[llvm-commits] [llvm] r60656 - in /llvm/trunk: include/llvm/CompilerDriver/Action.h include/llvm/CompilerDriver/Common.td include/llvm/CompilerDriver/Tool.h include/llvm/CompilerDriver/Tools.td tools/llvmc/driver/CompilationGraph.cpp tools/llvmc/driver/Tool.cpp utils/TableGen/LLVMCConfigurationEmitter.cpp

Mikhail Glushenkov foldr at codedgers.com
Sun Dec 7 08:41:12 PST 2008


Author: foldr
Date: Sun Dec  7 10:41:11 2008
New Revision: 60656

URL: http://llvm.org/viewvc/llvm-project?rev=60656&view=rev
Log:
Use (actions) instead of option properties, support external options.

Also includes a major refactoring. See documentation for more
information.

Added:
    llvm/trunk/tools/llvmc/driver/Tool.cpp
Modified:
    llvm/trunk/include/llvm/CompilerDriver/Action.h
    llvm/trunk/include/llvm/CompilerDriver/Common.td
    llvm/trunk/include/llvm/CompilerDriver/Tool.h
    llvm/trunk/include/llvm/CompilerDriver/Tools.td
    llvm/trunk/tools/llvmc/driver/CompilationGraph.cpp
    llvm/trunk/utils/TableGen/LLVMCConfigurationEmitter.cpp

Modified: llvm/trunk/include/llvm/CompilerDriver/Action.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CompilerDriver/Action.h?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CompilerDriver/Action.h (original)
+++ llvm/trunk/include/llvm/CompilerDriver/Action.h Sun Dec  7 10:41:11 2008
@@ -27,14 +27,22 @@
     std::string Command_;
     /// Args_ - Command arguments. Stdout redirection ("> file") is allowed.
     std::vector<std::string> Args_;
+    /// StopCompilation_ - Should we stop compilation after executing
+    /// this action?
+    bool StopCompilation_;
+    /// OutFile_ - The output file name.
+    std::string OutFile_;
+
   public:
-    Action() {}
-    Action (const std::string& C, const StrVector& A)
-      : Command_(C), Args_(A)
+    Action (const std::string& C, const StrVector& A,
+            bool S, const std::string& O)
+      : Command_(C), Args_(A), StopCompilation_(S), OutFile_(O)
     {}
 
     /// Execute - Executes the represented action.
-    int Execute() const;
+    int Execute () const;
+    bool StopCompilation () const { return StopCompilation_; }
+    const std::string& OutFile() { return OutFile_; }
   };
 
 }

Modified: llvm/trunk/include/llvm/CompilerDriver/Common.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CompilerDriver/Common.td?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CompilerDriver/Common.td (original)
+++ llvm/trunk/include/llvm/CompilerDriver/Common.td Sun Dec  7 10:41:11 2008
@@ -15,7 +15,7 @@
       list<dag> properties = l;
 }
 
-// Possible Tool properties
+// Possible Tool properties.
 
 def in_language;
 def out_language;
@@ -23,8 +23,9 @@
 def cmd_line;
 def join;
 def sink;
+def actions;
 
-// Possible option types
+// Possible option types.
 
 def alias_option;
 def switch_option;
@@ -33,17 +34,16 @@
 def prefix_option;
 def prefix_list_option;
 
-// Possible option properties
+def extern_switch;
+def extern_parameter;
+def extern_list;
+
+// Possible option properties.
 
-def append_cmd;
-def forward;
-def forward_as;
 def help;
 def hidden;
 def really_hidden;
 def required;
-def stop_compilation;
-def unpack_values;
 
 // Empty DAG marker.
 def empty;
@@ -51,6 +51,10 @@
 // The 'case' construct.
 def case;
 
+// Boolean operators.
+def and;
+def or;
+
 // Primitive tests.
 def switch_on;
 def parameter_equals;
@@ -59,9 +63,13 @@
 def not_empty;
 def default;
 
-// Boolean operators.
-def and;
-def or;
+// Possible actions.
+
+def append_cmd;
+def forward;
+def forward_as;
+def stop_compilation;
+def unpack_values;
 
 // Increase/decrease the edge weight.
 def inc_weight;

Modified: llvm/trunk/include/llvm/CompilerDriver/Tool.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CompilerDriver/Tool.h?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CompilerDriver/Tool.h (original)
+++ llvm/trunk/include/llvm/CompilerDriver/Tool.h Sun Dec  7 10:41:11 2008
@@ -36,22 +36,29 @@
     virtual ~Tool() {}
 
     virtual Action GenerateAction (const PathVector& inFiles,
-                                   const llvm::sys::Path& outFile,
+                                   bool  HasChildren,
+                                   const llvm::sys::Path& TempDir,
                                    const InputLanguagesSet& InLangs,
                                    const LanguageMap& LangMap) const = 0;
 
     virtual Action GenerateAction (const llvm::sys::Path& inFile,
-                                   const llvm::sys::Path& outFile,
+                                   bool  HasChildren,
+                                   const llvm::sys::Path& TempDir,
                                    const InputLanguagesSet& InLangs,
                                    const LanguageMap& LangMap) const = 0;
 
     virtual const char*  Name() const = 0;
     virtual const char** InputLanguages() const = 0;
     virtual const char*  OutputLanguage() const = 0;
-    virtual const char*  OutputSuffix() const = 0;
 
-    virtual bool IsLast() const = 0;
     virtual bool IsJoin() const = 0;
+
+  protected:
+    /// OutFileName - Generate the output file name.
+    llvm::sys::Path OutFilename(const llvm::sys::Path& In,
+                                const llvm::sys::Path& TempDir,
+                                bool StopCompilation,
+                                const char* OutputSuffix) const;
   };
 
   /// JoinTool - A Tool that has an associated input file list.
@@ -61,10 +68,11 @@
     void ClearJoinList() { JoinList_.clear(); }
     bool JoinListEmpty() const { return JoinList_.empty(); }
 
-    Action GenerateAction(const llvm::sys::Path& outFile,
+    Action GenerateAction(bool  HasChildren,
+                          const llvm::sys::Path& TempDir,
                           const InputLanguagesSet& InLangs,
                           const LanguageMap& LangMap) const {
-      return GenerateAction(JoinList_, outFile, InLangs, LangMap);
+      return GenerateAction(JoinList_, HasChildren, TempDir, InLangs, LangMap);
     }
     // We shouldn't shadow base class's version of GenerateAction.
     using Tool::GenerateAction;

Modified: llvm/trunk/include/llvm/CompilerDriver/Tools.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CompilerDriver/Tools.td?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/include/llvm/CompilerDriver/Tools.td (original)
+++ llvm/trunk/include/llvm/CompilerDriver/Tools.td Sun Dec  7 10:41:11 2008
@@ -11,6 +11,35 @@
 //
 //===----------------------------------------------------------------------===//
 
+def OptList : OptionList<[
+ (switch_option "emit-llvm",
+    (help "Emit LLVM bitcode files instead of native object files")),
+ (switch_option "E",
+    (help "Stop after the preprocessing stage, do not run the compiler")),
+ (switch_option "fsyntax-only",
+    (help "Stop after checking the input for syntax errors")),
+ (switch_option "opt",
+    (help "Enable opt")),
+ (switch_option "S",
+    (help "Stop after compilation, do not assemble")),
+ (switch_option "c",
+    (help "Compile and assemble, but do not link")),
+ (parameter_option "linker",
+    (help "Choose linker (possible values: gcc, g++)")),
+ (parameter_list_option "include",
+    (help "Include the named file prior to preprocessing")),
+ (prefix_list_option "I",
+    (help "Add a directory to include path")),
+ (prefix_list_option "Wa,",
+    (help "Pass options to assembler")),
+ (prefix_list_option "L",
+    (help "Add a directory to link path")),
+ (prefix_list_option "l",
+    (help "Search a library when linking")),
+ (prefix_list_option "Wl,",
+    (help "Pass options to linker"))
+]>;
+
 class llvm_gcc_based <string cmd_prefix, string in_lang> : Tool<
 [(in_language in_lang),
  (out_language "llvm-bitcode"),
@@ -25,16 +54,13 @@
               !strconcat(cmd_prefix, " -fsyntax-only $INFILE"),
             (default),
               !strconcat(cmd_prefix, " -c $INFILE -o $OUTFILE -emit-llvm"))),
- (switch_option "emit-llvm", (stop_compilation),
-   (help "Emit LLVM intermediate files instead of native object files")),
- (switch_option "E", (stop_compilation),
-   (help "Stop after the preprocessing stage, do not run the compiler")),
- (switch_option "fsyntax-only", (stop_compilation),
-   (help "Stop after checking the input for syntax errors")),
- (parameter_list_option "include", (forward),
-   (help "Include the named file prior to preprocessing")),
- (prefix_list_option "I", (forward),
-   (help "Add a directory to include path")),
+ (actions
+     (case
+         (switch_on "emit-llvm"), (stop_compilation),
+         (switch_on "E"), (stop_compilation),
+         (switch_on "fsyntax-only"), (stop_compilation),
+         (not_empty "include"), (forward "include"),
+         (not_empty "I"), (forward "include"))),
  (sink)
 ]>;
 
@@ -46,7 +72,6 @@
 def opt : Tool<
 [(in_language "llvm-bitcode"),
  (out_language "llvm-bitcode"),
- (switch_option "opt", (help "Enable opt")),
  (output_suffix "bc"),
  (cmd_line "opt -f $INFILE -o $OUTFILE")
 ]>;
@@ -62,8 +87,8 @@
 [(in_language "llvm-bitcode"),
  (out_language "assembler"),
  (output_suffix "s"),
- (switch_option "S", (stop_compilation),
-                (help "Stop after compilation, do not assemble")),
+ (actions (case
+          (switch_on "S"), (stop_compilation))),
  (cmd_line "llc -f $INFILE -o $OUTFILE")
 ]>;
 
@@ -72,36 +97,28 @@
  (out_language "object-code"),
  (output_suffix "o"),
  (cmd_line "llvm-gcc -c -x assembler $INFILE -o $OUTFILE"),
- (switch_option "c", (stop_compilation),
-                (help "Compile and assemble, but do not link")),
- (prefix_list_option "Wa,", (unpack_values), (help "Pass options to assembler"))
+ (actions (case
+          (switch_on "c"), (stop_compilation),
+          (not_empty "Wa,"), (unpack_values "Wa,")))
 ]>;
 
-// Default linker
-def llvm_gcc_linker : Tool<
+// Base class for linkers
+class llvm_gcc_based_linker <string cmd_prefix> : Tool<
 [(in_language "object-code"),
  (out_language "executable"),
  (output_suffix "out"),
- (cmd_line "llvm-gcc $INFILE -o $OUTFILE"),
+ (cmd_line !strconcat(cmd_prefix, " $INFILE -o $OUTFILE")),
  (join),
- (prefix_list_option "L", (forward), (help "Add a directory to link path")),
- (prefix_list_option "l", (forward), (help "Search a library when linking")),
- (prefix_list_option "Wl,", (unpack_values), (help "Pass options to linker"))
+ (actions (case
+          (not_empty "L"), (forward "L"),
+          (not_empty "l"), (forward "l"),
+          (not_empty "Wl,"), (unpack_values "Wl,")))
 ]>;
 
+// Default linker
+def llvm_gcc_linker : llvm_gcc_based_linker<"llvm-gcc">;
 // Alternative linker for C++
-def llvm_gcc_cpp_linker : Tool<
-[(in_language "object-code"),
- (out_language "executable"),
- (output_suffix "out"),
- (cmd_line "llvm-g++ $INFILE -o $OUTFILE"),
- (join),
- (parameter_option "linker",
-                   (help "Choose linker (possible values: gcc, g++)")),
- (prefix_list_option "L", (forward)),
- (prefix_list_option "l", (forward)),
- (prefix_list_option "Wl,", (unpack_values))
-]>;
+def llvm_gcc_cpp_linker : llvm_gcc_based_linker<"llvm-g++">;
 
 // Language map
 

Modified: llvm/trunk/tools/llvmc/driver/CompilationGraph.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvmc/driver/CompilationGraph.cpp?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/tools/llvmc/driver/CompilationGraph.cpp (original)
+++ llvm/trunk/tools/llvmc/driver/CompilationGraph.cpp Sun Dec  7 10:41:11 2008
@@ -29,7 +29,6 @@
 using namespace llvmc;
 
 extern cl::list<std::string> InputFilenames;
-extern cl::opt<std::string> OutputFilename;
 extern cl::list<std::string> Languages;
 
 namespace llvmc {
@@ -143,30 +142,6 @@
   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,
@@ -174,12 +149,10 @@
                                          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;
+  while(true) {
     Tool* CurTool = CurNode->ToolPtr.getPtr();
 
     if (CurTool->IsJoin()) {
@@ -188,32 +161,19 @@
       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());
-    }
+    Action CurAction = CurTool->GenerateAction(In, CurNode->HasChildren(),
+                                               TempDir, InLangs, LangMap);
 
-    if (int ret = CurTool->GenerateAction(In, Out, InLangs, LangMap).Execute())
+    if (int ret = CurAction.Execute())
       throw error_code(ret);
 
-    if (Last)
+    if (CurAction.StopCompilation())
       return;
 
     CurNode = &getNode(ChooseEdge(CurNode->OutEdges,
                                   InLangs,
                                   CurNode->Name())->ToolName());
-    In = Out; Out.clear();
+    In = CurAction.OutFile();
   }
 }
 
@@ -351,36 +311,24 @@
     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());
-    }
+    Action CurAction = JT->GenerateAction(CurNode->HasChildren(),
+                                          TempDir, InLangs, LangMap);
 
-    if (int ret = JT->GenerateAction(Out, InLangs, LangMap).Execute())
+    if (int ret = CurAction.Execute())
       throw error_code(ret);
 
-    if (!IsLast) {
-      const Node* NextNode =
-        &getNode(ChooseEdge(CurNode->OutEdges, InLangs,
-                            CurNode->Name())->ToolName());
+    if (CurAction.StopCompilation())
+      return 0;
+
+    const Node* NextNode =
+      &getNode(ChooseEdge(CurNode->OutEdges, InLangs,
+                          CurNode->Name())->ToolName());
       PassThroughGraph(Out, NextNode, InLangs, TempDir, LangMap);
-    }
   }
 
   return 0;

Added: llvm/trunk/tools/llvmc/driver/Tool.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvmc/driver/Tool.cpp?rev=60656&view=auto

