[llvm] [MachineSink] Extend loop sinking capability (PR #117247)

[Matt Arsenault via llvm-commits]

================
@@ -771,31 +787,62 @@ bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
 
   if (SinkInstsIntoCycle) {
     SmallVector<MachineCycle *, 8> Cycles(CI->toplevel_cycles());
-    for (auto *Cycle : Cycles) {
-      MachineBasicBlock *Preheader = Cycle->getCyclePreheader();
-      if (!Preheader) {
-        LLVM_DEBUG(dbgs() << "CycleSink: Can't find preheader\n");
-        continue;
-      }
-      SmallVector<MachineInstr *, 8> Candidates;
-      FindCycleSinkCandidates(Cycle, Preheader, Candidates);
-
-      // Walk the candidates in reverse order so that we start with the use
-      // of a def-use chain, if there is any.
-      // TODO: Sort the candidates using a cost-model.
-      unsigned i = 0;
-      for (MachineInstr *I : llvm::reverse(Candidates)) {
-        if (i++ == SinkIntoCycleLimit) {
-          LLVM_DEBUG(dbgs() << "CycleSink:   Limit reached of instructions to "
-                               "be analysed.");
-          break;
+    SchedModel.init(STI);
+    bool HasHighPressure;
+    DenseMap<std::pair<MachineInstr *, MachineBasicBlock *>, MachineInstr *>
----------------
arsenm wrote:

Could use a typedef to shrink the type 

https://github.com/llvm/llvm-project/pull/117247