Rename llvmc2/src to llvmc2/core.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57000 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 755 insertions, 0 deletions

diff --git a/tools/llvmc2/core/Action.cpp b/tools/llvmc2/core/Action.cpp
new file mode 100644
index 0000000000..c0a1b849bc
--- /dev/null
+++ b/tools/llvmc2/core/Action.cpp
@@ -0,0 +1,78 @@
+//===--- Action.cpp - The LLVM Compiler Driver ------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open
+// Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Action class - implementation and auxiliary functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CompilerDriver/Action.h"
+
+#include "llvm/Support/CommandLine.h"
+#include "llvm/System/Program.h"
+
+#include <iostream>
+#include <stdexcept>
+
+using namespace llvm;
+using namespace llvmc;
+
+extern cl::opt<bool> DryRun;
+extern cl::opt<bool> VerboseMode;
+
+namespace {
+  int ExecuteProgram(const std::string& name,
+                     const StrVector& args) {
+    sys::Path prog = sys::Program::FindProgramByName(name);
+
+    if (prog.isEmpty())
+      throw std::runtime_error("Can't find program '" + name + "'");
+    if (!prog.canExecute())
+      throw std::runtime_error("Program '" + name + "' is not executable.");
+
+    // Build the command line vector and the redirects array.
+    const sys::Path* redirects[3] = {0,0,0};
+    sys::Path stdout_redirect;
+
+    std::vector<const char*> argv;
+    argv.reserve((args.size()+2));
+    argv.push_back(name.c_str());
+
+    for (StrVector::const_iterator B = args.begin(), E = args.end();
+         B!=E; ++B) {
+      if (*B == ">") {
+        ++B;
+        stdout_redirect.set(*B);
+        redirects[1] = &stdout_redirect;
+      }
+      else {
+        argv.push_back((*B).c_str());
+      }
+    }
+    argv.push_back(0);  // null terminate list.
+
+    // Invoke the program.
+    return sys::Program::ExecuteAndWait(prog, &argv[0], 0, &redirects[0]);
+  }
+
+  void print_string (const std::string& str) {
+    std::cerr << str << ' ';
+  }
+}
+
+int llvmc::Action::Execute() const {
+  if (DryRun || VerboseMode) {
+    std::cerr << Command_ << " ";
+    std::for_each(Args_.begin(), Args_.end(), print_string);
+    std::cerr << '\n';
+  }
+  if (DryRun)
+    return 0;
+  else
+    return ExecuteProgram(Command_, Args_);
+}
diff --git a/tools/llvmc2/core/CompilationGraph.cpp b/tools/llvmc2/core/CompilationGraph.cpp
new file mode 100644
index 0000000000..838b940501
--- /dev/null
+++ b/tools/llvmc2/core/CompilationGraph.cpp
@@ -0,0 +1,442 @@
+//===--- CompilationGraph.cpp - The LLVM Compiler Driver --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open
+// Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Compilation graph - implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Error.h"
+#include "llvm/CompilerDriver/CompilationGraph.h"
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/DOTGraphTraits.h"
+#include "llvm/Support/GraphWriter.h"
+
+#include <algorithm>
+#include <iterator>
+#include <limits>
+#include <queue>
+#include <stdexcept>
+
+using namespace llvm;
+using namespace llvmc;
+
+extern cl::list<std::string> InputFilenames;
+extern cl::opt<std::string> OutputFilename;
+extern cl::list<std::string> Languages;
+
+namespace llvmc {
+
+  const std::string& LanguageMap::GetLanguage(const sys::Path& File) const {
+    LanguageMap::const_iterator Lang = this->find(File.getSuffix());
+    if (Lang == this->end())
+      throw std::runtime_error("Unknown suffix: " + File.getSuffix());
+    return Lang->second;
+  }
+}
+
+namespace {
+
+  /// ChooseEdge - Return the edge with the maximum weight.
