ELF: Store EhInputSection relocations to simplify code. NFC

lld/ELF/InputSection.cpp

@@ -1358,20 +1358,21 @@ SyntheticSection *EhInputSection::getParent() const {
 // .eh_frame is a sequence of CIE or FDE records.
 // This function splits an input section into records and returns them.
 template <class ELFT> void EhInputSection::split() {
-  const RelsOrRelas<ELFT> rels = relsOrRelas<ELFT>(/*supportsCrel=*/false);
-  // getReloc expects the relocations to be sorted by r_offset. See the comment
-  // in scanRelocs.
-  if (rels.areRelocsRel()) {
-    SmallVector<typename ELFT::Rel, 0> storage;
-    split<ELFT>(sortRels(rels.rels, storage));
-  } else {
-    SmallVector<typename ELFT::Rela, 0> storage;
-    split<ELFT>(sortRels(rels.relas, storage));
-  }
-}
+  const RelsOrRelas<ELFT> elfRels = relsOrRelas<ELFT>();
+  if (elfRels.areRelocsCrel())
+    preprocessRelocs<ELFT>(elfRels.crels);
+  else if (elfRels.areRelocsRel())
+    preprocessRelocs<ELFT>(elfRels.rels);
+  else
+    preprocessRelocs<ELFT>(elfRels.relas);
+
+  // The loop below expects the relocations to be sorted by offset.
+  auto cmp = [](const Relocation &a, const Relocation &b) {
+    return a.offset < b.offset;
+  };
+  if (!llvm::is_sorted(rels, cmp))
+    llvm::stable_sort(rels, cmp);
 
-template <class ELFT, class RelTy>
-void EhInputSection::split(ArrayRef<RelTy> rels) {
   ArrayRef<uint8_t> d = content();
   const char *msg = nullptr;
   unsigned relI = 0;
@@ -1397,10 +1398,10 @@ void EhInputSection::split(ArrayRef<RelTy> rels) {
     // Find the first relocation that points to [off,off+size). Relocations
     // have been sorted by r_offset.
     const uint64_t off = d.data() - content().data();
-    while (relI != rels.size() && rels[relI].r_offset < off)
+    while (relI != rels.size() && rels[relI].offset < off)
       ++relI;
     unsigned firstRel = -1;
-    if (relI != rels.size() && rels[relI].r_offset < off + size)
+    if (relI != rels.size() && rels[relI].offset < off + size)
       firstRel = relI;
     (id == 0 ? cies : fdes).emplace_back(off, this, size, firstRel);
     d = d.slice(size);
@@ -1410,6 +1411,23 @@ void EhInputSection::split(ArrayRef<RelTy> rels) {
                    << getObjMsg(d.data() - content().data());
 }
 
+template <class ELFT, class RelTy>
+void EhInputSection::preprocessRelocs(Relocs<RelTy> elfRels) {
+  Ctx &ctx = file->ctx;
+  rels.reserve(elfRels.size());
+  for (auto rel : elfRels) {
+    uint64_t offset = rel.r_offset;
+    Symbol &sym = file->getSymbol(rel.getSymbol(ctx.arg.isMips64EL));
+    RelType type = rel.getType(ctx.arg.isMips64EL);
+    RelExpr expr = ctx.target->getRelExpr(type, sym, content().data() + offset);
+    int64_t addend =
+        RelTy::HasAddend
+            ? getAddend<ELFT>(rel)
+            : ctx.target->getImplicitAddend(content().data() + offset, type);
+    rels.push_back({expr, type, offset, addend, &sym});
+  }
+}
+
 // Return the offset in an output section for a given input offset.
 uint64_t EhInputSection::getParentOffset(uint64_t offset) const {
   auto it = partition_point(

lld/ELF/InputSection.h

@@ -394,14 +394,18 @@ class EhInputSection : public InputSectionBase {
                  StringRef name);
   static bool classof(const SectionBase *s) { return s->kind() == EHFrame; }
   template <class ELFT> void split();
-  template <class ELFT, class RelTy> void split(ArrayRef<RelTy> rels);
+  template <class ELFT, class RelTy> void preprocessRelocs(Relocs<RelTy> rels);
 
