[BOLT] Refactor MCInstReference and move it to Core (NFC)

bolt/include/bolt/Core/MCInstUtils.h

@@ -0,0 +1,181 @@
+//===- bolt/Core/MCInstUtils.h ----------------------------------*- 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 BOLT_CORE_MCINSTUTILS_H
+#define BOLT_CORE_MCINSTUTILS_H
+
+#include "bolt/Core/BinaryBasicBlock.h"
+#include <map>
+#include <variant>
+
+namespace llvm {
+class MCCodeEmitter;
+}
+
+namespace llvm {
+namespace bolt {
+
+class BinaryFunction;
+
+/// MCInstReference represents a reference to a constant MCInst as stored either
+/// in a BinaryFunction (i.e. before a CFG is created), or in a BinaryBasicBlock
+/// (after a CFG is created).
+///
+/// The reference may be invalidated when the function containing the referenced
+/// instruction is modified.
+class MCInstReference {
+public:
+  using nocfg_const_iterator = std::map<uint32_t, MCInst>::const_iterator;
+
+  /// Constructs an empty reference.
+  MCInstReference() : Reference(RefInBB(nullptr, /*Index=*/0)) {}
+
+  /// Constructs a reference to the instruction inside the basic block.
+  MCInstReference(const BinaryBasicBlock &BB, const MCInst &Inst)
+      : Reference(RefInBB(&BB, getInstIndexInBB(BB, Inst))) {}
+  /// Constructs a reference to the instruction inside the basic block.
+  MCInstReference(const BinaryBasicBlock &BB, unsigned Index)
+      : Reference(RefInBB(&BB, Index)) {}
+
+  /// Constructs a reference to the instruction inside the function without
+  /// CFG information.
+  MCInstReference(const BinaryFunction &BF, nocfg_const_iterator It)
+      : Reference(RefInBF(&BF, It)) {}
+
+  /// Locates an instruction inside a function and returns a reference.
+  static MCInstReference get(const MCInst &Inst, const BinaryFunction &BF);
+
+  bool operator==(const MCInstReference &Other) const {
+    return Reference == Other.Reference;
+  }
+
+  const MCInst &getMCInst() const {
+    assert(!empty() && "Empty reference");
+    if (auto *Ref = tryGetRefInBB()) {
+      [[maybe_unused]] unsigned NumInstructions = Ref->BB->size();
+      assert(Ref->Index < NumInstructions && "Invalid reference");
+      return Ref->BB->getInstructionAtIndex(Ref->Index);
+    }
+    return getRefInBF().It->second;
+  }
+
+  operator const MCInst &() const { return getMCInst(); }
+
+  bool empty() const {
+    if (auto *Ref = tryGetRefInBB())
+      return Ref->BB == nullptr;
+    return getRefInBF().BF == nullptr;
+  }
+
+  bool hasCFG() const { return !empty() && tryGetRefInBB() != nullptr; }
+
+  const BinaryFunction *getFunction() const {
+    assert(!empty() && "Empty reference");
+    if (auto *Ref = tryGetRefInBB())
+      return Ref->BB->getFunction();
+    return getRefInBF().BF;
+  }
+
+  const BinaryBasicBlock *getBasicBlock() const {
+    assert(!empty() && "Empty reference");
+    if (auto *Ref = tryGetRefInBB())
+      return Ref->BB;
+    return nullptr;
+  }
+
+  /// Computes the original address of the instruction (or offset from base
+  /// for PIC), assuming the containing function was not modified.
+  ///
+  /// This function is intended for the use cases like debug printing, as it
+  /// is only as precise as BinaryContext::computeCodeSize() is and requires
+  /// iterating over the prefix of the basic block (when CFG is available).
+  ///
+  /// MCCodeEmitter is not thread safe and the default instance from
+  /// BinaryContext is used by default, thus pass an instance explicitly if
+  /// this function may be called from multithreaded code.
+  uint64_t computeAddress(const MCCodeEmitter *Emitter = nullptr) const;
+
+  raw_ostream &print(raw_ostream &OS) const;
+
+private:
+  static unsigned getInstIndexInBB(const BinaryBasicBlock &BB,
+                                   const MCInst &Inst) {
+    // Usage of pointer arithmetic assumes the instructions are stored in a
+    // vector, see BasicBlockStorageIsVector in MCInstUtils.cpp.
+    const MCInst *FirstInstInBB = &*BB.begin();
+    return &Inst - FirstInstInBB;
+  }
+
+  // Two cases are possible:
+  // * functions with CFG reconstructed - a function stores a collection of
+  //   basic blocks, each basic block stores a contiguous vector of MCInst
+  // * functions without CFG - there are no basic blocks created,
+  //   the instructions are directly stored in std::map in BinaryFunction
+  //
+  // In both cases, the direct parent of MCInst is stored together with an
+  // index or iterator pointing to the instruction.
+
+  // Helper struct: CFG is available, the direct parent is a basic block.
+  struct RefInBB {
+    RefInBB(const BinaryBasicBlock *BB, unsigned Index)
+        : BB(BB), Index(Index) {}
+    RefInBB(const RefInBB &Other) = default;
+    RefInBB &operator=(const RefInBB &Other) = default;
+
+    const BinaryBasicBlock *BB;
+    unsigned Index;
+
+    bool operator==(const RefInBB &Other) const {
+      return BB == Other.BB && Index == Other.Index;
+    }
+  };
+
+  // Helper struct: CFG is *not* available, the direct parent is a function,
+  // iterator's type is std::map<uint32_t, MCInst>::iterator (the mapped value
+  // is an instruction's offset).
+  struct RefInBF {
+    RefInBF(const BinaryFunction *BF, nocfg_const_iterator It)
+        : BF(BF), It(It) {}
+    RefInBF(const RefInBF &Other) = default;
+    RefInBF &operator=(const RefInBF &Other) = default;
+
+    const BinaryFunction *BF;
+    nocfg_const_iterator It;
+
+    bool operator==(const RefInBF &Other) const {
+      return BF == Other.BF && It->first == Other.It->first;
+    }
+  };
+
+  std::variant<RefInBB, RefInBF> Reference;
+
+  // Utility methods to be used like this:
+  //
+  //     if (auto *Ref = tryGetRefInBB())
+  //       return Ref->doSomething(...);
+  //     return getRefInBF().doSomethingElse(...);
+  const RefInBB *tryGetRefInBB() const {
+    assert(std::get_if<RefInBB>(&Reference) ||
+           std::get_if<RefInBF>(&Reference));
+    return std::get_if<RefInBB>(&Reference);
+  }
+  const RefInBF &getRefInBF() const {
+    assert(std::get_if<RefInBF>(&Reference));
+    return *std::get_if<RefInBF>(&Reference);
+  }
+};
+
+static inline raw_ostream &operator<<(raw_ostream &OS,
+                                      const MCInstReference &Ref) {
+  return Ref.print(OS);
+}
+
+} // namespace bolt
+} // namespace llvm
+
+#endif

