[ObjWriter] Emit the MH_SUBSECTIONS_VIA_SYMBOLS header flag for Mach-O #471
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Thank you for looking into this. |
We can give it another try... this may not be the full solution but it may help enough to make a difference. I am mainly submitting this as a fix for the Xcode 15 crashes. |
steveisok
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Sep 22, 2023
lambdageek
approved these changes
Sep 22, 2023
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bot doesn't work here. i'll open backport PRs by hand |
carlossanlop
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Sep 22, 2023
#471) (#472) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk. Co-authored-by: Filip Navara <filip.navara@gmail.com>
radekdoulik
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May 9, 2024
dotnet#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
akoeplinger
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May 17, 2024
#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
radekdoulik
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Aug 16, 2024
#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
radekdoulik
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Sep 2, 2024
#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
radekdoulik
pushed a commit
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Sep 12, 2024
#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
radekdoulik
pushed a commit
that referenced
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Sep 19, 2024
#471) The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how `-ffunction-sections` behaves on ELF. Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches. Old ld64 linker tends to run into deep stack loop without this switch if `-dead_strip` is used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.
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The flag tells the linker that there are no functions with overlapping code and thus the code sections can be divided into subsections based on the symbols. This is similar in effect to how
-ffunction-sectionsbehaves on ELF.Notably, this enables optimization such as dead code stripping and identical code folding, if requested through linker switches.
Old ld64 linker tends to run into deep stack loop without this switch if
-dead_stripis used (encountered in Xamarin, not used by regular NativeAOT), and often ends up stack overflowing. New Xcode 15+ linker completely fails to produce correct unwind tables without this flag, which results in the NativeAOT executables crashing during GC or on first stack walk.