[baggepinnen]

Split out of #5173.

Summary

distribute_shift distributed a shift into every operator term except Sample and Hold. An operator term such as a clock change defined by another package (SynchToolkit.Latest(x, init)) denotes the value of the signal at the current tick of the receiving clock and is a symbol of its own, so distributing the back-shift that the discrete reassembly of ModelingToolkitTearing performs into it produces a reference to a nonexistent xₜ₋₁. The default for Operator subtypes is now false; Shift and Differential keep distributing, as before.

Behaviour change

Only operators defined outside ModelingToolkitBase are affected: Sample, Hold, Pre and Initial were already excluded. A package whose operator term must be entered by shifts can define distribute_shift_into_operator(::MyOperator) = true.

Tests

A regression test with an operator defined in the test file checks that the shift of a sum is distributed to the variable but not into the operator term, and that Sample, Hold, Shift and Differential behave as before.

🤖 Generated with Claude Code

https://claude.ai/code/session_01QBgBrXDidWG1G2KF64gAte

[github-actions]

Benchmark Results (Julia vlts)

Time benchmarks

	master	3db6d36...	master / 3db6d36...
ODEProblem	3.15 ± 0.11 ms	3.15 ± 0.098 ms	1 ± 0.047
init	0.0544 ± 0.0081 ms	0.054 ± 0.014 ms	1.01 ± 0.29
large_parameter_init/ODEProblem	8.69 ± 0.87 ms	8.63 ± 0.89 ms	1.01 ± 0.14
large_parameter_init/init	0.0636 ± 0.021 ms	0.057 ± 0.014 ms	1.11 ± 0.45
mtkcompile	5.62 ± 0.3 ms	5.65 ± 0.34 ms	0.994 ± 0.079
sparse_analytical_jacobian/ODEProblem	10.6 ± 0.64 ms	10.6 ± 0.69 ms	1 ± 0.089
sparse_analytical_jacobian/f_iip	0.04 ± 0.01 μs	0.04 ± 0.01 μs	1 ± 0.35
sparse_analytical_jacobian/f_oop	0.239 ± 0.0043 ms	0.238 ± 0.0041 ms	1 ± 0.025
time_to_load	4.17 ± 0.036 s	4.15 ± 0.027 s	1 ± 0.011

Memory benchmarks

	master	3db6d36...	master / 3db6d36...
ODEProblem	0.0346 M allocs: 1.82 MB	0.0346 M allocs: 1.82 MB	1
init	0.508 k allocs: 0.0846 MB	0.508 k allocs: 0.0846 MB	1
large_parameter_init/ODEProblem	0.147 M allocs: 5.54 MB	0.147 M allocs: 5.54 MB	1
large_parameter_init/init	0.64 k allocs: 0.179 MB	0.64 k allocs: 0.179 MB	1
mtkcompile	0.0594 M allocs: 3.37 MB	0.0594 M allocs: 3.37 MB	1
sparse_analytical_jacobian/ODEProblem	0.106 M allocs: 5.33 MB	0.106 M allocs: 5.33 MB	1
sparse_analytical_jacobian/f_iip	0 allocs: 0 B	0 allocs: 0 B
sparse_analytical_jacobian/f_oop	0.634 k allocs: 19.6 kB	0.634 k allocs: 19.6 kB	1
time_to_load	0.153 k allocs: 14.6 kB	0.153 k allocs: 14.6 kB	1

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	master	3db6d36...	master / 3db6d36...
ODEProblem	2.81 ± 0.064 ms	2.82 ± 0.059 ms	0.997 ± 0.031
init	31.4 ± 8.2 μs	0.0323 ± 0.009 ms	0.973 ± 0.37
large_parameter_init/ODEProblem	7.2 ± 0.84 ms	7.16 ± 0.85 ms	1.01 ± 0.17
large_parameter_init/init	0.0357 ± 0.0033 ms	0.0354 ± 0.0034 ms	1.01 ± 0.13
mtkcompile	5.06 ± 0.33 ms	4.95 ± 0.33 ms	1.02 ± 0.095
sparse_analytical_jacobian/ODEProblem	9.25 ± 0.7 ms	9.11 ± 0.63 ms	1.01 ± 0.1
sparse_analytical_jacobian/f_iip	0.04 ± 0.01 μs	0.04 ± 0.01 μs	1 ± 0.35
sparse_analytical_jacobian/f_oop	0.0587 ± 0.0062 ms	0.0587 ± 0.0063 ms	0.999 ± 0.15
time_to_load	3.13 ± 0.043 s	3.1 ± 0.053 s	1.01 ± 0.022

Memory benchmarks

	master	3db6d36...	master / 3db6d36...
ODEProblem	0.034 M allocs: 1.61 MB	0.034 M allocs: 1.61 MB	1
init	0.475 k allocs: 0.0602 MB	0.475 k allocs: 0.0602 MB	1
large_parameter_init/ODEProblem	0.143 M allocs: 4.86 MB	0.144 M allocs: 4.86 MB	1
large_parameter_init/init	0.757 k allocs: 0.166 MB	0.757 k allocs: 0.166 MB	1
mtkcompile	0.0557 M allocs: 2.63 MB	0.0558 M allocs: 2.64 MB	0.994
sparse_analytical_jacobian/ODEProblem	0.102 M allocs: 4.24 MB	0.102 M allocs: 4.24 MB	1
sparse_analytical_jacobian/f_iip	0 allocs: 0 B	0 allocs: 0 B
sparse_analytical_jacobian/f_oop	0.848 k allocs: 27 kB	0.848 k allocs: 27 kB	1
time_to_load	0.201 k allocs: 12.1 kB	0.201 k allocs: 12.1 kB	1