[dwarfdump] Do not apply relocations in mach-o files if there is no LoadedObjectInfo.

[oota-llvm.git] / lib / DebugInfo / DWARF / DWARFContext.cpp

diff --git a/lib/DebugInfo/DWARF/DWARFContext.cpp b/lib/DebugInfo/DWARF/DWARFContext.cpp
index 1faa2ba5921d562005b70b9b0f4493cba4d12faa..aecd991ff0db2c32c60b3e4e435054eab4ab4215 100644 (file)
--- a/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -352,7 +352,7 @@ void DWARFContext::parseTypeUnits() {
   if (!TUs.empty())
     return;
   for (const auto &I : getTypesSections()) {
-    TUs.push_back(DWARFUnitSection<DWARFTypeUnit>());
+    TUs.emplace_back();
     TUs.back().parse(*this, I.second);
   }
 }
@@ -365,7 +365,7 @@ void DWARFContext::parseDWOTypeUnits() {
   if (!DWOTUs.empty())
     return;
   for (const auto &I : getTypesDWOSections()) {
-    DWOTUs.push_back(DWARFUnitSection<DWARFTypeUnit>());
+    DWOTUs.emplace_back();
     DWOTUs.back().parseDWO(*this, I.second);
   }
 }
@@ -540,7 +540,8 @@ static bool consumeCompressedDebugSectionHeader(StringRef &data,
   return true;
 }
 
-DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj)
+DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj,
+    const LoadedObjectInfo *L)
     : IsLittleEndian(Obj.isLittleEndian()),
       AddressSize(Obj.getBytesInAddress()) {
   for (const SectionRef &Section : Obj.sections()) {
@@ -554,7 +555,13 @@ DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj)
     if (IsVirtual)
       continue;
     StringRef data;
-    Section.getContents(data);
+
+    section_iterator RelocatedSection = Section.getRelocatedSection();
+    // Try to obtain an already relocated version of this section.
+    // Else use the unrelocated section from the object file. We'll have to
+    // apply relocations ourselves later.
+    if (!L || !L->getLoadedSectionContents(*RelocatedSection,data))
+      Section.getContents(data);
 
     name = name.substr(name.find_first_not_of("._")); // Skip . and _ prefixes.
 
@@ -617,12 +624,27 @@ DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj)
       TypesDWOSections[Section].Data = data;
     }
 
-    section_iterator RelocatedSection = Section.getRelocatedSection();
     if (RelocatedSection == Obj.section_end())
       continue;
 
     StringRef RelSecName;
+    StringRef RelSecData;
     RelocatedSection->getName(RelSecName);
+
+    // If the section we're relocating was relocated already by the JIT,
+    // then we used the relocated version above, so we do not need to process
+    // relocations for it now.
+    if (L && L->getLoadedSectionContents(*RelocatedSection,RelSecData))
+      continue;
+
+    // In Mach-o files, the relocations do not need to be applied if
+    // there is no load offset to apply. The value read at the
+    // relocation point already factors in the section address
+    // (actually applying the relocations will produce wrong results
+    // as the section address will be added twice).
+    if (!L && dyn_cast<MachOObjectFile>(&Obj))
+      continue;
+
     RelSecName = RelSecName.substr(
         RelSecName.find_first_not_of("._")); // Skip . and _ prefixes.
 
@@ -653,23 +675,62 @@ DWARFContextInMemory::DWARFContextInMemory(const object::ObjectFile &Obj)
     if (Section.relocation_begin() != Section.relocation_end()) {
       uint64_t SectionSize = RelocatedSection->getSize();
       for (const RelocationRef &Reloc : Section.relocations()) {
-        uint64_t Address;
-        Reloc.getOffset(Address);
-        uint64_t Type;
-        Reloc.getType(Type);
+        uint64_t Address = Reloc.getOffset();
+        uint64_t Type = Reloc.getType();
         uint64_t SymAddr = 0;
+        uint64_t SectionLoadAddress = 0;
         object::symbol_iterator Sym = Reloc.getSymbol();
-        if (Sym != Obj.symbol_end())
-          Sym->getAddress(SymAddr);
+        object::section_iterator RSec = Obj.section_end();
+
+        // First calculate the address of the symbol or section as it appears
+        // in the objct file
+        if (Sym != Obj.symbol_end()) {
+          ErrorOr<uint64_t> SymAddrOrErr = Sym->getAddress();
+          if (std::error_code EC = SymAddrOrErr.getError()) {
+            errs() << "error: failed to compute symbol address: "
+                   << EC.message() << '\n';
+            continue;
+          }
+          SymAddr = *SymAddrOrErr;
+          // Also remember what section this symbol is in for later
+          RSec = *Sym->getSection();
+        } else if (auto *MObj = dyn_cast<MachOObjectFile>(&Obj)) {
+          // MachO also has relocations that point to sections and
+          // scattered relocations.
+          auto RelocInfo = MObj->getRelocation(Reloc.getRawDataRefImpl());
+          if (MObj->isRelocationScattered(RelocInfo)) {
+            // FIXME: it's not clear how to correctly handle scattered
+            // relocations.
+            continue;
+          } else {
+            RSec = MObj->getRelocationSection(Reloc.getRawDataRefImpl());
+            SymAddr = RSec->getAddress();
+          }
+        }
+
+        // If we are given load addresses for the sections, we need to adjust:
+        // SymAddr = (Address of Symbol Or Section in File) -
+        //           (Address of Section in File) +
+        //           (Load Address of Section)
+        if (L != nullptr && RSec != Obj.section_end()) {
+          // RSec is now either the section being targeted or the section
+          // containing the symbol being targeted. In either case,
+          // we need to perform the same computation.
+          StringRef SecName;
+          RSec->getName(SecName);
+//           llvm::dbgs() << "Name: '" << SecName
+//                        << "', RSec: " << RSec->getRawDataRefImpl()
+//                        << ", Section: " << Section.getRawDataRefImpl() << "\n";
+          SectionLoadAddress = L->getSectionLoadAddress(*RSec);
+          if (SectionLoadAddress != 0)
+            SymAddr += SectionLoadAddress - RSec->getAddress();
+        }
 
         object::RelocVisitor V(Obj);
         object::RelocToApply R(V.visit(Type, Reloc, SymAddr));
         if (V.error()) {
           SmallString<32> Name;
-          std::error_code ec(Reloc.getTypeName(Name));
-          if (ec) {
-            errs() << "Aaaaaa! Nameless relocation! Aaaaaa!\n";
-          }
+          Reloc.getTypeName(Name);
           errs() << "error: failed to compute relocation: "
                  << Name << "\n";
           continue;