   // Splittable sections are handled as a sequence of data
   // rather than a single large blob of data.
   SmallVector<EhSectionPiece, 0> cies, fdes;
 
   SyntheticSection *getParent() const;
   uint64_t getParentOffset(uint64_t offset) const;
+
+  // Preprocessed relocations in uniform format to avoid REL/RELA/CREL
+  // relocation format handling throughout the codebase.
+  SmallVector<Relocation, 0> rels;
 };
 
 // This is a section that is added directly to an output section

lld/ELF/MarkLive.cpp

@@ -68,10 +68,9 @@ template <class ELFT, bool TrackWhyLive> class MarkLive {
   void mark();
 
   template <class RelTy>
-  void resolveReloc(InputSectionBase &sec, RelTy &rel, bool fromFDE);
+  void resolveReloc(InputSectionBase &sec, const RelTy &rel, bool fromFDE);
 
-  template <class RelTy>
-  void scanEhFrameSection(EhInputSection &eh, ArrayRef<RelTy> rels);
+  void scanEhFrameSection(EhInputSection &eh);
 
   Ctx &ctx;
   // The index of the partition that we are currently processing.
@@ -115,23 +114,38 @@ static uint64_t getAddend(Ctx &, InputSectionBase &sec,
 template <class ELFT, bool TrackWhyLive>
 template <class RelTy>
 void MarkLive<ELFT, TrackWhyLive>::resolveReloc(InputSectionBase &sec,
-                                                RelTy &rel, bool fromFDE) {
+                                                const RelTy &rel,
+                                                bool fromFDE) {
   // If a symbol is referenced in a live section, it is used.
-  Symbol &sym = sec.file->getRelocTargetSym(rel);
-  sym.used = true;
+  Symbol *sym;
+  if constexpr (std::is_same_v<RelTy, Relocation>) {
+    assert(isa<EhInputSection>(sec));
+    sym = rel.sym;
+  } else {
+    sym = &sec.file->getRelocTargetSym(rel);
+  }
+  sym->used = true;
 
   LiveReason reason;
-  if (TrackWhyLive)
-    reason = {SecOffset(&sec, rel.r_offset), "referenced by"};
+  if (TrackWhyLive) {
+    if constexpr (std::is_same_v<RelTy, Relocation>)
+      reason = {SecOffset(&sec, rel.offset), "referenced by"};
+    else
+      reason = {SecOffset(&sec, rel.r_offset), "referenced by"};
+  }
 
-  if (auto *d = dyn_cast<Defined>(&sym)) {
+  if (auto *d = dyn_cast<Defined>(sym)) {
     auto *relSec = dyn_cast_or_null<InputSectionBase>(d->section);
     if (!relSec)
       return;
 
     uint64_t offset = d->value;
-    if (d->isSection())
-      offset += getAddend<ELFT>(ctx, sec, rel);
+    if (d->isSection()) {
+      if constexpr (std::is_same_v<RelTy, Relocation>)
+        offset += rel.addend;
+      else
+        offset += getAddend<ELFT>(ctx, sec, rel);
+    }
 
     // fromFDE being true means this is referenced by a FDE in a .eh_frame
     // piece. The relocation points to the described function or to a LSDA. We
@@ -141,8 +155,9 @@ void MarkLive<ELFT, TrackWhyLive>::resolveReloc(InputSectionBase &sec,
     // associated text section is live, the LSDA will be retained due to section
     // group/SHF_LINK_ORDER rules (b) if the associated text section should be
     // discarded, marking the LSDA will unnecessarily retain the text section.
-    if (!(fromFDE && ((relSec->flags & (SHF_EXECINSTR | SHF_LINK_ORDER)) ||
-                      relSec->nextInSectionGroup))) {
+    if (!(fromFDE && std::is_same_v<RelTy, Relocation> &&
+          ((relSec->flags & (SHF_EXECINSTR | SHF_LINK_ORDER)) ||
+           relSec->nextInSectionGroup))) {
       Symbol *canonicalSym = d;
       if (TrackWhyLive && d->isSection()) {
         // This is expensive, so ideally this would be deferred until it's known
@@ -159,15 +174,15 @@ void MarkLive<ELFT, TrackWhyLive>::resolveReloc(InputSectionBase &sec,
     return;
   }
 
