[llvm] [SandboxVectorizer] Implement topdown/bottomup vectorizers in unison (PR #205249)

[via llvm-commits]

================
@@ -285,9 +287,55 @@ Action *BottomUpVec::vectorizeRec(ArrayRef<Value *> Bndl,
       DebugBndlCnt++ >= StopBundle && StopBundle != StopBundleDisabled;
   LLVM_DEBUG(dbgs() << DEBUG_PREFIX << "canVectorize() Bundle:\n";
              VecUtils::dump(Bndl));
-  const auto &LegalityRes = StopForDebug ? Legality.getForcedPackForDebugging()
-                                         : Legality.canVectorize(Bndl);
+  const auto &LegalityRes =
+      StopForDebug
+          ? Legality.getForcedPackForDebugging()
+          : Legality.canVectorize(Bndl,
+                                  /*SkipScheduling=*/Legality.getDirection() ==
----------------
vporpo wrote:

The issue is that the scheduler defaults to bottom-up and we are attempting to schedule top-down. This is not producing a meaningful error message at the moment (it is one of the things that need to be fixed). I just created https://github.com/llvm/llvm-project/pull/208602 which adds the direction argument to Scheduler/Legality. So once you rebase on top of that and set the scheduling direction to `Dir` upon construction you should be good to go.

https://github.com/llvm/llvm-project/pull/205249