+  template <class C>
+  const Edge* ChooseEdge(const C& EdgesContainer,
+                         const InputLanguagesSet& InLangs,
+                         const std::string& NodeName = "root") {
+    const Edge* MaxEdge = 0;
+    unsigned MaxWeight = 0;
+    bool SingleMax = true;
+
+    for (typename C::const_iterator B = EdgesContainer.begin(),
+           E = EdgesContainer.end(); B != E; ++B) {
+      const Edge* e = B->getPtr();
+      unsigned EW = e->Weight(InLangs);
+      if (EW > MaxWeight) {
+        MaxEdge = e;
+        MaxWeight = EW;
+        SingleMax = true;
+      } else if (EW == MaxWeight) {
+        SingleMax = false;
+      }
+    }
+
+    if (!SingleMax)
+      throw std::runtime_error("Node " + NodeName +
+                               ": multiple maximal outward edges found!"
+                               " Most probably a specification error.");
+    if (!MaxEdge)
+      throw std::runtime_error("Node " + NodeName +
+                               ": no maximal outward edge found!"
+                               " Most probably a specification error.");
+    return MaxEdge;
+  }
+
+}
+
+CompilationGraph::CompilationGraph() {
+  NodesMap["root"] = Node(this);
+}
+
+Node& CompilationGraph::getNode(const std::string& ToolName) {
+  nodes_map_type::iterator I = NodesMap.find(ToolName);
+  if (I == NodesMap.end())
+    throw std::runtime_error("Node " + ToolName + " is not in the graph");
+  return I->second;
+}
+
+const Node& CompilationGraph::getNode(const std::string& ToolName) const {
+  nodes_map_type::const_iterator I = NodesMap.find(ToolName);
+  if (I == NodesMap.end())
+    throw std::runtime_error("Node " + ToolName + " is not in the graph!");
+  return I->second;
+}
+
+// Find the tools list corresponding to the given language name.
+const CompilationGraph::tools_vector_type&
+CompilationGraph::getToolsVector(const std::string& LangName) const
+{
+  tools_map_type::const_iterator I = ToolsMap.find(LangName);
+  if (I == ToolsMap.end())
+    throw std::runtime_error("No tool corresponding to the language "
+                             + LangName + " found");
+  return I->second;
+}
+
+void CompilationGraph::insertNode(Tool* V) {
+  if (NodesMap.count(V->Name()) == 0) {
+    Node N;
+    N.OwningGraph = this;
+    N.ToolPtr = V;
+    NodesMap[V->Name()] = N;
+  }
+}
+
+void CompilationGraph::insertEdge(const std::string& A, Edge* Edg) {
+  Node& B = getNode(Edg->ToolName());
+  if (A == "root") {
+    const char** InLangs = B.ToolPtr->InputLanguages();
+    for (;*InLangs; ++InLangs)
+      ToolsMap[*InLangs].push_back(IntrusiveRefCntPtr<Edge>(Edg));
+    NodesMap["root"].AddEdge(Edg);
+  }
+  else {
+    Node& N = getNode(A);
+    N.AddEdge(Edg);
+  }
+  // Increase the inward edge counter.
+  B.IncrInEdges();
+}
+
+namespace {
+  sys::Path MakeTempFile(const sys::Path& TempDir, const std::string& BaseName,
+                         const std::string& Suffix) {
+    sys::Path Out;
+
+    // Make sure we don't end up with path names like '/file.o' if the
+    // TempDir is empty.
+    if (TempDir.empty()) {
+      Out.set(BaseName);
+    }
+    else {
+      Out = TempDir;
+      Out.appendComponent(BaseName);
+    }
+    Out.appendSuffix(Suffix);
+    // NOTE: makeUnique always *creates* a unique temporary file,
+    // which is good, since there will be no races. However, some
+    // tools do not like it when the output file already exists, so
+    // they have to be placated with -f or something like that.
+    Out.makeUnique(true, NULL);
+    return Out;
+  }
+}
+
+// Pass input file through the chain until we bump into a Join node or
+// a node that says that it is the last.
+void CompilationGraph::PassThroughGraph (const sys::Path& InFile,
+                                         const Node* StartNode,
+                                         const InputLanguagesSet& InLangs,
+                                         const sys::Path& TempDir,
+                                         const LanguageMap& LangMap) const {
+  bool Last = false;
+  sys::Path In = InFile;
+  const Node* CurNode = StartNode;
+
+  while(!Last) {
+    sys::Path Out;
+    Tool* CurTool = CurNode->ToolPtr.getPtr();
+
+    if (CurTool->IsJoin()) {
+      JoinTool& JT = dynamic_cast<JoinTool&>(*CurTool);
+      JT.AddToJoinList(In);
+      break;
+    }
+
+    // Since toolchains do not have to end with a Join node, we should
+    // check if this Node is the last.
