cgen: improve code generation for seq types
#1272
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Move the `tySequence` handling from `getTypeDescWeak` to `getTypeDesc`. Behaviour is largely the same, but with the important difference that the `tySequence` type is only pushed to the type stack *once*, removing the need to use a C `#ifdef` pre-processor block around the payload struct definition.
* for pointer indirections, only a forward declaration is requested * in field contexts, `getTypeDescAux` can be called directly
The `T` object type wasn't actually used anywhere in alive code, meaning no code was generated for it, and thus that the regression it intended to catch would have never been caught. The `p` procedure is now exported, forcing code generation to run for it (and subsequently the `T` type).
saem
approved these changes
Apr 9, 2024
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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
seqpayload type definition per C fileseqif not used in apointer-like type (e.g.:
ptr seq[T],ref seq[T])Together, these improvements reduce the amount of C code output by the
NimSkull compiler, slightly improving compile times.
Details
Move the
tySequencehandling fromgetTypeDescWeaktogetTypeDescAux, preventing different instances referring to the sametype, or the same instance, being pushed to the type stack multiple
times within a single module.
For each
tySequencetype instance pushed to the type stack, a payloadis emitted, with preventing duplicates previously being deferred to the
C compiler through use of a C pre-processor guard (
#ifdef). Since thetype instance is now only pushed to the type stack once per module, the
pre-processor guard is unnecessary and thus removed.
In addition, for
ptr seq,ref seq, etc. types, only a forward-declaration of the sequence type is requested, preventing the full type
and all its dependencies being pulled in.
Finally, the
trecursive_tabletest, intended to catch C codegenerator bugs with recursive
seqtypes, is fixed. Sincepwasneither used nor exported, the
Ttype was never actually processed bythe code generator.