[llvm] [CodeGen][NewPM] Handle `--regalloc-npm` option (PR #94748)

[Arthur Eubanks via llvm-commits]

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@@ -582,12 +583,28 @@ class PassBuilder {
 
   /// Register callbacks to parse target specific filter field if regalloc pass
   /// needs it. E.g. AMDGPU requires regalloc passes can handle sgpr and vgpr
-  /// separately.
+  /// separately. Currently "all" and "none" are preserved filter name.
   void registerRegClassFilterParsingCallback(
       const std::function<RegClassFilterFunc(StringRef)> &C) {
     RegClassFilterParsingCallbacks.push_back(C);
   }
 
+  /// Parse command line option `--regalloc-npm`
+  /// Should only be called by CodeGenPassBuilder.
+  Error parseRegAllocOpt(StringRef Text);
+
+  /// Target hook to set default regalloc.
+  void setDefaultRegAllocBuilder(
+      const std::function<void(StringMap<MachineFunctionPassManager> &)> &C) {
+    DefaultRegAllocBuilder = C;
+  }
+
+  /// Used by CodeGenPassBuilder to add correct regalloc pass.
+  /// Should only be called by CodeGenPassBuilder.
+  StringMap<MachineFunctionPassManager> &getRegAllocMap() {
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aeubanks wrote:

it seems very roundabout to use a map that creates a MachineFunctionPassManager. can this instead be a callback that takes a MachineFunctionPassManager and adds a regalloc pass to it? like the optimization pipeline callbacks

https://github.com/llvm/llvm-project/pull/94748