==============================================================================
--- llvm/trunk/tools/llvmc/driver/Tool.cpp (added)
+++ llvm/trunk/tools/llvmc/driver/Tool.cpp Sun Dec  7 10:41:11 2008
@@ -0,0 +1,74 @@
+//===--- Tool.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.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Tool base class - implementation details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CompilerDriver/Tool.h"
+
+#include "llvm/System/Path.h"
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+using namespace llvmc;
+
+extern cl::opt<std::string> OutputFilename;
+
+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;
+  }
+}
+
+sys::Path Tool::OutFilename(const sys::Path& In,
+                            const sys::Path& TempDir,
+                            bool StopCompilation,
+                            const char* OutputSuffix) const {
+  sys::Path Out;
+
+  if (StopCompilation) {
+    if (!OutputFilename.empty()) {
+      Out.set(OutputFilename);
+    }
+    else if (IsJoin()) {
+      Out.set("a");
+      Out.appendSuffix(OutputSuffix);
+    }
+    else {
+      Out.set(In.getBasename());
+      Out.appendSuffix(OutputSuffix);
+    }
+  }
+  else {
+    if (IsJoin())
+      Out = MakeTempFile(TempDir, "tmp", OutputSuffix);
+    else
+      Out = MakeTempFile(TempDir, In.getBasename(), OutputSuffix);
+  }
+  return Out;
+}

Modified: llvm/trunk/utils/TableGen/LLVMCConfigurationEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/LLVMCConfigurationEmitter.cpp?rev=60656&r1=60655&r2=60656&view=diff

==============================================================================
--- llvm/trunk/utils/TableGen/LLVMCConfigurationEmitter.cpp (original)
+++ llvm/trunk/utils/TableGen/LLVMCConfigurationEmitter.cpp Sun Dec  7 10:41:11 2008
@@ -45,7 +45,6 @@
 const char * Indent1 = "    ";
 const char * Indent2 = "        ";
 const char * Indent3 = "            ";
-const char * Indent4 = "                ";
 
 // Default help string.
 const char * DefaultHelpString = "NO HELP MESSAGE PROVIDED";
@@ -56,6 +55,13 @@
 //===----------------------------------------------------------------------===//
 /// Helper functions
 
+/// Id - An 'identity' function object.
+struct Id {
+  template<typename T>
+  void operator()(const T&) const {
+  }
+};
+
 int InitPtrToInt(const Init* ptr) {
   const IntInit& val = dynamic_cast<const IntInit&>(*ptr);
   return val.getValue();
@@ -89,426 +95,330 @@
   return d->getOperator()->getAsString() == "empty";
 }
 
+// EscapeVariableName - Escape commas and other symbols not allowed
+// in the C++ variable names. Makes it possible to use options named
+// like "Wa," (useful for prefix options).
+std::string EscapeVariableName(const std::string& Var) {
+  std::string ret;
+  for (unsigned i = 0; i != Var.size(); ++i) {
+    char cur_char = Var[i];
+    if (cur_char == ',') {
+      ret += "_comma_";
+    }
+    else if (cur_char == '+') {
+      ret += "_plus_";
+    }
+    else if (cur_char == '-') {
+      ret += "_dash_";
+    }
+    else {
+      ret.push_back(cur_char);
+    }
+  }
+  return ret;
+}
+
 //===----------------------------------------------------------------------===//
 /// Back-end specific code
 
-// A command-line option can have one of the following types:
-//
-// Alias - an alias for another option.
-//
-// Switch - a simple switch without arguments, e.g. -O2
-//
-// Parameter - an option that takes one(and only one) argument, e.g. -o file,
-// --output=file
-//
-// ParameterList - same as Parameter, but more than one occurence
-// of the option is allowed, e.g. -lm -lpthread
-//
-// Prefix - argument is everything after the prefix,
-// e.g. -Wa,-foo,-bar, -DNAME=VALUE
-//
-// PrefixList - same as Prefix, but more than one option occurence is
-// allowed.
 
+/// OptionType - One of six different option types. See the
+/// documentation for detailed description of differences.
+/// Extern* options are those that are defined in some other plugin.
 namespace OptionType {
-  enum OptionType { Alias, Switch,
-                    Parameter, ParameterList, Prefix, PrefixList};
+  enum OptionType { Alias, Switch, Parameter, ParameterList,
+                    Prefix, PrefixList,
+                    ExternSwitch, ExternParameter, ExternList };
+
+bool IsList (OptionType t) {
+  return (t == ParameterList || t == PrefixList || t == ExternList);
+}
+
+bool IsSwitch (OptionType t) {
+  return (t == Switch || t == ExternSwitch);
+}
+
+bool IsParameter (OptionType t) {
+  return (t == Parameter || t == Prefix || t == ExternParameter);
 }
 
-bool IsListOptionType (OptionType::OptionType t) {
-  return (t == OptionType::ParameterList || t == OptionType::PrefixList);
 }
 
-// Code duplication here is necessary because one option can affect
-// several tools and those tools may have different actions associated
-// with this option. GlobalOptionDescriptions are used to generate
-// the option registration code, while ToolOptionDescriptions are used
-// to generate tool-specific code.
+OptionType::OptionType stringToOptionType(const std::string& T) {
+  if (T == "alias_option")
+    return OptionType::Alias;
+  else if (T == "switch_option")
+    return OptionType::Switch;
+  else if (T == "parameter_option")
+    return OptionType::Parameter;
+  else if (T == "parameter_list_option")
+    return OptionType::ParameterList;
+  else if (T == "prefix_option")
+    return OptionType::Prefix;
+  else if (T == "prefix_list_option")
+    return OptionType::PrefixList;
+  else if (T == "extern_switch")
+    return OptionType::ExternSwitch;
+  else if (T == "extern_parameter")
+    return OptionType::ExternParameter;
+  else if (T == "extern_list")
+    return OptionType::ExternList;
+  else
+    throw "Unknown option type: " + T + '!';
+}
+
+namespace OptionDescriptionFlags {
+  enum OptionDescriptionFlags { Required = 0x1, Hidden = 0x2,
+                                ReallyHidden = 0x4 };
+}
 
-/// OptionDescription - Base class for option descriptions.
+/// OptionDescription - Represents data contained in a single
+/// OptionList entry.
 struct OptionDescription {
   OptionType::OptionType Type;
   std::string Name;
+  unsigned Flags;
+  std::string Help;
 
   OptionDescription(OptionType::OptionType t = OptionType::Switch,
-                    const std::string& n = "")
-  : Type(t), Name(n)
+                    const std::string& n = "",
+                    const std::string& h = DefaultHelpString)
+    : Type(t), Name(n), Flags(0x0), Help(h)
   {}
 
-  const char* GenTypeDeclaration() const {
-    switch (Type) {
-    case OptionType::Alias:
-      return "cl::alias";
-    case OptionType::PrefixList:
-    case OptionType::ParameterList:
-      return "cl::list<std::string>";
-    case OptionType::Switch:
-      return "cl::opt<bool>";
-    case OptionType::Parameter:
-    case OptionType::Prefix:
-    default:
-      return "cl::opt<std::string>";
-    }
-  }
+  /// GenTypeDeclaration - Returns the C++ variable type of this
+  /// option.
+  const char* GenTypeDeclaration() const;
+
+  /// GenVariableName - Returns the variable name used in the
+  /// generated C++ code.
+  std::string GenVariableName() const;
 
-  // Escape commas and other symbols not allowed in the C++ variable
-  // names. Makes it possible to use options with names like "Wa,"
-  // (useful for prefix options).
-  std::string EscapeVariableName(const std::string& Var) const {
-    std::string ret;
-    for (unsigned i = 0; i != Var.size(); ++i) {
-      char cur_char = Var[i];
-      if (cur_char == ',') {
-        ret += "_comma_";
-      }
-      else if (cur_char == '+') {
-        ret += "_plus_";
-      }
-      else if (cur_char == '-') {
-        ret += "_dash_";
-      }
-      else {
-        ret.push_back(cur_char);
-      }
-    }
-    return ret;
-  }
+  /// Merge - Merge two option descriptions.
+  void Merge (const OptionDescription& other);
 
-  std::string GenVariableName() const {
-    const std::string& EscapedName = EscapeVariableName(Name);
-    switch (Type) {
-    case OptionType::Alias:
-     return "AutoGeneratedAlias" + EscapedName;
-    case OptionType::Switch:
-      return "AutoGeneratedSwitch" + EscapedName;
-    case OptionType::Prefix:
-      return "AutoGeneratedPrefix" + EscapedName;
-    case OptionType::PrefixList:
-      return "AutoGeneratedPrefixList" + EscapedName;
-    case OptionType::Parameter:
-      return "AutoGeneratedParameter" + EscapedName;
-    case OptionType::ParameterList:
-    default:
-      return "AutoGeneratedParameterList" + EscapedName;
-    }
-  }
+  // Misc convenient getters/setters.
+
+  bool isAlias() const;
+  bool isExtern() const;
+
+  bool isRequired() const;
+  void setRequired();
+
+  bool isHidden() const;
+  void setHidden();
 
+  bool isReallyHidden() const;
+  void setReallyHidden();
 };
 
-// Global option description.
+void OptionDescription::Merge (const OptionDescription& other)
+{
+  if (other.Type != Type)
+    throw "Conflicting definitions for the option " + Name + "!";
+
+  if (Help == other.Help || Help == DefaultHelpString)
+    Help = other.Help;
+  else if (other.Help != DefaultHelpString) {
+    llvm::cerr << "Warning: several different help strings"
+      " defined for option " + Name + "\n";
+  }
 
-namespace GlobalOptionDescriptionFlags {
-  enum GlobalOptionDescriptionFlags { Required = 0x1, Hidden = 0x2,
-                                      ReallyHidden = 0x4 };
+  Flags |= other.Flags;
 }
 
-struct GlobalOptionDescription : public OptionDescription {
-  std::string Help;
-  unsigned Flags;
+bool OptionDescription::isAlias() const {
+  return Type == OptionType::Alias;
+}
 
-  // We need to provide a default constructor because
-  // StringMap can only store DefaultConstructible objects.
-  GlobalOptionDescription() : OptionDescription(), Flags(0)
-  {}
+bool OptionDescription::isExtern() const {
+  return (Type == OptionType::ExternList || Type == OptionType::ExternParameter
+          || Type == OptionType::ExternSwitch);
+}
 
-  GlobalOptionDescription (OptionType::OptionType t, const std::string& n,
-                           const std::string& h = DefaultHelpString)
-    : OptionDescription(t, n), Help(h), Flags(0)
-  {}
+bool OptionDescription::isRequired() const {
+  return Flags & OptionDescriptionFlags::Required;
+}
+void OptionDescription::setRequired() {
+  Flags |= OptionDescriptionFlags::Required;
+}
 
-  bool isRequired() const {
-    return Flags & GlobalOptionDescriptionFlags::Required;
-  }
-  void setRequired() {
-    Flags |= GlobalOptionDescriptionFlags::Required;
-  }
+bool OptionDescription::isHidden() const {
+  return Flags & OptionDescriptionFlags::Hidden;
+}
+void OptionDescription::setHidden() {
+  Flags |= OptionDescriptionFlags::Hidden;
+}
 
-  bool isHidden() const {
-    return Flags & GlobalOptionDescriptionFlags::Hidden;
-  }
-  void setHidden() {
-    Flags |= GlobalOptionDescriptionFlags::Hidden;
-  }
+bool OptionDescription::isReallyHidden() const {
+  return Flags & OptionDescriptionFlags::ReallyHidden;
+}
+void OptionDescription::setReallyHidden() {
+  Flags |= OptionDescriptionFlags::ReallyHidden;
+}
 
-  bool isReallyHidden() const {
-    return Flags & GlobalOptionDescriptionFlags::ReallyHidden;
-  }
-  void setReallyHidden() {
-    Flags |= GlobalOptionDescriptionFlags::ReallyHidden;
+const char* OptionDescription::GenTypeDeclaration() const {
+  switch (Type) {
+  case OptionType::Alias:
+    return "cl::alias";
+  case OptionType::ExternList:
+  case OptionType::PrefixList:
+  case OptionType::ParameterList:
+    return "cl::list<std::string>";
+  case OptionType::Switch:
+  case OptionType::ExternSwitch:
+    return "cl::opt<bool>";
+  case OptionType::ExternParameter:
+  case OptionType::Parameter:
+  case OptionType::Prefix:
+  default:
+    return "cl::opt<std::string>";
   }
+}
 
-  /// Merge - Merge two option descriptions.
-  void Merge (const GlobalOptionDescription& other)
-  {
-    if (other.Type != Type)
-      throw "Conflicting definitions for the option " + Name + "!";
-
-    if (Help == other.Help || Help == DefaultHelpString)
-      Help = other.Help;
-    else if (other.Help != DefaultHelpString) {
-      llvm::cerr << "Warning: several different help strings"
-        " defined for option " + Name + "\n";
-    }
-
-    Flags |= other.Flags;
+std::string OptionDescription::GenVariableName() const {
+  const std::string& EscapedName = EscapeVariableName(Name);
+  switch (Type) {
+  case OptionType::Alias:
+    return "AutoGeneratedAlias_" + EscapedName;
+  case OptionType::PrefixList:
+  case OptionType::ParameterList:
+  case OptionType::ExternList:
+    return "AutoGeneratedList_" + EscapedName;
+  case OptionType::ExternSwitch:
+  case OptionType::Switch:
+    return "AutoGeneratedSwitch_" + EscapedName;
+  case OptionType::ExternParameter:
+  case OptionType::Prefix:
+  case OptionType::Parameter:
+  default:
+    return "AutoGeneratedParameter_" + EscapedName;
   }
-};
+}
 
-/// GlobalOptionDescriptions - A GlobalOptionDescription array
-/// together with some flags affecting generation of option
-/// declarations.
-struct GlobalOptionDescriptions {
-  typedef StringMap<GlobalOptionDescription> container_type;
-  typedef container_type::const_iterator const_iterator;
+/// OptionDescriptions - An OptionDescription array plus some helper
+/// functions.
+class OptionDescriptions {
+  typedef StringMap<OptionDescription> container_type;
 
-  /// Descriptions - A list of GlobalOptionDescriptions.
+  /// Descriptions - A list of OptionDescriptions.
   container_type Descriptions;
-  /// HasSink - Should the emitter generate a "cl::sink" option?
-  bool HasSink;
 
+public:
   /// FindOption - exception-throwing wrapper for find().
-  const GlobalOptionDescription& FindOption(const std::string& OptName) const {
-    const_iterator I = Descriptions.find(OptName);
-    if (I != Descriptions.end())
-      return I->second;
-    else
-      throw OptName + ": no such option!";
-  }
+  const OptionDescription& FindOption(const std::string& OptName) const;
 
