Revert "[gold] Add preliminary FatLTO support to the Gold plugin"

This reverts commit 421e402. One of the test needs a requires line, but we've also seen some issues for downstream projects that may need coordination, so I'm reverting this for until we can address those issues. see https://reviews.llvm.org/D152973#4520240 for context.
llvm · Jul 20, 2023 · 2f34288 · 2f34288
1 parent eb3f2fe
commit 2f34288
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Showing 8 changed files with 22 additions and 152 deletions.
diff --git a/llvm/lib/Object/ObjectFile.cpp b/llvm/lib/Object/ObjectFile.cpp
@@ -79,7 +79,7 @@ uint32_t ObjectFile::getSymbolAlignment(DataRefImpl DRI) const { return 0; }
 bool ObjectFile::isSectionBitcode(DataRefImpl Sec) const {
   Expected<StringRef> NameOrErr = getSectionName(Sec);
   if (NameOrErr)
-    return *NameOrErr == ".llvm.lto";
+    return *NameOrErr == ".llvmbc" || *NameOrErr == ".llvm.lto";
   consumeError(NameOrErr.takeError());
   return false;
 }

diff --git a/llvm/test/LTO/X86/Inputs/bcsection.macho.s b/llvm/test/LTO/X86/Inputs/bcsection.macho.s
@@ -2,4 +2,4 @@
 .asciz "Wrong Section"
 
 .section __LLVM,__bitcode
-.incbin "llvm.lto.section.bc"
+.incbin "bcsection.bc"
diff --git a/llvm/test/LTO/X86/Inputs/llvm.lto.section.s b/llvm/test/LTO/X86/Inputs/llvm.lto.section.s
diff --git a/llvm/test/LTO/X86/bcsection.ll b/llvm/test/LTO/X86/bcsection.ll
@@ -2,17 +2,23 @@
 ; RUN: llvm-as -o %t/bcsection.bc %s
 
 ; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-pc-win32 -o %t/bcsection.coff.bco %p/Inputs/bcsection.s
-; RUN: llvm-nm %t/bcsection.coff.bco | FileCheck %s --allow-empty
-; RUN: not llvm-lto -exported-symbol=main -exported-symbol=_main -o %t/bcsection.coff.o %t/bcsection.coff.bco
+; RUN: llvm-nm %t/bcsection.coff.bco | FileCheck %s
+; RUN: llvm-lto -exported-symbol=main -exported-symbol=_main -o %t/bcsection.coff.o %t/bcsection.coff.bco
+; RUN: llvm-nm %t/bcsection.coff.o | FileCheck %s
 
 ; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-unknown-linux-gnu -o %t/bcsection.elf.bco %p/Inputs/bcsection.s
-; RUN: llvm-nm %t/bcsection.elf.bco | FileCheck %s --allow-empty
-; RUN: not llvm-lto -exported-symbol=main -exported-symbol=_main -o %t/bcsection.elf.o %t/bcsection.elf.bco
+; RUN: llvm-nm %t/bcsection.elf.bco | FileCheck %s
+; RUN: llvm-lto -exported-symbol=main -exported-symbol=_main -o %t/bcsection.elf.o %t/bcsection.elf.bco
+; RUN: llvm-nm %t/bcsection.elf.o | FileCheck %s
+
+; RUN: llvm-mc -I=%t -filetype=obj -triple=x86_64-apple-darwin11 -o %t/bcsection.macho.bco %p/Inputs/bcsection.macho.s
+; RUN: llvm-nm %t/bcsection.macho.bco | FileCheck %s
+; RUN: llvm-lto -exported-symbol=main -exported-symbol=_main -o %t/bcsection.macho.o %t/bcsection.macho.bco
+; RUN: llvm-nm %t/bcsection.macho.o | FileCheck %s
 
 target triple = "x86_64-unknown-linux-gnu"
 
-;; The .llvmbc section is not intended for use with LTO, so there should be nothing here
-; CHECK-NOT: main
+; CHECK: main
 define i32 @main() {
   ret i32 0
 }
diff --git a/llvm/test/LTO/X86/llvm.lto.section.ll b/llvm/test/LTO/X86/llvm.lto.section.ll
diff --git a/llvm/test/tools/gold/X86/fatlto/fatlto.invalid.s b/llvm/test/tools/gold/X86/fatlto/fatlto.invalid.s
diff --git a/llvm/test/tools/gold/X86/fatlto/fatlto.test b/llvm/test/tools/gold/X86/fatlto/fatlto.test
diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
@@ -538,6 +538,14 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
     BufferRef = Buffer->getMemBufferRef();
   }
 
+  // Only use bitcode files for LTO.  InputFile::create() will load bitcode
+  // from the .llvmbc section within a binary object, this bitcode is typically
+  // generated by -fembed-bitcode and is not to be used by LLVMgold.so for LTO.
+  if (identify_magic(BufferRef.getBuffer()) != file_magic::bitcode) {
+    *claimed = 0;
+    return LDPS_OK;
+  }
+
   *claimed = 1;
 
   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);