[llvm-objcopy][ELF] Add OriginalType & OriginalFlags

`llvm::objcopy::elf::*Section::classof` matches Type and Flags, yet Type
and Flags are mutable (by setSectionFlagsAndTypes and upcoming
--only-keep-debug feature). Add OriginalType & OriginalFlags to be used
in classof, to prevent classof results from changing.

Reviewed By: jakehehrlich, jhenderson, alexshap

Differential Revision: https://reviews.llvm.org/D69739

Author: MaskRay

llvm/tools/llvm-objcopy/ELF/Object.cpp

@@ -1009,7 +1009,7 @@ void GnuDebugLinkSection::init(StringRef File) {
   Size = alignTo(FileName.size() + 1, 4) + 4;
   // The CRC32 will only be aligned if we align the whole section.
   Align = 4;
-  Type = ELF::SHT_PROGBITS;
+  Type = OriginalType = ELF::SHT_PROGBITS;
   Name = ".gnu_debuglink";
   // For sections not found in segments, OriginalOffset is only used to
   // establish the order that sections should go in. By using the maximum
@@ -1521,8 +1521,8 @@ template <class ELFT> void ELFBuilder<ELFT>::readSectionHeaders() {
     }
     auto &Sec = makeSection(Shdr);
     Sec.Name = unwrapOrError(ElfFile.getSectionName(&Shdr));
-    Sec.Type = Shdr.sh_type;
-    Sec.Flags = Shdr.sh_flags;
+    Sec.Type = Sec.OriginalType = Shdr.sh_type;
+    Sec.Flags = Sec.OriginalFlags = Shdr.sh_flags;
     Sec.Addr = Shdr.sh_addr;
     Sec.Offset = Shdr.sh_offset;
     Sec.OriginalOffset = Shdr.sh_offset;

llvm/tools/llvm-objcopy/ELF/Object.h

@@ -384,10 +384,13 @@ class SectionBase {
   std::string Name;
   Segment *ParentSegment = nullptr;
   uint64_t HeaderOffset;
-  uint64_t OriginalOffset = std::numeric_limits<uint64_t>::max();
   uint32_t Index;
   bool HasSymbol = false;
 
+  uint64_t OriginalFlags = 0;
+  uint64_t OriginalType = ELF::SHT_NULL;
+  uint64_t OriginalOffset = std::numeric_limits<uint64_t>::max();
+
   uint64_t Addr = 0;
   uint64_t Align = 1;
   uint32_t EntrySize = 0;
@@ -490,17 +493,17 @@ class OwnedDataSection : public SectionBase {
   OwnedDataSection(StringRef SecName, ArrayRef<uint8_t> Data)
       : Data(std::begin(Data), std::end(Data)) {
     Name = SecName.str();
-    Type = ELF::SHT_PROGBITS;
+    Type = OriginalType = ELF::SHT_PROGBITS;
     Size = Data.size();
     OriginalOffset = std::numeric_limits<uint64_t>::max();
   }
 
   OwnedDataSection(const Twine &SecName, uint64_t SecAddr, uint64_t SecFlags,
                    uint64_t SecOff) {
     Name = SecName.str();
-    Type = ELF::SHT_PROGBITS;
+    Type = OriginalType = ELF::SHT_PROGBITS;
     Addr = SecAddr;
-    Flags = SecFlags;
+    Flags = OriginalFlags = SecFlags;
     OriginalOffset = SecOff;
   }
 
@@ -530,7 +533,7 @@ class CompressedSection : public SectionBase {
   void accept(MutableSectionVisitor &Visitor) override;
 
   static bool classof(const SectionBase *S) {
-    return (S->Flags & ELF::SHF_COMPRESSED) ||
+    return (S->OriginalFlags & ELF::SHF_COMPRESSED) ||
            (StringRef(S->Name).startswith(".zdebug"));
   }
 };
@@ -543,7 +546,7 @@ class DecompressedSection : public SectionBase {
       : SectionBase(Sec) {
     Size = Sec.getDecompressedSize();
     Align = Sec.getDecompressedAlign();
-    Flags = (Flags & ~ELF::SHF_COMPRESSED);
+    Flags = OriginalFlags = (Flags & ~ELF::SHF_COMPRESSED);
     if (StringRef(Name).startswith(".zdebug"))
       Name = "." + Name.substr(2);
   }
@@ -567,7 +570,7 @@ class StringTableSection : public SectionBase {
 
 public:
   StringTableSection() : StrTabBuilder(StringTableBuilder::ELF) {
-    Type = ELF::SHT_STRTAB;
+    Type = OriginalType = ELF::SHT_STRTAB;
   }
 
   void addString(StringRef Name);
@@ -577,9 +580,9 @@ class StringTableSection : public SectionBase {
   void accept(MutableSectionVisitor &Visitor) override;
 
   static bool classof(const SectionBase *S) {
-    if (S->Flags & ELF::SHF_ALLOC)
+    if (S->OriginalFlags & ELF::SHF_ALLOC)
       return false;
-    return S->Type == ELF::SHT_STRTAB;
+    return S->OriginalType == ELF::SHT_STRTAB;
   }
 };
 