-  /// insertDescription - Insert new GlobalOptionDescription into
-  /// GlobalOptionDescriptions list
-  void insertDescription (const GlobalOptionDescription& o)
-  {
-    container_type::iterator I = Descriptions.find(o.Name);
-    if (I != Descriptions.end()) {
-      GlobalOptionDescription& D = I->second;
-      D.Merge(o);
-    }
-    else {
-      Descriptions[o.Name] = o;
-    }
-  }
+  /// insertDescription - Insert new OptionDescription into
+  /// OptionDescriptions list
+  void InsertDescription (const OptionDescription& o);
 
   // Support for STL-style iteration
+  typedef container_type::const_iterator const_iterator;
   const_iterator begin() const { return Descriptions.begin(); }
   const_iterator end() const { return Descriptions.end(); }
 };
 
-
-// Tool-local option description.
-
-// Properties without arguments are implemented as flags.
-namespace ToolOptionDescriptionFlags {
-  enum ToolOptionDescriptionFlags { StopCompilation = 0x1,
-                                    Forward = 0x2, UnpackValues = 0x4};
-}
-namespace OptionPropertyType {
-  enum OptionPropertyType { AppendCmd, ForwardAs, OutputSuffix };
+const OptionDescription&
+OptionDescriptions::FindOption(const std::string& OptName) const
+{
+  const_iterator I = Descriptions.find(OptName);
+  if (I != Descriptions.end())
+    return I->second;
+  else
+    throw OptName + ": no such option!";
 }
 
-typedef std::pair<OptionPropertyType::OptionPropertyType, std::string>
-OptionProperty;
-typedef SmallVector<OptionProperty, 4> OptionPropertyList;
-
-struct ToolOptionDescription : public OptionDescription {
-  unsigned Flags;
-  OptionPropertyList Props;
-
-  // StringMap can only store DefaultConstructible objects
-  ToolOptionDescription() : OptionDescription(), Flags(0) {}
-
-  ToolOptionDescription (OptionType::OptionType t, const std::string& n)
-    : OptionDescription(t, n)
-  {}
-
-  // Various boolean properties
-  bool isStopCompilation() const {
-    return Flags & ToolOptionDescriptionFlags::StopCompilation;
-  }
-  void setStopCompilation() {
-    Flags |= ToolOptionDescriptionFlags::StopCompilation;
-  }
-
-  bool isForward() const {
-    return Flags & ToolOptionDescriptionFlags::Forward;
-  }
-  void setForward() {
-    Flags |= ToolOptionDescriptionFlags::Forward;
-  }
-
-  bool isUnpackValues() const {
-    return Flags & ToolOptionDescriptionFlags::UnpackValues;
-  }
-  void setUnpackValues() {
-    Flags |= ToolOptionDescriptionFlags::UnpackValues;
+void OptionDescriptions::InsertDescription (const OptionDescription& o)
+{
+  container_type::iterator I = Descriptions.find(o.Name);
+  if (I != Descriptions.end()) {
+    OptionDescription& D = I->second;
+    D.Merge(o);
   }
-
-  void AddProperty (OptionPropertyType::OptionPropertyType t,
-                    const std::string& val)
-  {
-    Props.push_back(std::make_pair(t, val));
+  else {
+    Descriptions[o.Name] = o;
   }
-};
-
-typedef StringMap<ToolOptionDescription> ToolOptionDescriptions;
-
-// Tool information record
-
-namespace ToolFlags {
-  enum ToolFlags { Join = 0x1, Sink = 0x2 };
 }
 
-struct ToolProperties : public RefCountedBase<ToolProperties> {
-  std::string Name;
-  Init* CmdLine;
-  StrVector InLanguage;
-  std::string OutLanguage;
-  std::string OutputSuffix;
-  unsigned Flags;
-  ToolOptionDescriptions OptDescs;
-
-  // Various boolean properties
-  void setSink()      { Flags |= ToolFlags::Sink; }
-  bool isSink() const { return Flags & ToolFlags::Sink; }
-  void setJoin()      { Flags |= ToolFlags::Join; }
-  bool isJoin() const { return Flags & ToolFlags::Join; }
-
-  // Default ctor here is needed because StringMap can only store
-  // DefaultConstructible objects
-  ToolProperties() : CmdLine(0), Flags(0) {}
-  ToolProperties (const std::string& n) : Name(n), CmdLine(0), Flags(0) {}
-};
-
-
-/// ToolPropertiesList - A list of Tool information records
-/// IntrusiveRefCntPtrs are used here because StringMap has no copy
-/// constructor (and we want to avoid copying ToolProperties anyway).
-typedef std::vector<IntrusiveRefCntPtr<ToolProperties> > ToolPropertiesList;
-
-
-/// CollectOptionProperties - Function object for iterating over a
-/// list (usually, a DAG) of option property records.
-class CollectOptionProperties {
-private:
+/// HandlerTable - A base class for function objects implemented as
+/// 'tables of handlers'.
+template <class T>
+class HandlerTable {
+protected:
   // Implementation details.
 
-  /// OptionPropertyHandler - a function that extracts information
-  /// about a given option property from its DAG representation.
-  typedef void (CollectOptionProperties::* OptionPropertyHandler)
-  (const DagInit*);
-
-  /// OptionPropertyHandlerMap - A map from option property names to
-  /// option property handlers
-  typedef StringMap<OptionPropertyHandler> OptionPropertyHandlerMap;
+  /// Handler -
+  typedef void (T::* Handler) (const DagInit*);
+  /// HandlerMap - A map from property names to property handlers
+  typedef StringMap<Handler> HandlerMap;
 
-  static OptionPropertyHandlerMap optionPropertyHandlers_;
+  static HandlerMap Handlers_;
   static bool staticMembersInitialized_;
 
-  /// This is where the information is stored
-
-  /// toolProps_ -  Properties of the current Tool.
-  ToolProperties* toolProps_;
-  /// optDescs_ - OptionDescriptions table (used to register options
-  /// globally).
-  GlobalOptionDescription& optDesc_;
-
+  T* childPtr;
 public:
 
-  explicit CollectOptionProperties(ToolProperties* TP,
-                                   GlobalOptionDescription& OD)
-    : toolProps_(TP), optDesc_(OD)
-  {
-    if (!staticMembersInitialized_) {
-      optionPropertyHandlers_["append_cmd"] =
-        &CollectOptionProperties::onAppendCmd;
-      optionPropertyHandlers_["forward"] =
-        &CollectOptionProperties::onForward;
-      optionPropertyHandlers_["forward_as"] =
-        &CollectOptionProperties::onForwardAs;
-      optionPropertyHandlers_["help"] =
-        &CollectOptionProperties::onHelp;
-      optionPropertyHandlers_["hidden"] =
-        &CollectOptionProperties::onHidden;
-      optionPropertyHandlers_["output_suffix"] =
-        &CollectOptionProperties::onOutputSuffix;
-      optionPropertyHandlers_["really_hidden"] =
-        &CollectOptionProperties::onReallyHidden;
-      optionPropertyHandlers_["required"] =
-        &CollectOptionProperties::onRequired;
-      optionPropertyHandlers_["stop_compilation"] =
-        &CollectOptionProperties::onStopCompilation;
-      optionPropertyHandlers_["unpack_values"] =
-        &CollectOptionProperties::onUnpackValues;
-
-      staticMembersInitialized_ = true;
-    }
-  }
+  HandlerTable(T* cp) : childPtr(cp)
+  {}
 
-  /// operator() - Gets called for every option property; Just forwards
-  /// to the corresponding property handler.
+  /// operator() - Just forwards to the corresponding property
+  /// handler.
   void operator() (Init* i) {
-    const DagInit& option_property = InitPtrToDag(i);
-    const std::string& option_property_name
-      = option_property.getOperator()->getAsString();
-    OptionPropertyHandlerMap::iterator method
-      = optionPropertyHandlers_.find(option_property_name);
-
-    if (method != optionPropertyHandlers_.end()) {
-      OptionPropertyHandler h = method->second;
-      (this->*h)(&option_property);
+    const DagInit& property = InitPtrToDag(i);
+    const std::string& property_name = property.getOperator()->getAsString();
+    typename HandlerMap::iterator method = Handlers_.find(property_name);
+
+    if (method != Handlers_.end()) {
+      Handler h = method->second;
+      (childPtr->*h)(&property);
     }
     else {
-      throw "Unknown option property: " + option_property_name + "!";
+      throw "No handler found for property " + property_name + "!";
     }
   }
 
-private:
+  void AddHandler(const char* Property, Handler Handl) {
+    Handlers_[Property] = Handl;
+  }
+};
 
-  /// Option property handlers --
-  /// Methods that handle properties that are common for all types of
-  /// options (like append_cmd, stop_compilation)
+template <class T> typename HandlerTable<T>::HandlerMap
+HandlerTable<T>::Handlers_;
+template <class T> bool HandlerTable<T>::staticMembersInitialized_ = false;
 
-  void onAppendCmd (const DagInit* d) {
-    checkNumberOfArguments(d, 1);
-    checkToolProps(d);
-    const std::string& cmd = InitPtrToString(d->getArg(0));
 
-    toolProps_->OptDescs[optDesc_.Name].
-      AddProperty(OptionPropertyType::AppendCmd, cmd);
-  }
+/// CollectOptionProperties - Function object for iterating over an
+/// option property list.
+class CollectOptionProperties : public HandlerTable<CollectOptionProperties> {
+private:
 
-  void onOutputSuffix (const DagInit* d) {
-    checkNumberOfArguments(d, 1);
-    checkToolProps(d);
-    const std::string& suf = InitPtrToString(d->getArg(0));
+  /// optDescs_ - OptionDescriptions table. This is where the
+  /// information is stored.
+  OptionDescription& optDesc_;
 
-    if (toolProps_->OptDescs[optDesc_.Name].Type != OptionType::Switch)
-      throw "Option " + optDesc_.Name
-        + " can't have 'output_suffix' property since it isn't a switch!";
+public:
 
-    toolProps_->OptDescs[optDesc_.Name].AddProperty
-      (OptionPropertyType::OutputSuffix, suf);
-  }
+  explicit CollectOptionProperties(OptionDescription& OD)
+    : HandlerTable<CollectOptionProperties>(this), optDesc_(OD)
+  {
+    if (!staticMembersInitialized_) {
+      AddHandler("help", &CollectOptionProperties::onHelp);
+      AddHandler("hidden", &CollectOptionProperties::onHidden);
+      AddHandler("really_hidden", &CollectOptionProperties::onReallyHidden);
+      AddHandler("required", &CollectOptionProperties::onRequired);
 
-  void onForward (const DagInit* d) {
-    checkNumberOfArguments(d, 0);
-    checkToolProps(d);
-    toolProps_->OptDescs[optDesc_.Name].setForward();
+      staticMembersInitialized_ = true;
+    }
   }
 
-  void onForwardAs (const DagInit* d) {
-    checkNumberOfArguments(d, 1);
-    checkToolProps(d);
-    const std::string& cmd = InitPtrToString(d->getArg(0));
+private:
 
-    toolProps_->OptDescs[optDesc_.Name].
-      AddProperty(OptionPropertyType::ForwardAs, cmd);
-  }
+  /// Option property handlers --
+  /// Methods that handle option properties such as (help) or (hidden).
 
   void onHelp (const DagInit* d) {
     checkNumberOfArguments(d, 1);
     const std::string& help_message = InitPtrToString(d->getArg(0));
-
     optDesc_.Help = help_message;
   }
 
@@ -530,20 +440,6 @@
     optDesc_.setRequired();
   }
 
-  void onStopCompilation (const DagInit* d) {
-    checkNumberOfArguments(d, 0);
-    checkToolProps(d);
-    if (optDesc_.Type != OptionType::Switch)
-      throw std::string("Only options of type Switch can stop compilation!");
-    toolProps_->OptDescs[optDesc_.Name].setStopCompilation();
-  }
-
-  void onUnpackValues (const DagInit* d) {
-    checkNumberOfArguments(d, 0);
-    checkToolProps(d);
-    toolProps_->OptDescs[optDesc_.Name].setUnpackValues();
-  }
-
   // Helper functions
 
   /// checkToolProps - Throw an error if toolProps_ == 0.
@@ -555,146 +451,128 @@
 
 };
 
-CollectOptionProperties::OptionPropertyHandlerMap
-CollectOptionProperties::optionPropertyHandlers_;
-
-bool CollectOptionProperties::staticMembersInitialized_ = false;
-
-
-/// processOptionProperties - Go through the list of option
-/// properties and call a corresponding handler for each.
-void processOptionProperties (const DagInit* d, ToolProperties* t,
-                              GlobalOptionDescription& o) {
-  checkNumberOfArguments(d, 2);
-  DagInit::const_arg_iterator B = d->arg_begin();
-  // Skip the first argument: it's always the option name.
-  ++B;
-  std::for_each(B, d->arg_end(), CollectOptionProperties(t, o));
-}
-
-/// AddOption - A function object wrapper for
-/// processOptionProperties. Used by CollectProperties and
-/// CollectPropertiesFromOptionList.
+/// AddOption - A function object that is applied to every option
+/// description. Used by CollectOptionDescriptions.
 class AddOption {
 private:
-  GlobalOptionDescriptions& OptDescs_;
-  ToolProperties* ToolProps_;
+  OptionDescriptions& OptDescs_;
 
 public:
-  explicit AddOption(GlobalOptionDescriptions& OD, ToolProperties* TP = 0)
-    : OptDescs_(OD), ToolProps_(TP)
+  explicit AddOption(OptionDescriptions& OD) : OptDescs_(OD)
   {}
 
   void operator()(const Init* i) {
     const DagInit& d = InitPtrToDag(i);
-    checkNumberOfArguments(&d, 2);
+    checkNumberOfArguments(&d, 1);
 
     const OptionType::OptionType Type =
-      getOptionType(d.getOperator()->getAsString());
+      stringToOptionType(d.getOperator()->getAsString());
     const std::string& Name = InitPtrToString(d.getArg(0));
 
