IPO: Introduce ThinLTOBitcodeWriter pass.

This pass prepares a module containing type metadata for ThinLTO by splitting
it into regular and thin LTO parts if possible, and writing both parts to
a multi-module bitcode file. Modules that do not contain type metadata are
written unmodified as a single module.

All globals with type metadata are added to the regular LTO module, and
the rest are added to the thin LTO module.

Differential Revision: https://reviews.llvm.org/D27324

llvm-svn: 289899

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 035629a8aa4..a93c06c1d13 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -99,6 +99,10 @@ static cl::opt<bool>
 OutputAssembly("S", cl::desc("Write output as LLVM assembly"));
 
 static cl::opt<bool>
+    OutputThinLTOBC("thinlto-bc",
+                    cl::desc("Write output as ThinLTO-ready bitcode"));
+
+static cl::opt<bool>
 NoVerify("disable-verify", cl::desc("Do not run the verifier"), cl::Hidden);
 
 static cl::opt<bool>
@@ -704,7 +708,9 @@ int main(int argc, char **argv) {
       if (EmitModuleHash)
         report_fatal_error("Text output is incompatible with -module-hash");
       Passes.add(createPrintModulePass(*OS, "", PreserveAssemblyUseListOrder));
-    } else
+    } else if (OutputThinLTOBC)
+      Passes.add(createWriteThinLTOBitcodePass(*OS));
+    else
       Passes.add(createBitcodeWriterPass(*OS, PreserveBitcodeUseListOrder,
                                          EmitSummaryIndex, EmitModuleHash));
   }