[llvm] [LegacyPM][DirectX] Add legacy scalarizer back for use in the DirectX backend (PR #107427)

[Xiang Li via llvm-commits]

================
@@ -375,6 +375,7 @@ static bool shouldPinPassToLegacyPM(StringRef Pass) {
       "fix-irreducible",
       "expand-large-fp-convert",
       "callbrprepare",
+      "scalarizer",
----------------
python3kgae wrote:

Will this work `-passes='function(scalarizer)' -dxil-op-lower` directly?

If it doesn't work,
We have dxil-op-lower for new pass manager at https://github.com/llvm/llvm-project/blob/54194e1506bdd6dc37988678a8047ad4d48168fa/llvm/lib/Target/DirectX/DXILOpLowering.h#L20C7-L20C21
Is it possible to use new pass manager for opt like  `-passes='function(scalarizer, dxil-op-lower)` so we don't need to modify optdirver.cpp?


https://github.com/llvm/llvm-project/pull/107427