-    GlobalOptionDescription OD(Type, Name);
-    if (Type != OptionType::Alias) {
-      processOptionProperties(&d, ToolProps_, OD);
-      if (ToolProps_) {
-        ToolProps_->OptDescs[Name].Type = Type;
-        ToolProps_->OptDescs[Name].Name = Name;
-      }
-    }
-    else {
+    OptionDescription OD(Type, Name);
+
+    if (!OD.isExtern())
+      checkNumberOfArguments(&d, 2);
+
+    if (OD.isAlias()) {
+      // Aliases store the aliased option name in the 'Help' field.
       OD.Help = InitPtrToString(d.getArg(1));
     }
-    OptDescs_.insertDescription(OD);
+    else if (!OD.isExtern()) {
+      processOptionProperties(&d, OD);
+    }
+    OptDescs_.InsertDescription(OD);
   }
 
 private:
-  OptionType::OptionType getOptionType(const std::string& T) const {
-    if (T == "alias_option")
-      return OptionType::Alias;
-    else if (T == "switch_option")
-      return OptionType::Switch;
-    else if (T == "parameter_option")
-      return OptionType::Parameter;
-    else if (T == "parameter_list_option")
-      return OptionType::ParameterList;
-    else if (T == "prefix_option")
-      return OptionType::Prefix;
-    else if (T == "prefix_list_option")
-      return OptionType::PrefixList;
-    else
-      throw "Unknown option type: " + T + '!';
+  /// processOptionProperties - Go through the list of option
+  /// properties and call a corresponding handler for each.
+  static void processOptionProperties (const DagInit* d, OptionDescription& o) {
+    checkNumberOfArguments(d, 2);
+    DagInit::const_arg_iterator B = d->arg_begin();
+    // Skip the first argument: it's always the option name.
+    ++B;
+    std::for_each(B, d->arg_end(), CollectOptionProperties(o));
   }
+
 };
 
+/// CollectOptionDescriptions - Collects option properties from all
+/// OptionLists.
+void CollectOptionDescriptions (RecordVector::const_iterator B,
+                                RecordVector::const_iterator E,
+                                OptionDescriptions& OptDescs)
+{
+  // For every OptionList:
+  for (; B!=E; ++B) {
+    RecordVector::value_type T = *B;
+    // Throws an exception if the value does not exist.
+    ListInit* PropList = T->getValueAsListInit("options");
 
-/// CollectProperties - Function object for iterating over a list of
-/// tool property records.
-class CollectProperties {
-private:
+    // For every option description in this list:
+    // collect the information and
+    std::for_each(PropList->begin(), PropList->end(), AddOption(OptDescs));
+  }
+}
 
-  // Implementation details
+// Tool information record
 
-  /// PropertyHandler - a function that extracts information
-  /// about a given tool property from its DAG representation
-  typedef void (CollectProperties::*PropertyHandler)(const DagInit*);
-
-  /// PropertyHandlerMap - A map from property names to property
-  /// handlers.
-  typedef StringMap<PropertyHandler> PropertyHandlerMap;
+namespace ToolFlags {
+  enum ToolFlags { Join = 0x1, Sink = 0x2 };
+}
 
-  // Static maps from strings to CollectProperties methods("handlers")
-  static PropertyHandlerMap propertyHandlers_;
-  static bool staticMembersInitialized_;
+struct ToolDescription : public RefCountedBase<ToolDescription> {
+  std::string Name;
+  Init* CmdLine;
+  Init* Actions;
+  StrVector InLanguage;
+  std::string OutLanguage;
+  std::string OutputSuffix;
+  unsigned Flags;
 
+  // Various boolean properties
+  void setSink()      { Flags |= ToolFlags::Sink; }
+  bool isSink() const { return Flags & ToolFlags::Sink; }
+  void setJoin()      { Flags |= ToolFlags::Join; }
+  bool isJoin() const { return Flags & ToolFlags::Join; }
+
+  // Default ctor here is needed because StringMap can only store
+  // DefaultConstructible objects
+  ToolDescription() : CmdLine(0), Actions(0), Flags(0) {}
+  ToolDescription (const std::string& n)
+  : Name(n), CmdLine(0), Actions(0), Flags(0)
+  {}
+};
 
-  /// This is where the information is stored
+/// ToolDescriptions - A list of Tool information records.
+typedef std::vector<IntrusiveRefCntPtr<ToolDescription> > ToolDescriptions;
 
-  /// toolProps_ -  Properties of the current Tool.
-  ToolProperties& toolProps_;
-  /// optDescs_ - OptionDescriptions table (used to register options
-  /// globally).
-  GlobalOptionDescriptions& optDescs_;
+
+/// CollectToolProperties - Function object for iterating over a list of
+/// tool property records.
+class CollectToolProperties : public HandlerTable<CollectToolProperties> {
+private:
+
+  /// toolDesc_ - Properties of the current Tool. This is where the
+  /// information is stored.
+  ToolDescription& toolDesc_;
 
 public:
 
-  explicit CollectProperties (ToolProperties& p, GlobalOptionDescriptions& d)
-    : toolProps_(p), optDescs_(d)
+  explicit CollectToolProperties (ToolDescription& d)
+    : HandlerTable<CollectToolProperties>(this) , toolDesc_(d)
   {
     if (!staticMembersInitialized_) {
-      propertyHandlers_["cmd_line"] = &CollectProperties::onCmdLine;
-      propertyHandlers_["in_language"] = &CollectProperties::onInLanguage;
-      propertyHandlers_["join"] = &CollectProperties::onJoin;
-      propertyHandlers_["out_language"] = &CollectProperties::onOutLanguage;
-      propertyHandlers_["output_suffix"] = &CollectProperties::onOutputSuffix;
-      propertyHandlers_["parameter_option"]
-        = &CollectProperties::addOption;
-      propertyHandlers_["parameter_list_option"] =
-        &CollectProperties::addOption;
-      propertyHandlers_["prefix_option"] = &CollectProperties::addOption;
-      propertyHandlers_["prefix_list_option"] =
-        &CollectProperties::addOption;
-      propertyHandlers_["sink"] = &CollectProperties::onSink;
-      propertyHandlers_["switch_option"] = &CollectProperties::addOption;
-      propertyHandlers_["alias_option"] = &CollectProperties::addOption;
 
-      staticMembersInitialized_ = true;
-    }
-  }
+      AddHandler("actions", &CollectToolProperties::onActions);
+      AddHandler("cmd_line", &CollectToolProperties::onCmdLine);
+      AddHandler("in_language", &CollectToolProperties::onInLanguage);
+      AddHandler("join", &CollectToolProperties::onJoin);
+      AddHandler("out_language", &CollectToolProperties::onOutLanguage);
+      AddHandler("output_suffix", &CollectToolProperties::onOutputSuffix);
+      AddHandler("sink", &CollectToolProperties::onSink);
 
-  /// operator() - Gets called for every tool property; Just forwards
-  /// to the corresponding property handler.
-  void operator() (Init* i) {
-    const DagInit& d = InitPtrToDag(i);
-    const std::string& property_name = d.getOperator()->getAsString();
-    PropertyHandlerMap::iterator method
-      = propertyHandlers_.find(property_name);
-
-    if (method != propertyHandlers_.end()) {
-      PropertyHandler h = method->second;
-      (this->*h)(&d);
-    }
-    else {
-      throw "Unknown tool property: " + property_name + "!";
+      staticMembersInitialized_ = true;
     }
   }
 
@@ -704,9 +582,14 @@
   /// Functions that extract information about tool properties from
   /// DAG representation.
 
+  void onActions (const DagInit* d) {
+    checkNumberOfArguments(d, 1);
+    toolDesc_.Actions = d->getArg(0);
+  }
+
   void onCmdLine (const DagInit* d) {
     checkNumberOfArguments(d, 1);
-    toolProps_.CmdLine = d->getArg(0);
+    toolDesc_.CmdLine = d->getArg(0);
   }
 
   void onInLanguage (const DagInit* d) {
@@ -716,12 +599,12 @@
     // Find out the argument's type.
     if (typeid(*arg) == typeid(StringInit)) {
       // It's a string.
-      toolProps_.InLanguage.push_back(InitPtrToString(arg));
+      toolDesc_.InLanguage.push_back(InitPtrToString(arg));
     }
     else {
       // It's a list.
       const ListInit& lst = InitPtrToList(arg);
-      StrVector& out = toolProps_.InLanguage;
+      StrVector& out = toolDesc_.InLanguage;
 
       // Copy strings to the output vector.
       for (ListInit::const_iterator B = lst.begin(), E = lst.end();
@@ -738,46 +621,33 @@
 
   void onJoin (const DagInit* d) {
     checkNumberOfArguments(d, 0);
-    toolProps_.setJoin();
+    toolDesc_.setJoin();
   }
 
   void onOutLanguage (const DagInit* d) {
     checkNumberOfArguments(d, 1);
-    toolProps_.OutLanguage = InitPtrToString(d->getArg(0));
+    toolDesc_.OutLanguage = InitPtrToString(d->getArg(0));
   }
 
   void onOutputSuffix (const DagInit* d) {
     checkNumberOfArguments(d, 1);
-    toolProps_.OutputSuffix = InitPtrToString(d->getArg(0));
+    toolDesc_.OutputSuffix = InitPtrToString(d->getArg(0));
   }
 
   void onSink (const DagInit* d) {
     checkNumberOfArguments(d, 0);
-    optDescs_.HasSink = true;
-    toolProps_.setSink();
-  }
-
-  // Just forwards to the AddOption function object. Somewhat
-  // non-optimal, but avoids code duplication.
-  void addOption (const DagInit* d) {
-    checkNumberOfArguments(d, 2);
-    AddOption(optDescs_, &toolProps_)(d);
+    toolDesc_.setSink();
   }
 
 };
 
-// Defintions of static members of CollectProperties.
-CollectProperties::PropertyHandlerMap CollectProperties::propertyHandlers_;
-bool CollectProperties::staticMembersInitialized_ = false;
-
 
-/// CollectToolProperties - Gather information about tool properties
+/// CollectToolDescriptions - Gather information about tool properties
 /// from the parsed TableGen data (basically a wrapper for the
-/// CollectProperties function object).
-void CollectToolProperties (RecordVector::const_iterator B,
-                            RecordVector::const_iterator E,
-                            ToolPropertiesList& TPList,
-                            GlobalOptionDescriptions& OptDescs)
+/// CollectToolProperties function object).
+void CollectToolDescriptions (RecordVector::const_iterator B,
+                              RecordVector::const_iterator E,
+                              ToolDescriptions& ToolDescs)
 {
   // Iterate over a properties list of every Tool definition
   for (;B!=E;++B) {
@@ -785,55 +655,211 @@
     // Throws an exception if the value does not exist.
     ListInit* PropList = T->getValueAsListInit("properties");
 
-    IntrusiveRefCntPtr<ToolProperties>
-      ToolProps(new ToolProperties(T->getName()));
+    IntrusiveRefCntPtr<ToolDescription>
+      ToolDesc(new ToolDescription(T->getName()));
 
     std::for_each(PropList->begin(), PropList->end(),
-                  CollectProperties(*ToolProps, OptDescs));
-    TPList.push_back(ToolProps);
+                  CollectToolProperties(*ToolDesc));
+    ToolDescs.push_back(ToolDesc);
   }
 }
 
+/// FillInEdgeVector - Merge all compilation graph definitions into
+/// one single edge list.
+void FillInEdgeVector(RecordVector::const_iterator B,
+                      RecordVector::const_iterator E, RecordVector& Out) {
+  for (; B != E; ++B) {
+    const ListInit* edges = (*B)->getValueAsListInit("edges");
+
+    for (unsigned i = 0; i < edges->size(); ++i)
+      Out.push_back(edges->getElementAsRecord(i));
+  }
+}
 
-/// CollectPropertiesFromOptionLists - Gather information about
-/// *global* option properties from all OptionLists.
-void CollectPropertiesFromOptionLists (RecordVector::const_iterator B,
-                                       RecordVector::const_iterator E,
-                                       GlobalOptionDescriptions& OptDescs)
-{
-  // Iterate over a properties list of every Tool definition
+/// CalculatePriority - Calculate the priority of this plugin.
+int CalculatePriority(RecordVector::const_iterator B,
+                      RecordVector::const_iterator E) {
+  int total = 0;
   for (; B!=E; ++B) {
-    RecordVector::value_type T = *B;
-    // Throws an exception if the value does not exist.
-    ListInit* PropList = T->getValueAsListInit("options");
+    total += static_cast<int>((*B)->getValueAsInt("priority"));
+  }
+  return total;
+}
 
-    std::for_each(PropList->begin(), PropList->end(), AddOption(OptDescs));
+/// NotInGraph - Helper function object for FilterNotInGraph.
+struct NotInGraph {
+private:
+  const llvm::StringSet<>& ToolsInGraph_;
+
+public:
+  NotInGraph(const llvm::StringSet<>& ToolsInGraph)
+  : ToolsInGraph_(ToolsInGraph)
+  {}
+
+  bool operator()(const IntrusiveRefCntPtr<ToolDescription>& x) {
+    return (ToolsInGraph_.count(x->Name) == 0);
+  }
+};
+
+/// FilterNotInGraph - Filter out from ToolDescs all Tools not
+/// mentioned in the compilation graph definition.
+void FilterNotInGraph (const RecordVector& EdgeVector,
+                       ToolDescriptions& ToolDescs) {
+
+  // List all tools mentioned in the graph.
+  llvm::StringSet<> ToolsInGraph;
+
+  for (RecordVector::const_iterator B = EdgeVector.begin(),
+         E = EdgeVector.end(); B != E; ++B) {
+
+    const Record* Edge = *B;
+    const std::string& A = Edge->getValueAsString("a");
+    const std::string& B = Edge->getValueAsString("b");
+
+    if (A != "root")
+      ToolsInGraph.insert(A);
+    ToolsInGraph.insert(B);
+  }
+
+  // Filter ToolPropertiesList.
+  ToolDescriptions::iterator new_end =
+    std::remove_if(ToolDescs.begin(), ToolDescs.end(),
+                   NotInGraph(ToolsInGraph));
+  ToolDescs.erase(new_end, ToolDescs.end());
+}
+
+/// FillInToolToLang - Fills in two tables that map tool names to
+/// (input, output) languages.  Helper function used by TypecheckGraph().
+void FillInToolToLang (const ToolDescriptions& ToolDescs,
+                       StringMap<StringSet<> >& ToolToInLang,
+                       StringMap<std::string>& ToolToOutLang) {
+  for (ToolDescriptions::const_iterator B = ToolDescs.begin(),
+         E = ToolDescs.end(); B != E; ++B) {
+    const ToolDescription& D = *(*B);
+    for (StrVector::const_iterator B = D.InLanguage.begin(),
+           E = D.InLanguage.end(); B != E; ++B)
+      ToolToInLang[D.Name].insert(*B);
+    ToolToOutLang[D.Name] = D.OutLanguage;
   }
 }
 
