[pdb] Add a pdb2yaml option to not dump file headers.

This will be useful once we start adding the ability to dump type
records and symbol records, since it will allow us to generate
mergeable information instead of information that specifies an
entire file.

llvm-svn: 275109

llvm/test/DebugInfo/PDB/pdbdump-yaml.test

@@ -1,5 +1,7 @@
 ; RUN: llvm-pdbdump pdb2yaml -stream-metadata -stream-directory -pdb-stream %p/Inputs/empty.pdb \
 ; RUN:   | FileCheck -check-prefix=YAML %s
+; RUN: llvm-pdbdump pdb2yaml -no-file-headers -stream-metadata -stream-directory -pdb-stream \
+; RUN:   %p/Inputs/empty.pdb | FileCheck -check-prefix=NO-HEADERS %s
 
 ; YAML:      ---
 ; YAML-NEXT: MSF:
@@ -74,3 +76,8 @@
 ; YAML-NEXT:   Signature:       1424295906
 ; YAML-NEXT:   Version:         20000404
 ; YAML-NEXT: ...
+
+; NO-HEADERS: ---
+; NO-HEADERS-NOT: MSF:
+; NO-HEADERS-NOT:   SuperBlock:
+; NO-HEADERS: ...

llvm/tools/llvm-pdbdump/PdbYaml.h

@@ -46,7 +46,7 @@ struct PdbInfoStream {
 };
 
 struct PdbObject {
-  MsfHeaders Headers;
+  Optional<MsfHeaders> Headers;
   Optional<std::vector<support::ulittle32_t>> StreamSizes;
   Optional<std::vector<StreamBlockList>> StreamMap;
   Optional<PdbInfoStream> PdbStream;

llvm/tools/llvm-pdbdump/YAMLOutputStyle.cpp

@@ -42,20 +42,24 @@ Error YAMLOutputStyle::dump() {
 }
 
 Error YAMLOutputStyle::dumpFileHeaders() {
+  if (opts::pdb2yaml::NoFileHeaders)
+    return Error::success();
+
   yaml::MsfHeaders Headers;
-  Obj.Headers.SuperBlock.NumBlocks = File.getBlockCount();
-  Obj.Headers.SuperBlock.BlockMapAddr = File.getBlockMapIndex();
-  Obj.Headers.BlockMapOffset = File.getBlockMapOffset();
-  Obj.Headers.SuperBlock.BlockSize = File.getBlockSize();
+  Obj.Headers.emplace();
+  Obj.Headers->SuperBlock.NumBlocks = File.getBlockCount();
+  Obj.Headers->SuperBlock.BlockMapAddr = File.getBlockMapIndex();
+  Obj.Headers->BlockMapOffset = File.getBlockMapOffset();
+  Obj.Headers->SuperBlock.BlockSize = File.getBlockSize();
   auto Blocks = File.getDirectoryBlockArray();
-  Obj.Headers.DirectoryBlocks.assign(Blocks.begin(), Blocks.end());
-  Obj.Headers.NumDirectoryBlocks = File.getNumDirectoryBlocks();
-  Obj.Headers.SuperBlock.NumDirectoryBytes = File.getNumDirectoryBytes();
-  Obj.Headers.NumStreams =
+  Obj.Headers->DirectoryBlocks.assign(Blocks.begin(), Blocks.end());
+  Obj.Headers->NumDirectoryBlocks = File.getNumDirectoryBlocks();
+  Obj.Headers->SuperBlock.NumDirectoryBytes = File.getNumDirectoryBytes();
+  Obj.Headers->NumStreams =
       opts::pdb2yaml::StreamMetadata ? File.getNumStreams() : 0;
-  Obj.Headers.SuperBlock.Unknown0 = File.getUnknown0();
-  Obj.Headers.SuperBlock.Unknown1 = File.getUnknown1();
-  Obj.Headers.FileSize = File.getFileSize();
+  Obj.Headers->SuperBlock.Unknown0 = File.getUnknown0();
+  Obj.Headers->SuperBlock.Unknown1 = File.getUnknown1();
+  Obj.Headers->FileSize = File.getFileSize();
 
