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[lld] Fix a bug where we continually re-follow type servers. 

Originally this was intended to be set up so that when linking
a PDB which refers to a type server, it would only visit the
PDB once, and on subsequent visitations it would just skip it
since all the records had already been added.

Due to some C++ scoping issues, this was not occurring and it
was revisiting the type server every time, which caused every
record to end up being thrown away on all subsequent visitations.

This doesn't affect the performance of linking clang-cl generated
object files because we don't use type servers, but when linking
object files and libraries generated with /Zi via MSVC, this means
only 1 object file has to be linked instead of N object files, so
the speedup is quite large.

llvm-svn: 303920
This commit is contained in:
Zachary Turner 2017-05-25 21:16:03 +00:00
parent 7f97c362a4
commit 2897e0306e
3 changed files with 14 additions and 13 deletions
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11
lld/COFF/PDB.cpp
View File

@ -99,6 +99,12 @@ static void addTypeInfo(pdb::TpiStreamBuilder &TpiBuilder,
static void mergeDebugT(SymbolTable *Symtab, pdb::PDBFileBuilder &Builder,
codeview::TypeTableBuilder &TypeTable,
codeview::TypeTableBuilder &IDTable) {
// Follow type servers. If the same type server is encountered more than
// once for this instance of `PDBTypeServerHandler` (for example if many
// object files reference the same TypeServer), the types from the
// TypeServer will only be visited once.
pdb::PDBTypeServerHandler Handler;
// Visit all .debug$T sections to add them to Builder.
for (ObjectFile *File : Symtab->ObjectFiles) {
ArrayRef<uint8_t> Data = getDebugSection(File, ".debug$T");
@ -109,11 +115,6 @@ static void mergeDebugT(SymbolTable *Symtab, pdb::PDBFileBuilder &Builder,
codeview::CVTypeArray Types;
BinaryStreamReader Reader(Stream);
SmallVector<TypeIndex, 128> SourceToDest;
// Follow type servers. If the same type server is encountered more than
// once for this instance of `PDBTypeServerHandler` (for example if many
// object files reference the same TypeServer), the types from the
// TypeServer will only be visited once.
pdb::PDBTypeServerHandler Handler;
Handler.addSearchPath(llvm::sys::path::parent_path(File->getName()));
if (auto EC = Reader.readArray(Types, Reader.getLength()))
fatal(EC, "Reader::readArray failed");

5
llvm/include/llvm/DebugInfo/PDB/Native/PDBTypeServerHandler.h
View File

@ -11,8 +11,7 @@
#define LLVM_DEBUGINFO_PDB_PDBTYPESERVERHANDLER_H
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/DebugInfo/CodeView/TypeRecord.h"
#include "llvm/DebugInfo/CodeView/TypeServerHandler.h"
#include "llvm/DebugInfo/PDB/Native/NativeSession.h"
@ -39,7 +38,7 @@ private:
bool RevisitAlways;
std::unique_ptr<NativeSession> Session;
SmallVector<SmallString<64>, 4> SearchPaths;
StringSet<> SearchPaths;
};
}
}

11
llvm/lib/DebugInfo/PDB/Native/PDBTypeServerHandler.cpp
View File

@ -47,7 +47,7 @@ void PDBTypeServerHandler::addSearchPath(StringRef Path) {
if (Path.empty() || !sys::fs::is_directory(Path))
return;
SearchPaths.push_back(Path);
SearchPaths.insert(Path);
}
Expected<bool>
@ -86,13 +86,14 @@ Expected<bool> PDBTypeServerHandler::handle(TypeServer2Record &TS,
cv_error_code::corrupt_record,
"TypeServer2Record does not contain filename!");
for (auto Path : SearchPaths) {
sys::path::append(Path, File);
if (!sys::fs::exists(Path))
for (auto &Path : SearchPaths) {
SmallString<64> PathStr = Path.getKey();
sys::path::append(PathStr, File);
if (!sys::fs::exists(PathStr))
continue;
std::unique_ptr<IPDBSession> ThisSession;
if (auto EC = loadDataForPDB(PDB_ReaderType::Native, Path, ThisSession)) {
if (auto EC = loadDataForPDB(PDB_ReaderType::Native, PathStr, ThisSession)) {
// It is not an error if this PDB fails to load, it just means that it
// doesn't match and we should continue searching.
ignoreErrors(std::move(EC));