[llvm] [MachineScheduler][NFCI] Add Offset and OffsetIsScalable args to shouldClusterMemOps (PR #73778)

[Philip Reames via llvm-commits]

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@@ -1496,12 +1496,18 @@ class TargetInstrInfo : public MCInstrInfo {
   /// to TargetPassConfig::createMachineScheduler() to have an effect.
   ///
   /// \p BaseOps1 and \p BaseOps2 are memory operands of two memory operations.
+  /// \p Offset1 and \p Offset2 are the byte offsets for the memory
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preames wrote:

The docs for ElementCount are a bit confusingly worded, but I think this is the right abstraction here.  An Offset1=12 and OffsetIsScalable1=false would be a ElementCount::getFixed(12).  

https://github.com/llvm/llvm-project/pull/73778