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| ID | Project | Category | View Status | Date Submitted | Last Update |
| 0004818 | OCaml | OCaml general | public | 2009-06-07 21:44 | 2009-09-16 11:45 |
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| Reporter | mottl | |
| Assigned To | | |
| Priority | normal | Severity | major | Reproducibility | always |
| Status | closed | Resolution | fixed | |
| Platform | | OS | | OS Version | |
| Product Version | 3.11.0 | |
| Target Version | | Fixed in Version | 3.11.2+dev | |
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| Summary | 0004818: Type alias breaks bigarray access performance |
| Description | There seems to be a bug optimizing bigarray access when certain bigarray type parameters are supplied via an intermediate type alias. This can lead to a fairly dramatic loss of performance.
The attached file "foo.ml" demonstrates the problem. It can be compiled as follows: ocamlopt bigarray.cmxa foo.ml -o foo
In the submitted form the code will run approx. 5-6 times slower than if you use the commented out line defining type "vec" without an intermediate type alias instead.
It seems to me that the code specializer for bigarray access does not resolve such type aliases correctly and hence chooses the much slower generic access functions. |
| Tags | No tags attached. |
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| Attached Files |  foo.ml [^] (323 bytes) 2009-06-07 21:44 |
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