diff options
| -rw-r--r-- | lld/COFF/ICF.cpp | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/lld/COFF/ICF.cpp b/lld/COFF/ICF.cpp index 2f979327b82..77c05b74ad3 100644 --- a/lld/COFF/ICF.cpp +++ b/lld/COFF/ICF.cpp @@ -168,6 +168,7 @@ bool ICF::equalsVariable(const SectionChunk *A, const SectionChunk *B) { return std::equal(A->Relocs.begin(), A->Relocs.end(), B->Relocs.begin(), Eq); } +// Find the first Chunk after Begin that has a different class from Begin. size_t ICF::findBoundary(size_t Begin, size_t End) { for (size_t I = Begin + 1; I < End; ++I) if (Chunks[Begin]->Class[Cnt % 2] != Chunks[I]->Class[Cnt % 2]) @@ -177,11 +178,8 @@ size_t ICF::findBoundary(size_t Begin, size_t End) { void ICF::forEachClassRange(size_t Begin, size_t End, std::function<void(size_t, size_t)> Fn) { - if (Begin > 0) - Begin = findBoundary(Begin - 1, End); - while (Begin < End) { - size_t Mid = findBoundary(Begin, Chunks.size()); + size_t Mid = findBoundary(Begin, End); Fn(Begin, Mid); Begin = Mid; } @@ -197,12 +195,22 @@ void ICF::forEachClass(std::function<void(size_t, size_t)> Fn) { return; } - // Split sections into 256 shards and call Fn in parallel. - size_t NumShards = 256; + // Shard into non-overlapping intervals, and call Fn in parallel. + // The sharding must be completed before any calls to Fn are made + // so that Fn can modify the Chunks in its shard without causing data + // races. + const size_t NumShards = 256; size_t Step = Chunks.size() / NumShards; - for_each_n(parallel::par, size_t(0), NumShards, [&](size_t I) { - size_t End = (I == NumShards - 1) ? Chunks.size() : (I + 1) * Step; - forEachClassRange(I * Step, End, Fn); + size_t Boundaries[NumShards + 1]; + Boundaries[0] = 0; + Boundaries[NumShards] = Chunks.size(); + for_each_n(parallel::par, size_t(1), NumShards, [&](size_t I) { + Boundaries[I] = findBoundary((I - 1) * Step, Chunks.size()); + }); + for_each_n(parallel::par, size_t(1), NumShards + 1, [&](size_t I) { + if (Boundaries[I - 1] < Boundaries[I]) { + forEachClassRange(Boundaries[I - 1], Boundaries[I], Fn); + } }); ++Cnt; } |