+    if (!CurNode->HasChildren() || CurTool->IsLast()) {
+      if (!OutputFilename.empty()) {
+        Out.set(OutputFilename);
+      }
+      else {
+        Out.set(In.getBasename());
+        Out.appendSuffix(CurTool->OutputSuffix());
+      }
+      Last = true;
+    }
+    else {
+      Out = MakeTempFile(TempDir, In.getBasename(), CurTool->OutputSuffix());
+    }
+
+    if (int ret = CurTool->GenerateAction(In, Out, InLangs, LangMap).Execute())
+      throw error_code(ret);
+
+    if (Last)
+      return;
+
+    CurNode = &getNode(ChooseEdge(CurNode->OutEdges,
+                                  InLangs,
+                                  CurNode->Name())->ToolName());
+    In = Out; Out.clear();
+  }
+}
+
+// Find the head of the toolchain corresponding to the given file.
+// Also, insert an input language into InLangs.
+const Node* CompilationGraph::
+FindToolChain(const sys::Path& In, const std::string* ForceLanguage,
+              InputLanguagesSet& InLangs, const LanguageMap& LangMap) const {
+
+  // Determine the input language.
+  const std::string& InLanguage =
+    ForceLanguage ? *ForceLanguage : LangMap.GetLanguage(In);
+
+  // Add the current input language to the input language set.
+  InLangs.insert(InLanguage);
+
+  // Find the toolchain for the input language.
+  const tools_vector_type& TV = getToolsVector(InLanguage);
+  if (TV.empty())
+    throw std::runtime_error("No toolchain corresponding to language "
+                             + InLanguage + " found");
+  return &getNode(ChooseEdge(TV, InLangs)->ToolName());
+}
+
+// Helper function used by Build().
+// Traverses initial portions of the toolchains (up to the first Join node).
+// This function is also responsible for handling the -x option.
+void CompilationGraph::BuildInitial (InputLanguagesSet& InLangs,
+                                     const sys::Path& TempDir,
+                                     const LanguageMap& LangMap) {
+  // This is related to -x option handling.
+  cl::list<std::string>::const_iterator xIter = Languages.begin(),
+    xBegin = xIter, xEnd = Languages.end();
+  bool xEmpty = true;
+  const std::string* xLanguage = 0;
+  unsigned xPos = 0, xPosNext = 0, filePos = 0;
+
+  if (xIter != xEnd) {
+    xEmpty = false;
+    xPos = Languages.getPosition(xIter - xBegin);
+    cl::list<std::string>::const_iterator xNext = llvm::next(xIter);
+    xPosNext = (xNext == xEnd) ? std::numeric_limits<unsigned>::max()
+      : Languages.getPosition(xNext - xBegin);
+    xLanguage = (*xIter == "none") ? 0 : &(*xIter);
+  }
+
+  // For each input file:
+  for (cl::list<std::string>::const_iterator B = InputFilenames.begin(),
+         CB = B, E = InputFilenames.end(); B != E; ++B) {
+    sys::Path In = sys::Path(*B);
+
+    // Code for handling the -x option.
+    // Output: std::string* xLanguage (can be NULL).
+    if (!xEmpty) {
+      filePos = InputFilenames.getPosition(B - CB);
+
+      if (xPos < filePos) {
+        if (filePos < xPosNext) {
+          xLanguage = (*xIter == "none") ? 0 : &(*xIter);
+        }
+        else { // filePos >= xPosNext
+          // Skip xIters while filePos > xPosNext
+          while (filePos > xPosNext) {
+            ++xIter;
+            xPos = xPosNext;
+
+            cl::list<std::string>::const_iterator xNext = llvm::next(xIter);
+            if (xNext == xEnd)
+              xPosNext = std::numeric_limits<unsigned>::max();
+            else
+              xPosNext = Languages.getPosition(xNext - xBegin);
+            xLanguage = (*xIter == "none") ? 0 : &(*xIter);
+          }
+        }
+      }
+    }
+
+    // Find the toolchain corresponding to this file.