@@ -648,7 +651,7 @@ class SectionIndexSection : public SectionBase {
     Name = ".symtab_shndx";
     Align = 4;
     EntrySize = 4;
-    Type = ELF::SHT_SYMTAB_SHNDX;
+    Type = OriginalType = ELF::SHT_SYMTAB_SHNDX;
   }
 };
 
@@ -666,7 +669,7 @@ class SymbolTableSection : public SectionBase {
   using SymPtr = std::unique_ptr<Symbol>;
 
 public:
-  SymbolTableSection() { Type = ELF::SHT_SYMTAB; }
+  SymbolTableSection() { Type = OriginalType = ELF::SHT_SYMTAB; }
 
   void addSymbol(Twine Name, uint8_t Bind, uint8_t Type, SectionBase *DefinedIn,
                  uint64_t Value, uint8_t Visibility, uint16_t Shndx,
@@ -695,7 +698,7 @@ class SymbolTableSection : public SectionBase {
       const DenseMap<SectionBase *, SectionBase *> &FromTo) override;
 
   static bool classof(const SectionBase *S) {
-    return S->Type == ELF::SHT_SYMTAB;
+    return S->OriginalType == ELF::SHT_SYMTAB;
   }
 };
 
@@ -724,7 +727,7 @@ class RelocationSectionBase : public SectionBase {
   void setSection(SectionBase *Sec) { SecToApplyRel = Sec; }
 
   static bool classof(const SectionBase *S) {
-    return S->Type == ELF::SHT_REL || S->Type == ELF::SHT_RELA;
+    return S->OriginalType == ELF::SHT_REL || S->OriginalType == ELF::SHT_RELA;
   }
 };
 
@@ -762,9 +765,9 @@ class RelocationSection
       const DenseMap<SectionBase *, SectionBase *> &FromTo) override;
 
   static bool classof(const SectionBase *S) {
-    if (S->Flags & ELF::SHF_ALLOC)
+    if (S->OriginalFlags & ELF::SHF_ALLOC)
       return false;
-    return S->Type == ELF::SHT_REL || S->Type == ELF::SHT_RELA;
+    return S->OriginalType == ELF::SHT_REL || S->OriginalType == ELF::SHT_RELA;
   }
 };
 
@@ -799,7 +802,7 @@ class GroupSection : public SectionBase {
       const DenseMap<SectionBase *, SectionBase *> &FromTo) override;
 
   static bool classof(const SectionBase *S) {
-    return S->Type == ELF::SHT_GROUP;
+    return S->OriginalType == ELF::SHT_GROUP;
   }
 };
 
@@ -808,7 +811,7 @@ class DynamicSymbolTableSection : public Section {
   explicit DynamicSymbolTableSection(ArrayRef<uint8_t> Data) : Section(Data) {}
 
   static bool classof(const SectionBase *S) {
-    return S->Type == ELF::SHT_DYNSYM;
+    return S->OriginalType == ELF::SHT_DYNSYM;
   }
 };
 
@@ -817,7 +820,7 @@ class DynamicSection : public Section {
   explicit DynamicSection(ArrayRef<uint8_t> Data) : Section(Data) {}
 
   static bool classof(const SectionBase *S) {
-    return S->Type == ELF::SHT_DYNAMIC;
+    return S->OriginalType == ELF::SHT_DYNAMIC;
   }
 };
 
@@ -838,9 +841,9 @@ class DynamicRelocationSection
       function_ref<bool(const SectionBase *)> ToRemove) override;
 
   static bool classof(const SectionBase *S) {
-    if (!(S->Flags & ELF::SHF_ALLOC))
+    if (!(S->OriginalFlags & ELF::SHF_ALLOC))
       return false;
-    return S->Type == ELF::SHT_REL || S->Type == ELF::SHT_RELA;
+    return S->OriginalType == ELF::SHT_REL || S->OriginalType == ELF::SHT_RELA;
   }
 };