[RuntimeDyld] Track symbol visibility in RuntimeDyld.

RuntimeDyld symbol info previously consisted of just a Section/Offset pair. This
patch replaces that pair type with a SymbolInfo class that also tracks symbol
visibility. A new method, RuntimeDyld::getExportedSymbolLoadAddress, is
introduced which only returns a non-zero result for exported symbols. For
non-exported or non-existant symbols this method will return zero. The
RuntimeDyld::getSymbolAddress method retains its current behavior, returning
non-zero results for all symbols regardless of visibility.

No in-tree clients of RuntimeDyld are changed. The newly introduced
functionality will be used by the Orc APIs.

No test case: Since this patch doesn't modify the behavior for any in-tree
clients we don't have a good tool to test this with yet. Once Orc is in we can
use it to write regression tests that test these changes.

llvm-svn: 226341

5 files changed, 89 insertions, 38 deletions

diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index 304014edb24..b0f44b12fd0 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -200,9 +200,14 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
         bool IsCode = SI->isText();
         unsigned SectionID =
             findOrEmitSection(Obj, *SI, IsCode, LocalSections);
-        DEBUG(dbgs() << "\tOffset: " << format("%p", (uintptr_t)SectOffset)
-                     << " flags: " << Flags << " SID: " << SectionID);
-        GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
+        DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name
+                     << " SID: " << SectionID << " Offset: "
+                     << format("%p", (uintptr_t)SectOffset)
+                     << " flags: " << Flags << "\n");
+        SymbolInfo::Visibility Vis =
+          (Flags & SymbolRef::SF_Exported) ?
+            SymbolInfo::Default : SymbolInfo::Hidden;
+        GlobalSymbolTable[Name] = {SectionID, SectOffset, Vis};
       }
     }
     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
@@ -444,7 +449,7 @@ void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
 void RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
                                         const CommonSymbolMap &CommonSymbols,
                                         uint64_t TotalSize,
-                                        SymbolTableMap &SymbolTable) {
+                                        RTDyldSymbolTable &SymbolTable) {
   // Allocate memory for the section
   unsigned SectionID = Sections.size();
   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void *),
@@ -473,7 +478,11 @@ void RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
       DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
                    << format("%p\n", Addr));
     }
-    SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
+    uint32_t Flags = it->first.getFlags();
+    SymbolInfo::Visibility Vis =
+      (Flags & SymbolRef::SF_Exported) ?
+        SymbolInfo::Default : SymbolInfo::Hidden;
+    SymbolTable[Name.data()] = {SectionID, Offset, Vis};
     Offset += Size;
     Addr += Size;
   }
@@ -589,14 +598,15 @@ void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
   // Relocation by symbol.  If the symbol is found in the global symbol table,
   // create an appropriate section relocation.  Otherwise, add it to
   // ExternalSymbolRelocations.
-  SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
+  RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
   if (Loc == GlobalSymbolTable.end()) {
     ExternalSymbolRelocations[SymbolName].push_back(RE);
   } else {
     // Copy the RE since we want to modify its addend.
     RelocationEntry RECopy = RE;
-    RECopy.Addend += Loc->second.second;
-    Relocations[Loc->second.first].push_back(RECopy);
+    const auto &SymInfo = Loc->second;
+    RECopy.Addend += SymInfo.getOffset();
+    Relocations[SymInfo.getSectionID()].push_back(RECopy);
   }
 }
 
@@ -721,7 +731,7 @@ void RuntimeDyldImpl::resolveExternalSymbols() {
       resolveRelocationList(Relocs, 0);
     } else {
       uint64_t Addr = 0;
-      SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
+      RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(Name);
       if (Loc == GlobalSymbolTable.end()) {
         // This is an external symbol, try to get its address from
         // MemoryManager.
@@ -736,8 +746,9 @@ void RuntimeDyldImpl::resolveExternalSymbols() {
       } else {
         // We found the symbol in our global table.  It was probably in a
         // Module that we loaded previously.
-        SymbolLoc SymLoc = Loc->second;
-        Addr = getSectionLoadAddress(SymLoc.first) + SymLoc.second;
+        const auto &SymInfo = Loc->second;
+        Addr = getSectionLoadAddress(SymInfo.getSectionID()) +
+               SymInfo.getOffset();
       }
 
