[llvm-nm] Always use opaque pointers (PR55506)

[nikic]

Summary

Always enable opaque pointers in llvm-nm, because the tool doesn't actually care, and this allows us to read both typed pointer and opaque pointer bitcode files in one archive. Previously this depended on the order inside the archive (it would work with an opaque pointer bitcode file first, but fail with a typed pointer bitcode file first).

Fixes https://github.com/llvm/llvm-project/issues/55506.

llvm/test/tools/llvm-nm/opaque-pointers.ll

+; RUN: llvm-as -opaque-pointers=0 < %s > %t.typed.bc
+; RUN: llvm-as -opaque-pointers=1 < %s > %t.opaque.bc
+; RUN: llvm-ar cr %t.a %t.typed.bc %t.opaque.bc
+; RUN: llvm-nm --just-symbol-name %t.a | FileCheck %s
+
+; CHECK-LABEL: typed.bc:
+; CHECK: test
+; CHECK-LABEL: opaque.bc:
+; CHECK: test
+
+define void @test() {
+  ret void
+}

llvm/tools/llvm-nm/llvm-nm.cpp

 
 static std::vector<NMSymbol> dumpSymbolNamesFromFile(StringRef Filename) {
   std::vector<NMSymbol> SymbolList;
   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
       MemoryBuffer::getFileOrSTDIN(Filename);
   if (error(BufferOrErr.getError(), Filename))
     return SymbolList;
 
+  // Always enable opaque pointers, to handle archives with mixed typed and
+  // opaque pointer bitcode files gracefully. As we're only reading symbols,
+  // the used pointer types don't matter.
   LLVMContext Context;
+  Context.setOpaquePointers(true);
   LLVMContext *ContextPtr = NoLLVMBitcode ? nullptr : &Context;
   Expected<std::unique_ptr<Binary>> BinaryOrErr =
       createBinary(BufferOrErr.get()->getMemBufferRef(), ContextPtr);
   if (!BinaryOrErr) {
     error(BinaryOrErr.takeError(), Filename);
     return SymbolList;
   }
   Binary &Bin = *BinaryOrErr.get();