Revert r270569 (teach llvm-mc to generate compressed debug sections in zlib
style). It appears that current ELF linkers are not ready for this.
llvm-svn: 270638
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 4ba5bf1..900dcf5 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -979,6 +979,26 @@
return RelaSection;
}
+// Include the debug info compression header:
+// "ZLIB" followed by 8 bytes representing the uncompressed size of the section,
+// useful for consumers to preallocate a buffer to decompress into.
+static bool
+prependCompressionHeader(uint64_t Size,
+ SmallVectorImpl<char> &CompressedContents) {
+ const StringRef Magic = "ZLIB";
+ if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size())
+ return false;
+ if (sys::IsLittleEndianHost)
+ sys::swapByteOrder(Size);
+ CompressedContents.insert(CompressedContents.begin(),
+ Magic.size() + sizeof(Size), 0);
+ std::copy(Magic.begin(), Magic.end(), CompressedContents.begin());
+ std::copy(reinterpret_cast<char *>(&Size),
+ reinterpret_cast<char *>(&Size + 1),
+ CompressedContents.begin() + Magic.size());
+ return true;
+}
+
void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
const MCAsmLayout &Layout) {
MCSectionELF &Section = static_cast<MCSectionELF &>(Sec);
@@ -1009,30 +1029,12 @@
return;
}
- uint64_t HdrSize =
- is64Bit() ? sizeof(ELF::Elf32_Chdr) : sizeof(ELF::Elf64_Chdr);
- if (UncompressedData.size() <= HdrSize + CompressedContents.size()) {
+ if (!prependCompressionHeader(UncompressedData.size(), CompressedContents)) {
getStream() << UncompressedData;
return;
}
-
- // Set the compressed flag. That is zlib style.
- Section.setFlags(Section.getFlags() | ELF::SHF_COMPRESSED);
-
- // Platform specific header is followed by compressed data.
- if (is64Bit()) {
- // Write Elf64_Chdr header.
- write(static_cast<ELF::Elf64_Word>(ELF::ELFCOMPRESS_ZLIB));
- write(static_cast<ELF::Elf64_Word>(0)); // ch_reserved field.
- write(static_cast<ELF::Elf64_Xword>(UncompressedData.size()));
- write(static_cast<ELF::Elf64_Xword>(Sec.getAlignment()));
- } else {
- // Write Elf32_Chdr header otherwise.
- write(static_cast<ELF::Elf32_Word>(ELF::ELFCOMPRESS_ZLIB));
- write(static_cast<ELF::Elf32_Word>(UncompressedData.size()));
- write(static_cast<ELF::Elf32_Word>(Sec.getAlignment()));
- }
-
+ Asm.getContext().renameELFSection(&Section,
+ (".z" + SectionName.drop_front(1)).str());
getStream() << CompressedContents;
}