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Faster appveyor#8

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dra27 merged 65 commits intotrunkfrom
faster-appveyor
Apr 20, 2020
Merged

Faster appveyor#8
dra27 merged 65 commits intotrunkfrom
faster-appveyor

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@dra27 dra27 commented Apr 17, 2020

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@dra27 dra27 force-pushed the faster-appveyor branch 2 times, most recently from 3df3733 to a6b4e78 Compare April 17, 2020 08:45
dra27 and others added 4 commits April 17, 2020 10:16
Correct implementation of --disable-stdlib-manpages
This commit removes an assert false and makes the missing
cmi case behaves like the abstract case.
@dra27 dra27 force-pushed the faster-appveyor branch 2 times, most recently from 761462b to 61fdca2 Compare April 17, 2020 10:14
@dra27 dra27 force-pushed the faster-appveyor branch from 61fdca2 to eaa2a01 Compare April 17, 2020 10:34
dra27 and others added 2 commits April 17, 2020 12:15
…s_error

packed modtype lookup can fail due to missing cmi
trefis and others added 27 commits April 18, 2020 11:01
This was useful when commuting optional arguments was allowed with
`ignore_labels = true`. Which it isn't anymore.
…390x (ocaml#9456)

Alpine Linux and perhaps other musl-based Linux distributions produce
position-independent executables (PIEs) by default.  If non-PIC object
files are given to the linker, it silently produces a wrong executable
that crashes when run.  This is the case for ocamlopt-generated code,
which by default is not PIC except on amd64 (x86_64) and s390x (Z systems).

Closes: ocaml#7562
forbid optional arguments reordering with -nolabels
@dra27 dra27 merged commit 7e53562 into trunk Apr 20, 2020
@dra27 dra27 deleted the faster-appveyor branch July 6, 2021 13:52
dra27 pushed a commit that referenced this pull request Jul 29, 2024
…l#13294)

The toplevel printer detects cycles by keeping a hashtable of values
that it has already traversed.

However, some OCaml runtime types (at least bigarrays) may be
partially uninitialized, and hashing them at arbitrary program points
may read uninitialized memory. In particular, the OCaml testsuite
fails when running with a memory-sanitizer enabled, as bigarray
printing results in reads to uninitialized memory:

```
==133712==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x4e6d11 in caml_ba_hash /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45
    #1 0x52474a in caml_hash /var/home/edwin/git/ocaml/runtime/hash.c:251:35
    #2 0x599ebf in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1065:14
    #3 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9
    #4 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3
    #5 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef)
    #6 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef)
    #7 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37)

  Uninitialized value was created by a heap allocation
    #0 0x47d306 in malloc (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x47d306) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37)
    #1 0x4e7960 in caml_ba_alloc /var/home/edwin/git/ocaml/runtime/bigarray.c:246:12
    #2 0x4e801f in caml_ba_create /var/home/edwin/git/ocaml/runtime/bigarray.c:673:10
    #3 0x59b8fc in caml_interprete /var/home/edwin/git/ocaml/runtime/interp.c:1058:14
    #4 0x5a909a in caml_main /var/home/edwin/git/ocaml/runtime/startup_byt.c:575:9
    #5 0x540ccb in main /var/home/edwin/git/ocaml/runtime/main.c:37:3
    #6 0x7f0910abb087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef)
    #7 0x7f0910abb14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: 8f53abaad945a669f2bdcd25f471d80e077568ef)
    #8 0x441804 in _start (/var/home/edwin/git/ocaml/runtime/ocamlrun+0x441804) (BuildId: 7a60eef57e1c2baf770bc38d10d6c227e60ead37)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /var/home/edwin/git/ocaml/runtime/bigarray.c:486:45 in caml_ba_hash
```

The only use of hashing in genprintval is to avoid cycles, that is, it
is only useful for OCaml values that contain other OCaml values
(including possibly themselves). Bigarrays cannot introduce cycles,
and they are always printed as "<abstr>" anyway.

The present commit proposes to be more conservative in which values
are hashed by the cycle detector to avoid this issue: we skip hashing
any value with tag above No_scan_tag -- which may not contain any
OCaml values.

Suggested-by: Gabriel Scherer <gabriel.scherer@gmail.com>

Signed-off-by: Edwin Török <edwin.torok@cloud.com>
Co-authored-by: Edwin Török <edwin.torok@cloud.com>
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8 participants