This is a small optimization to reduce JIT overhead during runtime.

https://github.com/openjdk/jdk/blob/a8871f5d26e5cb42c031c7b736ec30b1b147a2bc/src/hotspot/share/oops/method.cpp#L715

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This is also a prerequisite for JDK-8305753 -- the JIT only calls compute_has_loops_flag() for methods that are compiled. As a result, different invocation of "java -Xshare:dump" may result in differences in the resulting archive, thus breaking the test test/hotspot/jtreg/runtime/cds/DeterministicDump.java