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  1. JDK
  2. JDK-8050147

StoreLoad barrier interferes with stack usages

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    • Bug
    • Resolution: Fixed
    • P4
    • 9
    • None
    • hotspot
    • b32
    • x86
    • generic

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      Description

        The issue was originally found in a larger benchmark, but can be also shown with targeted tests.

        In short, on x86, we emit "lock addl %(esp+0), 0" as the substitute for StoreLoad barrier, and while this thing seems faster than "mfence", we interfere with things residing on the top of the stack: call arguments, for one example. The interaction appears to be either the true data dependency via %(esp+0), or the implicit dependency via the cache line containing %(esp+0) locked with lock-prefixed instruction.

        This bug suggests to reconsider the instruction sequence emitted for the StoreLoad barrier, see comments.

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                shade Aleksey Shipilev
                shade Aleksey Shipilev
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                  Created:
                  Updated:
                  Resolved: