cgen: fix performance regression with x in {...}
#807
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Summary ======= Fix a regression in the C code generator that led to slightly less efficient code being generated for `x in set` where set is a constant set construction expression. Details ======= The decision of whether to emit set construction code or to use an `||` (or) chain of comparisons was still based on the presence of the `nfAllConst` flag, but node flags don't reach the code generators ever since the introduction of the MIR and `astgen`, meaning that the `||` chain was always chosen for set literals with less than 8 elements. Testing for the flag is replaced with a call to `isDeepConstExpr`, restoring the originally intended behaviour (i.e., emit set construction code for sets with a size-in-bytes < `sizeof(int)`). In addition, the other remaining usage of `nfAllConst` in `ccgexprs.genSetConstr` is removed completely: fully constant construction expression are already handled by its single callsite (`ccgexprs.expr`).
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Using |
saem
approved these changes
Jul 19, 2023
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/merge |
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Merge requested by: @saem Contents after the first section break of the PR description has been removed and preserved below:
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Summary
Fix a regression in the C code generator that led to slightly less
efficient code being generated for
x in setwhere set is a constantset construction expression.
Details
The decision of whether to emit set construction code or to use an
||(or) chain of comparisons was still based on the presence of thenfAllConstflag, but node flags don't reach the code generators eversince the introduction of the MIR and
astgen, meaning that the||chain was always chosen for set literals with less than 8 elements.
Testing for the flag is replaced with a call to
isDeepConstExpr,restoring the originally intended behaviour (i.e., emit set construction
code for sets with a size-in-bytes <=
sizeof(int)).In addition, the other remaining usage of
nfAllConstinccgexprs.genSetConstris removed completely: fully constantconstruction expressions are already handled by its single callsite
(
ccgexprs.expr).