Add gc tests

[jmid]

This PR adds initial tests of the Gc module - and in particular testing of Gc.compact.

Exercising Gc.counters already triggered a known issue locally, which has recently been fixed on trunk: ocaml/ocaml#13370 I therefore expect the parallel test to fail on 5.2.0 and earlier.

This can be extended (and improved) in many ways adding (big)arrays, Weak, Ephemeron, custom blocks, finalizers, and dynamic Gc_ctrl changes.

[jmid]

CI summary for ca8cf93:

• 11 5.2 workflows failed as expected due to the Gc test
  • 32bit 5.2 failed with a segfault
  • Bytecode aborted with Fatal error: allocation failure during minor GC
  • Cygwin 5.2 aborted with Fatal error: allocation failure during minor GC
  • FP 5.2 aborted with Fatal error: allocation failure during minor GC
  • Linux 5.2 aborted with Fatal error: allocation failure during minor GC
  • Linux 5.2 debug aborted with Fatal error: allocation failure during minor GC
  • MinGW 5.2 exited with code -1073741819
  • MinGW bytecode 5.2 exited with code -1073741819
  • macOS-ARM64 5.2 failed with a segfault
  • macOS-intel 5.2 got signal BUS
  • freebsd-amd64-5.2 failed with a segfault
• 3 Cygwin/MinGW trunk workflows failed with a version mismatch after the 5.3 branching
  • Cygwin trunk
  • MinGW bytecode trunk
  • MinGW trunk
• Linux trunk debug failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470

Out of 33 workflows 15 failed with 12 genuine issues and 3 ci-setup issues

[jmid]

I removed the stress test, as the positive parallel test is already stress testing.
I've also rebased based on #471 which should take care of the MinGW+Cygwin version mismatching.

I still expect the 5.2 workflows to trigger ocaml/ocaml#13370 (unsure whether the cmd should be disabled under 5.2 testing 🤔 )

[jmid]

CI summary for 9ef90b5:

• 7 5.2 workflows failed as expected due to the Gc test
  • 32bit 5.2 failed the parallel STM Gc test with Allocated_bytes : -7.47499188671e+196
  • Bytecode 5.2 aborted with Fatal error: allocation failure during minor GC
  • Cygwin 5.2 aborted with Fatal error: allocation failure during minor GC
  • FP 5.2 aborted with Fatal error: allocation failure during minor GC
  • MinGW 5.2 failed with Fatal error: allocation failure during minor GC
  • macOS-intel 5.2 failed with BUS error
  • linux-s390x-5.2 - aborted with Fatal error: allocation failure during minor GC
• 3 debug runtime runs failed with an assertion error:
  • Linux 5.2 debug aborted with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live
  • Linux 5.3 debug failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live
  • Linux trunk debug failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live

Out of 45 workflows 10 failed, all with genuine issues

[jmid]

CI summary for 6b2669b

• 10 5.2 workflows failed as expected due to the Gc test [ocaml5-issue] Gc.counters unsafe root registration #474
  • 32bit 5.2 failed STM Gc test parallel with a negative allocated_bytes
  • Cygwin 5.2 aborted with Fatal error: allocation failure during minor GC
  • FP 5.2 aborted with Fatal error: allocation failure during minor GC
  • Linux 5.2 debug aborted with Fatal error: allocation failure during minor GC
  • MinGW bytecode 5.2 failed with Fatal error: allocation failure during minor GC
  • macOS-ARM64 5.2 failed with signal BUS
  • macOS-intel 5.2 failed with signal BUS
  • linux-arm64-5.2 aborted with Fatal error: allocation failure during minor GC
  • linux-s390x-5.2 aborted with Fatal error: allocation failure during minor GC
  • freebsd-amd64-5.2 aborted with Fatal error: allocation failure during minor GC
• 2 debug runtime workflows failed with an assertion error [ocaml5-issue] Assertion failure on live words in GC test #470
  • Linux 5.3 debug failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live
  • Linux trunk debug failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live
• linux-ppc64le-5.2 found an unexpected STM Sys test parallel counterexample Unexpected STM Sys parallel test counterexample on s390x and ppc64le #466

Out of 45 workflows 13 failed with with 12 genuine issues and 1 false alarm

[jmid]

CI summary for e9c9a6a

• all 3 Linux debug runs aborted with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470
  • Linux 5.2 debug
  • Linux 5.3 debug
  • Linux trunk debug
• linux-s390x-5.2 failed STM Gc test parallel with a quick_stat output mismatch

Out of 45 workflows 4 failed with genuine issues

[jmid]

