Switch lowering: cluster adjacent fall-through cases even at -O0
It's cheap to do, and codegen is much faster if cases can be merged
into clusters.
llvm-svn: 236905
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 52d12fc..832437c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -8012,10 +8012,12 @@
MachineBasicBlock *DefaultMBB = FuncInfo.MBBMap[SI.getDefaultDest()];
- if (TM.getOptLevel() != CodeGenOpt::None) {
- // Cluster adjacent cases with the same destination.
- sortAndRangeify(Clusters);
+ // Cluster adjacent cases with the same destination. We do this at all
+ // optimization levels because it's cheap to do and will make codegen faster
+ // if there are many clusters.
+ sortAndRangeify(Clusters);
+ if (TM.getOptLevel() != CodeGenOpt::None) {
// Replace an unreachable default with the most popular destination.
// FIXME: Exploit unreachable default more aggressively.
bool UnreachableDefault =