[libcxx-commits] [PATCH] D115367: [NFC][libcxxabi] Pulled guard byte code out of GuardObject

[Louis Dionne via Phabricator via libcxx-commits]

ldionne added inline comments.


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Comment at: libcxxabi/src/cxa_guard_impl.h:15
  *
  * The first "guard byte" (which is checked by the compiler) is set only upon
  * the completion of cxa release.
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This is confusing me -- does the compiler really check the guard byte? Isn't it what we do in the library when we do `guard_byte.load(std::_AO_Acquire) != UNSET`?


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Comment at: libcxxabi/src/cxa_guard_impl.h:232
   AcquireResult cxa_guard_acquire() {
-    AtomicInt<uint8_t> guard_byte(guard_byte_address);
-    if (guard_byte.load(std::_AO_Acquire) != UNSET)
+    // use short-circuit evalutation to avoid calling init_byte.acquire when
+    // guard_byte.acquire returns true. (i.e. don't call it when we know from
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Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115367/new/

https://reviews.llvm.org/D115367