[mips] SelectionDAGISel subclasses now follow the optimization level.

Summary:
It was recently discovered that, for Mips's SelectionDAGISel subclasses,
all optimization levels caused SelectionDAGISel to behave like -O2.

This change adds the necessary plumbing to initialize the optimization level.

Reviewers: andrew.w.kaylor

Subscribers: andrew.w.kaylor, sdardis, dean, llvm-commits, vradosavljevic, petarj, qcolombet, probinson, dsanders

Differential Revision: https://reviews.llvm.org/D14900

llvm-svn: 275410
diff --git a/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp b/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
index ff24e53..d9528da 100644
--- a/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
@@ -1033,6 +1033,7 @@
   return true;
 }
 
-FunctionPass *llvm::createMipsSEISelDag(MipsTargetMachine &TM) {
-  return new MipsSEDAGToDAGISel(TM);
+FunctionPass *llvm::createMipsSEISelDag(MipsTargetMachine &TM,
+                                        CodeGenOpt::Level OptLevel) {
+  return new MipsSEDAGToDAGISel(TM, OptLevel);
 }