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

[Arthur Eubanks via llvm-commits]

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@@ -409,13 +409,33 @@ class RequireAllMachineFunctionPropertiesPass
 
 } // namespace
 
+static void defaultRegAllocBuilder(TargetMachine *TM,
+                                   StringMap<MachineFunctionPassManager> &M) {
+  if (!TM)
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aeubanks wrote:

should always be non-null here

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