Track undefined sym in the symtab. Remove hack for missing relocs against undef.

src/IceELFObjectWriter.cpp

 //===- subzero/src/IceELFObjectWriter.cpp - ELF object file writer --------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the writer for ELF relocatable object files.
@@ skipping 514 matching lines @@
 template void ELFObjectWriter::writeConstantPool<ConstantFloat>(Type Ty);
 
 template void ELFObjectWriter::writeConstantPool<ConstantDouble>(Type Ty);
 
 void ELFObjectWriter::writeAllRelocationSections(bool IsELF64) {
   writeRelocationSections(IsELF64, RelTextSections);
   writeRelocationSections(IsELF64, RelDataSections);
   writeRelocationSections(IsELF64, RelRODataSections);
 }
 
+void ELFObjectWriter::setUndefinedSyms(const ConstantList &UndefSyms) {
+  for (const Constant *S : UndefSyms) {
+    const auto Sym = llvm::cast<ConstantRelocatable>(S);
+    IceString Name = Sym->getName();
+    assert(Sym->getOffset() == 0);
+    assert(Sym->getSuppressMangling());
+    SymTab->noteUndefinedSym(Name, NullSection);
+    StrTab->add(Name);
+  }
+}
+
 void ELFObjectWriter::writeRelocationSections(bool IsELF64,
                                               RelSectionList &RelSections) {
   for (ELFRelocationSection *RelSec : RelSections) {
     Elf64_Off Offset = alignFileOffset(RelSec->getSectionAlign());
     RelSec->setFileOffset(Offset);
-    RelSec->setSize(RelSec->getSectionDataSize(Ctx, SymTab));
+    RelSec->setSize(RelSec->getSectionDataSize());
     if (IsELF64) {
       RelSec->writeData<true>(Ctx, Str, SymTab);
     } else {
       RelSec->writeData<false>(Ctx, Str, SymTab);
     }
   }
 }
 
 void ELFObjectWriter::writeNonUserSections() {
   bool IsELF64 = isELF64(Ctx.getTargetArch());
@@ skipping 40 matching lines @@
   if (IsELF64) {
     writeELFHeaderInternal<true>(ShOffset, ShStrTab->getNumber(),
                                  AllSections.size());
   } else {
     writeELFHeaderInternal<false>(ShOffset, ShStrTab->getNumber(),
                                   AllSections.size());
   }
 }
 
 } // end of namespace Ice