Minutes_2018_06_28

Numba Meeting: 2018-06-28

Attendees: Stan, Siu, Stuart, Ehsan, Todd

#3066: array.dtype.type not working inside prange
#3065: Pickle SmartArray objects
#3064: SmartArray.__init__(shape, dtype, order) is broken
#3063: Exception in CUDA simulator before syncthreads deadlocks process exit.
#3061: Generator iterator fails from within NPM function if created outside the NPM function
- Be able to create new RandomStates in nopython mode
- Need to fix error message to make it clear that iterators can't pass from python to nopython mode
#3058: Array allocation for dt64
- HPAT uses a lot of datetime64
- Siu will take a look and comment on issue
#3057: "AssertionError: Failed at object (object mode frontend)" exception from simple code bug
- another loop lifting + inlining fail
- General category of problem caused by mutating IR nodes in compiler passes
- May be a bigger issue as we add "with-lifting"
- Should look into this during 0.40 dev cycle
#3053: [0.37.0/armel,armhf] tests broken
- May be fixed in 0.40
#3052: [0.37.0/armel] LLVM Error during sphinx build
#3051: [0.37.0/mips,mipsel] Bus error during test
- Never tried this
#3050: [0.37.0/ppc64el] segmentation fault during test
- May be fixed in 0.40 / LLVM 6.0.x?
#3049: [0.37.0/s390x] Segmentation fault during test
- Never tried this
#3047: Test failure on i7-3930K (win-64) (py27)
- Should be fixed

3046 Pairwise sum implementation.
- needs fix
3045 Fix #3027 - Numba reassigns sys.stdout
- stuart will respond
3038 Fix random integer generation to match results from NumPy.
- Stuart will review
3033 Add support for multidimensional CFFI arrays
- Needs review
3023 [WIP] ROCm Target testing... DO NOT MERGE! Support for AMDGCN/ROCm.
- Siu will review
- Plan to merge in 0.40dev
3017 Add facility to support with-contexts
- Needs some revision, another review pass
- Ehsan will re-review once fixed
#2999 Support LowLevelCallable
- Really wanted actual example to test
#2983 [WIP] invert mapping b/w binop operators and the operator module
- Needs some review from Siu
#2977 Added docstring coding convention and specified line terminator to developer docs
#2976 [WIP] Expansion of developer documentation.
#2968 Adding xnd kernels
- Ready to review
#2959 np.unique return_counts support
#2950 Fix dispatcher to only consider contiguous-ness.
- Causing problems on ARM (but also affects everywhere)
- Siu and Stuart need to chat
#2942 Fix linkage nature (declspec(dllexport)) of some test functions
- Merge in next dev cycle
- Open issue for related potential issues?
#2894: [WIP] Implement jitclass default constructor arguments.
- Very close
#2817: [WIP] Emit LLVM optimization remarks
- Low priority, still want this

Find issue for "template" jitclass, note that it would be useful for HPAT

===========================

Dictionaries!

Implementation of lists in Numba opened up a huge can of worms
- Temporary lists that exist only in nopython mode are relatively straightforward
- Python lists passed as arguments have to be walked to translate into nopython mode list, which is potentially slow
- What to do about list mutations in nopython mode? Current Numba implementation goes through much effort to reflect these changes back to Python when function exits
- Nested list of list implementation was unable to achieve reflection properly for arbitrarily nested lists
New approach for containers:
- Python containers (list, set, dict in future) passed into nopython mode will be automatically translated to nopython mode data structures, but will be immutable (compiler enforced)
- Locally created list/set/dict containers will be mutable
- Create Python-wrapped nopython mode containers ("Numba list", "Numba dict") that can be passed as arguments, have constant-time unboxing, and can be mutated in the function.
- Deprecate (with warning) support for mutating Python lists and sets passed into Numba