[Hexagon] Run late copy propagation and dead code elimination passes

llvm-svn: 323346
diff --git a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
index 363b703..df65cfd 100644
--- a/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonTargetMachine.cpp
@@ -299,6 +299,11 @@
   TargetPassConfig::addIRPasses();
   bool NoOpt = (getOptLevel() == CodeGenOpt::None);
 
+  if (!NoOpt) {
+    addPass(createConstantPropagationPass());
+    addPass(createDeadCodeEliminationPass());
+  }
+
   addPass(createAtomicExpandPass());
   if (!NoOpt) {
     if (EnableLoopPrefetch)