Set output section's st_entsize based on input section's st_entsize.

Each input section knows its sh_entsize value, so we can set output
section's sh_entsize based on input sections values.

llvm-svn: 296577

lld/ELF/OutputSections.cpp

@@ -66,42 +66,8 @@ void OutputSection::writeHeaderTo(typename ELFT::Shdr *Shdr) {
   Shdr->sh_name = ShName;
 }
 
-template <class ELFT> static uint64_t getEntsize(uint32_t Type) {
-  switch (Type) {
-  case SHT_RELA:
-    return sizeof(typename ELFT::Rela);
-  case SHT_REL:
-    return sizeof(typename ELFT::Rel);
-  case SHT_MIPS_REGINFO:
-    return sizeof(Elf_Mips_RegInfo<ELFT>);
-  case SHT_MIPS_OPTIONS:
-    return sizeof(Elf_Mips_Options<ELFT>) + sizeof(Elf_Mips_RegInfo<ELFT>);
-  case SHT_MIPS_ABIFLAGS:
-    return sizeof(Elf_Mips_ABIFlags<ELFT>);
-  default:
-    return 0;
-  }
-}
-
 OutputSection::OutputSection(StringRef Name, uint32_t Type, uint64_t Flags)
-    : Name(Name), Addralign(1), Flags(Flags), Type(Type) {
-  switch (Config->EKind) {
-  case ELFNoneKind:
-    llvm_unreachable("unknown kind");
-  case ELF32LEKind:
-    this->Entsize = getEntsize<ELF32LE>(Type);
-    break;
-  case ELF32BEKind:
-    this->Entsize = getEntsize<ELF32BE>(Type);
-    break;
-  case ELF64LEKind:
-    this->Entsize = getEntsize<ELF64LE>(Type);
-    break;
-  case ELF64BEKind:
-    this->Entsize = getEntsize<ELF64BE>(Type);
-    break;
-  }
-}
+    : Name(Name), Addralign(1), Flags(Flags), Type(Type) {}
 
 template <typename ELFT>
 static bool compareByFilePosition(InputSection *A, InputSection *B) {
@@ -153,10 +119,15 @@ void OutputSection::addSection(InputSectionBase *C) {
   Sections.push_back(S);
   S->OutSec = this;
   this->updateAlignment(S->Alignment);
-  // Keep sh_entsize value of the input section to be able to perform merging
-  // later during a final linking using the generated relocatable object.
-  if (Config->Relocatable && (S->Flags & SHF_MERGE))
-    this->Entsize = S->Entsize;
+
+  // If this section contains a table of fixed-size entries, sh_entsize
+  // holds the element size. Consequently, if this contains two or more
+  // input sections, all of them must have the same sh_entsize. However,
+  // you can put different types of input sections into one output
+  // sectin by using linker scripts. I don't know what to do here.
+  // Probably we sholuld handle that as an error. But for now we just
+  // pick the largest sh_entsize.
+  this->Entsize = std::max(this->Entsize, S->Entsize);
 }
 
 // This function is called after we sort input sections

lld/ELF/SyntheticSections.cpp

@@ -125,7 +125,9 @@ template <class ELFT> MergeInputSection<ELFT> *elf::createCommentSection() {
 template <class ELFT>
 MipsAbiFlagsSection<ELFT>::MipsAbiFlagsSection(Elf_Mips_ABIFlags Flags)
     : SyntheticSection(SHF_ALLOC, SHT_MIPS_ABIFLAGS, 8, ".MIPS.abiflags"),
-      Flags(Flags) {}
+      Flags(Flags) {
+  this->Entsize = sizeof(Elf_Mips_ABIFlags);
+}
 
 template <class ELFT> void MipsAbiFlagsSection<ELFT>::writeTo(uint8_t *Buf) {
   memcpy(Buf, &Flags, sizeof(Flags));
@@ -182,7 +184,9 @@ MipsAbiFlagsSection<ELFT> *MipsAbiFlagsSection<ELFT>::create() {
 template <class ELFT>
 MipsOptionsSection<ELFT>::MipsOptionsSection(Elf_Mips_RegInfo Reginfo)
     : SyntheticSection(SHF_ALLOC, SHT_MIPS_OPTIONS, 8, ".MIPS.options"),
-      Reginfo(Reginfo) {}
+      Reginfo(Reginfo) {
+  this->Entsize = sizeof(Elf_Mips_Options) + sizeof(Elf_Mips_RegInfo);
+}
 