       // FIXME: Implement error handling that doesn't kill the host program!
@@ -834,6 +845,12 @@ uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) const {
   return Dyld->getSymbolLoadAddress(Name);
 }
 
+uint64_t RuntimeDyld::getExportedSymbolLoadAddress(StringRef Name) const {
+  if (!Dyld)
+    return 0;
+  return Dyld->getExportedSymbolLoadAddress(Name);
+}
+
 void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
 
 void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
index f3e5c77cd08..309a9b48296 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
@@ -850,14 +850,16 @@ std::pair<uint64_t, std::string> RuntimeDyldCheckerImpl::getStubAddrFor(
 
 StringRef
 RuntimeDyldCheckerImpl::getSubsectionStartingAt(StringRef Name) const {
-  RuntimeDyldImpl::SymbolTableMap::const_iterator pos =
+  RTDyldSymbolTable::const_iterator pos =
       getRTDyld().GlobalSymbolTable.find(Name);
   if (pos == getRTDyld().GlobalSymbolTable.end())
     return StringRef();
-  RuntimeDyldImpl::SymbolLoc Loc = pos->second;
-  uint8_t *SectionAddr = getRTDyld().getSectionAddress(Loc.first);
-  return StringRef(reinterpret_cast<const char *>(SectionAddr) + Loc.second,
-                   getRTDyld().Sections[Loc.first].Size - Loc.second);
+  const auto &SymInfo = pos->second;
+  uint8_t *SectionAddr = getRTDyld().getSectionAddress(SymInfo.getSectionID());
+  return StringRef(reinterpret_cast<const char *>(SectionAddr) +
+                     SymInfo.getOffset(),
+                   getRTDyld().Sections[SymInfo.getSectionID()].Size -
+                     SymInfo.getOffset());
 }
 
 void RuntimeDyldCheckerImpl::registerSection(
@@ -887,9 +889,10 @@ void RuntimeDyldCheckerImpl::registerStubMap(
       // If this is a (Section, Offset) pair, do a reverse lookup in the
       // global symbol table to find the name.
       for (auto &GSTEntry : getRTDyld().GlobalSymbolTable) {
-        if (GSTEntry.second.first == StubMapEntry.first.SectionID &&
-            GSTEntry.second.second ==
-                static_cast<uint64_t>(StubMapEntry.first.Offset)) {
+        const auto &SymInfo = GSTEntry.second;
+        if (SymInfo.getSectionID() == StubMapEntry.first.SectionID &&
+            SymInfo.getOffset() ==
+              static_cast<uint64_t>(StubMapEntry.first.Offset)) {
           SymbolName = GSTEntry.first();
           break;
         }
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 2664a10ece5..0f3ca0f2f39 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -920,15 +920,16 @@ relocation_iterator RuntimeDyldELF::processRelocationRef(
   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
 
   // Search for the symbol in the global symbol table
-  SymbolTableMap::const_iterator gsi = GlobalSymbolTable.end();
+  RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
   if (Symbol != Obj.symbol_end()) {
     gsi = GlobalSymbolTable.find(TargetName.data());
     Symbol->getType(SymType);
   }
   if (gsi != GlobalSymbolTable.end()) {
-    Value.SectionID = gsi->second.first;
-    Value.Offset = gsi->second.second;
-    Value.Addend = gsi->second.second + Addend;
+    const auto &SymInfo = gsi->second;
+    Value.SectionID = SymInfo.getSectionID();
+    Value.Offset = SymInfo.getOffset();
+    Value.Addend = SymInfo.getOffset() + Addend;
   } else {
     switch (SymType) {
     case SymbolRef::ST_Debug: {
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
index 2f3e3a8f034..c985eb33d8d 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
@@ -156,6 +156,28 @@ public:
   }
 };
 
