[PATCH] D131618: [WIP][Do NOT review] LLD related changes for -ffat-lto-objects support

[Arda Unal via Phabricator via llvm-commits]

arda updated this revision to Diff 451904.
arda added a comment.

Reverting the magic number based design. FatLTO object files stay as ELF files
with embedded bitcode. That's also how GCC does it. Current change checks if
there is a bitcode section named .fatlto.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D131618/new/

https://reviews.llvm.org/D131618

Files:
  lld/ELF/InputFiles.cpp
  llvm/lib/Object/ObjectFile.cpp


Index: llvm/lib/Object/ObjectFile.cpp
===================================================================
--- llvm/lib/Object/ObjectFile.cpp
+++ llvm/lib/Object/ObjectFile.cpp
@@ -79,7 +79,7 @@
 bool ObjectFile::isSectionBitcode(DataRefImpl Sec) const {
   Expected<StringRef> NameOrErr = getSectionName(Sec);
   if (NameOrErr)
-    return *NameOrErr == ".llvmbc";
+    return *NameOrErr == ".llvmbc" || *NameOrErr == ".fatlto";
   consumeError(NameOrErr.takeError());
   return false;
 }
Index: lld/ELF/InputFiles.cpp
===================================================================
--- lld/ELF/InputFiles.cpp
+++ lld/ELF/InputFiles.cpp
@@ -1712,9 +1712,16 @@
 
 InputFile *elf::createObjectFile(MemoryBufferRef mb, StringRef archiveName,
                                  uint64_t offsetInArchive) {
+  Expected<MemoryBufferRef> bcData = IRObjectFile::findBitcodeInMemBuffer(mb);
+
+  // If it is a fatLTO object file
+  if (!errorToBool(bcData .takeError()))
+    return make<BitcodeFile>(*bcData, archiveName, offsetInArchive, /*lazy=*/false);
+
   if (isBitcode(mb))
     return make<BitcodeFile>(mb, archiveName, offsetInArchive, /*lazy=*/false);
 
+
   switch (getELFKind(mb, archiveName)) {
   case ELF32LEKind:
     return make<ObjFile<ELF32LE>>(mb, archiveName);


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