Lower signatures exposing struct registers to byval struct pointers

tools/opt/opt.cpp

Index: tools/opt/opt.cpp
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index 67403357c987d33cfaa3091ed62e83e5ce9735d2..876856ad6018925ed81b0a88ea46471be68604d9 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -425,6 +425,7 @@ int main(int argc, char **argv) {
   initializeGlobalCleanupPass(Registry);
   initializeGlobalizeConstantVectorsPass(Registry);
   initializeInsertDivideCheckPass(Registry);
+  initializeSimplifyStructRegSignaturesPass(Registry);
   initializePNaClABIVerifyFunctionsPass(Registry);
   initializePNaClABIVerifyModulePass(Registry);
   initializePNaClSjLjEHPass(Registry);