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

[via llvm-commits]

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@@ -292,8 +304,11 @@ bool MachinePipeliner::scheduleLoop(MachineLoop &L) {
   }
 
   ++NumTrytoPipeline;
+  if (useSwingModuloScheduler())
+    Changed = swingModuloScheduler(L);
 
-  Changed = swingModuloScheduler(L);
+  if (useWindowScheduler(Changed))
+    Changed = runWindowScheduler(L);
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hiraditya wrote:

Should we run one scheduler after another? This came up in a discussion today at the vectorizer meeting. cc: @ayalz 

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