C++: Fix MemoryLocation with multiple VirtualVariables#3577
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MathiasVP merged 3 commits intoMay 29, 2020
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While investigating a bug with `TInstruction` sharing, I discovered that we had a case where alias analysis could create two `VirtualVariable`s for the same `Allocation`. For an indirect parameter allocation, we were using the type of the pointer variable as the type of the indirect allocation, instead of just `Unknown`. If the `IRType` of the pointer variable was the same type as the type of at least one access to the indirect allocation, we'd create both an `EntireAllocationVirtualVariable` and a `VariableVirtualVariable` for the allocation. I added a new consistency test to guard against this in the future. This also turned out to be the root cause of the one existing known consistency failure in the IR tests.
MathiasVP
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May 28, 2020
MathiasVP
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LGTM! (apart from the failing testcase that needs to be accepted)
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Looks like this conflicts with #3571 (which added a consistency failure that I think this will resolve). |
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Yup, that’s exactly what happened. I’ve merged and it’s all good now. |
MathiasVP
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May 29, 2020
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While investigating a bug with
TInstructionsharing, I discovered that we had a case where alias analysis could create twoVirtualVariables for the sameAllocation. For an indirect parameter allocation, we were using the type of the pointer variable as the type of the indirect allocation, instead of justUnknown. If theIRTypeof the pointer variable was the same type as the type of at least one access to the indirect allocation, we'd create both anEntireAllocationVirtualVariableand aVariableVirtualVariablefor the allocation.I added a new consistency test to guard against this in the future. This also turned out to be the root cause of the one existing known consistency failure in the IR tests.