[llvm-branch-commits] [llvm] [BOLT] Factor out MCInstReference from gadget scanner (NFC) (PR #138655)

[Maksim Panchenko via llvm-branch-commits]

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@@ -0,0 +1,168 @@
+//===- 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 <tuple>
+#include <variant>
+
+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).
+class MCInstReference {
+  using nocfg_const_iterator = std::map<uint32_t, MCInst>::const_iterator;
+
+  // 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
+  // iterator pointing to the instruction.
+
+  // Helper struct: CFG is available, the direct parent is a basic block,
+  // iterator's type is `MCInst *`.
+  struct RefInBB {
+    RefInBB(const BinaryBasicBlock *BB, const MCInst *Inst)
+        : BB(BB), It(Inst) {}
+    RefInBB(const RefInBB &Other) = default;
+    RefInBB &operator=(const RefInBB &Other) = default;
+
+    const BinaryBasicBlock *BB;
+    BinaryBasicBlock::const_iterator It;
+
+    bool operator<(const RefInBB &Other) const {
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maksfb wrote:

What are expected uses for this comparison? I'm concerned about non-deterministic order of `BinaryBasicBlock *`.

https://github.com/llvm/llvm-project/pull/138655