[FFmpeg-trac] #9399(avcodec:new): ld: warning: could not create compact unwind
FFmpeg
trac at avcodec.org
Mon Aug 30 02:10:52 EEST 2021
#9399: ld: warning: could not create compact unwind
-------------------------------------+-------------------------------------
Reporter: Daniel | Type: defect
Schürmann |
Status: new | Priority: normal
Component: avcodec | Version:
Keywords: dwarf stack | unspecified
size compact unwind | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
When trying to link ffmpeg statically with Mixxx on macOS, the Apple
linker is complaining:
{{{
2021-08-18T22:06:41.3473950Z ld: warning: could not create compact unwind
for _ff_cfhd_init_vlcs: stack subq instruction is too different from dwarf
stack size
2021-08-18T22:06:41.3475230Z ld: warning: could not create compact unwind
for _ff_rl_init_vlc: stack subq instruction is too different from dwarf
stack size
}}}
This happens with gcc and clang 12.0.0.12000032
The issue was original reported here:
https://github.com/microsoft/vcpkg/issues/19699
Only these two functions are reported. When I disable cfhd encoder and
decoder, one warning disappears.
I can also specify {{{ LDFLAGS="-Wl,-no_compact_unwind" }}} to make remove
this warning, but that will affect all functions.
Both functions locate big arrays on the stack, my guess it that these
arrays are too big for compact unwind.
What is the best option to lower the used stack?
Do you know what is the limit for unwinding, the dwarf stack size?
Thank you.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/9399>
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