[lld] Write the correct age and machine type to the PDB.

[zturner]

Summary

The age has to be written in two places and the two values have to agree with each other. Prior to this change, when I ran llvm-pdbdump raw -all on a PDB generated with lld it would error out. This patch fixes that. Now when I link two trivial object files with LLD and dump the resulting PDB, I get actual data. So far it only prints the section contents, but I'll look into getting symbol and type information in next.

[inglorion]

lgtm

[ruiu]

LGTM

lld/COFF/PDB.cpp

void coff::createPDB(StringRef Path, SymbolTable *Symtab,
 
   // Create streams in MSF for predefined streams, namely
   // PDB, TPI, DBI and IPI.
   for (int I = 0; I < (int)pdb::kSpecialStreamCount; ++I)
     ExitOnErr(Builder.getMsfBuilder().addStream(0));
 
   // Add an Info stream.
   auto &InfoBuilder = Builder.getInfoBuilder();
-  InfoBuilder.setAge(DI ? DI->PDB70.Age : 0);
+  uint32_t Age = DI ? DI->PDB70.Age : 0;
+  InfoBuilder.setAge(Age);
 
   pdb::PDB_UniqueId uuid{};
   if (DI)
     memcpy(&uuid, &DI->PDB70.Signature, sizeof(uuid));
   InfoBuilder.setGuid(uuid);
   // Should be the current time, but set 0 for reproducibilty.
   InfoBuilder.setSignature(0);
   InfoBuilder.setVersion(pdb::PdbRaw_ImplVer::PdbImplVC70);
 
   // Add an empty DPI stream.
   auto &DbiBuilder = Builder.getDbiBuilder();
   DbiBuilder.setVersionHeader(pdb::PdbDbiV110);
+  DbiBuilder.setAge(Age);
+  if (!Symtab->ObjectFiles.empty()) {
+    auto M = Symtab->ObjectFiles.front()->getMachineType();
+    DbiBuilder.setMachineType(static_cast<pdb::PDB_Machine>(M));
+  }
 
   codeview::TypeTableBuilder TypeTable(BAlloc);
   codeview::TypeTableBuilder IDTable(BAlloc);
   mergeDebugT(Symtab, Builder, TypeTable, IDTable);
 
   // Add Section Contributions.
   std::vector<pdb::SectionContrib> Contribs =
       pdb::DbiStreamBuilder::createSectionContribs(getInputSections(Symtab));