Skip to content

[mcmc/base_adapter][NFC] add const and noexcept where appropriate #3350

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Merged
merged 1 commit into from
Jul 30, 2025
Merged

[mcmc/base_adapter][NFC] add const and noexcept where appropriate #3350

merged 1 commit into from
Jul 30, 2025
+24 −24

Conversation

kedartal
Copy link
Contributor

Allow querying the adapting() status of a const sampler, and mark loading/storing the bool member noexcept

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company): Tal Kedar, K2DQ LLC

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

@kedartal kedartal marked this pull request as draft July 30, 2025 13:14
@kedartal kedartal force-pushed the adapting_accessor branch from 44673ee to 1f827ce Compare July 30, 2025 13:39
@kedartal kedartal marked this pull request as ready for review July 30, 2025 13:40
@kedartal
[mcmc/base_adapter][NFC] add const and noexcept where appropriate
210fe90 
allow querying the `adapting()` status of a const sampler, and
mark loading/storing the bool member noexcept, after checking the relevant
overrides in the derived `adapt_...` samplers.
@kedartal kedartal force-pushed the adapting_accessor branch from 09933bb to 210fe90 Compare July 30, 2025 13:46
@stan-buildbot
Copy link
Contributor

Name Old Result New Result Ratio Performance change( 1 - new / old )
arma/arma.stan 0.33 0.35 0.94 -6.18% slower
low_dim_corr_gauss/low_dim_corr_gauss.stan 0.01 0.01 0.86 -16.92% slower
gp_regr/gen_gp_data.stan 0.02 0.03 0.97 -3.54% slower
gp_regr/gp_regr.stan 0.09 0.1 0.99 -0.8% slower
sir/sir.stan 70.01 72.88 0.96 -4.1% slower
irt_2pl/irt_2pl.stan 4.3 4.5 0.95 -4.84% slower
eight_schools/eight_schools.stan 0.06 0.06 0.87 -15.28% slower
pkpd/sim_one_comp_mm_elim_abs.stan 0.26 0.27 0.97 -2.7% slower
pkpd/one_comp_mm_elim_abs.stan 19.75 20.55 0.96 -4.04% slower
garch/garch.stan 0.45 0.46 0.98 -2.03% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan 2.89 2.88 1.0 0.05% faster
arK/arK.stan 1.84 2.05 0.9 -11.06% slower
gp_pois_regr/gp_pois_regr.stan 2.86 3.31 0.87 -15.45% slower
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan 10.05 9.5 1.06 5.5% faster
performance.compilation 178.71 192.53 0.93 -7.73% slower
Mean result: 0.947012270353255

Jenkins Console Log
Blue Ocean
Commit hash: 107cb07da5f07ab5bb08c566864260b2ab41c5d9

Machine information No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 20.04.3 LTS Release: 20.04 Codename: focal

CPU:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 46 bits physical, 48 bits virtual
CPU(s): 80
On-line CPU(s) list: 0-79
Thread(s) per core: 2
Core(s) per socket: 20
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 85
Model name: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
Stepping: 4
CPU MHz: 2400.000
CPU max MHz: 3700.0000
CPU min MHz: 1000.0000
BogoMIPS: 4800.00
Virtualization: VT-x
L1d cache: 1.3 MiB
L1i cache: 1.3 MiB
L2 cache: 40 MiB
L3 cache: 55 MiB
NUMA node0 CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79
Vulnerability Gather data sampling: Mitigation; Microcode
Vulnerability Itlb multihit: KVM: Mitigation: VMX disabled
Vulnerability L1tf: Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown: Mitigation; PTI
Vulnerability Mmio stale data: Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Reg file data sampling: Not affected
Vulnerability Retbleed: Mitigation; IBRS
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2: Mitigation; IBRS; IBPB conditional; STIBP conditional; RSB filling; PBRSB-eIBRS Not affected; BHI Not affected
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Mitigation; Clear CPU buffers; SMT vulnerable
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 invpcid_single pti intel_ppin ssbd mba ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke md_clear flush_l1d arch_capabilities

G++:
g++ (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Clang:
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

@bob-carpenter
Copy link
Member

bob-carpenter commented Jul 30, 2025 •
edited
Loading

Hi, @kedartal:

Thanks for submitting a PR. It looks OK, and I traced through stepsize adaptation to make sure the noexcept annotations were correct.

Before I merge, can you tell me what "[NFC]" means in the PR title? I tried looking it up on the web but couldn't find anything relevant.

@kedartal
Copy link
Contributor Author

@bob-carpenter "No functional change" is how learnt it -- the commit does not contain any (intentional) changes to logic and so, in theory, no correctness implications. The idea is to allow skipping those when going over a set of commits to understand code changes.

@bob-carpenter
Copy link
Member

"No functional change"

Thanks. I don't understand the line between functional change and not, but it doesn't matter for this PR.

bob-carpenter
bob-carpenter approved these changes Jul 30, 2025
View reviewed changes
Copy link
Member

@bob-carpenter bob-carpenter left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks---I tracked through all the functions and verified they actually were const and/or noexcept.

@bob-carpenter bob-carpenter merged commit c89d0bf into stan-dev:develop Jul 30, 2025
3 checks passed
@kedartal
Copy link
Contributor Author

@bob-carpenter Thanks!
The way I think about it, a functional change can potentially alter the output for some input. Fixing a typo in a comment or renaming a local variable are classic NFC examples. It's not a formal definition though, the NFC tag is meant for people going over commit headlines in the future, conveying that "this commit does not make meaningful changes in what the code does" -- and the semantics of "meaningful" can change even within the same codebase :)

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@bob-carpenter bob-carpenter bob-carpenter approved these changes

Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

Successfully merging this pull request may close these issues.
3 participants
@kedartal @stan-buildbot @bob-carpenter