[lld] [llvm] [llvm][lld] Respect temporal profile weights in balanced partitioning (PR #213837)

[Karim Alweheshy via llvm-commits]

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@@ -227,6 +241,14 @@ unsigned BalancedPartitioning::runIteration(const FunctionNodeRange Nodes,
       Signature.CachedGainLR = Cost - logCost(L - 1, R + 1);
     if (R > 0)
       Signature.CachedGainRL = Cost - logCost(L + 1, R - 1);
+    // Scaling a utility's move gain is mathematically equivalent to adding
+    // Weight distinct utility nodes with the same signature, but avoids
+    // expanding the graph. Weight == 1 deliberately takes no FP operation so
+    // unweighted inputs preserve their previous behavior.
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karim-alweheshy wrote:

The equivalence is to Weight distinct utility nodes that have the same signature, so the total move gain is the sum of Weight identical per-utility gains. It does not scale L and R inside logCost. WeightedUtilitiesMatchReplication now checks the exact weighted-versus-explicit-replication order.

https://github.com/llvm/llvm-project/pull/213837