diff options
Diffstat (limited to 'lld/ELF/ICF.cpp')
| -rw-r--r-- | lld/ELF/ICF.cpp | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/lld/ELF/ICF.cpp b/lld/ELF/ICF.cpp index f13a5049e01..191fa8e2b6e 100644 --- a/lld/ELF/ICF.cpp +++ b/lld/ELF/ICF.cpp @@ -163,7 +163,7 @@ template <class ELFT> static uint32_t getHash(InputSection *S) { // Returns true if section S is subject of ICF. static bool isEligible(InputSection *S) { - if (!S->Live || S->KeepUnique || !(S->Flags & SHF_ALLOC)) + if (!S->Live || !(S->Flags & SHF_ALLOC)) return false; // Don't merge writable sections. .data.rel.ro sections are marked as writable @@ -468,10 +468,29 @@ template <class ELFT> void ICF<ELFT>::run() { forEachClassRange(0, Sections.size(), [&](size_t Begin, size_t End) { if (End - Begin == 1) return; - print("selected section " + toString(Sections[Begin])); - for (size_t I = Begin + 1; I < End; ++I) { + InputSection *Target = nullptr; + bool SeenUnique = false, Replaced = false; + for (size_t I = Begin; I < End; ++I) { + // We aren't allowed to merge two KeepUnique sections as this would break + // the guarantees provided by --keep-unique and --icf=safe, but there's + // no reason why we can't merge a non-KeepUnique section with a KeepUnique + // section. We implement this by only considering the first KeepUnique + // section in the equivalence class for merging. If we see any more + // KeepUnique sections, we ignore them. + if (Sections[I]->KeepUnique) { + if (SeenUnique) + continue; + SeenUnique = true; + } + if (!Target) { + Target = Sections[I]; + continue; + } + if (!Replaced) + print("selected section " + toString(Target)); print(" removing identical section " + toString(Sections[I])); - Sections[Begin]->replace(Sections[I]); + Target->replace(Sections[I]); + Replaced = true; // At this point we know sections merged are fully identical and hence // we want to remove duplicate implicit dependencies such as link order |