+/// TypecheckGraph - Check that names for output and input languages
+/// on all edges do match. This doesn't do much when the information
+/// about the whole graph is not available (i.e. when compiling most
+/// plugins).
+void TypecheckGraph (const RecordVector& EdgeVector,
+                     const ToolDescriptions& ToolDescs) {
+  StringMap<StringSet<> > ToolToInLang;
+  StringMap<std::string> ToolToOutLang;
+
+  FillInToolToLang(ToolDescs, ToolToInLang, ToolToOutLang);
+  StringMap<std::string>::iterator IAE = ToolToOutLang.end();
+  StringMap<StringSet<> >::iterator IBE = ToolToInLang.end();
+
+  for (RecordVector::const_iterator B = EdgeVector.begin(),
+         E = EdgeVector.end(); B != E; ++B) {
+    const Record* Edge = *B;
+    const std::string& A = Edge->getValueAsString("a");
+    const std::string& B = Edge->getValueAsString("b");
+    StringMap<std::string>::iterator IA = ToolToOutLang.find(A);
+    StringMap<StringSet<> >::iterator IB = ToolToInLang.find(B);
+
+    if (A != "root") {
+      if (IA != IAE && IB != IBE && IB->second.count(IA->second) == 0)
+        throw "Edge " + A + "->" + B
+          + ": output->input language mismatch";
+    }
+
+    if (B == "root")
+      throw std::string("Edges back to the root are not allowed!");
+  }
+}
+
+/// WalkCase - Walks the 'case' expression DAG and invokes
+/// TestCallback on every test, and StatementCallback on every
+/// statement. Handles 'case' nesting, but not the 'and' and 'or'
+/// combinators.
+// TODO: Re-implement EmitCaseConstructHandler on top of this function?
+template <typename F1, typename F2>
+void WalkCase(Init* Case, F1 TestCallback, F2 StatementCallback) {
+  const DagInit& d = InitPtrToDag(Case);
+  bool even = false;
+  for (DagInit::const_arg_iterator B = d.arg_begin(), E = d.arg_end();
+       B != E; ++B) {
+    Init* arg = *B;
+    if (even && dynamic_cast<DagInit*>(arg)
+        && static_cast<DagInit*>(arg)->getOperator()->getAsString() == "case")
+      WalkCase(arg, TestCallback, StatementCallback);
+    else if (!even)
+      TestCallback(arg);
+    else
+      StatementCallback(arg);
+    even = !even;
+  }
+}
+
+/// ExtractOptionNames - A helper function object used by
+/// CheckForSuperfluousOptions() to walk the 'case' DAG.
+class ExtractOptionNames {
+  llvm::StringSet<>& OptionNames_;
+public:
+  ExtractOptionNames(llvm::StringSet<>& OptionNames) : OptionNames_(OptionNames)
+  {}
+
+  void operator()(const Init* Statement) {
+    const DagInit& Stmt = InitPtrToDag(Statement);
+    const std::string& ActionName = Stmt.getOperator()->getAsString();
+    if (ActionName == "forward" || ActionName == "forward_as" ||
+        ActionName == "unpack_values" || ActionName == "switch_on" ||
+        ActionName == "parameter_equals" || ActionName == "element_in_list" ||
+        ActionName == "not_empty") {
+      checkNumberOfArguments(&Stmt, 1);
+      const std::string& Name = InitPtrToString(Stmt.getArg(0));
+      OptionNames_.insert(Name);
+    }
+    else if (ActionName == "and" || ActionName == "or") {
+      for (unsigned i = 0, NumArgs = Stmt.getNumArgs(); i < NumArgs; ++i) {
+        this->operator()(Stmt.getArg(i));
+      }
+    }
+  }
+};
+
 /// CheckForSuperfluousOptions - Check that there are no side
 /// effect-free options (specified only in the OptionList). Otherwise,
 /// output a warning.
-void CheckForSuperfluousOptions (const ToolPropertiesList& TPList,
-                                 const GlobalOptionDescriptions& OptDescs) {
+void CheckForSuperfluousOptions (const RecordVector& Edges,
+                                 const ToolDescriptions& ToolDescs,
+                                 const OptionDescriptions& OptDescs) {
   llvm::StringSet<> nonSuperfluousOptions;
 
-  // Add all options mentioned in the TPList to the set of
+  // Add all options mentioned in the ToolDesc.Actions to the set of
   // non-superfluous options.
-  for (ToolPropertiesList::const_iterator B = TPList.begin(),
-         E = TPList.end(); B != E; ++B) {
-    const ToolProperties& TP = *(*B);
-    for (ToolOptionDescriptions::const_iterator B = TP.OptDescs.begin(),
-           E = TP.OptDescs.end(); B != E; ++B) {
-      nonSuperfluousOptions.insert(B->first());
-    }
+  for (ToolDescriptions::const_iterator B = ToolDescs.begin(),
+         E = ToolDescs.end(); B != E; ++B) {
+    const ToolDescription& TD = *(*B);
+    ExtractOptionNames Callback(nonSuperfluousOptions);
+    if (TD.Actions)
+      WalkCase(TD.Actions, Callback, Callback);
+  }
+
+  // Add all options mentioned in the 'case' clauses of the
+  // OptionalEdges of the compilation graph to the set of
+  // non-superfluous options.
+  for (RecordVector::const_iterator B = Edges.begin(), E = Edges.end();
+       B != E; ++B) {
+    const Record* Edge = *B;
+    DagInit* Weight = Edge->getValueAsDag("weight");
+
+    if (!isDagEmpty(Weight))
+      WalkCase(Weight, ExtractOptionNames(nonSuperfluousOptions), Id());
   }
 
   // Check that all options in OptDescs belong to the set of
   // non-superfluous options.
-  for (GlobalOptionDescriptions::const_iterator B = OptDescs.begin(),
+  for (OptionDescriptions::const_iterator B = OptDescs.begin(),
          E = OptDescs.end(); B != E; ++B) {
-    const GlobalOptionDescription& Val = B->second;
+    const OptionDescription& Val = B->second;
     if (!nonSuperfluousOptions.count(Val.Name)
         && Val.Type != OptionType::Alias)
       llvm::cerr << "Warning: option '-" << Val.Name << "' has no effect! "
@@ -845,14 +871,14 @@
 /// EmitCaseConstructHandler.
 bool EmitCaseTest1Arg(const std::string& TestName,
                       const DagInit& d,
-                      const GlobalOptionDescriptions& OptDescs,
+                      const OptionDescriptions& OptDescs,
                       std::ostream& O) {
   checkNumberOfArguments(&d, 1);
   const std::string& OptName = InitPtrToString(d.getArg(0));
   if (TestName == "switch_on") {
-    const GlobalOptionDescription& OptDesc = OptDescs.FindOption(OptName);
-    if (OptDesc.Type != OptionType::Switch)
-      throw OptName + ": incorrect option type!";
+    const OptionDescription& OptDesc = OptDescs.FindOption(OptName);
+    if (!OptionType::IsSwitch(OptDesc.Type))
+      throw OptName + ": incorrect option type - should be a switch!";
     O << OptDesc.GenVariableName();
     return true;
   } else if (TestName == "input_languages_contain") {
@@ -871,9 +897,10 @@
       return true;
     }
     else {
-      const GlobalOptionDescription& OptDesc = OptDescs.FindOption(OptName);
-      if (OptDesc.Type == OptionType::Switch)
-        throw OptName + ": incorrect option type!";
+      const OptionDescription& OptDesc = OptDescs.FindOption(OptName);
+      if (OptionType::IsSwitch(OptDesc.Type))
+        throw OptName
+          + ": incorrect option type - should be a list or parameter!";
       O << '!' << OptDesc.GenVariableName() << ".empty()";
       return true;
     }
@@ -887,24 +914,22 @@
 bool EmitCaseTest2Args(const std::string& TestName,
                        const DagInit& d,
                        const char* IndentLevel,
-                       const GlobalOptionDescriptions& OptDescs,
+                       const OptionDescriptions& OptDescs,
                        std::ostream& O) {
   checkNumberOfArguments(&d, 2);
   const std::string& OptName = InitPtrToString(d.getArg(0));
   const std::string& OptArg = InitPtrToString(d.getArg(1));
-  const GlobalOptionDescription& OptDesc = OptDescs.FindOption(OptName);
+  const OptionDescription& OptDesc = OptDescs.FindOption(OptName);
 
   if (TestName == "parameter_equals") {
-    if (OptDesc.Type != OptionType::Parameter
-        && OptDesc.Type != OptionType::Prefix)
-      throw OptName + ": incorrect option type!";
+    if (!OptionType::IsParameter(OptDesc.Type))
+      throw OptName + ": incorrect option type - should be a parameter!";
     O << OptDesc.GenVariableName() << " == \"" << OptArg << "\"";
     return true;
   }
   else if (TestName == "element_in_list") {
-    if (OptDesc.Type != OptionType::ParameterList
-        && OptDesc.Type != OptionType::PrefixList)
-      throw OptName + ": incorrect option type!";
+    if (!OptionType::IsList(OptDesc.Type))
+      throw OptName + ": incorrect option type - should be a list!";
     const std::string& VarName = OptDesc.GenVariableName();
     O << "std::find(" << VarName << ".begin(),\n"
       << IndentLevel << Indent1 << VarName << ".end(), \""
@@ -918,14 +943,14 @@
 // Forward declaration.
 // EmitLogicalOperationTest and EmitCaseTest are mutually recursive.
 void EmitCaseTest(const DagInit& d, const char* IndentLevel,
-                  const GlobalOptionDescriptions& OptDescs,
+                  const OptionDescriptions& OptDescs,
                   std::ostream& O);
 
 /// EmitLogicalOperationTest - Helper function used by
 /// EmitCaseConstructHandler.
 void EmitLogicalOperationTest(const DagInit& d, const char* LogicOp,
                               const char* IndentLevel,
-                              const GlobalOptionDescriptions& OptDescs,
+                              const OptionDescriptions& OptDescs,
                               std::ostream& O) {
   O << '(';
   for (unsigned j = 0, NumArgs = d.getNumArgs(); j < NumArgs; ++j) {
@@ -940,7 +965,7 @@
 
 /// EmitCaseTest - Helper function used by EmitCaseConstructHandler.
 void EmitCaseTest(const DagInit& d, const char* IndentLevel,
-                  const GlobalOptionDescriptions& OptDescs,
+                  const OptionDescriptions& OptDescs,
                   std::ostream& O) {
   const std::string& TestName = d.getOperator()->getAsString();
 
@@ -960,178 +985,55 @@
 // Takes a function object that should emit code for every case clause.
 // Callback's type is
 // void F(Init* Statement, const char* IndentLevel, std::ostream& O).
-template <typename F>
-void EmitCaseConstructHandler(const DagInit* d, const char* IndentLevel,
-                              F Callback, bool EmitElseIf,
-                              const GlobalOptionDescriptions& OptDescs,
-                              std::ostream& O) {
-  assert(d->getOperator()->getAsString() == "case");
-
-  unsigned numArgs = d->getNumArgs();
-  if (d->getNumArgs() < 2)
-    throw "There should be at least one clause in the 'case' expression:\n"
-      + d->getAsString();
-
-  for (unsigned i = 0; i != numArgs; ++i) {
-    const DagInit& Test = InitPtrToDag(d->getArg(i));
-
-    // Emit the test.
-    if (Test.getOperator()->getAsString() == "default") {
-      if (i+2 != numArgs)
-        throw std::string("The 'default' clause should be the last in the"
-                          "'case' construct!");
-      O << IndentLevel << "else {\n";
-    }
-    else {
-      O << IndentLevel << ((i != 0 && EmitElseIf) ? "else if (" : "if (");
-      EmitCaseTest(Test, IndentLevel, OptDescs, O);
-      O << ") {\n";
-    }
-
-    // Emit the corresponding statement.
-    ++i;
-    if (i == numArgs)
-      throw "Case construct handler: no corresponding action "
-        "found for the test " + Test.getAsString() + '!';
-
-    Init* arg = d->getArg(i);
-    if (dynamic_cast<DagInit*>(arg)
-        && static_cast<DagInit*>(arg)->getOperator()->getAsString() == "case") {
-      EmitCaseConstructHandler(static_cast<DagInit*>(arg),
-                               (std::string(IndentLevel) + Indent1).c_str(),
-                               Callback, EmitElseIf, OptDescs, O);
-    }
-    else {
-      Callback(arg, IndentLevel, O);
-    }
-    O << IndentLevel << "}\n";
-  }
-}
-
-/// EmitForwardOptionPropertyHandlingCode - Helper function used to
-/// implement EmitOptionPropertyHandlingCode(). Emits code for
-/// handling the (forward) and (forward_as) option properties.
-void EmitForwardOptionPropertyHandlingCode (const ToolOptionDescription& D,
-                                            const std::string& NewName,
-                                            std::ostream& O) {
-  const std::string& Name = NewName.empty()
-    ? ("-" + D.Name)
-    : NewName;
-
-  switch (D.Type) {
-  case OptionType::Switch:
-    O << Indent3 << "vec.push_back(\"" << Name << "\");\n";
-    break;
-  case OptionType::Parameter:
-    O << Indent3 << "vec.push_back(\"" << Name << "\");\n";
-    O << Indent3 << "vec.push_back(" << D.GenVariableName() << ");\n";
-    break;
-  case OptionType::Prefix:
-    O << Indent3 << "vec.push_back(\"" << Name << "\" + "
-      << D.GenVariableName() << ");\n";
-    break;
-  case OptionType::PrefixList:
-    O << Indent3 << "for (" << D.GenTypeDeclaration()
-      << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
-      << Indent3 << "E = " << D.GenVariableName() << ".end(); B != E; ++B)\n"
-      << Indent4 << "vec.push_back(\"" << Name << "\" + "
-      << "*B);\n";
-    break;
-  case OptionType::ParameterList:
-    O << Indent3 << "for (" << D.GenTypeDeclaration()
-      << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
-      << Indent3 << "E = " << D.GenVariableName()
-      << ".end() ; B != E; ++B) {\n"
-      << Indent4 << "vec.push_back(\"" << Name << "\");\n"
-      << Indent4 << "vec.push_back(*B);\n"
-      << Indent3 << "}\n";
-    break;
-  case OptionType::Alias:
-  default:
-    throw std::string("Aliases are not allowed in tool option descriptions!");
-  }
-}
-
-// ToolOptionHasInterestingProperties - A helper function used by
-// EmitOptionPropertyHandlingCode() that tells us whether we should
-// emit any property handling code at all.
-bool ToolOptionHasInterestingProperties(const ToolOptionDescription& D) {
-  bool ret = false;
-  for (OptionPropertyList::const_iterator B = D.Props.begin(),
-         E = D.Props.end(); B != E; ++B) {
-      const OptionProperty& OptProp = *B;
-      if (OptProp.first == OptionPropertyType::AppendCmd
-          || OptProp.first == OptionPropertyType::ForwardAs)
-        ret = true;
-    }
-  if (D.isForward() || D.isUnpackValues())
-    ret = true;
-  return ret;
-}
+template <typename F>
+void EmitCaseConstructHandler(const Init* Dag, const char* IndentLevel,
+                              F Callback, bool EmitElseIf,
+                              const OptionDescriptions& OptDescs,
+                              std::ostream& O) {
+  const DagInit* d = &InitPtrToDag(Dag);
+  if (d->getOperator()->getAsString() != "case")
+    throw std::string("EmitCaseConstructHandler should be invoked"
+                      " only on 'case' expressions!");
 
