[llvm] [LLVM][rtsan] Add nosanitize_realtime instrumentation (PR #106125)

[Chris Apple via llvm-commits]

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@@ -51,6 +53,7 @@ RealtimeSanitizerPass::RealtimeSanitizerPass(
 PreservedAnalyses RealtimeSanitizerPass::run(Function &F,
                                              AnalysisManager<Function> &AM) {
   if (F.hasFnAttribute(Attribute::SanitizeRealtime)) {
+    assert(!F.hasFnAttribute(Attribute::NoSanitizeRealtime));
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cjappl wrote:

I guess another way to say the same thing as the previous comment:

ASan instruments and inspects every function in a binary. Asan disables on a per function basis.

RTSan instruments and inspects only in a specific context. RTSan disables on a per context basis.

This is the root of the difference and why we have to disable in this way, we are keeping state that tracks if we are in the context our sanitizer cares about.

https://github.com/llvm/llvm-project/pull/106125