Add support for emitting ~generic vectorized C++ code.

The compiler now supports an --emit-c++ option, which generates generic
vector C++ code.  To actually compile this code, the user must provide
C++ code that implements a variety of types and operations (e.g. adding
two floating-point vector values together, comparing them, etc).

There are two examples of this required code in examples/intrinsics:
generic-16.h is a "generic" 16-wide implementation that does all required
with scalar math; it's useful for demonstrating the requirements of the
implementation.  Then, sse4.h shows a simple implementation of a SSE4
target that maps the emitted function calls to SSE intrinsics.

When using these example implementations with the ispc test suite,
all but one or two tests pass with gcc and clang on Linux and OSX.
There are currently ~10 failures with icc on Linux, and ~50 failures with
MSVC 2010.  (To be fixed in coming days.)

Performance varies: when running the examples through the sse4.h
target, some have the same performance as when compiled with --target=sse4
from ispc directly (options), while noise is 12% slower, rt is 26%
slower, and aobench is 2.2x slower.  The details of this haven't yet been
carefully investigated, but will be in coming days as well.

Issue #92.

module.cpp

@@ -76,7 +76,6 @@
 #include <llvm/Target/TargetMachine.h>
 #include <llvm/Target/TargetOptions.h>
 #include <llvm/Target/TargetData.h>
-#include <llvm/PassManager.h>
 #include <llvm/Analysis/Verifier.h>
 #include <llvm/Support/CFG.h>
 #include <clang/Frontend/CompilerInstance.h>
@@ -584,7 +583,8 @@ Module::AddFunctionDefinition(Symbol *sym, const std::vector<Symbol *> &args,
 
 
 bool
-Module::writeOutput(OutputType outputType, const char *outFileName) {
+Module::writeOutput(OutputType outputType, const char *outFileName,
+                    const char *includeFileName) {
 #if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
     if (diBuilder != NULL && outputType != Header)
         diBuilder->finalize();
@@ -610,6 +610,14 @@ Module::writeOutput(OutputType outputType, const char *outFileName) {
             if (strcasecmp(suffix, "o") && strcasecmp(suffix, "obj"))
                 fileType = "object";
             break;
+#ifndef LLVM_2_9
+        case CXX:
+            if (strcasecmp(suffix, "c") && strcasecmp(suffix, "cc") &&
+                strcasecmp(suffix, "c++") && strcasecmp(suffix, "cxx") &&
+                strcasecmp(suffix, "cpp"))
+                fileType = "c++";
+            break;
+#endif // !LLVM_2_9
         case Header:
             if (strcasecmp(suffix, "h") && strcasecmp(suffix, "hh") &&
                 strcasecmp(suffix, "hpp"))
@@ -623,12 +631,18 @@ Module::writeOutput(OutputType outputType, const char *outFileName) {
 
     if (outputType == Header)
         return writeHeader(outFileName);
-    else {
-        if (outputType == Bitcode)
-            return writeBitcode(module, outFileName);
-        else
-            return writeObjectFileOrAssembly(outputType, outFileName);
+    else if (outputType == Bitcode)
+        return writeBitcode(module, outFileName);
+#ifndef LLVM_2_9
+    else if (outputType == CXX) {
+        extern bool WriteCXXFile(llvm::Module *module, const char *fn, 
+                                 int vectorWidth, const char *includeName);
+        return WriteCXXFile(module, outFileName, g->target.vectorWidth,
+                            includeFileName);
     }
+#endif // !LLVM_2_9
+    else
+        return writeObjectFileOrAssembly(outputType, outFileName);
 }
 
 
@@ -1568,7 +1582,8 @@ lCreateDispatchModule(std::map<std::string, FunctionTargetVariants> &functions)
 int
 Module::CompileAndOutput(const char *srcFile, const char *arch, const char *cpu, 
                          const char *target, bool generatePIC, OutputType outputType, 
-                         const char *outFileName, const char *headerFileName) {
+                         const char *outFileName, const char *headerFileName,
+                         const char *includeFileName) {
     if (target == NULL || strchr(target, ',') == NULL) {
         // We're only compiling to a single target
         if (!Target::GetTarget(arch, cpu, target, generatePIC, &g->target))
@@ -1577,7 +1592,7 @@ Module::CompileAndOutput(const char *srcFile, const char *arch, const char *cpu,
         m = new Module(srcFile);
         if (m->CompileFile() == 0) {
             if (outFileName != NULL)
-                if (!m->writeOutput(outputType, outFileName))
+                if (!m->writeOutput(outputType, outFileName, includeFileName))
                     return 1;
             if (headerFileName != NULL)
                 if (!m->writeOutput(Module::Header, headerFileName))
@@ -1590,6 +1605,14 @@ Module::CompileAndOutput(const char *srcFile, const char *arch, const char *cpu,
         return errorCount > 0;
     }
     else {
+#ifndef LLVM_2_9
+        if (outputType == CXX) {
+            Error(SourcePos(), "Illegal to specify more then one target when "
+                  "compiling C++ output.");
+            return 1;
+        }
+#endif // !LLVM_2_9
+
         // The user supplied multiple targets
         std::vector<std::string> targets = lExtractTargets(target);
         Assert(targets.size() > 1);