Minutes_2019_09_03

Attendees: Siu, Stan, Aaron, Ehsan, Pearu, Stuart, Val, Todd, James, Tianhong

0. Feature Discussion

@lower_cast etc issues, RefType, and no implicit casting?!
- forbidden implicit cast?
  - still implicit for user
  - re-use Expr.cast
  - better
- adding RefType like iterator_impl?
- discussion at: https://github.com/numba/numba/issues/4494
should we fix anything on jitclass? use it in prod for e.g. numba-numba_scipy
- jitclass based API breaks "turn @jit off"
- we'd want to fix inconsistencies
  - hopefully in a more fundamental level
  - but also need quick fixes to address current user problems
compiler.py rewrite update PR#4513
- Why changing the passes?
  - motivated by:
    - lack of definition of a pass
    - lack of contract (i.e. what is modified? what a pass depends on?)
  - new code provides:
    - structures; i.e. analysis pass, transformation pass
    - strict ordering/sequence; i.e inter-pass dependency
    - auto-recompute stale states
- Why changing the compiler (pipeline)?
  - tangled states
  - needs better modularity
literally update PR#4467
- literal types for: int, str, function

Other open PRs:

should be ready to merge. autojit https://github.com/numba/numba/pull/4331
wip bounds checking https://github.com/numba/numba/pull/4432
- Stuart investigating trouble with ir.Loc
- Aaron proposed a way to raise exception base on runtime value
- still having some test failures.

#4505 - Trouble converting between typed list and array with string values
**** #4504 - Errors with various reduce calls - is fixing this going to break anything else? - should be fine
#4503 - Support the array_equals / array_equiv numpy function
#4502 - Boxer doesn't handle dispatcher type
#4500 - GUFuncs created in main are not serializable
**** #4499 - Accept Numpy (1.17+) Generator and BitGenerator objects in jitted code
- when?!
#4497 - Add unicode types in the documention
#4496 - isinstance on jitclass instances returns False on parent class
#4495 - Jitclass method call fails with keyword argument
#4494 - lower_constant and lower_cast should probably return new references
#4492 - No matching definition when using deferred_type
#4490 - Error while instanciating a jitclass with optional arguments in a jit function
#4489 - Loops in Prange produces incorrect result
#4488 - numba.errors.LoweringError: Failed in object mode pipeline (step: object mode backend) array.3
#4487 - prange fail
**** #4486 - [feature request] user defined priorities of automatic threading layer choice
#4485 - Detect workqueue re-entrant to avoid deadlock

**** #4506 - [WIP] Preparations to make @lower_castand @lower_constant return new references
#4501 - Add pre-commit hooks
#4493 - Fix Overload Inliner wrt CUDA Intrinsics

Finish pending rewrite passes
Python 3.8 support
Document best practices for constructing new compiler pipelines
Define autodiscovery system for Numba extensions (like numba_scipy or HPAT) that don't need direct user import
Allow opt-in dispatching of functions by literal value
Making caching aware of transitive dependencies
Define declarative typing system for @overload (to be used in future releases)
Numba Runtime C API for extensions to register reference-counted memory with the runtime.
Start using new CI system in parallel with existing one
Priority bug fixes:
- Low performance of JIT method calls (requested by Pandas devs)
- Others TBD