JIT: Add a stress mode that poisons implicit byrefs #80691
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This stress mode poisons all implicit byrefs before returns from the method. GC pointers are nulled out and other parts of the structs are filled with 0xcd bytes. This should help expose incorrectly elided copies in the recently added last-use copy elision optimization.
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch, @kunalspathak Issue DetailsThis stress mode poisons all implicit byrefs before returns from the method. GC pointers are nulled out and other parts of the structs are filled with 0xcd bytes. This should help expose incorrectly elided copies in the recently added last-use copy elision optimization.
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/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress |
src/coreclr/jit/importer.cpp
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| GenTree* addr; | ||
| if (start > 0) | ||
| { | ||
| addr = gtNewLclFldAddrNode(lclNum, start, TYP_BYREF); | ||
| } | ||
| else | ||
| { | ||
| addr = gtNewLclVarAddrNode(lclNum, TYP_BYREF); | ||
| } | ||
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| GenTree* blk = new (this, GT_BLK) GenTreeBlk(GT_BLK, TYP_STRUCT, addr, typGetBlkLayout(count)); |
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GLOB_REFs are missing for this assignment and the one below.
Nit: this can use block-based TYP_STRUCT LCL_FLD.
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Thanks, addressed I think. Can you take another look?
src/coreclr/jit/importer.cpp
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| //------------------------------------------------------------------------ | ||
| // impPoisonImplicitByrefsBeforeReturn: | ||
| // Spill the stack and insert IR that poisons all implicit byrefs. | ||
| // | ||
| void Compiler::impPoisonImplicitByrefsBeforeReturn() |
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Nit: a little comment for why do we want to do this?
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/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress |
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Azure Pipelines successfully started running 2 pipeline(s). |
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/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress |
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Azure Pipelines successfully started running 2 pipeline(s). |
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The failures are known or will be fixed by #80734. cc @dotnet/jit-contrib PTAL @AndyAyersMS |
This stress mode poisons all implicit byrefs before returns from the method. GC pointers are nulled out and other parts of the structs are filled with 0xcd bytes.
This should help expose incorrectly elided copies in the recently added last-use copy elision optimization.