Suzero. X8664. NaCl Sandboxing.

src/IceELFSection.h

 //===- subzero/src/IceELFSection.h - Model of ELF sections ------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 338 matching lines @@
 
 template <bool IsELF64>
 void ELFRelocationSection::writeData(const GlobalContext &Ctx, ELFStreamer &Str,
                                      const ELFSymbolTableSection *SymTab) {
   for (const AssemblerFixup &Fixup : Fixups) {
     const ELFSym *Symbol;
     if (Fixup.isNullSymbol()) {
       Symbol = SymTab->getNullSymbol();
     } else {
       constexpr Assembler *Asm = nullptr;
-      Symbol = SymTab->findSymbol(Fixup.symbol(&Ctx, Asm));
+      IceString Name = Fixup.symbol(&Ctx, Asm);
+      Symbol = SymTab->findSymbol(Name);
+      if (!Symbol)
+        llvm::report_fatal_error(Name + ": Missing symbol mentioned in reloc");
     }
-    if (!Symbol)
-      llvm::report_fatal_error("Missing symbol mentioned in reloc");
 
     if (IsELF64) {
-      // TODO(jpp): check that Fixup.offset() is correct even for pc-rel.
       Elf64_Rela Rela;
       Rela.r_offset = Fixup.position();
       Rela.setSymbolAndType(Symbol->getNumber(), Fixup.kind());
       Rela.r_addend = Fixup.offset();
+      if (Fixup.kind() == llvm::ELF::R_X86_64_PC32) {
+        // In ELF64, PC-relative relocations' addends need to account for the
+        // immediate size. For now, this is always 4 (because x86-64 sandboxed
+        // is the only ELF64 target currently implemented.)
+        constexpr int32_t RelocImmediateSize = 4;
+        Rela.r_addend -= RelocImmediateSize;
+      }
       Str.writeAddrOrOffset<IsELF64>(Rela.r_offset);
       Str.writeELFXword<IsELF64>(Rela.r_info);
       Str.writeELFXword<IsELF64>(Rela.r_addend);
     } else {
       Elf32_Rel Rel;
       Rel.r_offset = Fixup.position();
       Rel.setSymbolAndType(Symbol->getNumber(), Fixup.kind());
       Str.writeAddrOrOffset<IsELF64>(Rel.r_offset);
       Str.writeELFWord<IsELF64>(Rel.r_info);
     }
   }
 }
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEELFSECTION_H