[dumpling] Support empty string parsing in oracle.

Bug: 441467877
Change-Id: I8346b2e0eba7877d86e2db1ceb35a236c4bf0545
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/9012879
Reviewed-by: Michael Achenbach <machenbach@google.com>
Commit-Queue: Danylo Mocherniuk <mdanylo@google.com>

Author: Danylo Mocherniuk

Sources/Fuzzilli/DumplingDiffOracle/Oracle.swift

@@ -201,7 +201,7 @@ public final class DiffOracle {
             }
 
             while i < frameArr.endIndex && frameArr[i].starts(with: prefix) {
-                let data = frameArr[i].dropFirst(1).split(separator: ":", maxSplits: 1)
+                let data = frameArr[i].dropFirst(1).split(separator: ":", maxSplits: 1, omittingEmptySubsequences: false)
                 let number = Int(data[0])!
                 let value = String(data[1])
 

Tests/FuzzilliTests/DiffOracleTests.swift

@@ -424,4 +424,30 @@ final class DiffOracleTests: XCTestCase {
 
         XCTAssertTrue(DiffOracle.relate(expected, with: trace))
     }
+
+    func testEmptyStringValueParsing() {
+        let unopt = """
+        ---I
+        b:10
+        f:1
+        n:0
+        m:6
+        r0:ValA
+        r5:
+
+        """
+
+        let opt = """
+        ---I
+        b:10
+        f:1
+        n:0
+        m:6
+        r0:ValA
+        r5:
+
+        """
+
+        XCTAssertTrue(DiffOracle.relate(opt, with: unopt), "Should handle empty register values (e.g. 'r5:') without crashing")
+    }
 }