-  if (auto *ss = dyn_cast<SharedSymbol>(&sym)) {
+  if (auto *ss = dyn_cast<SharedSymbol>(sym)) {
     if (!ss->isWeak()) {
       cast<SharedFile>(ss->file)->isNeeded = true;
       if (TrackWhyLive)
-        whyLive.try_emplace(&sym, reason);
+        whyLive.try_emplace(sym, reason);
     }
   }
 
-  for (InputSectionBase *sec : cNamedSections.lookup(sym.getName()))
+  for (InputSectionBase *sec : cNamedSections.lookup(sym->getName()))
     enqueue(sec, /*offset=*/0, /*sym=*/nullptr, reason);
 }
 
@@ -186,9 +201,8 @@ void MarkLive<ELFT, TrackWhyLive>::resolveReloc(InputSectionBase &sec,
 // the gc pass. With that we would be able to also gc some sections holding
 // LSDAs and personality functions if we found that they were unused.
 template <class ELFT, bool TrackWhyLive>
-template <class RelTy>
-void MarkLive<ELFT, TrackWhyLive>::scanEhFrameSection(EhInputSection &eh,
-                                                      ArrayRef<RelTy> rels) {
+void MarkLive<ELFT, TrackWhyLive>::scanEhFrameSection(EhInputSection &eh) {
+  ArrayRef<Relocation> rels = eh.rels;
   for (const EhSectionPiece &cie : eh.cies)
     if (cie.firstRelocation != unsigned(-1))
       resolveReloc(eh, rels[cie.firstRelocation], false);
@@ -198,7 +212,7 @@ void MarkLive<ELFT, TrackWhyLive>::scanEhFrameSection(EhInputSection &eh,
       continue;
     uint64_t pieceEnd = fde.inputOff + fde.size;
     for (size_t j = firstRelI, end2 = rels.size();
-         j < end2 && rels[j].r_offset < pieceEnd; ++j)
+         j < end2 && rels[j].offset < pieceEnd; ++j)
       resolveReloc(eh, rels[j], true);
   }
 }
@@ -360,14 +374,8 @@ void MarkLive<ELFT, TrackWhyLive>::run() {
   // that point to .eh_frames. Otherwise, the garbage collector would drop
   // all of them. We also want to preserve personality routines and LSDA
   // referenced by .eh_frame sections, so we scan them for that here.
-  for (EhInputSection *eh : ctx.ehInputSections) {
-    const RelsOrRelas<ELFT> rels =
-        eh->template relsOrRelas<ELFT>(/*supportsCrel=*/false);
-    if (rels.areRelocsRel())
-      scanEhFrameSection(*eh, rels.rels);
-    else if (rels.relas.size())
-      scanEhFrameSection(*eh, rels.relas);
-  }
+  for (EhInputSection *eh : ctx.ehInputSections)
+    scanEhFrameSection(*eh);
   for (InputSectionBase *sec : ctx.inputSections) {
     if (sec->flags & SHF_GNU_RETAIN) {
       enqueue(sec, /*offset=*/0, /*sym=*/nullptr, {std::nullopt, "retained"});

lld/ELF/SyntheticSections.cpp

@@ -403,12 +403,12 @@ EhFrameSection::EhFrameSection(Ctx &ctx)
 // Search for an existing CIE record or create a new one.
 // CIE records from input object files are uniquified by their contents
 // and where their relocations point to.
-template <class RelTy>
-CieRecord *EhFrameSection::addCie(EhSectionPiece &cie, ArrayRef<RelTy> rels) {
+CieRecord *EhFrameSection::addCie(EhSectionPiece &cie,
+                                  ArrayRef<Relocation> rels) {
   Symbol *personality = nullptr;
   unsigned firstRelI = cie.firstRelocation;
   if (firstRelI != (unsigned)-1)
-    personality = &cie.sec->file->getRelocTargetSym(rels[firstRelI]);
+    personality = rels[firstRelI].sym;
 
