Test Enzyme on demo models

[penelopeysm]

This PR is mostly a speculative attempt to see how Enzyme fares on our demo models.

Enzyme AD takes very long to run (technically, the preparation step takes a long time) and so this PR comments out all other tests (including AD tests on other backends).

tldr so far: All tests pass (both forward- and reverse-mode of Enzyme) with all demo models when using TypedVarInfo, but UntypedVarInfo segfaults

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 4.31%. Comparing base (e4fa7f2) to head (d6bf74a).

❗ There is a different number of reports uploaded between BASE (e4fa7f2) and HEAD (d6bf74a). Click for more details.

HEAD has 6 uploads less than BASE

Flag	BASE (e4fa7f2)	HEAD (d6bf74a)
	12	6

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #813       +/-   ##
==========================================
- Coverage   84.43%   4.31%   -80.13%     
==========================================
  Files          34      34               
  Lines        3849    3804       -45     
==========================================
- Hits         3250     164     -3086     
- Misses        599    3640     +3041     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[coveralls]

Pull Request Test Coverage Report for Build 13958820972

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2913 unchanged lines in 27 files lost coverage.
• Overall coverage decreased (-80.1%) to 4.405%

---

Files with Coverage Reduction	New Missed Lines	%
src/varname.jl	6	0.0%
ext/DynamicPPLForwardDiffExt.jl	7	0.0%
src/test_utils/model_interface.jl	7	0.0%
src/model_utils.jl	11	0.0%
src/distribution_wrappers.jl	16	0.0%
src/transforming.jl	17	0.0%
src/extract_priors.jl	19	0.0%
src/test_utils/varinfo.jl	23	0.0%
src/values_as_in_model.jl	23	0.0%
src/logdensityfunction.jl	25	0.0%

Totals
Change from base Build 13957720054:	-80.1%
Covered Lines:	164
Relevant Lines:	3723

---

💛 - Coveralls

[github-actions]

Benchmark Report for Commit d6bf74a7846be978e13625907d2e19db86e713f3

Computer Information

Julia Version 1.11.4
Commit 8561cc3d68d (2025-03-10 11:36 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 4 × AMD EPYC 7763 64-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, znver3)
Threads: 1 default, 0 interactive, 1 GC (on 4 virtual cores)

Benchmark Results

|                 Model | Dimension |  AD Backend |      VarInfo Type | Linked | Eval Time / Ref Time | AD Time / Eval Time |
|-----------------------|-----------|-------------|-------------------|--------|----------------------|---------------------|
| Simple assume observe |         1 | forwarddiff |             typed |  false |                  9.6 |                 1.6 |
|           Smorgasbord |       201 | forwarddiff |             typed |  false |                621.3 |                42.1 |
|           Smorgasbord |       201 | forwarddiff | simple_namedtuple |   true |                369.1 |                55.9 |
|           Smorgasbord |       201 | forwarddiff |           untyped |   true |               1228.8 |                28.4 |
|           Smorgasbord |       201 | forwarddiff |       simple_dict |   true |               4178.7 |                20.9 |
|           Smorgasbord |       201 | reversediff |             typed |   true |               1469.6 |                29.6 |
|           Smorgasbord |       201 |    mooncake |             typed |   true |                948.5 |                 5.5 |
|    Loop univariate 1k |      1000 |    mooncake |             typed |   true |               5636.4 |                 4.1 |
|       Multivariate 1k |      1000 |    mooncake |             typed |   true |               1098.2 |                 8.4 |
|   Loop univariate 10k |     10000 |    mooncake |             typed |   true |              62319.2 |                 3.8 |
|      Multivariate 10k |     10000 |    mooncake |             typed |   true |               9089.9 |                 9.6 |
|               Dynamic |        10 |    mooncake |             typed |   true |                126.0 |                12.4 |
|              Submodel |         1 |    mooncake |             typed |   true |                 27.1 |                 6.9 |
|                   LDA |        12 | reversediff |             typed |   true |                469.8 |                 4.7 |