-/// EmitOptionPropertyHandlingCode - Helper function used by
-/// EmitGenerateActionMethod(). Emits code that handles option
-/// properties.
-void EmitOptionPropertyHandlingCode (const ToolOptionDescription& D,
-                                     std::ostream& O)
-{
-  if (!ToolOptionHasInterestingProperties(D))
-    return;
-  // Start of the if-clause.
-  O << Indent2 << "if (";
-  if (D.Type == OptionType::Switch)
-    O << D.GenVariableName();
-  else
-    O << '!' << D.GenVariableName() << ".empty()";
+  unsigned numArgs = d->getNumArgs();
+  if (d->getNumArgs() < 2)
+    throw "There should be at least one clause in the 'case' expression:\n"
+      + d->getAsString();
 
-  O <<") {\n";
+  for (unsigned i = 0; i != numArgs; ++i) {
+    const DagInit& Test = InitPtrToDag(d->getArg(i));
 
-  // Handle option properties that take an argument.
-  for (OptionPropertyList::const_iterator B = D.Props.begin(),
-        E = D.Props.end(); B!=E; ++B) {
-    const OptionProperty& val = *B;
-
-    switch (val.first) {
-      // (append_cmd cmd) property
-    case OptionPropertyType::AppendCmd:
-      O << Indent3 << "vec.push_back(\"" << val.second << "\");\n";
-      break;
-      // (forward_as) property
-    case OptionPropertyType::ForwardAs:
-      EmitForwardOptionPropertyHandlingCode(D, val.second, O);
-      break;
-      // Other properties with argument
-    default:
-      break;
+    // Emit the test.
+    if (Test.getOperator()->getAsString() == "default") {
+      if (i+2 != numArgs)
+        throw std::string("The 'default' clause should be the last in the"
+                          "'case' construct!");
+      O << IndentLevel << "else {\n";
+    }
+    else {
+      O << IndentLevel << ((i != 0 && EmitElseIf) ? "else if (" : "if (");
+      EmitCaseTest(Test, IndentLevel, OptDescs, O);
+      O << ") {\n";
     }
-  }
 
-  // Handle flags
-
-  // (forward) property
-  if (D.isForward())
-    EmitForwardOptionPropertyHandlingCode(D, "", O);
-
-  // (unpack_values) property
-  if (D.isUnpackValues()) {
-    if (IsListOptionType(D.Type)) {
-      O << Indent3 << "for (" << D.GenTypeDeclaration()
-        << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
-        << Indent3 << "E = " << D.GenVariableName()
-        << ".end(); B != E; ++B)\n"
-        << Indent4 << "llvm::SplitString(*B, vec, \",\");\n";
-    }
-    else if (D.Type == OptionType::Prefix || D.Type == OptionType::Parameter){
-      O << Indent3 << "llvm::SplitString("
-        << D.GenVariableName() << ", vec, \",\");\n";
+    // Emit the corresponding statement.
+    ++i;
+    if (i == numArgs)
+      throw "Case construct handler: no corresponding action "
+        "found for the test " + Test.getAsString() + '!';
+
+    Init* arg = d->getArg(i);
+    const DagInit* nd = dynamic_cast<DagInit*>(arg);
+    if (nd && (nd->getOperator()->getAsString() == "case")) {
+      // Handle the nested 'case'.
+      EmitCaseConstructHandler(nd, (std::string(IndentLevel) + Indent1).c_str(),
+                               Callback, EmitElseIf, OptDescs, O);
     }
     else {
-      throw std::string("Switches can't have unpack_values property!");
+      Callback(arg, (std::string(IndentLevel) + Indent1).c_str(), O);
     }
+    O << IndentLevel << "}\n";
   }
-
-  // End of the if-clause.
-  O << Indent2 << "}\n";
 }
 
 /// SubstituteSpecialCommands - Perform string substitution for $CALL
@@ -1172,7 +1074,7 @@
 /// EmitCmdLineVecFill - Emit code that fills in the command line
 /// vector. Helper function used by EmitGenerateActionMethod().
 void EmitCmdLineVecFill(const Init* CmdLine, const std::string& ToolName,
-                        bool Version, const char* IndentLevel,
+                        bool IsJoin, const char* IndentLevel,
                         std::ostream& O) {
   StrVector StrVec;
   SplitString(InitPtrToString(CmdLine), StrVec);
@@ -1186,7 +1088,7 @@
     O << IndentLevel;
     if (cmd.at(0) == '$') {
       if (cmd == "$INFILE") {
-        if (Version)
+        if (IsJoin)
           O << "for (PathVector::const_iterator B = inFiles.begin()"
             << ", E = inFiles.end();\n"
             << IndentLevel << "B != E; ++B)\n"
@@ -1195,7 +1097,7 @@
           O << "vec.push_back(inFile.toString());\n";
       }
       else if (cmd == "$OUTFILE") {
-        O << "vec.push_back(outFile.toString());\n";
+        O << "vec.push_back(out_file);\n";
       }
       else {
         O << "vec.push_back(" << SubstituteSpecialCommands(cmd);
@@ -1216,151 +1118,236 @@
 /// EmitCmdLineVecFill(). Used by EmitGenerateActionMethod() as an
 /// argument to EmitCaseConstructHandler().
 class EmitCmdLineVecFillCallback {
-  bool Version;
+  bool IsJoin;
   const std::string& ToolName;
  public:
-  EmitCmdLineVecFillCallback(bool Ver, const std::string& TN)
-    : Version(Ver), ToolName(TN) {}
+  EmitCmdLineVecFillCallback(bool J, const std::string& TN)
+    : IsJoin(J), ToolName(TN) {}
+
+  void operator()(const Init* Statement, const char* IndentLevel,
+                  std::ostream& O) const
+  {
+    EmitCmdLineVecFill(Statement, ToolName, IsJoin,
+                       IndentLevel, O);
+  }
+};
+
+/// EmitForwardOptionPropertyHandlingCode - Helper function used to
+/// implement EmitActionHandler. Emits code for
+/// handling the (forward) and (forward_as) option properties.
+void EmitForwardOptionPropertyHandlingCode (const OptionDescription& D,
+                                            const char* Indent,
+                                            const std::string& NewName,
+                                            std::ostream& O) {
+  const std::string& Name = NewName.empty()
+    ? ("-" + D.Name)
+    : NewName;
+
+  switch (D.Type) {
+  case OptionType::Switch:
+  case OptionType::ExternSwitch:
+    O << Indent << "vec.push_back(\"" << Name << "\");\n";
+    break;
+  case OptionType::Parameter:
+  case OptionType::ExternParameter:
+    O << Indent << "vec.push_back(\"" << Name << "\");\n";
+    O << Indent << "vec.push_back(" << D.GenVariableName() << ");\n";
+    break;
+  case OptionType::Prefix:
+    O << Indent << "vec.push_back(\"" << Name << "\" + "
+      << D.GenVariableName() << ");\n";
+    break;
+  case OptionType::PrefixList:
+    O << Indent << "for (" << D.GenTypeDeclaration()
+      << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
+      << Indent << "E = " << D.GenVariableName() << ".end(); B != E; ++B)\n"
+      << Indent << Indent1 << "vec.push_back(\"" << Name << "\" + "
+      << "*B);\n";
+    break;
+  case OptionType::ParameterList:
+  case OptionType::ExternList:
+    O << Indent << "for (" << D.GenTypeDeclaration()
+      << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
+      << Indent << "E = " << D.GenVariableName()
+      << ".end() ; B != E; ++B) {\n"
+      << Indent << Indent1 << "vec.push_back(\"" << Name << "\");\n"
+      << Indent << Indent1 << "vec.push_back(*B);\n"
+      << Indent << "}\n";
+    break;
+  case OptionType::Alias:
+  default:
+    throw std::string("Aliases are not allowed in tool option descriptions!");
+  }
+}
+
+/// EmitActionHandler - Emit code that handles actions. Used by
+/// EmitGenerateActionMethod() as an argument to
+/// EmitCaseConstructHandler().
+class EmitActionHandler {
+  const OptionDescriptions& OptDescs;
+ public:
+  EmitActionHandler(const OptionDescriptions& OD)
+    : OptDescs(OD) {}
 
   void operator()(const Init* Statement, const char* IndentLevel,
                   std::ostream& O) const
   {
-    EmitCmdLineVecFill(Statement, ToolName, Version,
-                       (std::string(IndentLevel) + Indent1).c_str(), O);
+    const DagInit& Dag = InitPtrToDag(Statement);
+    const std::string& ActionName = Dag.getOperator()->getAsString();
+
+    if (ActionName == "append_cmd") {
+      checkNumberOfArguments(&Dag, 1);
+      const std::string& Cmd = InitPtrToString(Dag.getArg(0));
+      O << IndentLevel << "vec.push_back(\"" << Cmd << "\");\n";
+    }
+    else if (ActionName == "forward") {
+      checkNumberOfArguments(&Dag, 1);
+      const std::string& Name = InitPtrToString(Dag.getArg(0));
+      EmitForwardOptionPropertyHandlingCode(OptDescs.FindOption(Name),
+                                            IndentLevel, "", O);
+    }
+    else if (ActionName == "forward_as") {
+      checkNumberOfArguments(&Dag, 2);
+      const std::string& Name = InitPtrToString(Dag.getArg(0));
+      const std::string& NewName = InitPtrToString(Dag.getArg(0));
+      EmitForwardOptionPropertyHandlingCode(OptDescs.FindOption(Name),
+                                            IndentLevel, NewName, O);
+    }
+    else if (ActionName == "output_suffix") {
+      checkNumberOfArguments(&Dag, 1);
+      const std::string& OutSuf = InitPtrToString(Dag.getArg(0));
+      O << IndentLevel << "output_suffix = \"" << OutSuf << "\";\n";
+    }
+    else if (ActionName == "stop_compilation") {
+      O << IndentLevel << "stop_compilation = true;\n";
+    }
+    else if (ActionName == "unpack_values") {
+      checkNumberOfArguments(&Dag, 1);
+      const std::string& Name = InitPtrToString(Dag.getArg(0));
+      const OptionDescription& D = OptDescs.FindOption(Name);
+
+      if (OptionType::IsList(D.Type)) {
+        O << IndentLevel << "for (" << D.GenTypeDeclaration()
+          << "::iterator B = " << D.GenVariableName() << ".begin(),\n"
+          << IndentLevel << "E = " << D.GenVariableName()
+          << ".end(); B != E; ++B)\n"
+          << IndentLevel << Indent1 << "llvm::SplitString(*B, vec, \",\");\n";
+      }
+      else if (OptionType::IsParameter(D.Type)){
+        O << Indent3 << "llvm::SplitString("
+          << D.GenVariableName() << ", vec, \",\");\n";
+      }
+      else {
+        throw "Option '" + D.Name +
+          "': switches can't have the 'unpack_values' property!";
+      }
+    }
+    else {
+      throw "Unknown action name: " + ActionName + "!";
+    }
   }
 };
 
 // EmitGenerateActionMethod - Emit one of two versions of the
 // Tool::GenerateAction() method.
-void EmitGenerateActionMethod (const ToolProperties& P,
-                               const GlobalOptionDescriptions& OptDescs,
-                               bool Version, std::ostream& O) {
-  if (Version)
+void EmitGenerateActionMethod (const ToolDescription& D,
+                               const OptionDescriptions& OptDescs,
+                               bool IsJoin, std::ostream& O) {
+  if (IsJoin)
     O << Indent1 << "Action GenerateAction(const PathVector& inFiles,\n";
   else
     O << Indent1 << "Action GenerateAction(const sys::Path& inFile,\n";
 
-  O << Indent2 << "const sys::Path& outFile,\n"
+  O << Indent2 << "bool HasChildren,\n"
+    << Indent2 << "const llvm::sys::Path& TempDir,\n"
     << Indent2 << "const InputLanguagesSet& InLangs,\n"
     << Indent2 << "const LanguageMap& LangMap) const\n"
     << Indent1 << "{\n"
     << Indent2 << "std::string cmd;\n"
-    << Indent2 << "std::vector<std::string> vec;\n";
+    << Indent2 << "std::vector<std::string> vec;\n"
+    << Indent2 << "bool stop_compilation = !HasChildren;\n"
+    << Indent2 << "const char* output_suffix = \"" << D.OutputSuffix << "\";\n"
+    << Indent2 << "std::string out_file;\n\n";
+
+  // For every understood option, emit handling code.
+  if (D.Actions)
+    EmitCaseConstructHandler(D.Actions, Indent2, EmitActionHandler(OptDescs),
+                             false, OptDescs, O);
+
+  O << '\n' << Indent2
+    << "out_file = OutFilename(" << (IsJoin ? "sys::Path(),\n" : "inFile,\n")
+    << Indent3 << "TempDir, stop_compilation, output_suffix).toString();\n\n";
 
   // cmd_line is either a string or a 'case' construct.
-  if (typeid(*P.CmdLine) == typeid(StringInit))
-    EmitCmdLineVecFill(P.CmdLine, P.Name, Version, Indent2, O);
+  if (!D.CmdLine)
+    throw "Tool " + D.Name + " has no cmd_line property!";
+  else if (typeid(*D.CmdLine) == typeid(StringInit))
+    EmitCmdLineVecFill(D.CmdLine, D.Name, IsJoin, Indent2, O);
   else
-    EmitCaseConstructHandler(&InitPtrToDag(P.CmdLine), Indent2,
-                             EmitCmdLineVecFillCallback(Version, P.Name),
+    EmitCaseConstructHandler(D.CmdLine, Indent2,
+                             EmitCmdLineVecFillCallback(IsJoin, D.Name),
                              true, OptDescs, O);
 
