[llvm-pdbutil] Fix yaml2pdb failing to parse yaml with register enums

Author: nikitalita

llvm/tools/llvm-pdbutil/PdbYaml.cpp

@@ -155,6 +155,13 @@ void MappingTraits<PdbDbiStream>::mapping(IO &IO, PdbDbiStream &Obj) {
   IO.mapOptional("PdbDllRbld", Obj.PdbDllRbld, uint16_t(0U));
   IO.mapOptional("Flags", Obj.Flags, uint16_t(1U));
   IO.mapOptional("MachineType", Obj.MachineType, PDB_Machine::x86);
+  // This is a workaround for IO not having document context with the
+  // machine type. The machine type is needed to properly parse Register enums
+  // in the PDB.
+  if (!IO.getContext()) {
+    Obj.FakeHeader.Machine = static_cast<uint16_t>(Obj.MachineType);
+    IO.setContext(&Obj.FakeHeader);
+  }
   IO.mapOptional("Modules", Obj.ModInfos);
 }
 

llvm/tools/llvm-pdbutil/PdbYaml.h

@@ -11,6 +11,7 @@
 
 #include "OutputStyle.h"
 
+#include "llvm/BinaryFormat/COFF.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
 #include "llvm/DebugInfo/MSF/MSFCommon.h"
@@ -80,6 +81,7 @@ struct PdbDbiStream {
   PDB_Machine MachineType = PDB_Machine::x86;
 
   std::vector<PdbDbiModuleInfo> ModInfos;
+  COFF::header FakeHeader;
 };
 
 struct PdbTpiStream {