IRMover: Merge flags LinkModuleInlineAsm and IsPerformingImport.

[pcc]

Summary

Currently these flags are always in the inverse of each other, so there is
no need to keep them separate.

Depends on D29470

[mehdi_amini]

Thanks for the cleanup!

LGTM.

llvm/include/llvm/Linker/IRMover.h

public:
 
   /// Move in the provide values in \p ValuesToLink from \p Src.
   ///
   /// - \p AddLazyFor is a call back that the IRMover will call when a global
   ///   value is referenced by one of the ValuesToLink (transitively) but was
   ///   not present in ValuesToLink. The GlobalValue and a ValueAdder callback
   ///   are passed as an argument, and the callback is expected to be called
   ///   if the GlobalValue needs to be added to the \p ValuesToLink and linked.
-  /// - \p LinkModuleInlineAsm is true if the ModuleInlineAsm string in Src
-  ///   should be linked with (concatenated into) the ModuleInlineAsm string
-  ///   for the destination module. It should be true for full LTO, but not
-  ///   when importing for ThinLTO, otherwise we can have duplicate symbols.
   /// - \p IsPerformingImport is true when this IR link is to perform ThinLTO
   ///   function importing from Src.
   Error move(std::unique_ptr<Module> Src, ArrayRef<GlobalValue *> ValuesToLink,
              std::function<void(GlobalValue &GV, ValueAdder Add)> AddLazyFor,
-             bool LinkModuleInlineAsm, bool IsPerformingImport);
+             bool IsPerformingImport);
   Module &getModule() { return Composite; }
 
 private:
   Module &Composite;
   IdentifiedStructTypeSet IdentifiedStructTypes;
   MDMapT SharedMDs; ///< A Metadata map to use for all calls to \a move().
 };
 
 } // End llvm namespace
 
 #endif

llvm/lib/LTO/LTO.cpp

if (Sym.getFlags() & object::BasicSymbolRef::SF_Common) {
       CommonRes.Prevailing |= Res.Prevailing;
     }
 
     // FIXME: use proposed local attribute for FinalDefinitionInLinkageUnit.
   }
 
   return RegularLTO.Mover->move(std::move(*MOrErr), Keep,
                                 [](GlobalValue &, IRMover::ValueAdder) {},
-                                /* LinkModuleInlineAsm */ true,
                                 /* IsPerformingImport */ false);
 }
 
 // Add a ThinLTO object to the link.
 // FIXME: This function should not need to take as many parameters once we have
 // a bitcode symbol table.
 Error LTO::addThinLTO(BitcodeModule BM, Module &M,
                       iterator_range<InputFile::symbol_iterator> Syms,

llvm/lib/Linker/IRMover.cpp

class IRLinker {
   DenseSet<GlobalValue *> ValuesToLink;
   std::vector<GlobalValue *> Worklist;
 
   void maybeAdd(GlobalValue *GV) {
     if (ValuesToLink.insert(GV).second)
       Worklist.push_back(GV);
   }
 
-  /// Flag whether the ModuleInlineAsm string in Src should be linked with
-  /// (concatenated into) the ModuleInlineAsm string for the destination
-  /// module. It should be true for full LTO, but not when importing for
-  /// ThinLTO, otherwise we can have duplicate symbols.
-  bool LinkModuleInlineAsm;
+  /// Whether we are importing globals for ThinLTO, as opposed to linking the
+  /// source module. If this flag is set, it means that we can rely on some
+  /// other object file to define any non-GlobalValue entities defined by the
+  /// source module. This currently causes us to not link retained types in
+  /// debug info metadata and module inline asm.
+  bool IsPerformingImport;
 
   /// Set to true when all global value body linking is complete (including
   /// lazy linking). Used to prevent metadata linking from creating new
   /// references.
   bool DoneLinkingBodies = false;
 
