[XLS] When comparing TreeBitLocations, compare node ID rather than pointer #2233
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…inter Do the same when caching BDD trees for each node in the `node_locations_` cache in the BDD query engine. This is generally both a correctness & a safety improvement. In this specific case, it was found as a fix for nondeterminism! Due to false matches when memory locations were reused for new Nodes, the BDD query engine's variable caches could nondeterministically match with an (no-longer-used) variable created for a deleted Node. This was safe, but resulted in effective changes to the variable order, which could cause the BDD to saturate in different places nondeterministically. PiperOrigin-RevId: 761693685
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[XLS] When comparing TreeBitLocations, compare node ID rather than pointer
Do the same when caching BDD trees for each node in the
node_locations_cache in the BDD query engine.This is generally both a correctness & a safety improvement. In this specific case, it was found as a fix for nondeterminism! Due to false matches when memory locations were reused for new Nodes, the BDD query engine's variable caches could nondeterministically match with an (no-longer-used) variable created for a deleted Node. This was safe, but resulted in effective changes to the variable order, which could cause the BDD to saturate in different places nondeterministically.