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    Implement ldrex/strex instructions in ARM simulator · 66ae5f7d
    binji authored
    This CL implements ldrex, ldrexb, ldrexh, strex, strexb, and strexh in the
    Simulator. These instructions provide "exclusive" access, which provides mutual
    exclusion for concurrent threads of execution.
    
    The ARM specification gives some leeway to implementors, but essentially
    describes each processor as having Local Monitor and Global Monitor. The Local
    Monitor is used to check the exclusivity state without having to synchronize
    with other processors. The Global Monitor is shared between processors. We
    model both to make it easier to match behavior with the spec.
    
    When running with multiple OS threads, each thread has its own isolate, and
    each isolate has its own Simulator. The Local Monitor is stored directly on the
    Simulator, and the Global Monitor is stored as a lazy singleton. The Global
    Monitor maintains a linked-list of all Simulators.
    
    All loads/stores (even non-exclusive) are guarded by the Global Monitor's mutex.
    
    BUG=v8:4614
    
    Review-Url: https://codereview.chromium.org/2006183004
    Cr-Commit-Position: refs/heads/master@{#42481}
    66ae5f7d
simulator-arm.h 19.4 KB