mirror of
https://github.com/rui314/mold.git
synced 2024-12-26 18:02:30 +03:00
253 lines
6.8 KiB
C++
253 lines
6.8 KiB
C++
#include "mold.h"
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using namespace llvm;
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using namespace llvm::ELF;
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InputChunk::InputChunk(Kind kind, ObjectFile *file, const ELF64LE::Shdr &shdr,
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StringRef name)
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: kind(kind), file(file), shdr(shdr), name(name) {
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output_section = OutputSection::get_instance(name, shdr.sh_flags, shdr.sh_type);
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u64 align = (shdr.sh_addralign == 0) ? 1 : shdr.sh_addralign;
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if (align > UINT32_MAX)
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error(toString(file) + ": section sh_addralign is too large");
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if (__builtin_popcount(align) != 1)
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error(toString(file) + ": section sh_addralign is not a power of two");
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}
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void InputSection::copy_buf() {
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if (shdr.sh_type == SHT_NOBITS || shdr.sh_size == 0)
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return;
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// Copy data
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ArrayRef<u8> data = check(file->obj.getSectionContents(shdr));
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memcpy(out::buf + output_section->shdr.sh_offset + offset, &data[0], data.size());
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// Apply relocations
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u8 *base = out::buf + output_section->shdr.sh_offset + offset;
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u64 sh_addr = output_section->shdr.sh_addr + offset;
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for (int i = 0; i < rels.size(); i++) {
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const ELF64LE::Rela &rel = rels[i];
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StringPieceRef &ref = rel_pieces[i];
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Symbol &sym = *file->symbols[rel.getSymbol(false)];
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u8 *loc = base + rel.r_offset;
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if (!sym.file)
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continue;
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#define S (ref.piece ? ref.piece->get_addr() : sym.get_addr())
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#define A (ref.piece ? ref.addend : rel.r_addend)
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#define P (sh_addr + rel.r_offset)
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#define L sym.get_plt_addr()
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#define G sym.get_got_addr()
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#define GOT out::got->shdr.sh_addr
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switch (rel.getType(false)) {
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case R_X86_64_NONE:
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break;
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case R_X86_64_64:
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*(u64 *)loc = S + A;
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break;
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case R_X86_64_PC32:
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*(u32 *)loc = S + A - P;
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break;
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case R_X86_64_GOT32:
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*(u64 *)loc = G - GOT + A;
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break;
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case R_X86_64_PLT32:
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if (sym.plt_idx == -1)
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*(u32 *)loc = S + A - P;
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else
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*(u32 *)loc = L + A - P;
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break;
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case R_X86_64_GOTPCREL:
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*(u32 *)loc = G + A - P;
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break;
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case R_X86_64_32:
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case R_X86_64_32S:
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*(u32 *)loc = S + A;
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break;
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case R_X86_64_16:
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*(u16 *)loc = S + A;
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break;
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case R_X86_64_PC16:
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*(u16 *)loc = S + A - P;
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break;
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case R_X86_64_8:
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*loc = S + A;
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break;
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case R_X86_64_PC8:
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*loc = S + A - P;
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break;
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case R_X86_64_TLSGD:
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if (sym.tlsgd_idx == -1) {
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// Relax GD to LE
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static const u8 insn[] = {
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0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
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0x48, 0x8d, 0x80, 0, 0, 0, 0, // lea x@tpoff, %rax
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};
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memcpy(loc - 4, insn, sizeof(insn));
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*(u32 *)(loc + 8) = S - out::tls_end + A + 4;
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i++;
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} else {
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*(u32 *)loc = sym.get_tlsgd_addr() + A - P;
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}
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break;
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case R_X86_64_TLSLD:
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if (sym.tlsld_idx == -1) {
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// Relax LD to LE
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static const u8 insn[] = {
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0x66, 0x66, 0x66, 0x64, 0x48, 0x8b, 0x04, 0x25, 0, 0, 0, 0, // mov %fs:0, %rax
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};
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memcpy(loc - 3, insn, sizeof(insn));
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i++;
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} else {
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*(u32 *)loc = sym.get_tlsld_addr() + A - P;
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}
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break;
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case R_X86_64_DTPOFF32:
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case R_X86_64_TPOFF32:
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*(u32 *)loc = S - out::tls_end;
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break;
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case R_X86_64_GOTTPOFF:
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*(u32 *)loc = sym.get_gottpoff_addr() + A - P;
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break;
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case R_X86_64_PC64:
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*(u64 *)loc = S + A - P;
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break;
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case R_X86_64_GOTPC32:
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*(u32 *)loc = GOT + A - P;
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break;
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case R_X86_64_GOTPCRELX:
