[llvm] [AMDGPU] Enable reordering of VMEM loads during clustering (PR #107986)

[Matt Arsenault via llvm-commits]

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@@ -483,12 +488,20 @@ static ScheduleDAGInstrs *createSIMachineScheduler(MachineSchedContext *C) {
   return new SIScheduleDAGMI(C);
 }
 
+static bool getReorderWhileLoadClustering(const MachineFunction *MF) {
+  if (!ReorderWhileLoadClustering)
+    return false;
+  return !!MF->getFunction().getFnAttributeAsParsedInteger(
+      "amdgpu-reorder-loads-while-clustering", 1);
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arsenm wrote:

If you really want to add another one of these explicit boolean attributes, should use getValueAsBool and "true" "false"

Do we really need both mechanisms here? At most I would think the debug cl::opt may be useful for a short period 

https://github.com/llvm/llvm-project/pull/107986