Be lazy about loading metadata in IRObjectFile.

This speeds up llvm-ar building lib64/libclangSema.a with debug IR files
from 8.658015807 seconds to just 0.351036519 seconds :-)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232221 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/GVMaterializer.h

@@ -53,6 +53,8 @@ public:
   ///
   virtual std::error_code MaterializeModule(Module *M) = 0;
 
+  virtual std::error_code materializeMetadata() = 0;
+
   virtual std::vector<StructType *> getIdentifiedStructTypes() const = 0;
 };
 

include/llvm/IR/Module.h

@@ -502,6 +502,8 @@ public:
   /// Materializer.
   std::error_code materializeAllPermanently();
 
+  std::error_code materializeMetadata();
+
 /// @}
 /// @name Direct access to the globals list, functions list, and symbol table
 /// @{

lib/Bitcode/Reader/BitcodeReader.h

@@ -255,7 +255,7 @@ public:
   static uint64_t decodeSignRotatedValue(uint64_t V);
 
   /// Materialize any deferred Metadata block.
-  std::error_code materializeMetadata();
+  std::error_code materializeMetadata() override;
 
 private:
   std::vector<StructType *> IdentifiedStructTypes;

lib/IR/Module.cpp

@@ -413,6 +413,12 @@ std::error_code Module::materializeAllPermanently() {
   return std::error_code();
 }
 
+std::error_code Module::materializeMetadata() {
+  if (!Materializer)
+    return std::error_code();
+  return Materializer->materializeMetadata();
+}
+
 //===----------------------------------------------------------------------===//
 // Other module related stuff.
 //

lib/Object/IRObjectFile.cpp

@@ -300,7 +300,9 @@ llvm::object::IRObjectFile::create(MemoryBufferRef Object,
   std::unique_ptr<MemoryBuffer> Buff(
       MemoryBuffer::getMemBuffer(BCOrErr.get(), false));
 
-  ErrorOr<Module *> MOrErr = getLazyBitcodeModule(std::move(Buff), Context);
+  ErrorOr<Module *> MOrErr =
+      getLazyBitcodeModule(std::move(Buff), Context, nullptr,
+                           /*ShouldLazyLoadMetadata*/ true);
   if (std::error_code EC = MOrErr.getError())
     return EC;
 

tools/gold/gold-plugin.cpp

@@ -598,6 +598,7 @@ getModuleForFile(LLVMContext &Context, claimed_file &F,
 
   Module &M = Obj.getModule();
 
+  M.materializeMetadata();
   UpgradeDebugInfo(M);
 
   SmallPtrSet<GlobalValue *, 8> Used;