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[compiler-rt][crt] make test case nontrivial in check_cxx_section_exists

Authored by jcai19 on Sep 16 2019, 10:52 AM.



.init_array gets optimized away when building with -O2 and as a result,
check_cxx_section_exists failed to pass -DCOMPILER_RT_HAS_INITFINI_ARRAY
when building crtbegin.o and crtend.o, which causes binaries linked with
them encounter segmentation fault. See for
details. This change prevents .init_array section to be optimized away
even with -O2 or higher optimization level.

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jcai19 created this revision.Sep 16 2019, 10:52 AM
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jcai19 added reviewers: echristo, MaskRay.
jcai19 added subscribers: manojgupta, llozano.

Could we make the function non-trivial e.g. __attribute__((constructor)) void f() { asm volatile ("nop"::); } to ensure that it's not optimized out even at -O2?

Can you declare a volatile variable and set that from f instead?

jcai19 updated this revision to Diff 220382.Sep 16 2019, 1:21 PM

Thanks for the comments. I have update my change accordinlgy.

jcai19 retitled this revision from [compiler-rt][crt] pass -O0 in check_cxx_section_exists to [compiler-rt][crt] make test case nontrivial in check_cxx_section_exists.Sep 16 2019, 1:22 PM
jcai19 edited the summary of this revision. (Show Details)
jcai19 updated this revision to Diff 220383.Sep 16 2019, 1:23 PM

Remove uncessary new line character.

Harbormaster completed remote builds in B38176: Diff 220383.
joerg accepted this revision.Sep 16 2019, 1:44 PM


This revision is now accepted and ready to land.Sep 16 2019, 1:44 PM
This revision was automatically updated to reflect the committed changes.