From 66283c6f7adef3acd098c3745458a202d573f2ea Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Mon, 29 Jul 2019 21:56:37 +0100
Subject: [PATCH] Add ExceptionTracingTransformer

---
 .../java/dev/openrs2/deob/Deobfuscator.java   |  4 +-
 .../ExceptionTracingTransformer.java          | 45 +++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 deob/src/main/java/dev/openrs2/deob/transform/ExceptionTracingTransformer.java

diff --git a/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java b/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
index c29bfc075f..0003f2755d 100644
--- a/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
+++ b/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
@@ -14,6 +14,7 @@ import dev.openrs2.asm.Transformer;
 import dev.openrs2.deob.path.ClassPath;
 import dev.openrs2.deob.path.TypedRemapper;
 import dev.openrs2.deob.transform.ClassForNameTransformer;
+import dev.openrs2.deob.transform.ExceptionTracingTransformer;
 import dev.openrs2.deob.transform.OpaquePredicateTransformer;
 import dev.openrs2.deob.transform.OriginalNameTransformer;
 import org.slf4j.Logger;
@@ -23,7 +24,8 @@ public final class Deobfuscator {
 	private static final Logger logger = LoggerFactory.getLogger(Deobfuscator.class);
 
 	private static final List<Transformer> TRANSFORMERS = List.of(
-		new OpaquePredicateTransformer()
+		new OpaquePredicateTransformer(),
+		new ExceptionTracingTransformer()
 	);
 
 	public static void main(String[] args) throws IOException {
diff --git a/deob/src/main/java/dev/openrs2/deob/transform/ExceptionTracingTransformer.java b/deob/src/main/java/dev/openrs2/deob/transform/ExceptionTracingTransformer.java
new file mode 100644
index 0000000000..5b285258de
--- /dev/null
+++ b/deob/src/main/java/dev/openrs2/deob/transform/ExceptionTracingTransformer.java
@@ -0,0 +1,45 @@
+package dev.openrs2.deob.transform;
+
+import dev.openrs2.asm.InsnMatcher;
+import dev.openrs2.asm.InsnNodeUtils;
+import dev.openrs2.asm.Library;
+import dev.openrs2.asm.Transformer;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public final class ExceptionTracingTransformer extends Transformer {
+	private static final Logger logger = LoggerFactory.getLogger(ExceptionTracingTransformer.class);
+
+	private static final InsnMatcher CATCH_MATCHER = InsnMatcher.compile("ASTORE ALOAD (| LDC INVOKESTATIC | NEW DUP (LDC INVOKESPECIAL | INVOKESPECIAL LDC INVOKEVIRTUAL) ((ILOAD | LLOAD | FLOAD | DLOAD | (ALOAD IFNULL LDC GOTO LDC) | BIPUSH) INVOKEVIRTUAL)* INVOKEVIRTUAL INVOKESTATIC) ATHROW");
+
+	private int tracingTryCatches;
+
+	@Override
+	public void preTransform(Library library) {
+		tracingTryCatches = 0;
+	}
+
+	@Override
+	public void transformCode(ClassNode clazz, MethodNode method) {
+		CATCH_MATCHER.match(method).forEach(match -> {
+			var foundTryCatch = method.tryCatchBlocks.removeIf(tryCatch -> {
+				if (!"java/lang/RuntimeException".equals(tryCatch.type)) {
+					return false;
+				}
+				return InsnNodeUtils.nextReal(tryCatch.handler) == match.get(0);
+			});
+
+			if (foundTryCatch) {
+				match.forEach(method.instructions::remove);
+				tracingTryCatches++;
+			}
+		});
+	}
+
+	@Override
+	public void postTransform(Library library) {
+		logger.info("Removed {} tracing try/catch blocks", tracingTryCatches);
+	}
+}