[llvm] [Sink] Allow sinking of loads to distant blocks (PR #135986)

[Matt Arsenault via llvm-commits]

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@@ -60,10 +63,62 @@ static bool isSafeToMove(Instruction *Inst, AliasAnalysis &AA,
   return true;
 }
 
+static cl::opt<unsigned> SinkLoadStoreLimit(
+    "sink-load-store-limit", cl::Hidden, cl::init(4),
+    cl::desc("Maximum number of stores in descendant blocks that will be "
+             "analyzed when attempting to sink a load."));
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arsenm wrote:

Can you avoid this super specific flag? Is there some threshold MemorySSA usually uses? At worst can it be a pass parameter instead? 

https://github.com/llvm/llvm-project/pull/135986