diff options
| -rw-r--r-- | lld/ELF/SyntheticSections.cpp | 54 | ||||
| -rw-r--r-- | lld/test/ELF/gdb-index.s | 18 |
2 files changed, 50 insertions, 22 deletions
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp index 34c35b98f41..6443c4dfe72 100644 --- a/lld/ELF/SyntheticSections.cpp +++ b/lld/ELF/SyntheticSections.cpp @@ -2366,23 +2366,51 @@ createSymbols(ArrayRef<std::vector<GdbIndexSection::NameTypeEntry>> NameTypes) { typedef GdbIndexSection::GdbSymbol GdbSymbol; typedef GdbIndexSection::NameTypeEntry NameTypeEntry; - // A map to uniquify symbols by name. - DenseMap<CachedHashStringRef, size_t> Map; + // The number of symbols we will handle in this function is of the order + // of millions for very large executables, so we use multi-threading to + // speed it up. + size_t NumShards = 32; + size_t Concurrency = 1; + if (ThreadsEnabled) + Concurrency = + std::min<size_t>(PowerOf2Floor(hardware_concurrency()), NumShards); + + // A sharded map to uniquify symbols by name. + std::vector<DenseMap<CachedHashStringRef, size_t>> Map(NumShards); + size_t Shift = 32 - countTrailingZeros(NumShards); // Instantiate GdbSymbols while uniqufying them by name. - std::vector<GdbSymbol> Ret; - for (ArrayRef<NameTypeEntry> Entries : NameTypes) { - for (const NameTypeEntry &Ent : Entries) { - size_t &Idx = Map[Ent.Name]; - if (Idx) { - Ret[Idx - 1].CuVector.push_back(Ent.Type); - continue; - } + std::vector<std::vector<GdbSymbol>> Symbols(NumShards); + parallelForEachN(0, Concurrency, [&](size_t ThreadId) { + for (ArrayRef<NameTypeEntry> Entries : NameTypes) { + for (const NameTypeEntry &Ent : Entries) { + size_t ShardId = Ent.Name.hash() >> Shift; + if ((ShardId & (Concurrency - 1)) != ThreadId) + continue; - Idx = Ret.size() + 1; - Ret.push_back({Ent.Name, {Ent.Type}, 0, 0}); + size_t &Idx = Map[ShardId][Ent.Name]; + if (Idx) { + Symbols[ShardId][Idx - 1].CuVector.push_back(Ent.Type); + continue; + } + + Idx = Symbols[ShardId].size() + 1; + Symbols[ShardId].push_back({Ent.Name, {Ent.Type}, 0, 0}); + } } - } + }); + + size_t NumSymbols = 0; + for (ArrayRef<GdbSymbol> V : Symbols) + NumSymbols += V.size(); + + // The return type is a flattened vector, so we'll copy each vector + // contents to Ret. + std::vector<GdbSymbol> Ret; + Ret.reserve(NumSymbols); + for (std::vector<GdbSymbol> &Vec : Symbols) + for (GdbSymbol &Sym : Vec) + Ret.push_back(std::move(Sym)); // CU vectors and symbol names are adjacent in the output file. // We can compute their offsets in the output file now. diff --git a/lld/test/ELF/gdb-index.s b/lld/test/ELF/gdb-index.s index 9c763ab5834..e7f96066bd0 100644 --- a/lld/test/ELF/gdb-index.s +++ b/lld/test/ELF/gdb-index.s @@ -34,16 +34,16 @@ # DWARF-NEXT: Low/High address = [0x201000, 0x201001) (Size: 0x1), CU id = 0 # DWARF-NEXT: Low/High address = [0x201004, 0x201006) (Size: 0x2), CU id = 1 # DWARF: Symbol table offset = 0x60, size = 1024, filled slots: -# DWARF-NEXT: 512: Name offset = 0x2b, CU vector offset = 0x14 -# DWARF-NEXT: String name: aaaaaaaaaaaaaaaa, CU vector index: 2 -# DWARF-NEXT: 754: Name offset = 0x27, CU vector offset = 0x8 -# DWARF-NEXT: String name: int, CU vector index: 1 -# DWARF-NEXT: 822: Name offset = 0x1c, CU vector offset = 0x0 -# DWARF-NEXT: String name: entrypoint, CU vector index: 0 +# DWARF-NEXT: 512: Name offset = 0x1c, CU vector offset = 0x0 +# DWARF-NEXT: String name: aaaaaaaaaaaaaaaa, CU vector index: 0 +# DWARF-NEXT: 754: Name offset = 0x38, CU vector offset = 0x10 +# DWARF-NEXT: String name: int, CU vector index: 2 +# DWARF-NEXT: 822: Name offset = 0x2d, CU vector offset = 0x8 +# DWARF-NEXT: String name: entrypoint, CU vector index: 1 # DWARF: Constant pool offset = 0x2060, has 3 CU vectors: -# DWARF-NEXT: 0(0x0): 0x30000000 -# DWARF-NEXT: 1(0x8): 0x90000000 0x90000001 -# DWARF-NEXT: 2(0x14): 0x30000001 +# DWARF-NEXT: 0(0x0): 0x30000001 +# DWARF-NEXT: 1(0x8): 0x30000000 +# DWARF-NEXT: 2(0x10): 0x90000000 0x90000001 # SECTION-NOT: debug_gnu_pubnames |
