Qiskit / qiskit / 8807324183

88%

Build Type

push

github

Committed by web-flow

Commit Message

Add fast-path construction to `NLocal` (#12099)

This class is hard to make the most efficient, due to how abstract the
base class is, with many different options and many private methods that
subclasses override.  Still, in cases where, _at the point of build_, we
can detect that rotation or entanglement layers are simple applications
of a single standard-library gate, we can skip the entire `copy` +
`assign` + `compose` pipeline and simply construct the gates in-place
with the correct parameters.  This skips huge tracts of overhead that
using the high-level, abstract interfaces (which are somewhat
necessarily more optimised to work with large operands) in tight inner
loops adds, culminating in about a 10x improvement in build time.

`NLocal` is so abstract that it's hard to hit similar performance to an
idiomatic direct construction of the relevant structure, but to be fair,
the concept of a circuit library is not necessarily to make the absolute
fastest constructors for tight loops, but to make it much simpler to
just get a circuit that works as intended.

Run Details

39 of 39 new or added lines in 1 file covered. (100.0%)

7 existing lines in 2 files now uncovered.

60362 of 67462 relevant lines covered (89.48%)

224590.47 hits per line