[PATCH] D106206: Lazy initialized the NotUnderValgrind flag

[Duncan P. N. Exon Smith via Phabricator via llvm-commits]

dexonsmith added inline comments.


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Comment at: llvm/lib/Support/Valgrind.cpp:27-38
+namespace {
+struct CreateNotUnderValgrind {
+  static void *call() { return new bool{!RUNNING_ON_VALGRIND}; }
+};
+} // namespace
+static const llvm::ManagedStatic<bool, CreateNotUnderValgrind> NotUnderValgrind;
 
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Can `NotUnderValgrind` be merged into `RunningOnValgrind`, skipping the managed static?

The only reason not to is if it `RUNNING_ON_VALGRIND` could return "true" on the first use, but "false" some time later in the same execution. I don't imagine that's possible...?

... but if it //is// possible, maybe switching to ManagedStatic isn't safe either, since there would be a reason to cache the value at load-time instead of at first use.


================
Comment at: llvm/lib/Support/Valgrind.cpp:41-42
 void llvm::sys::ValgrindDiscardTranslations(const void *Addr, size_t Len) {
-  if (NotUnderValgrind)
+  if (*NotUnderValgrind)
     return;
 
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Seems to me like this could use `RunningOnValgrind`, unless there's a case where `RUNNING_ON_VALGRIND` returns different answers at load-time vs later...


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D106206/new/

https://reviews.llvm.org/D106206