[clang] nonblocking/nonallocating attributes (was: nolock/noalloc) (PR #84983)

[via cfe-commits]

================
@@ -13804,3 +13807,78 @@ StringRef ASTContext::getCUIDHash() const {
   CUIDHash = llvm::utohexstr(llvm::MD5Hash(LangOpts.CUID), /*LowerCase=*/true);
   return CUIDHash;
 }
+
+using FunctionEffectSpan = llvm::ArrayRef<FunctionEffect>;
+
+llvm::hash_code hash_value(const FunctionEffect &Effect) {
+  return llvm::hash_value(Effect.opaqueRepr());
+}
+
+namespace llvm {
+template <> struct DenseMapInfo<FunctionEffectSpan> {
+  static FunctionEffectSpan getEmptyKey() {
+    return {static_cast<const FunctionEffect *>(nullptr), size_t(0)};
+  }
+  static FunctionEffectSpan getTombstoneKey() {
+    return {reinterpret_cast<const FunctionEffect *>(intptr_t(-1)), size_t(0)};
+  }
+  static unsigned getHashValue(const FunctionEffectSpan &Val) {
+    hash_code hash1 = hash_value(Val.size());
+    // Treat the FunctionEffects as a span of integers
+    const FunctionEffect *Begin = Val.begin();
+    const FunctionEffect *End = Val.end();
+    hash_code hash2 =
+        hash_combine_range(reinterpret_cast<const uint32_t *>(Begin),
+                           reinterpret_cast<const uint32_t *>(End));
+    return hash_combine(hash1, hash2);
+  }
+  static bool isEqual(const FunctionEffectSpan &LHS,
+                      const FunctionEffectSpan &RHS) {
+    if (LHS.size() != RHS.size()) {
+      return false;
+    }
+    // distinguish empty from tombstone
+    if (LHS.size() == 0) {
+      return LHS.data() == RHS.data();
+    }
+    return std::equal(LHS.begin(), LHS.end(), RHS.begin());
+  }
+};
+} // namespace llvm
+
+FunctionEffectSet
+ASTContext::getUniquedFunctionEffectSet(llvm::ArrayRef<uint32_t> FX) {
+  static_assert(sizeof(FunctionEffect) == sizeof(uint32_t));
+  const auto *ptr = reinterpret_cast<const FunctionEffect *>(FX.data());
+  return UniquedFunctionEffectSet.getUniqued({ptr, FX.size()});
----------------
Sirraide wrote:

I think this is technically *fine* assuming that the pointer in the `ArrayRef` started out as a `FunctionEffect*`, but it’s still quite the hack imo.

https://github.com/llvm/llvm-project/pull/84983