   /// The Error encountered during materialization. We use an Optional here to
   /// avoid needing to manage an unconsumed success value.
class IRLinker {
   void prepareCompileUnitsForImport();
   void linkNamedMDNodes();
 
 public:
   IRLinker(Module &DstM, MDMapT &SharedMDs,
            IRMover::IdentifiedStructTypeSet &Set, std::unique_ptr<Module> SrcM,
            ArrayRef<GlobalValue *> ValuesToLink,
            std::function<void(GlobalValue &, IRMover::ValueAdder)> AddLazyFor,
-           bool LinkModuleInlineAsm, bool IsPerformingImport)
+           bool IsPerformingImport)
       : DstM(DstM), SrcM(std::move(SrcM)), AddLazyFor(std::move(AddLazyFor)),
         TypeMap(Set), GValMaterializer(*this), LValMaterializer(*this),
-        SharedMDs(SharedMDs), LinkModuleInlineAsm(LinkModuleInlineAsm),
+        SharedMDs(SharedMDs), IsPerformingImport(IsPerformingImport),
         Mapper(ValueMap, RF_MoveDistinctMDs | RF_IgnoreMissingLocals, &TypeMap,
                &GValMaterializer),
         AliasMCID(Mapper.registerAlternateMappingContext(AliasValueMap,
                                                          &LValMaterializer)) {
     ValueMap.getMDMap() = std::move(SharedMDs);
     for (GlobalValue *GV : ValuesToLink)
       maybeAdd(GV);
     if (IsPerformingImport)
emitWarning("Linking two modules of different target triples: " +
                 SrcM->getModuleIdentifier() + "' is '" +
                 SrcM->getTargetTriple() + "' whereas '" +
                 DstM.getModuleIdentifier() + "' is '" + DstM.getTargetTriple() +
                 "'\n");
 
   DstM.setTargetTriple(mergeTriples(SrcTriple, DstTriple));
 
   // Append the module inline asm string.
-  if (LinkModuleInlineAsm && !SrcM->getModuleInlineAsm().empty()) {
+  if (!IsPerformingImport && !SrcM->getModuleInlineAsm().empty()) {
     if (DstM.getModuleInlineAsm().empty())
       DstM.setModuleInlineAsm(SrcM->getModuleInlineAsm());
     else
       DstM.setModuleInlineAsm(DstM.getModuleInlineAsm() + "\n" +
                               SrcM->getModuleInlineAsm());
   }
 
   // Loop over all of the linked values to compute type mappings.
IRMover::IRMover(Module &M) : Composite(M) {
   for (auto *MD : StructTypes.getVisitedMetadata()) {
     SharedMDs[MD].reset(const_cast<MDNode *>(MD));
   }
 }
 
 Error IRMover::move(
     std::unique_ptr<Module> Src, ArrayRef<GlobalValue *> ValuesToLink,
     std::function<void(GlobalValue &, ValueAdder Add)> AddLazyFor,
-    bool LinkModuleInlineAsm, bool IsPerformingImport) {
+    bool IsPerformingImport) {
   IRLinker TheIRLinker(Composite, SharedMDs, IdentifiedStructTypes,
                        std::move(Src), ValuesToLink, std::move(AddLazyFor),
-                       LinkModuleInlineAsm, IsPerformingImport);
+                       IsPerformingImport);
   Error E = TheIRLinker.run();
   Composite.dropTriviallyDeadConstantArrays();
   return E;
 }

llvm/lib/Linker/LinkModules.cpp

bool ModuleLinker::run() {
 
   // FIXME: Propagate Errors through to the caller instead of emitting
   // diagnostics.
   bool HasErrors = false;
   if (Error E = Mover.move(std::move(SrcM), ValuesToLink.getArrayRef(),
                            [this](GlobalValue &GV, IRMover::ValueAdder Add) {
                              addLazyFor(GV, Add);
                            },
-                           /* LinkModuleInlineAsm */ true,
                            /* IsPerformingImport */ false)) {
     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
       DstM.getContext().diagnose(LinkDiagnosticInfo(DS_Error, EIB.message()));
       HasErrors = true;
     });
   }
   if (HasErrors)
     return true;

llvm/lib/Transforms/IPO/FunctionImport.cpp

#endif
     if (PrintImports) {
       for (const auto *GV : GlobalsToImport)
         dbgs() << DestModule.getSourceFileName() << ": Import " << GV->getName()
                << " from " << SrcModule->getSourceFileName() << "\n";
     }
 
     if (Mover.move(std::move(SrcModule), GlobalsToImport.getArrayRef(),
                    [](GlobalValue &, IRMover::ValueAdder) {},
-                   /*LinkModuleInlineAsm=*/false, /*IsPerformingImport=*/true))
+                   /*IsPerformingImport=*/true))
       report_fatal_error("Function Import: link error");
 
     ImportedCount += GlobalsToImport.size();
     NumImportedModules++;
   }
 
   NumImportedFunctions += ImportedCount;