consider calls as complex openarray assignment to iterator params #24333
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narimiran
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…4333) fixes #13417, fixes #19703 When passing an expression to an `openarray` iterator parameter: If the expression is a statement list (considered "complex"), it's assigned in a non-deep-copying way to a temporary variable first, then this variable is used as a parameter. If it's not a statement list, i.e. a call or a symbol, the parameter is substituted directly with the given expression. In the case of calls, this results in the call potentially being executed more than once, or can cause redefined variables in the codegen. To fix this, calls are also considered as "complex" assignments to openarrays, as long as the return type of the call is not `openarray` as the generated assignment in that case has issues/is unimplemented (caused a segfault [here in datamancer](https://github.com/SciNim/Datamancer/blob/47ba4d81bf240a7755b73bc48c1cec9b638d18ae/src/datamancer/dataframe.nim#L1580)). As for why creating a temporary isn't the default only with exceptions for things like `nkSym`, the "non-deep-copying" way of assignment apparently still causes arrays to be copied according to a comment in the code. I'm not sure to what extent this is true: if it still happens on ARC/ORC, if it happens for every array length, or if we can fix it by passing arrays by reference. Otherwise, a more general way to assign to openarrays might be needed, but I'm not sure if the compiler can easily do this. (cherry picked from commit d303c28)
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fixes #13417, fixes #19703
When passing an expression to an
openarrayiterator parameter: If the expression is a statement list (considered "complex"), it's assigned in a non-deep-copying way to a temporary variable first, then this variable is used as a parameter. If it's not a statement list, i.e. a call or a symbol, the parameter is substituted directly with the given expression. In the case of calls, this results in the call potentially being executed more than once, or can cause redefined variables in the codegen.To fix this, calls are also considered as "complex" assignments to openarrays, as long as the return type of the call is not
openarrayas the generated assignment in that case has issues/is unimplemented (caused a segfault here in datamancer).As for why creating a temporary isn't the default only with exceptions for things like
nkSym, the "non-deep-copying" way of assignment apparently still causes arrays to be copied according to a comment in the code. I'm not sure to what extent this is true: if it still happens on ARC/ORC, if it happens for every array length, or if we can fix it by passing arrays by reference. Otherwise, a more general way to assign to openarrays might be needed, but I'm not sure if the compiler can easily do this.