+/// @brief Symbol info for RuntimeDyld.
+class SymbolInfo {
+public:
+  typedef enum { Hidden = 0, Default = 1 } Visibility;
+
+  SymbolInfo() : Offset(0), SectionID(0), Vis(Hidden) {}
+
+  SymbolInfo(unsigned SectionID, uint64_t Offset, Visibility Vis)
+    : Offset(Offset), SectionID(SectionID), Vis(Vis) {}
+
+  unsigned getSectionID() const { return SectionID; }
+  uint64_t getOffset() const { return Offset; }
+  Visibility getVisibility() const { return Vis; }
+
+private:
+  uint64_t Offset;
+  unsigned SectionID : 31;
+  Visibility Vis : 1;
+};
+
+typedef StringMap<SymbolInfo> RTDyldSymbolTable;
+
 class RuntimeDyldImpl {
   friend class RuntimeDyld::LoadedObjectInfo;
   friend class RuntimeDyldCheckerImpl;
@@ -178,11 +200,8 @@ protected:
   // references it.
   typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
 
-  // A global symbol table for symbols from all loaded modules.  Maps the
-  // symbol name to a (SectionID, offset in section) pair.
-  typedef std::pair<unsigned, uintptr_t> SymbolLoc;
-  typedef StringMap<SymbolLoc> SymbolTableMap;
-  SymbolTableMap GlobalSymbolTable;
+  // A global symbol table for symbols from all loaded modules.
+  RTDyldSymbolTable GlobalSymbolTable;
 
   // Pair representing the size and alignment requirement for a common symbol.
   typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
@@ -289,7 +308,7 @@ protected:
   /// symbol table.
   void emitCommonSymbols(const ObjectFile &Obj,
                          const CommonSymbolMap &CommonSymbols,
-                         uint64_t TotalSize, SymbolTableMap &SymbolTable);
+                         uint64_t TotalSize, RTDyldSymbolTable &SymbolTable);
 
   /// \brief Emits section data from the object file to the MemoryManager.
   /// \param IsCode if it's true then allocateCodeSection() will be
@@ -374,21 +393,31 @@ public:
   uint8_t* getSymbolAddress(StringRef Name) const {
     // FIXME: Just look up as a function for now. Overly simple of course.
     // Work in progress.
-    SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
+    RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
     if (pos == GlobalSymbolTable.end())
       return nullptr;
-    SymbolLoc Loc = pos->second;
-    return getSectionAddress(Loc.first) + Loc.second;
+    const auto &SymInfo = pos->second;
+    return getSectionAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
   }
 
   uint64_t getSymbolLoadAddress(StringRef Name) const {
     // FIXME: Just look up as a function for now. Overly simple of course.
     // Work in progress.
-    SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
+    RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
     if (pos == GlobalSymbolTable.end())
       return 0;
-    SymbolLoc Loc = pos->second;
-    return getSectionLoadAddress(Loc.first) + Loc.second;
+    const auto &SymInfo = pos->second;
+    return getSectionLoadAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
+  }
+
+  uint64_t getExportedSymbolLoadAddress(StringRef Name) const {
+    RTDyldSymbolTable::const_iterator pos = GlobalSymbolTable.find(Name);
+    if (pos == GlobalSymbolTable.end())
+      return 0;
+    const auto &SymInfo = pos->second;
+    if (SymInfo.getVisibility() == SymbolInfo::Hidden)
+      return 0;
+    return getSectionLoadAddress(SymInfo.getSectionID()) + SymInfo.getOffset();
   }
 
   void resolveRelocations();
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
index 21893d2909e..2d3966270fc 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
@@ -64,11 +64,12 @@ RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
     symbol_iterator Symbol = RI->getSymbol();
     StringRef TargetName;
     Symbol->getName(TargetName);
-    SymbolTableMap::const_iterator SI =
+    RTDyldSymbolTable::const_iterator SI =
       GlobalSymbolTable.find(TargetName.data());
     if (SI != GlobalSymbolTable.end()) {
-      Value.SectionID = SI->second.first;
-      Value.Offset = SI->second.second + RE.Addend;
+      const auto &SymInfo = SI->second;
+      Value.SectionID = SymInfo.getSectionID();
+      Value.Offset = SymInfo.getOffset() + RE.Addend;
     } else {
       Value.SymbolName = TargetName.data();
       Value.Offset = RE.Addend;