LibRegex: Bail out of atomic rewrite if a block doesn't contain compares

If a block jumps before performing a compare, we'd need to recursively
find the first of the jumped-to block. While this is doable, it's not
really worth spending the time as most such cases won't actually qualify
for atomic loop rewrite anyway.
Fixes an invalid rewrite when `.+` is followed by an alternation, e.g.
/.+(a|b|c)/.

1 files changed, 2 insertions, 0 deletions

diff --git a/Tests/LibRegex/Regex.cpp b/Tests/LibRegex/Regex.cpp
index 82db3cc9c6..3fef06d6d5 100644
--- a/Tests/LibRegex/Regex.cpp
+++ b/Tests/LibRegex/Regex.cpp
@@ -986,6 +986,8 @@ TEST_CASE(optimizer_atomic_groups)
         Tuple { "a+"sv, ""sv, false },
         // 'y' and [^x] have an overlap ('y'), the loop should not be rewritten here.
         Tuple { "[^x]+y"sv, "ay"sv, true },
+        // .+ should not be rewritten here, as it's followed by something that would be matched by `.`.
+        Tuple { ".+(a|b|c)"sv, "xxa"sv, true },
     };
 
     for (auto& test : tests) {