   // Search for an existing CIE by CIE contents/relocation target pair.
   CieRecord *&rec = cieMap[{cie.data(), personality}];
@@ -424,25 +424,20 @@ CieRecord *EhFrameSection::addCie(EhSectionPiece &cie, ArrayRef<RelTy> rels) {
 
 // There is one FDE per function. Returns a non-null pointer to the function
 // symbol if the given FDE points to a live function.
-template <class RelTy>
-Defined *EhFrameSection::isFdeLive(EhSectionPiece &fde, ArrayRef<RelTy> rels) {
-  auto *sec = cast<EhInputSection>(fde.sec);
-  unsigned firstRelI = fde.firstRelocation;
-
+Defined *EhFrameSection::isFdeLive(EhSectionPiece &fde,
+                                   ArrayRef<Relocation> rels) {
   // An FDE should point to some function because FDEs are to describe
   // functions. That's however not always the case due to an issue of
   // ld.gold with -r. ld.gold may discard only functions and leave their
   // corresponding FDEs, which results in creating bad .eh_frame sections.
   // To deal with that, we ignore such FDEs.
+  unsigned firstRelI = fde.firstRelocation;
   if (firstRelI == (unsigned)-1)
     return nullptr;
 
-  const RelTy &rel = rels[firstRelI];
-  Symbol &b = sec->file->getRelocTargetSym(rel);
-
   // FDEs for garbage-collected or merged-by-ICF sections, or sections in
   // another partition, are dead.
-  if (auto *d = dyn_cast<Defined>(&b))
+  if (auto *d = dyn_cast<Defined>(rels[firstRelI].sym))
     if (!d->folded && d->section && d->section->partition == partition)
       return d;
   return nullptr;
@@ -452,13 +447,13 @@ Defined *EhFrameSection::isFdeLive(EhSectionPiece &fde, ArrayRef<RelTy> rels) {
 // is one CIE record per input object file which is followed by
 // a list of FDEs. This function searches an existing CIE or create a new
 // one and associates FDEs to the CIE.
-template <class ELFT, class RelTy>
-void EhFrameSection::addRecords(EhInputSection *sec, ArrayRef<RelTy> rels) {
+template <endianness e> void EhFrameSection::addRecords(EhInputSection *sec) {
+  auto rels = sec->rels;
   offsetToCie.clear();
   for (EhSectionPiece &cie : sec->cies)
-    offsetToCie[cie.inputOff] = addCie<RelTy>(cie, rels);
+    offsetToCie[cie.inputOff] = addCie(cie, rels);
   for (EhSectionPiece &fde : sec->fdes) {
-    uint32_t id = endian::read32<ELFT::Endianness>(fde.data().data() + 4);
+    uint32_t id = endian::read32<e>(fde.data().data() + 4);
     CieRecord *rec = offsetToCie[fde.inputOff + 4 - id];
     if (!rec)
       Fatal(ctx) << sec << ": invalid CIE reference";
@@ -470,23 +465,11 @@ void EhFrameSection::addRecords(EhInputSection *sec, ArrayRef<RelTy> rels) {
   }
 }
 