+    const Node* N = FindToolChain(In, xLanguage, InLangs, LangMap);
+    // Pass file through the chain starting at head.
+    PassThroughGraph(In, N, InLangs, TempDir, LangMap);
+  }
+}
+
+// Sort the nodes in topological order.
+void CompilationGraph::TopologicalSort(std::vector<const Node*>& Out) {
+  std::queue<const Node*> Q;
+  Q.push(&getNode("root"));
+
+  while (!Q.empty()) {
+    const Node* A = Q.front();
+    Q.pop();
+    Out.push_back(A);
+    for (Node::const_iterator EB = A->EdgesBegin(), EE = A->EdgesEnd();
+         EB != EE; ++EB) {
+      Node* B = &getNode((*EB)->ToolName());
+      B->DecrInEdges();
+      if (B->HasNoInEdges())
+        Q.push(B);
+    }
+  }
+}
+
+namespace {
+  bool NotJoinNode(const Node* N) {
+    return N->ToolPtr ? !N->ToolPtr->IsJoin() : true;
+  }
+}
+
+// Call TopologicalSort and filter the resulting list to include
+// only Join nodes.
+void CompilationGraph::
+TopologicalSortFilterJoinNodes(std::vector<const Node*>& Out) {
+  std::vector<const Node*> TopSorted;
+  TopologicalSort(TopSorted);
+  std::remove_copy_if(TopSorted.begin(), TopSorted.end(),
+                      std::back_inserter(Out), NotJoinNode);
+}
+
+int CompilationGraph::Build (const sys::Path& TempDir,
+                             const LanguageMap& LangMap) {
+
+  InputLanguagesSet InLangs;
+
+  // Traverse initial parts of the toolchains and fill in InLangs.
+  BuildInitial(InLangs, TempDir, LangMap);
+
+  std::vector<const Node*> JTV;
+  TopologicalSortFilterJoinNodes(JTV);
+
+  // For all join nodes in topological order:
+  for (std::vector<const Node*>::iterator B = JTV.begin(), E = JTV.end();
+       B != E; ++B) {
+
+    sys::Path Out;
+    const Node* CurNode = *B;
+    JoinTool* JT = &dynamic_cast<JoinTool&>(*CurNode->ToolPtr.getPtr());
+    bool IsLast = false;
+
+    // Are there any files in the join list?
+    if (JT->JoinListEmpty())
+      continue;
+
+    // Is this the last tool in the toolchain?
+    // NOTE: we can process several toolchains in parallel.
+    if (!CurNode->HasChildren() || JT->IsLast()) {
+      if (OutputFilename.empty()) {
+        Out.set("a");
+        Out.appendSuffix(JT->OutputSuffix());
+      }
+      else
+        Out.set(OutputFilename);
+      IsLast = true;
+    }
+    else {
+      Out = MakeTempFile(TempDir, "tmp", JT->OutputSuffix());
+    }
+
+    if (int ret = JT->GenerateAction(Out, InLangs, LangMap).Execute())
+      throw error_code(ret);
+
+    if (!IsLast) {
+      const Node* NextNode =
+        &getNode(ChooseEdge(CurNode->OutEdges, InLangs,
+                            CurNode->Name())->ToolName());
+      PassThroughGraph(Out, NextNode, InLangs, TempDir, LangMap);
+    }
+  }
+
+  return 0;
+}
+
+// Code related to graph visualization.
