[PM] Disable the loop vectorizer from the new PM's pipeline as it

currenty relies on the old PM's dependency system forming LCSSA.

The new PM will require a different design for this, and for now this is
causing most of the issues I'm currently seeing in testing. I'd like to
get to a testable baseline and then work on re-enabling things one at
a time.

llvm-svn: 290644

lib/Passes/PassBuilder.cpp

@@ -490,7 +490,11 @@ PassBuilder::buildPerModuleDefaultPipeline(OptimizationLevel Level,
   // rather than on each loop in an inside-out manner, and so they are actually
   // function passes.
   OptimizePM.addPass(LoopDistributePass());
+#if 0
+  // FIXME: LoopVectorize relies on "requiring" LCSSA which isn't supported in
+  // the new PM.
   OptimizePM.addPass(LoopVectorizePass());
+#endif
   // FIXME: Need to port Loop Load Elimination and add it here.
   OptimizePM.addPass(InstCombinePass());