-template <class ELFT>
-void EhFrameSection::addSectionAux(EhInputSection *sec) {
-  if (!sec->isLive())
-    return;
-  const RelsOrRelas<ELFT> rels =
-      sec->template relsOrRelas<ELFT>(/*supportsCrel=*/false);
-  if (rels.areRelocsRel())
-    addRecords<ELFT>(sec, rels.rels);
-  else
-    addRecords<ELFT>(sec, rels.relas);
-}
-
 // Used by ICF<ELFT>::handleLSDA(). This function is very similar to
 // EhFrameSection::addRecords().
-template <class ELFT, class RelTy>
+template <class ELFT>
 void EhFrameSection::iterateFDEWithLSDAAux(
-    EhInputSection &sec, ArrayRef<RelTy> rels, DenseSet<size_t> &ciesWithLSDA,
+    EhInputSection &sec, DenseSet<size_t> &ciesWithLSDA,
     llvm::function_ref<void(InputSection &)> fn) {
   for (EhSectionPiece &cie : sec.cies)
     if (hasLSDA(cie))
@@ -497,7 +480,7 @@ void EhFrameSection::iterateFDEWithLSDAAux(
       continue;
 
     // The CIE has a LSDA argument. Call fn with d's section.
-    if (Defined *d = isFdeLive(fde, rels))
+    if (Defined *d = isFdeLive(fde, sec.rels))
       if (auto *s = dyn_cast_or_null<InputSection>(d->section))
         fn(*s);
   }
@@ -509,12 +492,7 @@ void EhFrameSection::iterateFDEWithLSDA(
   DenseSet<size_t> ciesWithLSDA;
   for (EhInputSection *sec : sections) {
     ciesWithLSDA.clear();
-    const RelsOrRelas<ELFT> rels =
-        sec->template relsOrRelas<ELFT>(/*supportsCrel=*/false);
-    if (rels.areRelocsRel())
-      iterateFDEWithLSDAAux<ELFT>(*sec, rels.rels, ciesWithLSDA, fn);
-    else
-      iterateFDEWithLSDAAux<ELFT>(*sec, rels.relas, ciesWithLSDA, fn);
+    iterateFDEWithLSDAAux<ELFT>(*sec, ciesWithLSDA, fn);
   }
 }
 
@@ -531,20 +509,16 @@ void EhFrameSection::finalizeContents() {
   case ELFNoneKind:
     llvm_unreachable("invalid ekind");
   case ELF32LEKind:
-    for (EhInputSection *sec : sections)
-      addSectionAux<ELF32LE>(sec);
-    break;
-  case ELF32BEKind:
-    for (EhInputSection *sec : sections)
-      addSectionAux<ELF32BE>(sec);
-    break;
   case ELF64LEKind:
     for (EhInputSection *sec : sections)
-      addSectionAux<ELF64LE>(sec);
+      if (sec->isLive())
+        addRecords<endianness::little>(sec);
     break;
+  case ELF32BEKind:
   case ELF64BEKind:
     for (EhInputSection *sec : sections)
-      addSectionAux<ELF64BE>(sec);
+      if (sec->isLive())
+        addRecords<endianness::big>(sec);
     break;
   }
 

lld/ELF/SyntheticSections.h

@@ -80,19 +80,14 @@ class EhFrameSection final : public SyntheticSection {
 
   uint64_t size = 0;
 
-  template <class ELFT, class RelTy>
-  void addRecords(EhInputSection *s, llvm::ArrayRef<RelTy> rels);
-  template <class ELFT> void addSectionAux(EhInputSection *s);
-  template <class ELFT, class RelTy>
-  void iterateFDEWithLSDAAux(EhInputSection &sec, ArrayRef<RelTy> rels,
+  template <llvm::endianness E> void addRecords(EhInputSection *s);
+  template <class ELFT>
+  void iterateFDEWithLSDAAux(EhInputSection &sec,
                              llvm::DenseSet<size_t> &ciesWithLSDA,
                              llvm::function_ref<void(InputSection &)> fn);
 
-  template <class RelTy>
-  CieRecord *addCie(EhSectionPiece &piece, ArrayRef<RelTy> rels);
-
-  template <class RelTy>
-  Defined *isFdeLive(EhSectionPiece &piece, ArrayRef<RelTy> rels);
+  CieRecord *addCie(EhSectionPiece &piece, ArrayRef<Relocation> rels);
+  Defined *isFdeLive(EhSectionPiece &piece, ArrayRef<Relocation> rels);
 
   uint64_t getFdePc(uint8_t *buf, size_t off, uint8_t enc) const;