Apple macOS < 10.14.5 / iOS < 12.3 JavaScriptCore - AIR Optimization Incorrectly Removes Assignment to Register

While fuzzing JavaScriptCore, I encountered the following JavaScript program which crashes jsc from current HEAD git commit 3c46422e45fef2de6ff13b66cd45705d63859555 in debug and release builds ./Tools/Scripts/build-jsc --jsc-only --debug or --release: // Run with --useConcurrentJIT=false...