+
+namespace llvm {
+  template <>
+  struct DOTGraphTraits<llvmc::CompilationGraph*>
+    : public DefaultDOTGraphTraits
+  {
+
+    template<typename GraphType>
+    static std::string getNodeLabel(const Node* N, const GraphType&)
+    {
+      if (N->ToolPtr)
+        if (N->ToolPtr->IsJoin())
+          return N->Name() + "\n (join" +
+            (N->HasChildren() ? ")"
+             : std::string(": ") + N->ToolPtr->OutputLanguage() + ')');
+        else
+          return N->Name();
+      else
+        return "root";
+    }
+
+    template<typename EdgeIter>
+    static std::string getEdgeSourceLabel(const Node* N, EdgeIter I) {
+      if (N->ToolPtr) {
+        return N->ToolPtr->OutputLanguage();
+      }
+      else {
+        const char** InLangs = I->ToolPtr->InputLanguages();
+        std::string ret;
+
+        for (; *InLangs; ++InLangs) {
+          if (*(InLangs + 1)) {
+            ret += *InLangs;
+            ret +=  ", ";
+          }
+          else {
+            ret += *InLangs;
+          }
+        }
+
+        return ret;
+      }
+    }
+  };
+
+}
+
+void CompilationGraph::writeGraph() {
+  std::ofstream O("compilation-graph.dot");
+
+  if (O.good()) {
+    llvm::WriteGraph(this, "compilation-graph");
+    O.close();
+  }
+  else {
+    throw std::runtime_error("Error opening file 'compilation-graph.dot'"
+                             " for writing!");
+  }
+}
+
+void CompilationGraph::viewGraph() {
+  llvm::ViewGraph(this, "compilation-graph");
+}
diff --git a/tools/llvmc2/core/Error.h b/tools/llvmc2/core/Error.h
new file mode 100644
index 0000000000..c0aaff1a72
--- /dev/null
+++ b/tools/llvmc2/core/Error.h
@@ -0,0 +1,33 @@
+//===--- Error.h - The LLVM Compiler Driver ---------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open
+// Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Exception classes for LLVMC.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVMC2_ERROR_H
+#define LLVM_TOOLS_LLVMC2_ERROR_H
+
+#include <stdexcept>
+
+namespace llvmc {
+
+  class error_code: public std::runtime_error {
+    int Code_;
+  public:
+    error_code (int c)
+      : std::runtime_error("Tool returned error code"), Code_(c)
+    {}
+
+    int code() const { return Code_; }
+  };
+
+}
+
+#endif //LLVM_TOOLS_LLVMC2_ERROR_H
diff --git a/tools/llvmc2/core/Makefile b/tools/llvmc2/core/Makefile
new file mode 100644
index 0000000000..7c04fe4aca
--- /dev/null
+++ b/tools/llvmc2/core/Makefile
@@ -0,0 +1,19 @@
+##===- tools/llvmc2/src/Makefile ---------------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open
+# Source License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+TOOLNAME = $(DRIVER_NAME)
+LINK_COMPONENTS = support system
+REQUIRES_EH := 1
+
+ifneq ($(BUILTIN_PLUGINS),)
+USEDLIBS = $(patsubst %,LLVMC%,$(BUILTIN_PLUGINS))
+endif
+
+include $(LEVEL)/Makefile.common
diff --git a/tools/llvmc2/core/Plugin.cpp b/tools/llvmc2/core/Plugin.cpp
new file mode 100644
index 0000000000..c9b3960c1e
--- /dev/null
+++ b/tools/llvmc2/core/Plugin.cpp
@@ -0,0 +1,64 @@
+//===--- Plugin.cpp - The LLVM Compiler Driver ------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open
+// Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Plugin support for llvmc2.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CompilerDriver/Plugin.h"
+
+#include <vector>
+
+namespace {
+
+  // Registry::Add<> does not do lifetime management (probably issues
+  // with static constructor/destructor ordering), so we have to
+  // implement it here.
+  //
+  // All this static registration/life-before-main model seems
+  // unnecessary convoluted to me.
