[llvm] [llvm-objcopy][ELF] Add an option to remove notes (PR #118739)

[Igor Kudrin via llvm-commits]

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@@ -609,6 +609,97 @@ static void addSymbol(Object &Obj, const NewSymbolInfo &SymInfo,
       Sec ? (uint16_t)SYMBOL_SIMPLE_INDEX : (uint16_t)SHN_ABS, 0);
 }
 
+namespace {
+struct RemoveNoteDetail {
+  struct DeletedRange {
+    uint64_t OldFrom;
+    uint64_t OldTo;
+    uint64_t NewPos;
+  };
+
+  template <class ELFT>
+  static std::vector<DeletedRange>
+  findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align,
+                    ArrayRef<RemoveNoteInfo> NotesToRemove);
+  static std::vector<uint8_t> updateData(ArrayRef<uint8_t> OldData,
+                                         ArrayRef<DeletedRange> ToRemove);
+};
+
+} // namespace
+
+template <class ELFT>
+std::vector<RemoveNoteDetail::DeletedRange>
+RemoveNoteDetail::findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align,
+                                    ArrayRef<RemoveNoteInfo> NotesToRemove) {
+  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT);
+  std::vector<DeletedRange> ToRemove;
+  uint64_t CurPos = 0;
+  uint64_t NewPos = 0;
+  while (CurPos + sizeof(Elf_Nhdr) <= Data.size()) {
+    auto Nhdr = reinterpret_cast<const Elf_Nhdr *>(Data.data() + CurPos);
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igorkudrin wrote:

`Elf_Nhdr` and `Elf_Note` use `llvm::support::detail::packed_endian_specific_integral` for fields, which handles reading data with any alignment.

https://github.com/llvm/llvm-project/pull/118739