",
+            "io.netty.",
+            "it.unimi.dsi.fastutil.",
+            "oshi.",
+            "com.sun.",
+            "com.ibm.",
+            "paulscode.",
+            "com.jcraft"
+    };
+    private static final String[] EXEMPT_DEV = new String[] {
+            "net.minecraft.",
+            "net.minecraftforge."
+    };
 
     private static final boolean RECALC_FRAMES = Boolean.parseBoolean(System.getProperty("FORGE_FORCE_FRAME_RECALC", "false"));
     private static final int WRITER_FLAGS = ClassWriter.COMPUTE_MAXS | (RECALC_FRAMES ? ClassWriter.COMPUTE_FRAMES : 0);
@@ -38,6 +58,8 @@ public class DeobfuscationTransformer implements IClassTransformer, IClassNameTr
     // If reported we need to add a custom implementation of ClassWriter.getCommonSuperClass
     // that does not cause class loading.
 
+    private boolean deobfuscatedEnvironment = (Boolean) Launch.blackboard.get("fml.deobfuscatedEnvironment");
+
     @Override
     public byte[] transform(String name, String transformedName, byte[] bytes)
     {
@@ -45,6 +67,9 @@ public class DeobfuscationTransformer implements IClassTransformer, IClassNameTr
         {
             return null;
         }
+
+        if (!shouldTransform(name)) return bytes;
+
         ClassReader classReader = new ClassReader(bytes);
         ClassWriter classWriter = new ClassWriter(WRITER_FLAGS);
         RemappingClassAdapter remapAdapter = new FMLRemappingAdapter(classWriter);
@@ -52,6 +77,20 @@ public class DeobfuscationTransformer implements IClassTransformer, IClassNameTr
         return classWriter.toByteArray();
     }
 
+    private boolean shouldTransform(String name)
+    {
+        boolean transformLib = Arrays.stream(EXEMPT_LIBS).noneMatch(name::startsWith);
+
+        if (deobfuscatedEnvironment)
+        {
+            return transformLib && Arrays.stream(EXEMPT_DEV).noneMatch(name::startsWith);
+        }
+        else
+        {
+            return transformLib;
+        }
+    }
+
     @Override
     public String remapClassName(String name)
     {

src/main/java/net/minecraftforge/fml/common/asm/transformers/TerminalTransformer.java

@@ -34,16 +34,18 @@ public class TerminalTransformer implements IClassTransformer
         ClassReader reader = new ClassReader(basicClass);
         ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
 
-        ClassVisitor visitor = writer;
-        visitor = new ExitVisitor(visitor);
+        ExitVisitor visitor = new ExitVisitor(writer);
 
         reader.accept(visitor, 0);
+
+        if (!visitor.dirty) return basicClass;
         return writer.toByteArray();
     }
 
     public static class ExitVisitor extends ClassVisitor
     {
         private String clsName = null;
+        private boolean dirty;
         private static final String callbackOwner = org.objectweb.asm.Type.getInternalName(ExitVisitor.class);
 
         private ExitVisitor(ClassVisitor cv)
@@ -89,6 +91,7 @@ public class TerminalTransformer implements IClassTransformer
                         }
                         owner = ExitVisitor.callbackOwner;
                         name = "systemExitCalled";
+                        dirty = true;
                     }
                     else if (opcode == Opcodes.INVOKEVIRTUAL && owner.equals("java/lang/Runtime") && name.equals("exit") && desc.equals("(I)V"))
                     {
@@ -104,6 +107,7 @@ public class TerminalTransformer implements IClassTransformer
                         owner = ExitVisitor.callbackOwner;
                         name = "runtimeExitCalled";
                         desc = "(Ljava/lang/Runtime;I)V";
+                        dirty = true;
                     }
                     else if (opcode == Opcodes.INVOKEVIRTUAL && owner.equals("java/lang/Runtime") && name.equals("halt") && desc.equals("(I)V"))
                     {
@@ -119,6 +123,7 @@ public class TerminalTransformer implements IClassTransformer
                         owner = ExitVisitor.callbackOwner;
                         name = "runtimeHaltCalled";
                         desc = "(Ljava/lang/Runtime;I)V";
+                        dirty = true;
                     }
 
                     super.visitMethodInsn(opcode, owner, name, desc, isIntf);