https://issues.dlang.org/show_bug.cgi?id=13395

          Issue ID: 13395
           Summary: Shared arrays must be loaded atomically
           Product: D
           Version: D2
          Hardware: x86
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: DMD
          Assignee: nobody@puremagic.com
          Reporter: andrei@erdani.com

D assumes N-bit machines support 2N-atomic loads, which is the case for all modern processors. The compiler should generate code to load and store all built-in shared slices atomically.

Apparently on i64 the only way to do so is by using CMPXCHG16B (http://stackoverflow.com/questions/4099002/x86-128-bit-atomic-ops). The instruction is supported by the front-end too.

Also core.atomic should support atomicLoad() for values that are 128-bit on
64-bit models.

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