bolt/include/bolt/Passes/PAuthGadgetScanner.h

@@ -11,187 +11,13 @@
 
 #include "bolt/Core/BinaryContext.h"
 #include "bolt/Core/BinaryFunction.h"
+#include "bolt/Core/MCInstUtils.h"
 #include "bolt/Passes/BinaryPasses.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
 
 namespace llvm {
 namespace bolt {
-
-/// @brief  MCInstReference represents a reference to an MCInst as stored either
-/// in a BinaryFunction (i.e. before a CFG is created), or in a BinaryBasicBlock
-/// (after a CFG is created). It aims to store the necessary information to be
-/// able to find the specific MCInst in either the BinaryFunction or
-/// BinaryBasicBlock data structures later, so that e.g. the InputAddress of
-/// the corresponding instruction can be computed.
-
-struct MCInstInBBReference {
-  BinaryBasicBlock *BB;
-  int64_t BBIndex;
-  MCInstInBBReference(BinaryBasicBlock *BB, int64_t BBIndex)
-      : BB(BB), BBIndex(BBIndex) {}
-  MCInstInBBReference() : BB(nullptr), BBIndex(0) {}
-  static MCInstInBBReference get(const MCInst *Inst, BinaryFunction &BF) {
-    for (BinaryBasicBlock &BB : BF)
-      for (size_t I = 0; I < BB.size(); ++I)
-        if (Inst == &BB.getInstructionAtIndex(I))
-          return MCInstInBBReference(&BB, I);
-    return {};
-  }
-  bool operator==(const MCInstInBBReference &RHS) const {
-    return BB == RHS.BB && BBIndex == RHS.BBIndex;
-  }
-  bool operator<(const MCInstInBBReference &RHS) const {
-    return std::tie(BB, BBIndex) < std::tie(RHS.BB, RHS.BBIndex);
-  }
-  operator MCInst &() const {
-    assert(BB != nullptr);
-    return BB->getInstructionAtIndex(BBIndex);
-  }
-  uint64_t getAddress() const {
-    // 4 bytes per instruction on AArch64.
-    // FIXME: the assumption of 4 byte per instruction needs to be fixed before
-    // this method gets used on any non-AArch64 binaries (but should be fine for
-    // pac-ret analysis, as that is an AArch64-specific feature).
-    return BB->getFunction()->getAddress() + BB->getOffset() + BBIndex * 4;
-  }
-};
-
-raw_ostream &operator<<(raw_ostream &OS, const MCInstInBBReference &);
-
-struct MCInstInBFReference {
-  BinaryFunction *BF;
-  uint64_t Offset;
-  MCInstInBFReference(BinaryFunction *BF, uint64_t Offset)
-      : BF(BF), Offset(Offset) {}
-
-  static MCInstInBFReference get(const MCInst *Inst, BinaryFunction &BF) {
-    for (auto &I : BF.instrs())
-      if (Inst == &I.second)
-        return MCInstInBFReference(&BF, I.first);
-    return {};
-  }
-
-  MCInstInBFReference() : BF(nullptr), Offset(0) {}
-  bool operator==(const MCInstInBFReference &RHS) const {
-    return BF == RHS.BF && Offset == RHS.Offset;
-  }
-  bool operator<(const MCInstInBFReference &RHS) const {
-    return std::tie(BF, Offset) < std::tie(RHS.BF, RHS.Offset);
-  }
-  operator MCInst &() const {
-    assert(BF != nullptr);
-    return *BF->getInstructionAtOffset(Offset);
-  }
-
-  uint64_t getOffset() const { return Offset; }
-
-  uint64_t getAddress() const { return BF->getAddress() + getOffset(); }
-};
-
-raw_ostream &operator<<(raw_ostream &OS, const MCInstInBFReference &);