CI summary for 6c1252f

• 9 workflows failed due to minor_heap_size page size rounding
  • 32bit 5.2, 5.3, trunk
  • Cygwin 5.2, 5.3, trunk
  • macOS-ARM64 5.2, trunk
  • linux-ppc64le-5.2
• all 3 Linux debug runs aborted with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live` [ocaml5-issue] Assertion failure on live words in GC test #470
  • Linux 5.2, 5.3, trunk debug
• linux-s390x-5.2 timed out during STM Gc stress test parallel s390x timeouts on s390x-worker-01 #421
• macOS-ARM64 5.3 segfaulted in STM Gc stress test parallel [ocaml5-issue] Segfault or hang on macOS in STM Gc stress test parallel #480

Out of 45 workflows 14 failed with 13 genuine issues and 1 CI infrastructure issue.
The macOS-ARM64 5.3 crash is disturbing.
fd0a3fd should address the pagesize rounding... 🤞

[jmid]

CI summary for fd0a3fd:

• 3 Linux debug workflows failed with runtime/shared_heap.c; line 1392 ### Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470
  • Linux 5.2, 5.3, trunk debug
• 4 MSVC workflows failed to compile due to a header issue fatal error C1189: #error: "No Target Architecture"
  • MSVC 5.3, trunk
  • MSVC bytecode 5.3, trunk

Out of 45 workflows, 3 failed with a genuine error and 4 due to a buggy Windows header in the test-suite.
1ebdda4 should address that, leaving only genuine errors.

Note to self: Having removed v=0 in debug mode triggers v=63 and adds a bit of noise to the logs for the Gc test...

[jmid]

CI summary for 1ebdda4:

• 3 Linux debug workflows aborted STM Gc stress test parallel with Assertion failed: local->stats.pool_live_words == pool_stats.live
  • Linux 5.2, Linux 5.3, trunk debug
• macOS-ARM64 5.2 segfaulted in STM Gc stress test parallel [ocaml5-issue] Segfault or hang on macOS in STM Gc stress test parallel #480

Out of 45 workflows 4 failed - all with genuine issues

[jmid]

CI summary for e5b93d3

• 3 32bit workflows all segfaulted in STM implicit Gc stress test parallel or STM implicit Gc test parallel
  • 32bit 5.2, 5.3, trunk
• 3 Linux debug workflows aborted STM Gc stress test parallel with ### Assertion failed: local->stats.pool_live_words == pool_stats.live
  • 5.2, 5.3, trunk debug
  • In addition, Linux 5.2 debug also failed STM implicit Gc test parallel with a negative allocated_bytes result
• macOS-ARM64 trunk segfaulted in STM Gc stress test parallel

Out of 45 workflows 7 failed all with genuine errors

[jmid]

CI summary for 6a86f20

• 32bit 5.2 segfaulted in STM implicit Gc test parallel
• 32bit 5.3 segfaulted in STM implicit Gc stress test parallel
• 32bit trunk segfaulted in STM implicit Gc stress test parallel
• Bytecode 5.2 aborted STM implicit Gc test parallel with allocation failure during minor GC
• Bytecode 5.3 segfaulted in STM implicit Gc stress test parallel
• Bytecode trunk segfaulted in STM implicit Gc test parallel
• Linux 5.2 debug
  • aborted STM Gc stress test parallel with Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470 and
  • failed STM implicit Gc test parallel with a negative allocated_bytes result
• Linux 5.3 debug failed STM Gc stress test parallel with Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470
• Linux trunk debug failed STM Gc stress test parallel with Assertion failed: local->stats.pool_live_words == pool_stats.live [ocaml5-issue] Assertion failure on live words in GC test #470
• linux-s390x-5.2 timedout in Lin Bytes test with Thread s390x timeouts on s390x-worker-01 #421
• linux-ppc64le-5.2 found an unexpected counterexample in STM Sys test parallel Unexpected STM Sys parallel test counterexample on s390x and ppc64le #466

Out of 45 workflows, 11 failed with 9 genuine issues, 1 CI timeout, and 1 false alarm

[jmid]

I've just pushed to trigger a fresh run, now that #13553 has been merged to trunk and cherry-picked to 5.3.

In other news, I've investigated the previously observed FreeBSD 5.2 crash.
This was easy to reproduce, but turned out to be a known one, namely db586e0b27 - Merge pull request #13370 from DemiMarie/fix-missing-gc-rule

[jmid]

CI summary for 4a93462:

• Linux 5.2 debug failed with an assertion error [ocaml5-issue] Assertion failure on live words in GC test #470
• Linux 5.3 debug failed with an assertion error [ocaml5-issue] Assertion failure on live words in GC test #470
• Linux trunk debug failed with an assertion error [ocaml5-issue] Assertion failure on live words in GC test #470
• macOS-intel 5.2 crashed in STM Gc stress test parallel [ocaml5-issue] Segfault or hang on macOS in STM Gc stress test parallel #480

Out of 41 workflows, 4 failed - all with genuine issues 🎉

(For some reason, the force push didn't trigger multicoretests-ci's four 5.2.0 workflows)