Unroll again after running BBVectorize

Because BBVectorize may significantly shorten a loop body, unroll
again after vectorization. This is especially important when using
runtime or partial unrolling.

llvm-svn: 173730

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 6dc1773..47b2b51 100644 (file)
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -214,6 +214,10 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
       MPM.add(createGVNPass());                   // Remove redundancies
     else
       MPM.add(createEarlyCSEPass());              // Catch trivial redundancies
+
+    // BBVectorize may have significantly shortened a loop body; unroll again.
+    if (!DisableUnrollLoops)
+      MPM.add(createLoopUnrollPass());
   }
 
   MPM.add(createAggressiveDCEPass());         // Delete dead instructions