[llvm] [MachineScheduler] Add support for scheduling while in SSA (PR #161054)

[Matt Arsenault via llvm-commits]

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@@ -708,6 +857,33 @@ MachineSchedulerPass::run(MachineFunction &MF,
       .preserve<LiveIntervalsAnalysis>();
 }
 
+PreservedAnalyses
+SSAMachineSchedulerPass::run(MachineFunction &MF,
+                             MachineFunctionAnalysisManager &MFAM) {
+  if (EnableSSAMachineSched.getNumOccurrences()) {
+    if (!EnableSSAMachineSched)
+      return PreservedAnalyses::all();
+  } else if (!MF.getSubtarget().enableSSAMachineScheduler()) {
+    LLVM_DEBUG(dbgs() << "Subtarget disables ssa-MI-sched.\n");
+    return PreservedAnalyses::all();
+  }
+  LLVM_DEBUG(dbgs() << "Before ssa-MI-sched:\n"; MF.print(dbgs()));
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arsenm wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/161054