[llvm] [NewPM][CodeGen] add TargetPassConfig like API (PR #70906)

[Arthur Eubanks via llvm-commits]

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@@ -455,18 +518,10 @@ template <typename DerivedT> class CodeGenPassBuilder {
   /// Utilities for targets to add passes to the pass manager.
   ///
 
-  /// createTargetRegisterAllocator - Create the register allocator pass for
-  /// this target at the current optimization level.
-  void addTargetRegisterAllocator(AddMachinePass &, bool Optimized) const;
-
-  /// addMachinePasses helper to create the target-selected or overriden
-  /// regalloc pass.
-  void addRegAllocPass(AddMachinePass &, bool Optimized) const;
-
-  /// Add core register alloator passes which do the actual register assignment
-  /// and rewriting. \returns true if any passes were added.
-  Error addRegAssignmentFast(AddMachinePass &) const;
-  Error addRegAssignmentOptimized(AddMachinePass &) const;
+  /// Add core register allocator passes which do the actual register assignment
+  /// and rewriting. \returns Error::success() if any passes were added.
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aeubanks wrote:

if no passes were added, this returns an error? that seems weird

https://github.com/llvm/llvm-project/pull/70906