Bitcode streaming

tools/llc/llc.cpp

Index: tools/llc/llc.cpp
diff --git a/tools/llc/llc.cpp b/tools/llc/llc.cpp
index fdc6fec98455e7b954b50293b286ab87dade8f99..306b1420b414b5a2478366580248bd723af42812 100644
--- a/tools/llc/llc.cpp
+++ b/tools/llc/llc.cpp
@@ -18,6 +18,7 @@
 #include "llvm/PassManager.h"
 #include "llvm/Pass.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Support/BitcodeStream.h"
 #include "llvm/Support/IRReader.h"
 #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
@@ -141,6 +142,16 @@ DisableRedZone("disable-red-zone",
   cl::desc("Do not emit code that uses the red zone."),
   cl::init(false));
 
+// Using bitcode streaming has a couple of ramifications. Primarily it means
+// that the module in the file will be compiled one function at a time rather
+// than the whole module. This allows earlier functions to be compiled before
+// later functions are read from the bitcode but of course means no whole-module
+// optimizations. For now, streaming is only supported for files and stdin.
+static cl::opt<bool>
+LazyBitcode("streaming-bitcode",
+  cl::desc("Use lazy bitcode streaming for file inputs"),
+  cl::init(false));
+
 // GetFileNameRoot - Helper function to get the basename of a filename.
 static inline std::string
 GetFileNameRoot(const std::string &InputFilename) {
@@ -248,7 +259,19 @@ int main(int argc, char **argv) {
   SMDiagnostic Err;
   std::auto_ptr<Module> M;
 
-  M.reset(ParseIRFile(InputFilename, Err, Context));
+  if (LazyBitcode) {
+    std::string StrError;
+    BitcodeStreamer *streamer = getBitcodeFileStreamer(InputFilename,&StrError);
+    if (streamer) {
+      M.reset(getStreamedBitcodeModule(InputFilename, streamer, Context,
+                                       &StrError));
+    }
+    if (!StrError.empty()) {
+      Err = SMDiagnostic(InputFilename, SourceMgr::DK_Error, StrError);
+    }
+  } else {
+    M.reset(ParseIRFile(InputFilename, Err, Context));
+  }
   if (M.get() == 0) {
     Err.print(argv[0], errs());
     return 1;
@@ -345,13 +368,18 @@ int main(int argc, char **argv) {
   if (!Out) return 1;
 
   // Build up all of the passes that we want to do to the module.
-  PassManager PM;
+  OwningPtr<PassManagerBase> PM;
+  if (LazyBitcode)
+    PM.reset(new FunctionPassManager(&mod));
+  else
+    PM.reset(new PassManager());
+
 
   // Add the target data from the target machine, if it exists, or the module.
   if (const TargetData *TD = Target.getTargetData())
-    PM.add(new TargetData(*TD));
+    PM->add(new TargetData(*TD));
   else
-    PM.add(new TargetData(&mod));
+    PM->add(new TargetData(&mod));
 
   // Override default to generate verbose assembly.
   Target.setAsmVerbosityDefault(true);
@@ -368,7 +396,7 @@ int main(int argc, char **argv) {
     formatted_raw_ostream FOS(Out->os());
 
     // Ask the target to add backend passes as necessary.
-    if (Target.addPassesToEmitFile(PM, FOS, FileType, NoVerify)) {
+    if (Target.addPassesToEmitFile(*PM, FOS, FileType, NoVerify)) {
       errs() << argv[0] << ": target does not support generation of this"
              << " file type!\n";
       return 1;
@@ -377,7 +405,16 @@ int main(int argc, char **argv) {
     // Before executing passes, print the final values of the LLVM options.
     cl::PrintOptionValues();
 
-    PM.run(mod);
+    if (LazyBitcode) {
+      FunctionPassManager *P = static_cast<FunctionPassManager*>(PM.get());
+      P->doInitialization();
+      for (Module::iterator I = mod.begin(), E = mod.end(); I != E; ++I) {
+        P->run(*I);
+      }
+      P->doFinalization();
+    } else {
+      static_cast<PassManager*>(PM.get())->run(mod);
+    }
   }
 
   // Declare success.