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 515 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();

[Jim Stichnoth, 2015/02/01 03:23:55]

The fact that this is IceString instead of IceString& makes me think it's too
bad all the getName() methods don't return references.  Most of the getName()
calls are only used for dumping or textual emission, but this use is probably
unavoidable.

Nothing to do about it yet, I guess.

[jvoung (off chromium), 2015/02/01 17:07:56]

Hmm I can check if they can be converted to return IceString& in a separate CL.

+    assert(Sym->getOffset() == 0 && Sym->getSuppressMangling());

[Jim Stichnoth, 2015/02/01 03:23:55]

I realize there are "violations" elsewhere, but I think it's better to use two
asserts here since you get more precise information on a failure.

[jvoung (off chromium), 2015/02/01 17:07:56]

Oops done.

+    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