Simplify the CFG after loop pass cleanup.

Summary:
Otherwise we might end up with some empty basic blocks or
single-entry-single-exit basic blocks.

This fixes PR32085

Reviewers: chandlerc, danielcdh

Subscribers: mehdi_amini, RKSimon, llvm-commits

Differential Revision: https://reviews.llvm.org/D30468

llvm-svn: 301395

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
index 50159783334..0d5910ebbfc 100644
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -680,6 +680,11 @@ void PassManagerBuilder::populateModulePassManager(
   MPM.add(createLoopSinkPass());
   // Get rid of LCSSA nodes.
   MPM.add(createInstructionSimplifierPass());
+
+  // LoopSink (and other loop passes since the last simplifyCFG) might have
+  // resulted in single-entry-single-exit or empty blocks. Clean up the CFG.
+  MPM.add(createCFGSimplificationPass());
+
   addExtensionsToPM(EP_OptimizerLast, MPM);
 }