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[yaml2obj][ELF] Start factoring into "single point of truth".

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llvm-svn: 184457
This commit is contained in:
Sean Silva 2013-06-20 19:11:44 +00:00
parent 459731fae0
commit 8006fd36a5
1 changed files with 51 additions and 19 deletions
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70
tools/yaml2obj/yaml2elf.cpp
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@ -134,20 +134,49 @@ static void createStringTableSectionHeader(Elf_Shdr &SHeader,
SHeader.sh_addralign = 1;
}
// FIXME: This function is hideous. Between the sheer number of parameters
// and the hideous ELF typenames, it's just a travesty. Factor the ELF
// output into a class (templated on ELFT) and share some typedefs.
namespace {
/// \brief "Single point of truth" for the ELF file construction.
/// TODO: This class still has a ways to go before it is truly a "single
/// point of truth".
template <class ELFT>
class ELFState {
/// \brief The future ".strtab" section.
StringTableBuilder DotStrtab;
/// \brief The section number of the ".strtab" section.
unsigned DotStrtabSecNo;
/// \brief The accumulated contents of all sections so far.
ContiguousBlobAccumulator &SectionContentAccum;
typedef typename object::ELFObjectFile<ELFT>::Elf_Ehdr Elf_Ehdr;
/// \brief The ELF file header.
Elf_Ehdr &Header;
public:
ELFState(Elf_Ehdr &Header_, ContiguousBlobAccumulator &Accum,
unsigned DotStrtabSecNo_)
: DotStrtab(), DotStrtabSecNo(DotStrtabSecNo_),
SectionContentAccum(Accum), Header(Header_) {}
unsigned getDotStrTabSecNo() const { return DotStrtabSecNo; }
StringTableBuilder &getStringTable() { return DotStrtab; }
ContiguousBlobAccumulator &getSectionContentAccum() {
return SectionContentAccum;
}
};
} // end anonymous namespace
// FIXME: This function is hideous. The hideous ELF type names are hideous.
// Factor the ELF output into a class (templated on ELFT) and share some
// typedefs.
template <class ELFT>
static void handleSymtabSectionHeader(
const ELFYAML::Section &Sec,
typename object::ELFObjectFile<ELFT>::Elf_Shdr &SHeader,
StringTableBuilder &StrTab, ContiguousBlobAccumulator &CBA,
unsigned DotStrtabSecNo) {
const ELFYAML::Section &Sec, ELFState<ELFT> &State,
typename object::ELFObjectFile<ELFT>::Elf_Shdr &SHeader) {
typedef typename object::ELFObjectFile<ELFT>::Elf_Sym Elf_Sym;
// TODO: Ensure that a manually specified `Link` field is diagnosed as an
// error for SHT_SYMTAB.
SHeader.sh_link = DotStrtabSecNo;
SHeader.sh_link = State.getDotStrTabSecNo();
// TODO: Once we handle symbol binding, this should be one greater than
// symbol table index of the last local symbol.
SHeader.sh_info = 0;
@ -165,11 +194,12 @@ static void handleSymtabSectionHeader(
Elf_Sym Symbol;
zero(Symbol);
if (!Sym.Name.empty())
Symbol.st_name = StrTab.addString(Sym.Name);
Symbol.st_name = State.getStringTable().addString(Sym.Name);
Symbol.setBindingAndType(Sym.Binding, Sym.Type);
Syms.push_back(Symbol);
}
ContiguousBlobAccumulator &CBA = State.getSectionContentAccum();
SHeader.sh_offset = CBA.currentOffset();
SHeader.sh_size = vectorDataSize(Syms);
writeVectorData(CBA.getOS(), Syms);
@ -217,6 +247,13 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
Header.e_shstrndx = Header.e_shnum - 1;
const unsigned DotStrtabSecNo = Header.e_shnum - 2;
// XXX: This offset is tightly coupled with the order that we write
// things to `OS`.
const size_t SectionContentBeginOffset =
Header.e_ehsize + Header.e_shentsize * Header.e_shnum;
ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
ELFState<ELFT> State(Header, CBA, DotStrtabSecNo);
SectionNameToIdxMap SN2I;
for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
StringRef Name = Sections[i].Name;
@ -231,11 +268,6 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
}
StringTableBuilder SHStrTab;
// XXX: This offset is tightly coupled with the order that we write
// things to `OS`.
const size_t SectionContentBeginOffset =
Header.e_ehsize + Header.e_shentsize * Header.e_shnum;
ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
std::vector<Elf_Shdr> SHeaders;
{
// Ensure SHN_UNDEF entry is present. An all-zero section header is a
@ -244,7 +276,6 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
zero(SHdr);
SHeaders.push_back(SHdr);
}
StringTableBuilder DotStrTab;
for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
const ELFYAML::Section &Sec = Sections[i];
Elf_Shdr SHeader;
@ -270,10 +301,11 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
SHeader.sh_info = 0;
SHeader.sh_addralign = Sec.AddressAlign;
SHeader.sh_entsize = 0;
// XXX: Really ugly right now. Need to put common state into a class.
// XXX: Really ugly right now. Should not be writing to `CBA` above
// (and setting sh_offset and sh_size) when going through this branch
// here.
if (Sec.Type == ELFYAML::ELF_SHT(SHT_SYMTAB))
handleSymtabSectionHeader<ELFT>(Sec, SHeader, DotStrTab, CBA,
DotStrtabSecNo);
handleSymtabSectionHeader<ELFT>(Sec, State, SHeader);
SHeaders.push_back(SHeader);
}
@ -281,7 +313,7 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
Elf_Shdr DotStrTabSHeader;
zero(DotStrTabSHeader);
DotStrTabSHeader.sh_name = SHStrTab.addString(StringRef(".strtab"));
createStringTableSectionHeader(DotStrTabSHeader, DotStrTab, CBA);
createStringTableSectionHeader(DotStrTabSHeader, State.getStringTable(), CBA);
// Section header string table header.
Elf_Shdr SHStrTabSHeader;