1010186 - PJS GC: bump-allocate smallish element vectors

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Lars T Hansen [:lth]]

Followup to bug 933313; optimization.

The PJS allocation code for array element vectors (CodeGenerator::visitNewDenseArrayPar() in jit/CodeGenerator.cpp) calls out-of-line to allocate element vectors.  If this code is exercised for short vectors (TBD) then we could probably do significantly better by inlining the allocation.

Comment 1

[Lars T Hansen [:lth]]

I'm going to call this as Not-A-Bug.  The case in question is for the implementation of the intrinsic-for-selfhosted-code NewDenseArray().  That intrinsic is used predominantly in situations where fairly large arrays are allocated (result arrays etc), not for the run-of-the-mill array values resulting from the Array syntax or the Array constructor.  The only exception to that rule is in the implementation of an iterator that returns both an index and a value, where a short array of this type might be constructed directly.

That there is specialized code for this operation for the parallel engine is probably more related to safety than to performance.