[llvm] [ADT] Add TrieRawHashMap (PR #69528)

[Aman LaChapelle via llvm-commits]

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@@ -0,0 +1,483 @@
+//===- TrieRawHashMap.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/TrieRawHashMap.h"
+#include "TrieHashIndexGenerator.h"
+#include "llvm/ADT/LazyAtomicPointer.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ThreadSafeAllocator.h"
+#include "llvm/Support/raw_ostream.h"
+#include <memory>
+
+using namespace llvm;
+
+namespace {
+struct TrieNode {
+  const bool IsSubtrie = false;
+
+  TrieNode(bool IsSubtrie) : IsSubtrie(IsSubtrie) {}
+
+  static void *operator new(size_t Size) { return ::malloc(Size); }
+  void operator delete(void *Ptr) { ::free(Ptr); }
+};
+
+struct TrieContent final : public TrieNode {
+  const uint8_t ContentOffset;
+  const uint8_t HashSize;
+  const uint8_t HashOffset;
+
+  void *getValuePointer() const {
+    auto *Content = reinterpret_cast<const uint8_t *>(this) + ContentOffset;
+    return const_cast<uint8_t *>(Content);
+  }
+
+  ArrayRef<uint8_t> getHash() const {
+    auto *Begin = reinterpret_cast<const uint8_t *>(this) + HashOffset;
+    return ArrayRef(Begin, Begin + HashSize);
+  }
+
+  TrieContent(size_t ContentOffset, size_t HashSize, size_t HashOffset)
+      : TrieNode(/*IsSubtrie=*/false), ContentOffset(ContentOffset),
+        HashSize(HashSize), HashOffset(HashOffset) {}
+
+  static bool classof(const TrieNode *TN) { return !TN->IsSubtrie; }
+};
+
+static_assert(sizeof(TrieContent) ==
+                  ThreadSafeTrieRawHashMapBase::TrieContentBaseSize,
+              "Check header assumption!");
+
+class TrieSubtrie final : public TrieNode {
+public:
+  TrieNode *get(size_t I) const { return Slots[I].load(); }
+
+  TrieSubtrie *
+  sink(size_t I, TrieContent &Content, size_t NumSubtrieBits, size_t NewI,
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bzcheeseman wrote:

Would be great to get some comments on this, it's not super obvious from inspection what the intended behavior is :)

https://github.com/llvm/llvm-project/pull/69528