   return Error::success();
 }

llvm/tools/llvm-pdbdump/llvm-pdbdump.cpp

@@ -261,18 +261,24 @@ cl::list<std::string> InputFilename(cl::Positional,
 }
 
 namespace pdb2yaml {
+cl::opt<bool>
+    NoFileHeaders("no-file-headers",
+                  cl::desc("Do not dump MSF file headers (you will not be able "
+                           "to generate a fresh PDB from the resulting YAML)"),
+                  cl::sub(PdbToYamlSubcommand), cl::init(false));
+
 cl::opt<bool> StreamMetadata(
     "stream-metadata",
     cl::desc("Dump the number of streams and each stream's size"),
-    cl::sub(PdbToYamlSubcommand));
+    cl::sub(PdbToYamlSubcommand), cl::init(false));
 cl::opt<bool> StreamDirectory(
     "stream-directory",
     cl::desc("Dump each stream's block map (implies -stream-metadata)"),
-    cl::sub(PdbToYamlSubcommand));
+    cl::sub(PdbToYamlSubcommand), cl::init(false));
 cl::opt<bool> PdbStream(
     "pdb-stream",
     cl::desc("Dump the PDB Stream (Stream 1) (implies -stream-metadata)"),
-    cl::sub(PdbToYamlSubcommand));
+    cl::sub(PdbToYamlSubcommand), cl::init(false));
 
 cl::list<std::string> InputFilename(cl::Positional,
                                     cl::desc("<input PDB file>"), cl::Required,
@@ -296,9 +302,12 @@ static void yamlToPdb(StringRef Path) {
   llvm::yaml::Input In(Buffer->getBuffer());
   pdb::yaml::PdbObject YamlObj;
   In >> YamlObj;
+  if (!YamlObj.Headers.hasValue())
+    ExitOnErr(make_error<GenericError>(generic_error_code::unspecified,
+                                       "Yaml does not contain MSF headers"));
 
   auto OutFileOrError = FileOutputBuffer::create(
-      opts::yaml2pdb::YamlPdbOutputFile, YamlObj.Headers.FileSize);
+      opts::yaml2pdb::YamlPdbOutputFile, YamlObj.Headers->FileSize);
   if (OutFileOrError.getError())
     ExitOnErr(make_error<GenericError>(generic_error_code::invalid_path,
                                        opts::yaml2pdb::YamlPdbOutputFile));
@@ -306,11 +315,11 @@ static void yamlToPdb(StringRef Path) {
   auto FileByteStream =
       llvm::make_unique<FileBufferByteStream>(std::move(*OutFileOrError));
   PDBFile Pdb(std::move(FileByteStream));
-  ExitOnErr(Pdb.setSuperBlock(&YamlObj.Headers.SuperBlock));
+  ExitOnErr(Pdb.setSuperBlock(&YamlObj.Headers->SuperBlock));
   if (YamlObj.StreamSizes.hasValue()) {
     Pdb.setStreamSizes(YamlObj.StreamSizes.getValue());
   }
-  Pdb.setDirectoryBlocks(YamlObj.Headers.DirectoryBlocks);
+  Pdb.setDirectoryBlocks(YamlObj.Headers->DirectoryBlocks);
 
   if (YamlObj.StreamMap.hasValue()) {
     std::vector<ArrayRef<support::ulittle32_t>> StreamMap;

llvm/tools/llvm-pdbdump/llvm-pdbdump.h

@@ -57,6 +57,7 @@ extern llvm::cl::opt<bool> DumpFpo;
 }
 
 namespace pdb2yaml {
+extern llvm::cl::opt<bool> NoFileHeaders;
 extern llvm::cl::opt<bool> StreamMetadata;
 extern llvm::cl::opt<bool> StreamDirectory;
 extern llvm::cl::opt<bool> PdbStream;