Rebase with main

Author: huangjd

llvm/include/llvm/ProfileData/ProfileFuncRef.h

@@ -0,0 +1,225 @@
+//===--- ProfileFuncRef.h - Sample profile function name ---*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the StringRefOrHashCode class. It is to represent function
+// names in a sample profile, which can be in one of two forms - either a
+// regular string, or a 64-bit hash code.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_PROFILEDATA_PROFILEFUNCREF_H
+#define LLVM_PROFILEDATA_PROFILEFUNCREF_H
+
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/Hashing.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/MD5.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdint>
+
+namespace llvm {
+namespace sampleprof {
+
+/// This class represents a function name that is read from a sample profile. It
+/// comes with two forms: a string or a hash code. For efficient storage, a
+/// sample profile may store function names as 64-bit MD5 values, so when
+/// reading the profile, this class can represnet them without converting it to
+/// a string first.
+/// When representing a hash code, we utilize the Length field to store it, and
+/// Data is set to null. When representing a string, it is same as StringRef,
+/// and can be pointer-casted as one.
+/// We disallow implicit cast to StringRef because there are too many instances
+/// that it may cause break the code, such as using it in a StringMap.
+class ProfileFuncRef {
+
+  const char *Data = nullptr;
+
+  /// Use uint64_t instead of size_t so that it can also hold a MD5 value.
+  uint64_t Length = 0;
+
+  /// Extension to memcmp to handle hash code representation. If both are hash
+  /// values, Lhs and Rhs are both null, function returns 0 (and needs an extra
+  /// comparison using getIntValue). If only one is hash code, it is considered
+  /// less than the StringRef one. Otherwise perform normal string comparison.
+  static int compareMemory(const char *Lhs, const char *Rhs, uint64_t Length) {
+    if (Lhs == Rhs)
+      return 0;
+    if (!Lhs)
+      return -1;
+    if (!Rhs)
+      return 1;
+    return ::memcmp(Lhs, Rhs, (size_t)Length);
+  }
+
+public:
+  ProfileFuncRef() = default;
+
+  /// Constructor from a StringRef.
+  explicit ProfileFuncRef(StringRef Str)
+      : Data(Str.data()), Length(Str.size()) {}
+
+  /// Constructor from a hash code.
+  explicit ProfileFuncRef(uint64_t HashCode)
+      : Data(nullptr), Length(HashCode) {
+    assert(HashCode != 0);
+  }
+
+  /// Constructor from a string. Check if Str is a number, which is generated by
+  /// converting a MD5 sample profile to a format that does not support MD5, and
+  /// if so, convert the numerical string to a hash code first. We assume that
+  /// no function name (from a profile) can be a pure number.
+  explicit ProfileFuncRef(const std::string &Str)
+      : Data(Str.data()), Length(Str.size()) {
+    // Only need to check for base 10 digits, fail faster if otherwise.
+    if (Str.length() > 0 && isdigit(Str[0]) &&
+        !StringRef(Str).getAsInteger(10, Length))
+      Data = nullptr;
+  }
+
+  /// Check for equality. Similar to StringRef::equals, but will also cover for
+  /// the case where one or both are hash codes. Comparing their int values are
+  /// sufficient. A hash code ProfileFuncName is considered not equal to a
+  /// StringRef ProfileFuncName regardless of actual contents.
+  bool equals(const ProfileFuncRef &Other) const {
+    return Length == Other.Length &&
+           compareMemory(Data, Other.Data, Length) == 0;
+  }
+
+  /// Total order comparison. If both ProfileFuncName are StringRef, this is the
+  /// same as StringRef::compare. If one of them is StringRef, it is considered
+  /// greater than the hash code ProfileFuncName. Otherwise this is the the
+  /// same as comparing their int values.
+  int compare(const ProfileFuncRef &Other) const {
