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[BOLT] Refactor MCInstReference and move it to Core (NFC) (llvm#138655)
Refactor MCInstReference class and move it from PAuth gadget scanner to Core. MCInstReference is a class representing a constant reference to an instruction inside a parent entity - either inside a basic block (which has a reference to its parent function) or directly inside a function (when CFG information is not available).
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‎bolt/include/bolt/Core/MCInstUtils.h

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//===- bolt/Core/MCInstUtils.h ----------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef BOLT_CORE_MCINSTUTILS_H
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#define BOLT_CORE_MCINSTUTILS_H
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#include "bolt/Core/BinaryBasicBlock.h"
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#include <map>
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#include <variant>
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namespace llvm {
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namespace bolt {
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class BinaryFunction;
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/// MCInstReference represents a reference to a constant MCInst as stored either
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/// in a BinaryFunction (i.e. before a CFG is created), or in a BinaryBasicBlock
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/// (after a CFG is created).
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class MCInstReference {
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using nocfg_const_iterator = std::map<uint32_t, MCInst>::const_iterator;
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// Two cases are possible:
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// * functions with CFG reconstructed - a function stores a collection of
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// basic blocks, each basic block stores a contiguous vector of MCInst
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// * functions without CFG - there are no basic blocks created,
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// the instructions are directly stored in std::map in BinaryFunction
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//
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// In both cases, the direct parent of MCInst is stored together with an
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// iterator pointing to the instruction.
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// Helper struct: CFG is available, the direct parent is a basic block,
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// iterator's type is `MCInst *`.
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struct RefInBB {
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RefInBB(const BinaryBasicBlock *BB, const MCInst *Inst)
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: BB(BB), It(Inst) {}
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RefInBB(const RefInBB &Other) = default;
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RefInBB &operator=(const RefInBB &Other) = default;
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const BinaryBasicBlock *BB;
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BinaryBasicBlock::const_iterator It;
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bool operator==(const RefInBB &Other) const {
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return BB == Other.BB && It == Other.It;
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}
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};
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// Helper struct: CFG is *not* available, the direct parent is a function,
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// iterator's type is std::map<uint32_t, MCInst>::iterator (the mapped value
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// is an instruction's offset).
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struct RefInBF {
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RefInBF(const BinaryFunction *BF, nocfg_const_iterator It)
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: BF(BF), It(It) {}
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RefInBF(const RefInBF &Other) = default;
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RefInBF &operator=(const RefInBF &Other) = default;
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const BinaryFunction *BF;
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nocfg_const_iterator It;
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bool operator==(const RefInBF &Other) const {
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return BF == Other.BF && It->first == Other.It->first;
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}
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};
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std::variant<RefInBB, RefInBF> Reference;
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// Utility methods to be used like this:
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//
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// if (auto *Ref = tryGetRefInBB())
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// return Ref->doSomething(...);
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// return getRefInBF().doSomethingElse(...);
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const RefInBB *tryGetRefInBB() const {
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assert(std::get_if<RefInBB>(&Reference) ||
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std::get_if<RefInBF>(&Reference));
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return std::get_if<RefInBB>(&Reference);
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}
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const RefInBF &getRefInBF() const {
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assert(std::get_if<RefInBF>(&Reference));
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return *std::get_if<RefInBF>(&Reference);
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}
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public:
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/// Constructs an empty reference.
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MCInstReference() : Reference(RefInBB(nullptr, nullptr)) {}
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/// Constructs a reference to the instruction inside the basic block.
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MCInstReference(const BinaryBasicBlock *BB, const MCInst *Inst)
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: Reference(RefInBB(BB, Inst)) {
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assert(BB && Inst && "Neither BB nor Inst should be nullptr");
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}
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/// Constructs a reference to the instruction inside the basic block.
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MCInstReference(const BinaryBasicBlock *BB, unsigned Index)
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: Reference(RefInBB(BB, &BB->getInstructionAtIndex(Index))) {
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assert(BB && "Basic block should not be nullptr");
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}
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/// Constructs a reference to the instruction inside the function without
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/// CFG information.
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MCInstReference(const BinaryFunction *BF, nocfg_const_iterator It)
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: Reference(RefInBF(BF, It)) {
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assert(BF && "Function should not be nullptr");
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}
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/// Locates an instruction inside a function and returns a reference.
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static MCInstReference get(const MCInst *Inst, const BinaryFunction &BF);
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bool operator==(const MCInstReference &Other) const {
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return Reference == Other.Reference;
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}
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const MCInst &getMCInst() const {
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assert(!empty() && "Empty reference");
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if (auto *Ref = tryGetRefInBB())
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return *Ref->It;
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return getRefInBF().It->second;
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}
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operator const MCInst &() const { return getMCInst(); }
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bool empty() const {
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if (auto *Ref = tryGetRefInBB())
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return Ref->BB == nullptr;
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return getRefInBF().BF == nullptr;
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}
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bool hasCFG() const { return !empty() && tryGetRefInBB() != nullptr; }
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const BinaryFunction *getFunction() const {
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assert(!empty() && "Empty reference");
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if (auto *Ref = tryGetRefInBB())
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return Ref->BB->getFunction();
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return getRefInBF().BF;
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}
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const BinaryBasicBlock *getBasicBlock() const {
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assert(!empty() && "Empty reference");
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if (auto *Ref = tryGetRefInBB())
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return Ref->BB;
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return nullptr;
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}
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raw_ostream &print(raw_ostream &OS) const;
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};
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static inline raw_ostream &operator<<(raw_ostream &OS,
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const MCInstReference &Ref) {
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return Ref.print(OS);
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}
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} // namespace bolt
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} // namespace llvm
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#endif

‎bolt/include/bolt/Passes/PAuthGadgetScanner.h

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

‎bolt/lib/Core/CMakeLists.txt

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GDBIndex.cpp
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HashUtilities.cpp
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JumpTable.cpp
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MCInstUtils.cpp
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MCPlusBuilder.cpp
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ParallelUtilities.cpp
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Relocation.cpp

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