-
-struct MCInstReference {
-  enum Kind { FunctionParent, BasicBlockParent };
-  Kind ParentKind;
-  union U {
-    MCInstInBBReference BBRef;
-    MCInstInBFReference BFRef;
-    U(MCInstInBBReference BBRef) : BBRef(BBRef) {}
-    U(MCInstInBFReference BFRef) : BFRef(BFRef) {}
-  } U;
-  MCInstReference(MCInstInBBReference BBRef)
-      : ParentKind(BasicBlockParent), U(BBRef) {}
-  MCInstReference(MCInstInBFReference BFRef)
-      : ParentKind(FunctionParent), U(BFRef) {}
-  MCInstReference(BinaryBasicBlock *BB, int64_t BBIndex)
-      : MCInstReference(MCInstInBBReference(BB, BBIndex)) {}
-  MCInstReference(BinaryFunction *BF, uint32_t Offset)
-      : MCInstReference(MCInstInBFReference(BF, Offset)) {}
-
-  static MCInstReference get(const MCInst *Inst, BinaryFunction &BF) {
-    if (BF.hasCFG())
-      return MCInstInBBReference::get(Inst, BF);
-    return MCInstInBFReference::get(Inst, BF);
-  }
-
-  bool operator<(const MCInstReference &RHS) const {
-    if (ParentKind != RHS.ParentKind)
-      return ParentKind < RHS.ParentKind;
-    switch (ParentKind) {
-    case BasicBlockParent:
-      return U.BBRef < RHS.U.BBRef;
-    case FunctionParent:
-      return U.BFRef < RHS.U.BFRef;
-    }
-    llvm_unreachable("");
-  }
-
-  bool operator==(const MCInstReference &RHS) const {
-    if (ParentKind != RHS.ParentKind)
-      return false;
-    switch (ParentKind) {
-    case BasicBlockParent:
-      return U.BBRef == RHS.U.BBRef;
-    case FunctionParent:
-      return U.BFRef == RHS.U.BFRef;
-    }
-    llvm_unreachable("");
-  }
-
-  operator MCInst &() const {
-    switch (ParentKind) {
-    case BasicBlockParent:
-      return U.BBRef;
-    case FunctionParent:
-      return U.BFRef;
-    }
-    llvm_unreachable("");
-  }
-
-  operator bool() const {
-    switch (ParentKind) {
-    case BasicBlockParent:
-      return U.BBRef.BB != nullptr;
-    case FunctionParent:
-      return U.BFRef.BF != nullptr;
-    }
-    llvm_unreachable("");
-  }
-
-  uint64_t getAddress() const {
-    switch (ParentKind) {
-    case BasicBlockParent:
-      return U.BBRef.getAddress();
-    case FunctionParent:
-      return U.BFRef.getAddress();
-    }
-    llvm_unreachable("");
-  }
-
-  BinaryFunction *getFunction() const {
-    switch (ParentKind) {
-    case FunctionParent:
-      return U.BFRef.BF;
-    case BasicBlockParent:
-      return U.BBRef.BB->getFunction();
-    }
-    llvm_unreachable("");
-  }
-
-  BinaryBasicBlock *getBasicBlock() const {
-    switch (ParentKind) {
-    case FunctionParent:
-      return nullptr;
-    case BasicBlockParent:
-      return U.BBRef.BB;
-    }
-    llvm_unreachable("");
-  }
-};
-
-raw_ostream &operator<<(raw_ostream &OS, const MCInstReference &);
-
 namespace PAuthGadgetScanner {
 
 // The report classes are designed to be used in an immutable manner.

bolt/lib/Core/CMakeLists.txt

@@ -32,6 +32,7 @@ add_llvm_library(LLVMBOLTCore
   GDBIndex.cpp
   HashUtilities.cpp
   JumpTable.cpp
+  MCInstUtils.cpp
   MCPlusBuilder.cpp
   ParallelUtilities.cpp
   Relocation.cpp