REAPPLY [ORC] Add automatic shared library resolver for unresolved symbols. llvm#148410 (llvm#164551)

This PR reapplies the changes previously introduced in llvm#148410.
It introduces a redesigned and rebuilt Cling-based auto-loading
workaround that enables scanning libraries and resolving unresolved
symbols within those libraries.

Author: SahilPatidar

llvm/include/llvm/ExecutionEngine/Orc/Shared/SymbolFilter.h

@@ -0,0 +1,173 @@
+//===- SymbolFilter.h - Utilities for Symbol Filtering ---------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_SHARED_SYMBOLFILTER_H
+#define LLVM_EXECUTIONENGINE_ORC_SHARED_SYMBOLFILTER_H
+
+#include "llvm/ExecutionEngine/Orc/Shared/SimplePackedSerialization.h"
+
+#include <cmath>
+#include <type_traits>
+#include <vector>
+
+namespace llvm {
+namespace orc {
+
+namespace shared {
+using SPSBloomFilter =
+    SPSTuple<bool, uint32_t, uint32_t, uint32_t, SPSSequence<uint64_t>>;
+}
+
+class BloomFilter {
+public:
+  using HashFunc = std::function<uint32_t(StringRef)>;
+
+  BloomFilter() = default;
+  BloomFilter(BloomFilter &&) noexcept = default;
+  BloomFilter &operator=(BloomFilter &&) noexcept = default;
+  BloomFilter(const BloomFilter &) = delete;
+  BloomFilter &operator=(const BloomFilter &) = delete;
+
+  BloomFilter(uint32_t SymbolCount, float FalsePositiveRate, HashFunc hashFn)
+      : HashFn(std::move(hashFn)) {
+    initialize(SymbolCount, FalsePositiveRate);
+  }
+  bool isInitialized() const { return Initialized; }
+
+  void add(StringRef Sym) {
+    assert(Initialized);
+    addHash(HashFn(Sym));
+  }
+
+  bool mayContain(StringRef Sym) const {
+    return !isEmpty() && testHash(HashFn(Sym));
+  }
+
+  bool isEmpty() const { return SymbolCount == 0; }
+
+private:
+  friend class shared::SPSSerializationTraits<shared::SPSBloomFilter,
+                                              BloomFilter>;
+  static constexpr uint32_t BitsPerEntry = 64;
+
+  bool Initialized = false;
+  uint32_t SymbolCount = 0;
+  uint32_t BloomSize = 0;
+  uint32_t BloomShift = 0;
+  std::vector<uint64_t> BloomTable;
+  HashFunc HashFn;
+
+  void initialize(uint32_t SymCount, float FalsePositiveRate) {
+    assert(SymCount > 0);
+    SymbolCount = SymCount;
+    Initialized = true;
+
+    float ln2 = std::log(2.0f);
+    float M = -1.0f * SymbolCount * std::log(FalsePositiveRate) / (ln2 * ln2);
+    BloomSize = static_cast<uint32_t>(std::ceil(M / BitsPerEntry));
+    BloomShift = std::min(6u, log2ceil(SymbolCount));
+    BloomTable.resize(BloomSize, 0);
+  }
+
+  void addHash(uint32_t Hash) {
+    uint32_t Hash2 = Hash >> BloomShift;
+    uint32_t N = (Hash / BitsPerEntry) % BloomSize;
+    uint64_t Mask =
+        (1ULL << (Hash % BitsPerEntry)) | (1ULL << (Hash2 % BitsPerEntry));
+    BloomTable[N] |= Mask;
+  }
+
+  bool testHash(uint32_t Hash) const {
+    uint32_t Hash2 = Hash >> BloomShift;
+    uint32_t N = (Hash / BitsPerEntry) % BloomSize;
+    uint64_t Mask =
+        (1ULL << (Hash % BitsPerEntry)) | (1ULL << (Hash2 % BitsPerEntry));
+    return (BloomTable[N] & Mask) == Mask;
+  }
+
+  static constexpr uint32_t log2ceil(uint32_t V) {
+    return V <= 1 ? 0 : 32 - countl_zero(V - 1);
+  }
+};
+
+class BloomFilterBuilder {
+public:
+  using HashFunc = BloomFilter::HashFunc;
+
+  BloomFilterBuilder() = default;
+
+  BloomFilterBuilder &setFalsePositiveRate(float Rate) {
+    assert(Rate > 0.0f && Rate < 1.0f);
+    FalsePositiveRate = Rate;
+    return *this;
+  }
+
+  BloomFilterBuilder &setHashFunction(HashFunc Fn) {
+    HashFn = std::move(Fn);
+    return *this;
+  }
+
+  BloomFilter build(ArrayRef<StringRef> Symbols) const {
+    assert(!Symbols.empty() && "Cannot build filter from empty symbol list.");
+    BloomFilter F(static_cast<uint32_t>(Symbols.size()), FalsePositiveRate,
+                  HashFn);
+    for (const auto &Sym : Symbols)
+      F.add(Sym);
+
+    return F;
+  }
+
+private:
+  float FalsePositiveRate = 0.02f;
+  HashFunc HashFn = [](StringRef S) -> uint32_t {
+    uint32_t H = 5381;
+    for (char C : S)
+      H = ((H << 5) + H) + static_cast<uint8_t>(C); // H * 33 + C
+    return H;
+  };
+};
+
+namespace shared {
+
+template <> class SPSSerializationTraits<SPSBloomFilter, BloomFilter> {
+public:
+  static size_t size(const BloomFilter &Filter) {
+    return SPSBloomFilter::AsArgList::size(
+        Filter.Initialized, Filter.SymbolCount, Filter.BloomSize,
+        Filter.BloomShift, Filter.BloomTable);
+  }
+
+  static bool serialize(SPSOutputBuffer &OB, const BloomFilter &Filter) {
+    return SPSBloomFilter::AsArgList::serialize(
+        OB, Filter.Initialized, Filter.SymbolCount, Filter.BloomSize,
+        Filter.BloomShift, Filter.BloomTable);
+  }
+
+  static bool deserialize(SPSInputBuffer &IB, BloomFilter &Filter) {
+    bool IsInitialized;
+    uint32_t SymbolCount = 0, BloomSize = 0, BloomShift = 0;
+    std::vector<uint64_t> BloomTable;
+
+    if (!SPSBloomFilter::AsArgList::deserialize(
+            IB, IsInitialized, SymbolCount, BloomSize, BloomShift, BloomTable))
+      return false;
+
+    Filter.Initialized = IsInitialized;
+    Filter.SymbolCount = SymbolCount;
+    Filter.BloomSize = BloomSize;
+    Filter.BloomShift = BloomShift;
+    Filter.BloomTable = std::move(BloomTable);
+
+    return true;
+  }
+};
+
+} // end namespace shared
+} // end namespace orc
+} // end namespace llvm
+#endif // LLVM_EXECUTIONENGINE_ORC_SHARED_SYMBOLFILTER_H