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case R_X86_64_REX_GOTPCRELX:
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*(u32 *)loc = G + A - P;
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break;
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default:
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error(toString(this) + ": unknown relocation: " +
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std::to_string(rel.getType(false)));
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}
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#undef S
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#undef A
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#undef P
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#undef L
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#undef G
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#undef GOT
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}
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static Counter counter("relocs");
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counter.inc(rels.size());
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}
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void InputSection::scan_relocations() {
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if (!(shdr.sh_flags & SHF_ALLOC))
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return;
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for (int i = 0; i < rels.size(); i++) {
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const ELF64LE::Rela &rel = rels[i];
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Symbol &sym = *file->symbols[rel.getSymbol(false)];
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if (!sym.file || sym.is_placeholder) {
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file->has_error = true;
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continue;
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}
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switch (rel.getType(false)) {
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case R_X86_64_NONE:
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break;
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case R_X86_64_8:
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case R_X86_64_16:
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case R_X86_64_32:
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case R_X86_64_32S:
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case R_X86_64_64:
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case R_X86_64_PC8:
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case R_X86_64_PC16:
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case R_X86_64_PC32:
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case R_X86_64_PC64:
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if (sym.is_imported) {
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if (sym.type == STT_OBJECT)
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sym.flags |= Symbol::NEEDS_COPYREL;
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else
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sym.flags |= Symbol::NEEDS_PLT;
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}
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break;
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case R_X86_64_GOT32:
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case R_X86_64_GOTPC32:
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case R_X86_64_GOTPCREL:
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case R_X86_64_GOTPCRELX:
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case R_X86_64_REX_GOTPCRELX:
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sym.flags |= Symbol::NEEDS_GOT;
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break;
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case R_X86_64_PLT32:
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if (sym.is_imported || sym.type == STT_GNU_IFUNC)
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sym.flags |= Symbol::NEEDS_PLT;
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break;
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case R_X86_64_TLSGD:
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assert(rels[i + 1].getType(false) == R_X86_64_PLT32);
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if (sym.is_imported)
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sym.flags |= Symbol::NEEDS_TLSGD;
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else
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i++;
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break;
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case R_X86_64_TLSLD:
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assert(rels[i + 1].getType(false) == R_X86_64_PLT32);
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if (sym.is_imported)
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sym.flags |= Symbol::NEEDS_TLSLD;
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else
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i++;
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break;
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case R_X86_64_TPOFF32:
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case R_X86_64_DTPOFF32:
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break;
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case R_X86_64_GOTTPOFF:
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sym.flags |= Symbol::NEEDS_GOTTPOFF;
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break;
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default:
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error(toString(this) + ": unknown relocation: " +
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std::to_string(rel.getType(false)));
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}
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}
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}
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void InputSection::report_undefined_symbols() {
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if (!(shdr.sh_flags & SHF_ALLOC))
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return;
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for (const ELF64LE::Rela &rel : rels) {
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Symbol &sym = *file->symbols[rel.getSymbol(false)];
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if (!sym.file || sym.is_placeholder)
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llvm::errs() << "undefined symbol: " << toString(file)
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<< ": " << sym.name << "\n";
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}
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}
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MergeableSection::MergeableSection(InputSection *isec, ArrayRef<u8> contents)
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: InputChunk(MERGEABLE, isec->file, isec->shdr, isec->name),
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parent(*MergedSection::get_instance(isec->name, isec->shdr.sh_flags,
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isec->shdr.sh_type)) {
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StringRef data((const char *)&contents[0], contents.size());
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u32 offset = 0;
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while (!data.empty()) {
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size_t end = data.find('\0');
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if (end == StringRef::npos)
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error(toString(this) + ": string is not null terminated");
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StringRef substr = data.substr(0, end + 1);
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data = data.substr(end + 1);
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StringPiece *piece = parent.map.insert(substr, StringPiece(substr));
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pieces.push_back({piece, offset});
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offset += substr.size();
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}
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static Counter counter("string_pieces");
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counter.inc(pieces.size());
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}
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std::string toString(InputChunk *chunk) {
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return (toString(chunk->file) + ":(" + chunk->name + ")").str();
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}
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