3 files changed, 78 insertions, 3 deletions
diff --git a/lib/Linker/LinkArchives.cpp b/lib/Linker/LinkArchives.cpp
index a35991ce2d..e5ec0b83b8 100644
--- a/lib/Linker/LinkArchives.cpp
+++ b/lib/Linker/LinkArchives.cpp
@@ -16,10 +16,23 @@
 #include "llvm/ADT/SetOperations.h"
 #include "llvm/Bitcode/Archive.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/CommandLine.h" // @LOCALMOD
+
 #include <memory>
 #include <set>
 using namespace llvm;
 
+// @LOCALMOD-START
+// NOTE: this has a similar effect as
+//        tools/llvm/llvm-preserve.ll
+// which in turn is similar to the GNUS's attribute((used))
+// TODO(robertm): This is a little hackish for now
+static cl::list<std::string>
+UndefList("referenced-list", cl::value_desc("list"),
+          cl::desc("A list of symbols assumed to be referenced externally"),
+          cl::CommaSeparated);
+// @LOCALMOD-END
+  
 /// GetAllUndefinedSymbols - calculates the set of undefined symbols that still
 /// exist in an LLVM module. This is a bit tricky because there may be two
 /// symbols with the same name but different LLVM types that will be resolved to
@@ -36,7 +49,10 @@ static void
 GetAllUndefinedSymbols(Module *M, std::set<std::string> &UndefinedSymbols) {
   std::set<std::string> DefinedSymbols;
   UndefinedSymbols.clear();
-
+  // @LOCALMOD-START
+  UndefinedSymbols.insert(UndefList.begin(), UndefList.end());
+  // @LOCALMOD-END
+  
   // If the program doesn't define a main, try pulling one in from a .a file.
   // This is needed for programs where the main function is defined in an
   // archive, such f2c'd programs.
diff --git a/lib/Linker/LinkItems.cpp b/lib/Linker/LinkItems.cpp
index 8c6ed423f0..0ab551d14d 100644
--- a/lib/Linker/LinkItems.cpp
+++ b/lib/Linker/LinkItems.cpp
@@ -51,6 +51,21 @@ Linker::LinkInItems(const ItemList& Items, ItemList& NativeItems) {
     }
   }
 
+  // @LOCALMOD-BEGIN
+  // At this point we have processed all the link items provided to us. Since
+  // we have an aggregated module at this point, the dependent libraries in
+  // that module should also be aggregated with duplicates eliminated. This is
+  // now the time to process the dependent libraries to resolve any remaining
+  // symbols.
+  bool is_native;
+  for (Module::lib_iterator I = Composite->lib_begin(),
+         E = Composite->lib_end(); I != E; ++I) {
+    if(LinkInLibrary(*I, is_native))
+      return true;
+    if (is_native)
+      NativeItems.push_back(std::make_pair(*I, true));
+  }
+  // @LOCALMOD-END
   return false;
 }
 
@@ -113,7 +128,18 @@ bool Linker::LinkInLibraries(const std::vector<std::string> &Libraries) {
   for (unsigned i = 0; i < Libraries.size(); ++i)
     if (LinkInLibrary(Libraries[i], is_native))
       return true;
-
+  // @LOCALMOD-BEGIN
+  // At this point we have processed all the libraries provided to us. Since
+  // we have an aggregated module at this point, the dependent libraries in
+  // that module should also be aggregated with duplicates eliminated. This is
+  // now the time to process the dependent libraries to resolve any remaining
+  // symbols.
+  const Module::LibraryListType& DepLibs = Composite->getLibraries();
+  for (Module::LibraryListType::const_iterator I = DepLibs.begin(),
+         E = DepLibs.end(); I != E; ++I)
+    if (LinkInLibrary(*I, is_native))
+      return true;
+  // @LOCALMOD-END
   return false;
 }
 
diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index e34dbcbe4c..15a4a1e24b 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -933,6 +933,19 @@ void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
     ValueMap[I] = DI;
   }
 
+  // @LOCALMOD-BEGIN
+  // Local patch for http://llvm.org/bugs/show_bug.cgi?id=11112
+  // and http://llvm.org/bugs/show_bug.cgi?id=10887
+  // Create an identity mapping for instructions so that alloca instructions
+  // do not get dropped and related debug info isn't lost.  E.g., prevent
+  //   call @llvm.dbg.declare(metadata !{i32 * %local_var}, ...)
+  // from becoming
+  //   call @llvm.dbg.declare(null, ...)
+  for (Function::iterator BB = Src->begin(), BE = Src->end(); BB != BE; ++BB)
+    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+      ValueMap[I] = I;
+  // @LOCALMOD-END
+
   if (Mode == Linker::DestroySource) {
     // Splice the body of the source function into the dest function.
     Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
@@ -950,6 +963,13 @@ void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
     SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
     CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", NULL, &TypeMap);
   }
+
+  // @LOCALMOD-BEGIN
+  // There is no need for the identity mapping anymore.
+  for (Function::iterator BB = Src->begin(), BE = Src->end(); BB != BE; ++BB)
+    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+      ValueMap.erase(I);
+  // @LOCALMOD-END
   
   // There is no need to map the arguments anymore.
   for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
@@ -1175,7 +1195,20 @@ bool ModuleLinker::run() {
       DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
                                SrcM->getModuleInlineAsm());
   }
-
+  // @LOCALMOD-BEGIN
+  // Update the destination module's dependent libraries list with the libraries
+  // from the source module. There's no opportunity for duplicates here as the
+  // Module ensures that duplicate insertions are discarded.
+  for (Module::lib_iterator SI = SrcM->lib_begin(), SE = SrcM->lib_end();
+       SI != SE; ++SI)
+    DstM->addLibrary(*SI);
+  
+  // If the source library's module id is in the dependent library list of the
+  // destination library, remove it since that module is now linked in.
+  StringRef ModuleId = SrcM->getModuleIdentifier();
+  if (!ModuleId.empty())
+    DstM->removeLibrary(sys::path::stem(ModuleId));
+  // @LOCALMOD-END
   // Loop over all of the linked values to compute type mappings.
   computeTypeMapping();