Take advantage of simplifications enabled by folding all indirect access to locals #79722
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch, @kunalspathak Issue DetailsWe delete code which needed to deal with the fact tracked locals in HIR could be accesses indirectly. Diffs: a few regressions in tests where we are more conservative with address-exposed locals accessed via
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Good on me for noticing it a few weeks ago in dotnet#79722... ``` // Otherwise, must be local lhs form. TODO-Bug: this doesn't account for LCL_FLD. // This will miss memory havoc induced by address-exposed local field stores. ```
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Forward sub can bring in local address nodes and not recognizing them pessimizes things
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@dotnet/jit-contrib |
| GenTreeLclVarCommon* lclVarTree = nullptr; | ||
| GenTree* addrArg = tree->AsOp()->gtOp1->gtEffectiveVal(/*commaOnly*/ true); | ||
| if (!addrArg->DefinesLocalAddr(&lclVarTree)) | ||
| { | ||
| fgCurMemoryUse |= memoryKindSet(GcHeap, ByrefExposed); | ||
| } | ||
| else | ||
| { | ||
| // Defines a local addr | ||
| assert(lclVarTree != nullptr); | ||
| fgMarkUseDef(lclVarTree->AsLclVarCommon()); | ||
| } |
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/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress |
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Failure is known according to build analysis. |
We delete code which needed to deal with the fact tracked locals in HIR could be accesses indirectly.
Diffs are primarily from the reintroduced morph folding. Sources:
GTF_ORDER_SIDEEFFon the local field (as it would on an indirection), allowing for someoptOptimizeBoolsaction.LCL_FLDis cheaper thanIND(LCL_VAR_ADDR).There is also a nice TP win,
0.3%-0.5%reduction in instruction retired under FullOpts.Note: diff better viewed with the "ignore whitespace changes" option.