 template <class ELFT> void MipsOptionsSection<ELFT>::writeTo(uint8_t *Buf) {
   auto *Options = reinterpret_cast<Elf_Mips_Options *>(Buf);
@@ -242,7 +246,9 @@ MipsOptionsSection<ELFT> *MipsOptionsSection<ELFT>::create() {
 template <class ELFT>
 MipsReginfoSection<ELFT>::MipsReginfoSection(Elf_Mips_RegInfo Reginfo)
     : SyntheticSection(SHF_ALLOC, SHT_MIPS_REGINFO, 4, ".reginfo"),
-      Reginfo(Reginfo) {}
+      Reginfo(Reginfo) {
+  this->Entsize = sizeof(Elf_Mips_RegInfo);
+}
 
 template <class ELFT> void MipsReginfoSection<ELFT>::writeTo(uint8_t *Buf) {
   if (!Config->Relocatable)
@@ -1013,6 +1019,7 @@ DynamicSection<ELFT>::DynamicSection()
     : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_DYNAMIC, sizeof(uintX_t),
                        ".dynamic") {
   this->Entsize = ELFT::Is64Bits ? 16 : 8;
+
   // .dynamic section is not writable on MIPS.
   // See "Special Section" in Chapter 4 in the following document:
   // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
@@ -1147,7 +1154,6 @@ template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
       add({DT_MIPS_RLD_MAP, In<ELFT>::MipsRldMap});
   }
 
-  this->OutSec->Entsize = this->Entsize;
   this->OutSec->Link = this->Link;
 
   // +1 for DT_NULL
@@ -1260,7 +1266,6 @@ template <class ELFT> void RelocationSection<ELFT>::finalizeContents() {
 
   // Set required output section properties.
   this->OutSec->Link = this->Link;
-  this->OutSec->Entsize = this->Entsize;
 }
 
 template <class ELFT>
@@ -1295,7 +1300,6 @@ static bool sortMipsSymbols(const SymbolTableEntry &L, const SymbolTableEntry &R
 // dynamic linking are inherently all globals.)
 template <class ELFT> void SymbolTableSection<ELFT>::finalizeContents() {
   this->OutSec->Link = StrTabSec.OutSec->SectionIndex;
-  this->OutSec->Entsize = this->Entsize;
 
   // If it is a .dynsym, there should be no local symbols, but we need
   // to do a few things for the dynamic linker.
@@ -1451,7 +1455,6 @@ GnuHashTableSection<ELFT>::GnuHashTableSection()
 }
 
 template <class ELFT> void GnuHashTableSection<ELFT>::finalizeContents() {
-  this->OutSec->Entsize = this->Entsize;
   this->OutSec->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
 
   // Computes bloom filter size in word size. We want to allocate 8
@@ -1587,7 +1590,6 @@ HashTableSection<ELFT>::HashTableSection()
 
 template <class ELFT> void HashTableSection<ELFT>::finalizeContents() {
   this->OutSec->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
-  this->OutSec->Entsize = this->Entsize;
 
   unsigned NumEntries = 2;                            // nbucket and nchain.
   NumEntries += In<ELFT>::DynSymTab->getNumSymbols(); // The chain entries.
@@ -1933,10 +1935,11 @@ template <class ELFT> size_t VersionDefinitionSection<ELFT>::getSize() const {
 template <class ELFT>
 VersionTableSection<ELFT>::VersionTableSection()
     : SyntheticSection(SHF_ALLOC, SHT_GNU_versym, sizeof(uint16_t),
-                       ".gnu.version") {}
+                       ".gnu.version") {
+  this->Entsize = sizeof(Elf_Versym);
+}
 
 template <class ELFT> void VersionTableSection<ELFT>::finalizeContents() {
-  this->OutSec->Entsize = this->Entsize = sizeof(Elf_Versym);
   // At the moment of june 2016 GNU docs does not mention that sh_link field
   // should be set, but Sun docs do. Also readelf relies on this field.
   this->OutSec->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;

lld/test/ELF/merge-string.s

@@ -70,7 +70,7 @@ zed:
 // NOMERGE-NEXT: Link: 0
 // NOMERGE-NEXT: Info: 0
 // NOMERGE-NEXT: AddressAlignment: 1
-// NOMERGE-NEXT: EntrySize: 0
+// NOMERGE-NEXT: EntrySize: 1
 // NOMERGE-NEXT: SectionData (
 // NOMERGE-NEXT:   0000: 61626300 61626300 626300 |abc.abc.bc.|
 // NOMERGE-NEXT: )