-  // For every understood option, emit handling code.
-  for (ToolOptionDescriptions::const_iterator B = P.OptDescs.begin(),
-        E = P.OptDescs.end(); B != E; ++B) {
-    const ToolOptionDescription& val = B->second;
-    EmitOptionPropertyHandlingCode(val, O);
-  }
-
   // Handle the Sink property.
-  if (P.isSink()) {
+  if (D.isSink()) {
     O << Indent2 << "if (!" << SinkOptionName << ".empty()) {\n"
       << Indent3 << "vec.insert(vec.end(), "
       << SinkOptionName << ".begin(), " << SinkOptionName << ".end());\n"
       << Indent2 << "}\n";
   }
 
-  O << Indent2 << "return Action(cmd, vec);\n"
+  O << Indent2 << "return Action(cmd, vec, stop_compilation, out_file);\n"
     << Indent1 << "}\n\n";
 }
 
 /// EmitGenerateActionMethods - Emit two GenerateAction() methods for
 /// a given Tool class.
-void EmitGenerateActionMethods (const ToolProperties& P,
-                                const GlobalOptionDescriptions& OptDescs,
+void EmitGenerateActionMethods (const ToolDescription& ToolDesc,
+                                const OptionDescriptions& OptDescs,
                                 std::ostream& O) {
-  if (!P.isJoin())
+  if (!ToolDesc.isJoin())
     O << Indent1 << "Action GenerateAction(const PathVector& inFiles,\n"
-      << Indent2 << "const llvm::sys::Path& outFile,\n"
+      << Indent2 << "bool HasChildren,\n"
+      << Indent2 << "const llvm::sys::Path& TempDir,\n"
       << Indent2 << "const InputLanguagesSet& InLangs,\n"
       << Indent2 << "const LanguageMap& LangMap) const\n"
       << Indent1 << "{\n"
-      << Indent2 << "throw std::runtime_error(\"" << P.Name
+      << Indent2 << "throw std::runtime_error(\"" << ToolDesc.Name
       << " is not a Join tool!\");\n"
       << Indent1 << "}\n\n";
   else
-    EmitGenerateActionMethod(P, OptDescs, true, O);
-
-  EmitGenerateActionMethod(P, OptDescs, false, O);
-}
-
-/// EmitIsLastMethod - Emit the IsLast() method for a given Tool
-/// class.
-void EmitIsLastMethod (const ToolProperties& P, std::ostream& O) {
-  O << Indent1 << "bool IsLast() const {\n"
-    << Indent2 << "bool last = false;\n";
-
-  for (ToolOptionDescriptions::const_iterator B = P.OptDescs.begin(),
-        E = P.OptDescs.end(); B != E; ++B) {
-    const ToolOptionDescription& val = B->second;
-
-    if (val.isStopCompilation())
-      O << Indent2
-        << "if (" << val.GenVariableName()
-        << ")\n" << Indent3 << "last = true;\n";
-  }
+    EmitGenerateActionMethod(ToolDesc, OptDescs, true, O);
 
-  O << Indent2 << "return last;\n"
-    << Indent1 <<  "}\n\n";
+  EmitGenerateActionMethod(ToolDesc, OptDescs, false, O);
 }
 
 /// EmitInOutLanguageMethods - Emit the [Input,Output]Language()
 /// methods for a given Tool class.
-void EmitInOutLanguageMethods (const ToolProperties& P, std::ostream& O) {
+void EmitInOutLanguageMethods (const ToolDescription& D, std::ostream& O) {
   O << Indent1 << "const char** InputLanguages() const {\n"
     << Indent2 << "return InputLanguages_;\n"
     << Indent1 << "}\n\n";
 
-  O << Indent1 << "const char* OutputLanguage() const {\n"
-    << Indent2 << "return \"" << P.OutLanguage << "\";\n"
-    << Indent1 << "}\n\n";
-}
-
-/// EmitOutputSuffixMethod - Emit the OutputSuffix() method for a
-/// given Tool class.
-void EmitOutputSuffixMethod (const ToolProperties& P, std::ostream& O) {
-  O << Indent1 << "const char* OutputSuffix() const {\n"
-    << Indent2 << "const char* ret = \"" << P.OutputSuffix << "\";\n";
-
-  for (ToolOptionDescriptions::const_iterator B = P.OptDescs.begin(),
-         E = P.OptDescs.end(); B != E; ++B) {
-    const ToolOptionDescription& OptDesc = B->second;
-    for (OptionPropertyList::const_iterator B = OptDesc.Props.begin(),
-           E = OptDesc.Props.end(); B != E; ++B) {
-      const OptionProperty& OptProp = *B;
-      if (OptProp.first == OptionPropertyType::OutputSuffix) {
-        O << Indent2 << "if (" << OptDesc.GenVariableName() << ")\n"
-          << Indent3 << "ret = \"" << OptProp.second << "\";\n";
-      }
-    }
-  }
+  if (D.OutLanguage.empty())
+    throw "Tool " + D.Name + " has no 'out_language' property!";
 
-  O << Indent2 << "return ret;\n"
+  O << Indent1 << "const char* OutputLanguage() const {\n"
+    << Indent2 << "return \"" << D.OutLanguage << "\";\n"
     << Indent1 << "}\n\n";
 }
 
 /// EmitNameMethod - Emit the Name() method for a given Tool class.
-void EmitNameMethod (const ToolProperties& P, std::ostream& O) {
+void EmitNameMethod (const ToolDescription& D, std::ostream& O) {
   O << Indent1 << "const char* Name() const {\n"
-    << Indent2 << "return \"" << P.Name << "\";\n"
+    << Indent2 << "return \"" << D.Name << "\";\n"
     << Indent1 << "}\n\n";
 }
 
 /// EmitIsJoinMethod - Emit the IsJoin() method for a given Tool
 /// class.
-void EmitIsJoinMethod (const ToolProperties& P, std::ostream& O) {
+void EmitIsJoinMethod (const ToolDescription& D, std::ostream& O) {
   O << Indent1 << "bool IsJoin() const {\n";
-  if (P.isJoin())
+  if (D.isJoin())
     O << Indent2 << "return true;\n";
   else
     O << Indent2 << "return false;\n";
@@ -1369,24 +1356,27 @@
 
 /// EmitStaticMemberDefinitions - Emit static member definitions for a
 /// given Tool class.
-void EmitStaticMemberDefinitions(const ToolProperties& P, std::ostream& O) {
-  O << "const char* " << P.Name << "::InputLanguages_[] = {";
-  for (StrVector::const_iterator B = P.InLanguage.begin(),
-         E = P.InLanguage.end(); B != E; ++B)
+void EmitStaticMemberDefinitions(const ToolDescription& D, std::ostream& O) {
+  if (D.InLanguage.empty())
+    throw "Tool " + D.Name + " has no 'in_language' property!";
+
+  O << "const char* " << D.Name << "::InputLanguages_[] = {";
+  for (StrVector::const_iterator B = D.InLanguage.begin(),
+         E = D.InLanguage.end(); B != E; ++B)
     O << '\"' << *B << "\", ";
   O << "0};\n\n";
 }
 
 /// EmitToolClassDefinition - Emit a Tool class definition.
-void EmitToolClassDefinition (const ToolProperties& P,
-                              const GlobalOptionDescriptions& OptDescs,
+void EmitToolClassDefinition (const ToolDescription& D,
+                              const OptionDescriptions& OptDescs,
                               std::ostream& O) {
-  if (P.Name == "root")
+  if (D.Name == "root")
     return;
 
   // Header
-  O << "class " << P.Name << " : public ";
-  if (P.isJoin())
+  O << "class " << D.Name << " : public ";
+  if (D.isJoin())
     O << "JoinTool";
   else
     O << "Tool";
@@ -1395,40 +1385,48 @@
     << Indent1 << "static const char* InputLanguages_[];\n\n";
 
   O << "public:\n";
-  EmitNameMethod(P, O);
-  EmitInOutLanguageMethods(P, O);
-  EmitOutputSuffixMethod(P, O);
-  EmitIsJoinMethod(P, O);
-  EmitGenerateActionMethods(P, OptDescs, O);
-  EmitIsLastMethod(P, O);
+  EmitNameMethod(D, O);
+  EmitInOutLanguageMethods(D, O);
+  EmitIsJoinMethod(D, O);
+  EmitGenerateActionMethods(D, OptDescs, O);
 
   // Close class definition
   O << "};\n";
 
-  EmitStaticMemberDefinitions(P, O);
+  EmitStaticMemberDefinitions(D, O);
 
 }
 
-/// EmitOptionDescriptions - Iterate over a list of option
-/// descriptions and emit registration code.
-void EmitOptionDescriptions (const GlobalOptionDescriptions& descs,
-                             std::ostream& O)
+/// EmitOptionDefintions - Iterate over a list of option descriptions
+/// and emit registration code.
+void EmitOptionDefintions (const OptionDescriptions& descs,
+                           bool HasSink,
+                           std::ostream& O)
 {
-  std::vector<GlobalOptionDescription> Aliases;
+  std::vector<OptionDescription> Aliases;
 
   // Emit static cl::Option variables.
-  for (GlobalOptionDescriptions::const_iterator B = descs.begin(),
+  for (OptionDescriptions::const_iterator B = descs.begin(),
          E = descs.end(); B!=E; ++B) {
-    const GlobalOptionDescription& val = B->second;
+    const OptionDescription& val = B->second;
 
     if (val.Type == OptionType::Alias) {
       Aliases.push_back(val);
       continue;
     }
 
+    if (val.isExtern())
+      O << "extern ";
+
     O << val.GenTypeDeclaration() << ' '
-      << val.GenVariableName()
-      << "(\"" << val.Name << '\"';
+      << val.GenVariableName();
+
+    if (val.isExtern()) {
+      O << ";\n";
+      continue;
+    }
+
+    O << "(\"" << val.Name << '\"';
 
     if (val.Type == OptionType::Prefix || val.Type == OptionType::PrefixList)
       O << ", cl::Prefix";
@@ -1462,26 +1460,22 @@
   }
 
   // Emit the aliases (they should go after all the 'proper' options).
-  for (std::vector<GlobalOptionDescription>::const_iterator
+  for (std::vector<OptionDescription>::const_iterator
          B = Aliases.begin(), E = Aliases.end(); B != E; ++B) {
-    const GlobalOptionDescription& val = *B;
+    const OptionDescription& val = *B;
 
     O << val.GenTypeDeclaration() << ' '
       << val.GenVariableName()
       << "(\"" << val.Name << '\"';
 
-    GlobalOptionDescriptions::container_type
-      ::const_iterator F = descs.Descriptions.find(val.Help);
-    if (F != descs.Descriptions.end())
-      O << ", cl::aliasopt(" << F->second.GenVariableName() << ")";
-    else
-      throw val.Name + ": alias to an unknown option!";
+    const OptionDescription& D = descs.FindOption(val.Help);
+    O << ", cl::aliasopt(" << D.GenVariableName() << ")";
 
     O << ", cl::desc(\"" << "An alias for -" + val.Help  << "\"));\n";
   }
 
   // Emit the sink option.
-  if (descs.HasSink)
+  if (HasSink)
     O << "cl::list<std::string> " << SinkOptionName << "(cl::Sink);\n";
 
   O << '\n';
@@ -1520,53 +1514,6 @@
   O << "}\n\n}\n\n";
 }
 
-/// FillInToolToLang - Fills in two tables that map tool names to
-/// (input, output) languages.  Used by the typechecker.
-void FillInToolToLang (const ToolPropertiesList& TPList,
-                       StringMap<StringSet<> >& ToolToInLang,
-                       StringMap<std::string>& ToolToOutLang) {
-  for (ToolPropertiesList::const_iterator B = TPList.begin(), E = TPList.end();
-       B != E; ++B) {
-    const ToolProperties& P = *(*B);
-    for (StrVector::const_iterator B = P.InLanguage.begin(),
-           E = P.InLanguage.end(); B != E; ++B)
-      ToolToInLang[P.Name].insert(*B);
-    ToolToOutLang[P.Name] = P.OutLanguage;
-  }
-}
-
-/// TypecheckGraph - Check that names for output and input languages
-/// on all edges do match. This doesn't do much when the information
-/// about the whole graph is not available (i.e. when compiling most
-/// plugins).
-void TypecheckGraph (const RecordVector& EdgeVector,
-                     const ToolPropertiesList& TPList) {
-  StringMap<StringSet<> > ToolToInLang;
-  StringMap<std::string> ToolToOutLang;
-
-  FillInToolToLang(TPList, ToolToInLang, ToolToOutLang);
-  StringMap<std::string>::iterator IAE = ToolToOutLang.end();
-  StringMap<StringSet<> >::iterator IBE = ToolToInLang.end();
-
-  for (RecordVector::const_iterator Beg = EdgeVector.begin(),
-         E = EdgeVector.end(); Beg != E; ++Beg) {
-    const Record* Edge = *Beg;
-    const std::string& A = Edge->getValueAsString("a");
-    const std::string& B = Edge->getValueAsString("b");
-    StringMap<std::string>::iterator IA = ToolToOutLang.find(A);
-    StringMap<StringSet<> >::iterator IB = ToolToInLang.find(B);
-
-    if (A != "root") {
-      if (IA != IAE && IB != IBE && IB->second.count(IA->second) == 0)
-        throw "Edge " + A + "->" + B
-          + ": output->input language mismatch";
-    }
-
-    if (B == "root")
-      throw std::string("Edges back to the root are not allowed!");
-  }
-}
-
 /// IncDecWeight - Helper function passed to EmitCaseConstructHandler()
 /// by EmitEdgeClass().
 void IncDecWeight (const Init* i, const char* IndentLevel,
@@ -1575,9 +1522,9 @@
   const std::string& OpName = d.getOperator()->getAsString();
 
   if (OpName == "inc_weight")
-    O << IndentLevel << Indent1 << "ret += ";
+    O << IndentLevel << "ret += ";
   else if (OpName == "dec_weight")
-    O << IndentLevel << Indent1 << "ret -= ";
+    O << IndentLevel << "ret -= ";
   else
     throw "Unknown operator in edge properties list: " + OpName + '!';
 
@@ -1590,7 +1537,7 @@
 
 /// EmitEdgeClass - Emit a single Edge# class.
 void EmitEdgeClass (unsigned N, const std::string& Target,
-                    DagInit* Case, const GlobalOptionDescriptions& OptDescs,
+                    DagInit* Case, const OptionDescriptions& OptDescs,
                     std::ostream& O) {
 
