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

[Matt Arsenault via llvm-commits]

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@@ -749,6 +752,30 @@ void AMDGPUTargetMachine::registerPassBuilderCallbacks(
           return onlyAllocateVGPRs;
         return nullptr;
       });
+
+  PB.setDefaultRegAllocBuilder(
+      [TM = this](StringMap<MachineFunctionPassManager> &RegAllocMap) {
+        auto Opts = getCGPassBuilderOption();
+        if (Opts.OptimizeRegAlloc.value_or(TM->getOptLevel() !=
+                                           CodeGenOptLevel::None)) {
+          // TODO: Add greedy register allocator.
+        } else {
+          RegAllocFastPassOptions Opts;
+          Opts.Filter = onlyAllocateSGPRs;
+          Opts.FilterName = "sgpr";
+          Opts.ClearVRegs = false;
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arsenm wrote:

Use initializer list? 

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