[NFC] WebAssembly build break #2

[jfb]

Summary

Same as r332530, move WasmSymbol::dump to an implementation file to avoid linker
issues when the dump function is seen in the header, doesn't get eliminated, and
then linking fails because of the missing dependency.

rdar://problem/40258137

[vsk]

LGTM, I've confirmed this fixes my local modules build.

[sbc100]

Why does this work? Doesn't LLVM_DUMP_METHOD force this method into the link regardless? I though that was the point of it.. so it would never be eliminated.

[vsk]

IIUC the dump method is still available via libObject, which should be sufficient?

[jfb]

In D46985#1102200, @sbc100 wrote:

Why does this work? Doesn't LLVM_DUMP_METHOD force this method into the link regardless? I though that was the point of it.. so it would never be eliminated.

I may be misunderstanding: I thought this was here for lldb's usage purpose (or any debugger, so you can dump while debugging), so if it gets generated then it cannot get eliminated even if unused. If you only see the header you only have a forward declaration, so there's nothing that could be eliminated anyways.

llvm/trunk/include/llvm/Object/Wasm.h

public:
 
   unsigned getVisibility() const {
     return Info.Flags & wasm::WASM_SYMBOL_VISIBILITY_MASK;
   }
 
   void print(raw_ostream &Out) const;
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-  LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
+  LLVM_DUMP_METHOD void dump() const;
 #endif
 };
 
 struct WasmSection {
   WasmSection() = default;
 
   uint32_t Type = 0; // Section type (See below)
   uint32_t Offset = 0; // Offset with in the file

llvm/trunk/lib/Object/WasmObjectFile.cpp

if (!isTypeData()) {
     Out << ", ElemIndex=" << Info.ElementIndex;
   } else if (isDefined()) {
     Out << ", Segment=" << Info.DataRef.Segment;
     Out << ", Offset=" << Info.DataRef.Offset;
     Out << ", Size=" << Info.DataRef.Size;
   }
 }
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
+#endif
+
 Expected<std::unique_ptr<WasmObjectFile>>
 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
   Error Err = Error::success();
   auto ObjectFile = llvm::make_unique<WasmObjectFile>(Buffer, Err);
   if (Err)
     return std::move(Err);
 
   return std::move(ObjectFile);