[llvm] [llvm][CodeGen] Add a new software pipeliner 'Window Scheduler' (PR #84443)

[Hua Tian via llvm-commits]

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@@ -484,9 +499,35 @@ void MachinePipeliner::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<MachineDominatorTree>();
   AU.addRequired<LiveIntervals>();
   AU.addRequired<MachineOptimizationRemarkEmitterPass>();
+  AU.addRequired<TargetPassConfig>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
+bool MachinePipeliner::runWindowScheduler(MachineLoop &L) {
+  MachineSchedContext Context;
+  Context.MF = MF;
+  Context.MLI = MLI;
+  Context.MDT = MDT;
+  Context.PassConfig = &getAnalysis<TargetPassConfig>();
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huaatian wrote:

Additionally, two ScheduleDAGs are used here: one for analyzing the dependencies between all instructions after copying, and the other for scheduling instructions in the window. The difference is that the former does not need to consider register pressure.

https://github.com/llvm/llvm-project/pull/84443