[llvm-lipo] Support object files with bitcode asm

[thevinster]

Summary

llvm-lipo crashes when trying to use inputs that contain bitcode asm instructions.
This happens when trying to create universal binaries for LLVM with LTO.
https://reviews.llvm.org/D118575 is a similar change that ran into this same issue, and I'm
mirroring the same change by registering the targets to fix this issue.

[alexander-shaposhnikov]

LGTM

llvm/test/tools/llvm-lipo/Inputs/arm64-asm.ll

+target triple = "arm64-apple-macosx11.0.0"
+
+module asm ".desc ___crashreporter_info__, 0x10"
+
+define void @somesymbol() {
+  ret void
+}

llvm/test/tools/llvm-lipo/Inputs/x86_64-asm.ll

+target triple = "x86_64-apple-macosx11.0.0"
+
+module asm ".desc ___crashreporter_info__, 0x10"
+
+define void @somesymbol() {
+  ret void
+}

llvm/test/tools/llvm-lipo/create-arch-asm.test

+# RUN: llvm-as %p/Inputs/arm64-asm.ll -o %t-arm64-asm.o
+# RUN: llvm-as %p/Inputs/x86_64-asm.ll -o %t-x86_64-asm.o
+
+# RUN: llvm-lipo %t-arm64-asm.o %t-x86_64-asm.o -create -output %t-universal.o
+# RUN: llvm-lipo %t-arm64-asm.o -arch x86_64 %t-x86_64-asm.o -create -output %t-universal-1.o
+# RUN: cmp %t-universal.o %t-universal-1.o
+# RUN: llvm-lipo -arch arm64 %t-arm64-asm.o -arch x86_64 %t-x86_64-asm.o -create -output %t-universal-2.o
+# RUN: cmp %t-universal.o %t-universal-2.o

llvm/tools/llvm-lipo/llvm-lipo.cpp

 #include "llvm/Object/MachOUniversalWriter.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/TargetSelect.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/TextAPI/Architecture.h"
 
 using namespace llvm;
 using namespace llvm::object;
 
 static const StringRef ToolName = "llvm-lipo";
 
if (const auto *MachO = dyn_cast<MachOObjectFile>(Binary)) {
     return;
   }
 
   // This should be always the case, as this is tested in readInputBinaries
   const auto *IR = cast<IRObjectFile>(Binary);
   Expected<Slice> SliceOrErr = createSliceFromIR(*IR, 0);
   if (!SliceOrErr)
     reportError(IR->getFileName(), SliceOrErr.takeError());
-  
   OS << SliceOrErr->getArchString() << " \n";
 }
 
 [[noreturn]] static void
 printArchs(LLVMContext &LLVMCtx, ArrayRef<OwningBinary<Binary>> InputBinaries) {
   assert(InputBinaries.size() == 1 && "Incorrect number of input binaries");
   printBinaryArchs(LLVMCtx, InputBinaries.front().getBinary(), outs());
   exit(EXIT_SUCCESS);
replaceSlices(LLVMContext &LLVMCtx,
   llvm::stable_sort(Slices);
   if (Error E = writeUniversalBinary(Slices, OutputFileName))
     reportError(std::move(E));
   exit(EXIT_SUCCESS);
 }
 
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
+  llvm::InitializeAllTargetInfos();
+  llvm::InitializeAllTargetMCs();
+  llvm::InitializeAllAsmParsers();
+
   Config C = parseLipoOptions(makeArrayRef(argv + 1, argc - 1));
   LLVMContext LLVMCtx;
   SmallVector<OwningBinary<Binary>, 1> InputBinaries =
       readInputBinaries(LLVMCtx, C.InputFiles);
 
   switch (C.ActionToPerform) {
   case LipoAction::VerifyArch:
     verifyArch(InputBinaries, C.VerifyArchList);