+
+  static bool pluginListInitialized = false;
+  typedef std::vector<const llvmc::BasePlugin*> PluginList;
+  static PluginList Plugins;
+}
+
+namespace llvmc {
+
+  PluginLoader::PluginLoader() {
+    if (!pluginListInitialized) {
+      for (PluginRegistry::iterator B = PluginRegistry::begin(),
+             E = PluginRegistry::end(); B != E; ++B)
+        Plugins.push_back(B->instantiate());
+    }
+    pluginListInitialized = true;
+  }
+
+  PluginLoader::~PluginLoader() {
+    if (pluginListInitialized) {
+      for (PluginList::iterator B = Plugins.begin(), E = Plugins.end();
+           B != E; ++B)
+        delete (*B);
+    }
+    pluginListInitialized = false;
+  }
+
+  void PluginLoader::PopulateLanguageMap(LanguageMap& langMap) {
+    for (PluginList::iterator B = Plugins.begin(), E = Plugins.end();
+         B != E; ++B)
+      (*B)->PopulateLanguageMap(langMap);
+  }
+
+  void PluginLoader::PopulateCompilationGraph(CompilationGraph& graph) {
+    for (PluginList::iterator B = Plugins.begin(), E = Plugins.end();
+         B != E; ++B)
+      (*B)->PopulateCompilationGraph(graph);
+  }
+
+}
diff --git a/tools/llvmc2/core/llvmc.cpp b/tools/llvmc2/core/llvmc.cpp
new file mode 100644
index 0000000000..f3a1e57192
--- /dev/null
+++ b/tools/llvmc2/core/llvmc.cpp
@@ -0,0 +1,119 @@
+//===--- llvmc.cpp - The LLVM Compiler Driver -------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open
+// Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This tool provides a single point of access to the LLVM
+//  compilation tools.  It has many options. To discover the options
+//  supported please refer to the tools' manual page or run the tool
+//  with the --help option.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Error.h"
+
+#include "llvm/CompilerDriver/CompilationGraph.h"
+#include "llvm/CompilerDriver/Plugin.h"
+
+#include "llvm/System/Path.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/PluginLoader.h"
+
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+namespace cl = llvm::cl;
+namespace sys = llvm::sys;
+using namespace llvmc;
+
+// Built-in command-line options.
+// External linkage here is intentional.
+
+cl::list<std::string> InputFilenames(cl::Positional, cl::desc("<input file>"),
+                                     cl::ZeroOrMore);
+cl::opt<std::string> OutputFilename("o", cl::desc("Output file name"),
+                                    cl::value_desc("file"));
+cl::list<std::string> Languages("x",
+          cl::desc("Specify the language of the following input files"),
+          cl::ZeroOrMore);
+cl::opt<bool> DryRun("dry-run",
+                     cl::desc("Only pretend to run commands"));
+cl::opt<bool> VerboseMode("v",
+                          cl::desc("Enable verbose mode"));
+cl::opt<bool> WriteGraph("write-graph",
+                         cl::desc("Write compilation-graph.dot file"),
+                         cl::Hidden);
+cl::opt<bool> ViewGraph("view-graph",
+                         cl::desc("Show compilation graph in GhostView"),
+                         cl::Hidden);
+cl::opt<bool> SaveTemps("save-temps",
+                         cl::desc("Keep temporary files"),
+                         cl::Hidden);
+
+namespace {
+  /// BuildTargets - A small wrapper for CompilationGraph::Build.
+  int BuildTargets(CompilationGraph& graph, const LanguageMap& langMap) {
+    int ret;
+    const sys::Path& tempDir = SaveTemps
+      ? sys::Path("")
+      : sys::Path(sys::Path::GetTemporaryDirectory());
+
+    try {
+      ret = graph.Build(tempDir, langMap);
+    }
+    catch(...) {
+      tempDir.eraseFromDisk(true);
+      throw;
+    }
+
+    if (!SaveTemps)
+      tempDir.eraseFromDisk(true);
+    return ret;
+  }
+}
+
+int main(int argc, char** argv) {
+  try {
+    LanguageMap langMap;
+    CompilationGraph graph;
+
+    cl::ParseCommandLineOptions
+      (argc, argv, "LLVM Compiler Driver (Work In Progress)", true);
+
+    PluginLoader Plugins;
+    Plugins.PopulateLanguageMap(langMap);
+    Plugins.PopulateCompilationGraph(graph);
+
+    if (WriteGraph) {
+      graph.writeGraph();
+      if (!ViewGraph)
+        return 0;
+    }
+
+    if (ViewGraph) {
+      graph.viewGraph();
+      return 0;
+    }
+
+    if (InputFilenames.empty()) {
+      throw std::runtime_error("no input files");
+    }
+
+    return BuildTargets(graph, langMap);
+  }
+  catch(llvmc::error_code& ec) {
+    return ec.code();
+  }
+  catch(const std::exception& ex) {
+    std::cerr << argv[0] << ": " << ex.what() << '\n';
+  }
+  catch(...) {
+    std::cerr << argv[0] << ": unknown error!\n";
+  }
+  return 1;
+}