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

[Arda Unal via Phabricator via llvm-commits]

arda created this revision.
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If -ffat-lto-objects enabled and the input files are FatLTO object
files, LTO optimized executable is generated using the LTO bitcode sections
that are embbeded in these FatLTO object files. Otherwise, regular linking is
done using the assembly section in these FatLTO object files.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D131618

Files:
  lld/ELF/Driver.cpp
  lld/ELF/InputFiles.h
  llvm/include/llvm/BinaryFormat/Magic.h
  llvm/lib/BinaryFormat/Magic.cpp
  llvm/lib/Object/Binary.cpp
  llvm/lib/Object/ObjectFile.cpp


Index: llvm/lib/Object/ObjectFile.cpp
===================================================================
--- llvm/lib/Object/ObjectFile.cpp
+++ llvm/lib/Object/ObjectFile.cpp
@@ -157,6 +157,7 @@
   case file_magic::elf_executable:
   case file_magic::elf_shared_object:
   case file_magic::elf_core:
+  case file_magic::fatlto_object:
     return createELFObjectFile(Object, InitContent);
   case file_magic::macho_object:
   case file_magic::macho_executable:
Index: llvm/lib/Object/Binary.cpp
===================================================================
--- llvm/lib/Object/Binary.cpp
+++ llvm/lib/Object/Binary.cpp
@@ -55,6 +55,7 @@
   case file_magic::elf_executable:
   case file_magic::elf_shared_object:
   case file_magic::elf_core:
+  case file_magic::fatlto_object:
   case file_magic::goff_object:
   case file_magic::macho_object:
   case file_magic::macho_executable:
Index: llvm/lib/BinaryFormat/Magic.cpp
===================================================================
--- llvm/lib/BinaryFormat/Magic.cpp
+++ llvm/lib/BinaryFormat/Magic.cpp
@@ -79,6 +79,12 @@
       return file_magic::offload_binary;
     break;
 
+  case 0xFA:
+    if (startswith(Magic, "\xFAtl\x70")) {
+      return file_magic::fatlto_object;
+    }
+    break;
+
   case 0xDE: // 0x0B17C0DE = BC wraper
     if (startswith(Magic, "\xDE\xC0\x17\x0B"))
       return file_magic::bitcode;
Index: llvm/include/llvm/BinaryFormat/Magic.h
===================================================================
--- llvm/include/llvm/BinaryFormat/Magic.h
+++ llvm/include/llvm/BinaryFormat/Magic.h
@@ -54,6 +54,7 @@
     cuda_fatbinary,      ///< CUDA Fatbinary object file
     offload_binary,      ///< LLVM offload object file
     dxcontainer_object,  ///< DirectX container file
+    fatlto_object,       ///< FatLTO object file
   };
 
   bool is_object() const { return V != unknown; }
Index: lld/ELF/InputFiles.h
===================================================================
--- lld/ELF/InputFiles.h
+++ lld/ELF/InputFiles.h
@@ -380,6 +380,10 @@
   return identify_magic(mb.getBuffer()) == llvm::file_magic::bitcode;
 }
 
+inline bool isFatLTOObject(MemoryBufferRef mb) {
+  return identify_magic(mb.getBuffer()) == llvm::file_magic::fatlto_object;
+}
+
 std::string replaceThinLTOSuffix(StringRef path);
 
 } // namespace elf
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -267,6 +267,7 @@
         make<SharedFile>(mbref, withLOption ? path::filename(path) : path));
     return;
   case file_magic::bitcode:
+  case file_magic::fatlto_object:
   case file_magic::elf_relocatable:
     if (inLib)
       files.push_back(createLazyFile(mbref, "", 0));


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