Fix TBDGen datalayout

This patch fixes the call to get the datalayout from the clang module.
Clang no longer holds onto the DataLayout object, so we have to do that
if we want to keep it around. Rather than instanciating it early, we can
just hold onto the string description, which clang does keep around, and
only construct the actual DataLayout once we need it.

Author: etcwilde

include/swift/AST/TBDGenRequests.h

@@ -70,7 +70,7 @@ class TBDGenDescriptor final {
   const TBDGenOptions &getOptions() const { return Opts; }
   TBDGenOptions &getOptions() { return Opts; }
 
-  const llvm::DataLayout &getDataLayout() const;
+  const StringRef getDataLayoutString() const;
   const llvm::Triple &getTarget() const;
 
   bool operator==(const TBDGenDescriptor &other) const;

lib/TBDGen/TBDGen.cpp

@@ -68,7 +68,7 @@ static bool isGlobalOrStaticVar(VarDecl *VD) {
 
 TBDGenVisitor::TBDGenVisitor(const TBDGenDescriptor &desc,
                              APIRecorder &recorder)
-    : TBDGenVisitor(desc.getTarget(), desc.getDataLayout(),
+    : TBDGenVisitor(desc.getTarget(), desc.getDataLayoutString(),
                     desc.getParentModule(), desc.getOptions(), recorder) {}
 
 void TBDGenVisitor::addSymbolInternal(StringRef name, SymbolKind kind,
@@ -390,7 +390,9 @@ void TBDGenVisitor::addSymbol(StringRef name, SymbolSource source,
   if (kind == SymbolKind::ObjectiveCClass) {
     mangled = name;
   } else {
-    llvm::Mangler::getNameWithPrefix(mangled, name, DataLayout);
+    if (!DataLayout)
+      DataLayout = llvm::DataLayout(DataLayoutDescription);
+    llvm::Mangler::getNameWithPrefix(mangled, name, *DataLayout);
   }
 
   addSymbolInternal(mangled, kind, source);

lib/TBDGen/TBDGenRequests.cpp

@@ -48,10 +48,10 @@ ModuleDecl *TBDGenDescriptor::getParentModule() const {
   return Input.get<FileUnit *>()->getParentModule();
 }
 
-const llvm::DataLayout &TBDGenDescriptor::getDataLayout() const {
+const StringRef TBDGenDescriptor::getDataLayoutString() const {
   auto &ctx = getParentModule()->getASTContext();
   auto *clang = static_cast<ClangImporter *>(ctx.getClangModuleLoader());
-  return clang->getTargetInfo().getDataLayout();
+  return llvm::StringRef(clang->getTargetInfo().getDataLayoutString());
 }
 
 const llvm::Triple &TBDGenDescriptor::getTarget() const {

lib/TBDGen/TBDGenVisitor.h

@@ -92,7 +92,9 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
   llvm::StringSet<> DuplicateSymbolChecker;
 #endif
 
-  const llvm::DataLayout &DataLayout;
+  Optional<llvm::DataLayout> DataLayout = None;
+  const StringRef DataLayoutDescription;
+
   UniversalLinkageInfo UniversalLinkInfo;
   ModuleDecl *SwiftModule;
   const TBDGenOptions &Opts;
@@ -167,10 +169,10 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
                                   const AutoDiffConfig &config);
 
 public:
-  TBDGenVisitor(const llvm::Triple &target, const llvm::DataLayout &dataLayout,
+  TBDGenVisitor(const llvm::Triple &target, const StringRef dataLayoutString,
                 ModuleDecl *swiftModule, const TBDGenOptions &opts,
                 APIRecorder &recorder)
-      : DataLayout(dataLayout),
+      : DataLayoutDescription(dataLayoutString),
         UniversalLinkInfo(target, opts.HasMultipleIGMs, /*forcePublic*/ false),
         SwiftModule(swiftModule), Opts(opts), recorder(recorder),
         previousInstallNameMap(parsePreviousModuleInstallNameMap()) {}