Naively computing the hash after the PDB data has been generated is in practice
as fast as other approaches I tried. I also tried online-computing the hash as
parts of the PDB were written out (https://reviews.llvm.org/D51887; that's also
where all the measuring data is) and computing the hash in parallel
(https://reviews.llvm.org/D51957). This approach here is simplest, without
being slower.
Differential Revision: https://reviews.llvm.org/D51956
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342333
91177308-0d34-0410-b5e6-
96231b3b80d8
InfoStreamBuilder &operator=(const InfoStreamBuilder &) = delete;
void setVersion(PdbRaw_ImplVer V);
+ void addFeature(PdbRaw_FeatureSig Sig);
+
+ // If this is true, the PDB contents are hashed and this hash is used as
+ // PDB GUID and as Signature. The age is always 1.
+ void setHashPDBContentsToGUID(bool B);
+
+ // These only have an effect if hashPDBContentsToGUID() is false.
void setSignature(uint32_t S);
void setAge(uint32_t A);
void setGuid(codeview::GUID G);
- void addFeature(PdbRaw_FeatureSig Sig);
+ bool hashPDBContentsToGUID() const { return HashPDBContentsToGUID; }
uint32_t getAge() const { return Age; }
codeview::GUID getGuid() const { return Guid; }
Optional<uint32_t> getSignature() const { return Signature; }
Optional<uint32_t> Signature;
codeview::GUID Guid;
+ bool HashPDBContentsToGUID = false;
+
NamedStreamMap &NamedStreams;
};
}
PDBStringTableBuilder &getStringTableBuilder();
GSIStreamBuilder &getGsiBuilder();
- Error commit(StringRef Filename);
+ // If HashPDBContentsToGUID is true on the InfoStreamBuilder, Guid is filled
+ // with the computed PDB GUID on return.
+ Error commit(StringRef Filename, codeview::GUID *Guid);
Expected<uint32_t> getNamedStreamIndex(StringRef Name) const;
Error addNamedStream(StringRef Name, StringRef Data);
void InfoStreamBuilder::setVersion(PdbRaw_ImplVer V) { Ver = V; }
+void InfoStreamBuilder::addFeature(PdbRaw_FeatureSig Sig) {
+ Features.push_back(Sig);
+}
+
+void InfoStreamBuilder::setHashPDBContentsToGUID(bool B) {
+ HashPDBContentsToGUID = B;
+}
+
void InfoStreamBuilder::setAge(uint32_t A) { Age = A; }
void InfoStreamBuilder::setSignature(uint32_t S) { Signature = S; }
void InfoStreamBuilder::setGuid(GUID G) { Guid = G; }
-void InfoStreamBuilder::addFeature(PdbRaw_FeatureSig Sig) {
- Features.push_back(Sig);
-}
Error InfoStreamBuilder::finalizeMsfLayout() {
uint32_t Length = sizeof(InfoStreamHeader) +
#include "llvm/Support/BinaryStreamWriter.h"
#include "llvm/Support/JamCRC.h"
#include "llvm/Support/Path.h"
+#include "llvm/Support/xxhash.h"
using namespace llvm;
using namespace llvm::codeview;
}
}
-Error PDBFileBuilder::commit(StringRef Filename) {
+Error PDBFileBuilder::commit(StringRef Filename, codeview::GUID *Guid) {
assert(!Filename.empty());
if (auto EC = finalizeMsfLayout())
return EC;
MSFLayout Layout;
- auto ExpectedMsfBuffer = Msf->commit(Filename, Layout);
+ Expected<FileBufferByteStream> ExpectedMsfBuffer =
+ Msf->commit(Filename, Layout);
if (!ExpectedMsfBuffer)
return ExpectedMsfBuffer.takeError();
FileBufferByteStream Buffer = std::move(*ExpectedMsfBuffer);
// Set the build id at the very end, after every other byte of the PDB
// has been written.
- // FIXME: Use a hash of the PDB rather than time(nullptr) for the signature.
- H->Age = Info->getAge();
- H->Guid = Info->getGuid();
- Optional<uint32_t> Sig = Info->getSignature();
- H->Signature = Sig.hasValue() ? *Sig : time(nullptr);
+ if (Info->hashPDBContentsToGUID()) {
+ // Compute a hash of all sections of the output file.
+ uint64_t Digest =
+ xxHash64({Buffer.getBufferStart(), Buffer.getBufferEnd()});
+
+ H->Age = 1;
+
+ memcpy(H->Guid.Guid, &Digest, 8);
+ // xxhash only gives us 8 bytes, so put some fixed data in the other half.
+ memcpy(H->Guid.Guid + 8, "LLD PDB.", 8);
+
+ // Put the hash in the Signature field too.
+ H->Signature = static_cast<uint32_t>(Digest);
+
+ // Return GUID to caller.
+ memcpy(Guid, H->Guid.Guid, 16);
+ } else {
+ H->Age = Info->getAge();
+ H->Guid = Info->getGuid();
+ Optional<uint32_t> Sig = Info->getSignature();
+ H->Signature = Sig.hasValue() ? *Sig : time(nullptr);
+ }
return Buffer.commit();
}
Builder.getStringTableBuilder().setStrings(*Strings.strings());
- ExitOnErr(Builder.commit(opts::yaml2pdb::YamlPdbOutputFile));
+ codeview::GUID IgnoredOutGuid;
+ ExitOnErr(Builder.commit(opts::yaml2pdb::YamlPdbOutputFile, &IgnoredOutGuid));
}
static PDBFile &loadPDB(StringRef Path, std::unique_ptr<IPDBSession> &Session) {
OutFile = opts::merge::InputFilenames[0];
llvm::sys::path::replace_extension(OutFile, "merged.pdb");
}
- ExitOnErr(Builder.commit(OutFile));
+
+ codeview::GUID IgnoredOutGuid;
+ ExitOnErr(Builder.commit(OutFile, &IgnoredOutGuid));
}
static void explain() {