From 08e8dd7b9db7bb4a9de26d44c1cbfd24e869c014 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Wed, 27 Jul 2022 21:50:45 +0200
Subject: Vendor import of llvm-project main
 llvmorg-15-init-17826-g1f8ae9d7e7e4, the last commit before the upstream
 release/16.x branch was created.

---
 llvm/lib/ObjCopy/ELF/ELFObject.cpp | 52 ++++++++------------------------------
 1 file changed, 10 insertions(+), 42 deletions(-)

(limited to 'llvm/lib/ObjCopy/ELF/ELFObject.cpp')

diff --git a/llvm/lib/ObjCopy/ELF/ELFObject.cpp b/llvm/lib/ObjCopy/ELF/ELFObject.cpp
index 8b44c09023f1..b127e1b43b8e 100644
--- a/llvm/lib/ObjCopy/ELF/ELFObject.cpp
+++ b/llvm/lib/ObjCopy/ELF/ELFObject.cpp
@@ -434,41 +434,13 @@ Error SectionWriter::visit(const OwnedDataSection &Sec) {
   return Error::success();
 }
 
-static constexpr std::array<uint8_t, 4> ZlibGnuMagic = {{'Z', 'L', 'I', 'B'}};
-
-static bool isDataGnuCompressed(ArrayRef<uint8_t> Data) {
-  return Data.size() > ZlibGnuMagic.size() &&
-         std::equal(ZlibGnuMagic.begin(), ZlibGnuMagic.end(), Data.data());
-}
-
-template <class ELFT>
-static std::tuple<uint64_t, uint64_t>
-getDecompressedSizeAndAlignment(ArrayRef<uint8_t> Data) {
-  const bool IsGnuDebug = isDataGnuCompressed(Data);
-  const uint64_t DecompressedSize =
-      IsGnuDebug
-          ? support::endian::read64be(Data.data() + ZlibGnuMagic.size())
-          : reinterpret_cast<const Elf_Chdr_Impl<ELFT> *>(Data.data())->ch_size;
-  const uint64_t DecompressedAlign =
-      IsGnuDebug ? 1
-                 : reinterpret_cast<const Elf_Chdr_Impl<ELFT> *>(Data.data())
-                       ->ch_addralign;
-
-  return std::make_tuple(DecompressedSize, DecompressedAlign);
-}
-
 template <class ELFT>
 Error ELFSectionWriter<ELFT>::visit(const DecompressedSection &Sec) {
-  const size_t DataOffset = isDataGnuCompressed(Sec.OriginalData)
-                                ? (ZlibGnuMagic.size() + sizeof(Sec.Size))
-                                : sizeof(Elf_Chdr_Impl<ELFT>);
-
-  ArrayRef<uint8_t> CompressedContent(Sec.OriginalData.data() + DataOffset,
-                                      Sec.OriginalData.size() - DataOffset);
+  ArrayRef<uint8_t> Compressed =
+      Sec.OriginalData.slice(sizeof(Elf_Chdr_Impl<ELFT>));
   SmallVector<uint8_t, 128> DecompressedContent;
-  if (Error Err =
-          compression::zlib::uncompress(CompressedContent, DecompressedContent,
-                                        static_cast<size_t>(Sec.Size)))
+  if (Error Err = compression::zlib::uncompress(Compressed, DecompressedContent,
+                                                static_cast<size_t>(Sec.Size)))
     return createStringError(errc::invalid_argument,
                              "'" + Sec.Name + "': " + toString(std::move(Err)));
 
@@ -518,7 +490,7 @@ Error BinarySectionWriter::visit(const CompressedSection &Sec) {
 template <class ELFT>
 Error ELFSectionWriter<ELFT>::visit(const CompressedSection &Sec) {
   uint8_t *Buf = reinterpret_cast<uint8_t *>(Out.getBufferStart()) + Sec.Offset;
-  Elf_Chdr_Impl<ELFT> Chdr;
+  Elf_Chdr_Impl<ELFT> Chdr = {};
   switch (Sec.CompressionType) {
   case DebugCompressionType::None:
     std::copy(Sec.OriginalData.begin(), Sec.OriginalData.end(), Buf);
@@ -1731,15 +1703,11 @@ Expected<SectionBase &> ELFBuilder<ELFT>::makeSection(const Elf_Shdr &Shdr) {
     if (!Name)
       return Name.takeError();
 
-    if (Name->startswith(".zdebug") || (Shdr.sh_flags & ELF::SHF_COMPRESSED)) {
-      uint64_t DecompressedSize, DecompressedAlign;
-      std::tie(DecompressedSize, DecompressedAlign) =
-          getDecompressedSizeAndAlignment<ELFT>(*Data);
-      return Obj.addSection<CompressedSection>(
-          CompressedSection(*Data, DecompressedSize, DecompressedAlign));
-    }
-
-    return Obj.addSection<Section>(*Data);
+    if (!(Shdr.sh_flags & ELF::SHF_COMPRESSED))
+      return Obj.addSection<Section>(*Data);
+    auto *Chdr = reinterpret_cast<const Elf_Chdr_Impl<ELFT> *>(Data->data());
+    return Obj.addSection<CompressedSection>(
+        CompressedSection(*Data, Chdr->ch_size, Chdr->ch_addralign));
   }
   }
 }
-- 
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