+    auto Res = compareMemory(Data, Other.Data, std::min(Length, Other.Length));
+    if (Res != 0)
+      return Res;
+    if (Length == Other.Length)
+      return 0;
+    return Length < Other.Length ? -1 : 1;
+  }
+
+  /// Convert to a string, usually for output purpose.
+  std::string str() const {
+    if (Data)
+      return std::string(Data, Length);
+    if (Length != 0)
+      return std::to_string(Length);
+    return std::string();
+  }
+
+  /// Convert to StringRef, a backing buffer must be provided in case this
+  /// object represents a hash code, which will be converted to a string into
+  /// the buffer. If this object represents a StringRef, the buffer is not used.
+  StringRef stringRef(std::string &Buffer) const {
+    if (Data)
+      return StringRef(Data, Length);
+    if (Length != 0) {
+      Buffer = std::to_string(Length);
+      return Buffer;
+    }
+    return StringRef();
+  }
+
+  friend raw_ostream &operator<<(raw_ostream &OS, const ProfileFuncRef &Obj);
+
+  /// Get hash code of this object. Returns this object's hash code if it is
+  /// already representing one, otherwise returns the MD5 of its string content.
+  /// Note that it is not the same as std::hash because we want to keep the
+  /// consistency that the same sample profile function in string form or MD5
+  /// form has the same hash code.
+  uint64_t getHashCode() const {
+    if (Data)
+      return MD5Hash(StringRef(Data, Length));
+    return Length;
+  }
+
+  bool empty() const { return Length == 0; }
+
+  /// Check if this object represents a StringRef, or a hash code.
+  bool isStringRef() const { return Data != nullptr; }
+};
+
+inline bool operator==(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return LHS.equals(RHS);
+}
+
+inline bool operator!=(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return !LHS.equals(RHS);
+}
+
+inline bool operator<(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return LHS.compare(RHS) < 0;
+}
+
+inline bool operator<=(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return LHS.compare(RHS) <= 0;
+}
+
+inline bool operator>(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return LHS.compare(RHS) > 0;
+}
+
+inline bool operator>=(const ProfileFuncRef &LHS, const ProfileFuncRef &RHS) {
+  return LHS.compare(RHS) >= 0;
+}
+
+inline raw_ostream &operator<<(raw_ostream &OS, const ProfileFuncRef &Obj) {
+  if (Obj.Data)
+    return OS << StringRef(Obj.Data, Obj.Length);
+  if (Obj.Length != 0)
+    return OS << Obj.Length;
+  return OS;
+}
+
+inline uint64_t MD5Hash(const sampleprof::ProfileFuncRef &Obj) {
+  return Obj.getHashCode();
+}
+
+inline hash_code hash_value(const sampleprof::ProfileFuncRef &Obj) {
+  return Obj.getHashCode();
+}
+
+} // end namespace sampleprof
+
+/// Template specialization for ProfileFuncName so that it can be used in LLVM
+/// map containers.
+template <> struct DenseMapInfo<sampleprof::ProfileFuncRef, void> {
+
+  static inline sampleprof::ProfileFuncRef getEmptyKey() {
+    return sampleprof::ProfileFuncRef(~0ULL);
+  }
+
+  static inline sampleprof::ProfileFuncRef getTombstoneKey() {
+    return sampleprof::ProfileFuncRef(~1ULL);
+  }
+
+  static unsigned getHashValue(const sampleprof::ProfileFuncRef &Val) {
+    return Val.getHashCode();
+  }
+
+  static bool isEqual(const sampleprof::ProfileFuncRef &LHS,
+                      const sampleprof::ProfileFuncRef &RHS) {
+    return LHS == RHS;
+  }
+};
+
+} // end namespace llvm
+
+namespace std {
+
+/// Template specialization for ProfileFuncName so that it can be used in STL
+/// containers.
+template <> struct hash<llvm::sampleprof::ProfileFuncRef> {
+  size_t operator()(const llvm::sampleprof::ProfileFuncRef &Val) const {
+    return Val.getHashCode();
+  }
+};
+
+} // end namespace std
+
+#endif // LLVM_PROFILEDATA_PROFILEFUNCREF_H