JIT: Null out SSA def nodes upon removal in RBO #108530
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AndyAyersMS
reviewed
Oct 3, 2024
| assert(candidateStmt->GetRootNode()->OperIs(GT_STORE_LCL_VAR)); | ||
| GenTreeLclVarCommon* const rootNode = candidateStmt->GetRootNode()->AsLclVarCommon(); | ||
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| LclVarDsc* const varDsc = lvaGetDesc(rootNode); |
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Since the local is in SSA you should be able to locate the LclSsaVarDsc directly. Something like:
unsigned const ssaNum = rootNode->GetSsaNum();
LclSsaVarDsc* const defDsc = varDsc->GetPerSsaData(ssaNum);
assert(defDsc->GetDefNode() == rootNode);
defDsc->SetDefNode(nullptr);
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Thanks, fixed
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AndyAyersMS
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Oct 4, 2024
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/backport to release/9.0 |
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Started backporting to release/9.0: https://github.com/dotnet/runtime/actions/runs/11182189273 |
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Fixes #108406. When removing redundant store nodes in RBO, we need to also update SSA definitions to no longer track the removed stores. Because call sites that use SSA definitions are responsible for null-checking the store node, the simplest method of removal is to null out the node pointer in the SSA def.
cc @dotnet/jit-contrib, @AndyAyersMS PTAL. I can include a regression test if you think it would be useful, but I think the new
DEBUG_DESTROY_NODEgives us better coverage anyway.