   // Class constructor.
@@ -1612,7 +1559,7 @@
 
 /// EmitEdgeClasses - Emit Edge* classes that represent graph edges.
 void EmitEdgeClasses (const RecordVector& EdgeVector,
-                      const GlobalOptionDescriptions& OptDescs,
+                      const OptionDescriptions& OptDescs,
                       std::ostream& O) {
   int i = 0;
   for (RecordVector::const_iterator Beg = EdgeVector.begin(),
@@ -1630,14 +1577,14 @@
 /// EmitPopulateCompilationGraph - Emit the PopulateCompilationGraph()
 /// function.
 void EmitPopulateCompilationGraph (const RecordVector& EdgeVector,
-                                   const ToolPropertiesList& ToolProps,
+                                   const ToolDescriptions& ToolDescs,
                                    std::ostream& O)
 {
   O << "namespace {\n\n";
   O << "void PopulateCompilationGraphLocal(CompilationGraph& G) {\n";
 
-  for (ToolPropertiesList::const_iterator B = ToolProps.begin(),
-         E = ToolProps.end(); B != E; ++B)
+  for (ToolDescriptions::const_iterator B = ToolDescs.begin(),
+         E = ToolDescs.end(); B != E; ++B)
     O << Indent1 << "G.insertNode(new " << (*B)->Name << "());\n";
 
   O << '\n';
@@ -1669,73 +1616,61 @@
 /// ExtractHookNames - Extract the hook names from all instances of
 /// $CALL(HookName) in the provided command line string. Helper
 /// function used by FillInHookNames().
-void ExtractHookNames(const Init* CmdLine, StrVector& HookNames) {
-  StrVector cmds;
-  llvm::SplitString(InitPtrToString(CmdLine), cmds);
-  for (StrVector::const_iterator B = cmds.begin(), E = cmds.end();
-       B != E; ++B) {
-    const std::string& cmd = *B;
-    if (cmd.find("$CALL(") == 0) {
-      if (cmd.size() == 6)
-        throw std::string("$CALL invocation: empty argument list!");
-      HookNames.push_back(std::string(cmd.begin() + 6,
-                                      cmd.begin() + cmd.find(")")));
-    }
-  }
-}
+class ExtractHookNames {
+  llvm::StringSet<>& HookNames_;
+public:
+  ExtractHookNames(llvm::StringSet<>& HookNames)
+  : HookNames_(HookNames_) {}
 
-/// ExtractHookNamesFromCaseConstruct - Extract hook names from the
-/// 'case' expression, handle nesting. Helper function used by
-/// FillInHookNames().
-void ExtractHookNamesFromCaseConstruct(Init* Case, StrVector& HookNames) {
-  const DagInit& d = InitPtrToDag(Case);
-  bool even = false;
-  for (DagInit::const_arg_iterator B = d.arg_begin(), E = d.arg_end();
-       B != E; ++B) {
-    Init* arg = *B;
-    if (even && dynamic_cast<DagInit*>(arg)
-        && static_cast<DagInit*>(arg)->getOperator()->getAsString() == "case")
-      ExtractHookNamesFromCaseConstruct(arg, HookNames);
-    else if (even)
-      ExtractHookNames(arg, HookNames);
-    even = !even;
+  void operator()(const Init* CmdLine) {
+    StrVector cmds;
+    llvm::SplitString(InitPtrToString(CmdLine), cmds);
+    for (StrVector::const_iterator B = cmds.begin(), E = cmds.end();
+         B != E; ++B) {
+      const std::string& cmd = *B;
+      if (cmd.find("$CALL(") == 0) {
+        if (cmd.size() == 6)
+          throw std::string("$CALL invocation: empty argument list!");
+        HookNames_.insert(std::string(cmd.begin() + 6,
+                                     cmd.begin() + cmd.find(")")));
+      }
+    }
   }
-}
+};
 
 /// FillInHookNames - Actually extract the hook names from all command
 /// line strings. Helper function used by EmitHookDeclarations().
-void FillInHookNames(const ToolPropertiesList& TPList,
-                     StrVector& HookNames) {
+void FillInHookNames(const ToolDescriptions& ToolDescs,
+                     llvm::StringSet<>& HookNames)
+{
   // For all command lines:
-  for (ToolPropertiesList::const_iterator B = TPList.begin(),
-         E = TPList.end(); B != E; ++B) {
-    const ToolProperties& P = *(*B);
-    if (!P.CmdLine)
+  for (ToolDescriptions::const_iterator B = ToolDescs.begin(),
+         E = ToolDescs.end(); B != E; ++B) {
+    const ToolDescription& D = *(*B);
+    if (!D.CmdLine)
       continue;
-    if (dynamic_cast<StringInit*>(P.CmdLine))
+    if (dynamic_cast<StringInit*>(D.CmdLine))
       // This is a string.
-      ExtractHookNames(P.CmdLine, HookNames);
+      ExtractHookNames(HookNames).operator()(D.CmdLine);
     else
       // This is a 'case' construct.
-      ExtractHookNamesFromCaseConstruct(P.CmdLine, HookNames);
+      WalkCase(D.CmdLine, Id(), ExtractHookNames(HookNames));
   }
 }
 
 /// EmitHookDeclarations - Parse CmdLine fields of all the tool
 /// property records and emit hook function declaration for each
 /// instance of $CALL(HookName).
-void EmitHookDeclarations(const ToolPropertiesList& ToolProps,
-                          std::ostream& O) {
-  StrVector HookNames;
-  FillInHookNames(ToolProps, HookNames);
+void EmitHookDeclarations(const ToolDescriptions& ToolDescs, std::ostream& O) {
+  llvm::StringSet<> HookNames;
+  FillInHookNames(ToolDescs, HookNames);
   if (HookNames.empty())
     return;
-  std::sort(HookNames.begin(), HookNames.end());
-  StrVector::const_iterator E = std::unique(HookNames.begin(), HookNames.end());
 
   O << "namespace hooks {\n";
-  for (StrVector::const_iterator B = HookNames.begin(); B != E; ++B)
-    O << Indent1 << "std::string " << *B << "();\n";
+  for (StringSet<>::const_iterator B = HookNames.begin(), E = HookNames.end();
+       B != E; ++B)
+    O << Indent1 << "std::string " << B->first() << "();\n";
 
   O << "}\n\n";
 }
@@ -1777,138 +1712,113 @@
     << "{ return s == NULL ? \"\" : s; }\n\n";
 }
 
-/// NotInGraph - Helper function object for FilterNotInGraph.
-struct NotInGraph {
-private:
-  const llvm::StringSet<>& ToolsInGraph_;
-
-public:
-  NotInGraph(const llvm::StringSet<>& ToolsInGraph)
-  : ToolsInGraph_(ToolsInGraph)
-  {}
 
-  bool operator()(const IntrusiveRefCntPtr<ToolProperties>& x) {
-    return (ToolsInGraph_.count(x->Name) == 0);
-  }
+/// PluginData - Holds all information about a plugin.
+struct PluginData {
+  OptionDescriptions OptDescs;
+  bool HasSink;
+  ToolDescriptions ToolDescs;
+  RecordVector Edges;
+  int Priority;
 };
 
-/// FilterNotInGraph - Filter out from ToolProps all Tools not
-/// mentioned in the compilation graph definition.
-void FilterNotInGraph (const RecordVector& EdgeVector,
-                       ToolPropertiesList& ToolProps) {
-
-  // List all tools mentioned in the graph.
-  llvm::StringSet<> ToolsInGraph;
-
-  for (RecordVector::const_iterator Beg = EdgeVector.begin(),
-         E = EdgeVector.end(); Beg != E; ++Beg) {
-
-    const Record* Edge = *Beg;
-    const std::string& A = Edge->getValueAsString("a");
-    const std::string& B = Edge->getValueAsString("b");
-
-    if (A != "root")
-      ToolsInGraph.insert(A);
-    ToolsInGraph.insert(B);
-  }
-
-  // Filter ToolPropertiesList.
-  ToolPropertiesList::iterator new_end =
-    std::remove_if(ToolProps.begin(), ToolProps.end(),
-                   NotInGraph(ToolsInGraph));
-  ToolProps.erase(new_end, ToolProps.end());
-}
-
-/// CalculatePriority - Calculate the priority of this plugin.
-int CalculatePriority(RecordVector::const_iterator B,
-                      RecordVector::const_iterator E) {
-  int total = 0;
-  for (; B!=E; ++B) {
-    total += static_cast<int>((*B)->getValueAsInt("priority"));
-  }
-  return total;
-}
-
-/// FillInEdgeVector - Merge all compilation graph definitions into
-/// one single edge list.
-void FillInEdgeVector(RecordVector::const_iterator B,
-                      RecordVector::const_iterator E, RecordVector& Out) {
-  for (; B != E; ++B) {
-    const ListInit* edges = (*B)->getValueAsListInit("edges");
-
-    for (unsigned i = 0; i < edges->size(); ++i)
-      Out.push_back(edges->getElementAsRecord(i));
-  }
-}
+/// HasSink - Go through the list of tool descriptions and check if
+/// there is one with the 'sink' property set.
+bool HasSink(const ToolDescriptions& ToolDescs) {
+  for (ToolDescriptions::const_iterator B = ToolDescs.begin(),
+         E = ToolDescs.end(); B != E; ++B)
+    if ((*B)->isSink())
+      return true;
 
-// End of anonymous namespace
+    return false;
 }
 
-/// run - The back-end entry point.
-void LLVMCConfigurationEmitter::run (std::ostream &O) {
-  try {
-
-  // Emit file header.
-  EmitSourceFileHeader("LLVMC Configuration Library", O);
-  EmitIncludes(O);
-
-  // Collect tool properties.
-  RecordVector Tools = Records.getAllDerivedDefinitions("Tool");
-  ToolPropertiesList ToolProps;
-  GlobalOptionDescriptions OptDescs;
-  CollectToolProperties(Tools.begin(), Tools.end(), ToolProps, OptDescs);
-
+/// CollectPluginData - Collect tool and option properties,
+/// compilation graph edges and plugin priority from the parse tree.
+void CollectPluginData (const RecordKeeper& Records, PluginData& Data) {
   // Collect option properties.
   const RecordVector& OptionLists =
     Records.getAllDerivedDefinitions("OptionList");
-  CollectPropertiesFromOptionLists(OptionLists.begin(), OptionLists.end(),
-                                   OptDescs);
+  CollectOptionDescriptions(OptionLists.begin(), OptionLists.end(),
+                            Data.OptDescs);
+
+  // Collect tool properties.
+  const RecordVector& Tools = Records.getAllDerivedDefinitions("Tool");
+  CollectToolDescriptions(Tools.begin(), Tools.end(), Data.ToolDescs);
+  Data.HasSink = HasSink(Data.ToolDescs);
 
   // Collect compilation graph edges.
   const RecordVector& CompilationGraphs =
     Records.getAllDerivedDefinitions("CompilationGraph");
-  RecordVector EdgeVector;
   FillInEdgeVector(CompilationGraphs.begin(), CompilationGraphs.end(),
-                   EdgeVector);
+                   Data.Edges);
 
+  // Calculate the priority of this plugin.
+  const RecordVector& Priorities =
+    Records.getAllDerivedDefinitions("PluginPriority");
+  Data.Priority = CalculatePriority(Priorities.begin(), Priorities.end());
+}
+
+/// CheckPluginData - Perform some sanity checks on the collected data.
+void CheckPluginData(PluginData& Data) {
   // Filter out all tools not mentioned in the compilation graph.
-  FilterNotInGraph(EdgeVector, ToolProps);
+  FilterNotInGraph(Data.Edges, Data.ToolDescs);
 
   // Typecheck the compilation graph.
-  TypecheckGraph(EdgeVector, ToolProps);
+  TypecheckGraph(Data.Edges, Data.ToolDescs);
 
   // Check that there are no options without side effects (specified
   // only in the OptionList).
-  CheckForSuperfluousOptions(ToolProps, OptDescs);
+  CheckForSuperfluousOptions(Data.Edges, Data.ToolDescs, Data.OptDescs);
+
+}
+
+void EmitPluginCode(const PluginData& Data, std::ostream& O) {
+  // Emit file header.
+  EmitIncludes(O);
 
   // Emit global option registration code.
-  EmitOptionDescriptions(OptDescs, O);
+  EmitOptionDefintions(Data.OptDescs, Data.HasSink, O);
 
   // Emit hook declarations.
-  EmitHookDeclarations(ToolProps, O);
+  EmitHookDeclarations(Data.ToolDescs, O);
 
   // Emit PopulateLanguageMap() function
   // (a language map maps from file extensions to language names).
   EmitPopulateLanguageMap(Records, O);
 
   // Emit Tool classes.
-  for (ToolPropertiesList::const_iterator B = ToolProps.begin(),
-         E = ToolProps.end(); B!=E; ++B)
-    EmitToolClassDefinition(*(*B), OptDescs, O);
+  for (ToolDescriptions::const_iterator B = Data.ToolDescs.begin(),
+         E = Data.ToolDescs.end(); B!=E; ++B)
+    EmitToolClassDefinition(*(*B), Data.OptDescs, O);
 
   // Emit Edge# classes.
-  EmitEdgeClasses(EdgeVector, OptDescs, O);
+  EmitEdgeClasses(Data.Edges, Data.OptDescs, O);
 
   // Emit PopulateCompilationGraph() function.
-  EmitPopulateCompilationGraph(EdgeVector, ToolProps, O);
+  EmitPopulateCompilationGraph(Data.Edges, Data.ToolDescs, O);
 
   // Emit code for plugin registration.
-  const RecordVector& Priorities =
-    Records.getAllDerivedDefinitions("PluginPriority");
-  EmitRegisterPlugin(CalculatePriority(Priorities.begin(),
-                                       Priorities.end()), O);
+  EmitRegisterPlugin(Data.Priority, O);
 
   // EOF
+}
+
+
+// End of anonymous namespace
+}
+
+/// run - The back-end entry point.
+void LLVMCConfigurationEmitter::run (std::ostream &O) {
+  try {
+  PluginData Data;
+
+  CollectPluginData(Records, Data);
+  CheckPluginData(Data);
+
+  EmitSourceFileHeader("LLVMC Configuration Library", O);
+  EmitPluginCode(Data, O);
+
   } catch (std::exception& Error) {
     throw Error.what() + std::string(" - usually this means a syntax error.");
   }





More information about the llvm-commits mailing list