[ObjC][GenDecl] Emit ObjC properties in __objc_methname section #84236
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Thanks for the accept @rjmccall. Could you land for me? I don't have access. |
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@swift-ci Please test |
This was referenced Sep 15, 2025
ellishg
added a commit
to llvm/llvm-project
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this pull request
Sep 22, 2025
Add the `--{no-}separate-cstring-literal-sections` option to emit
cstring literals into sections defined by their section name. This
allows for changes like swiftlang/swift#84300
and swiftlang/swift#84236 to actually have an
affect. The default behavior has not changed.
The reason this is useful is because strings in different sections might
have different access patterns at runtime. By splitting these strings
into separate sections, we may reduce the number of page faults during
startup. For example, the ObjC runtime accesses all strings in
`__objc_classname` before main.
llvm-sync bot
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Sep 22, 2025
…8720)
Add the `--{no-}separate-cstring-literal-sections` option to emit
cstring literals into sections defined by their section name. This
allows for changes like swiftlang/swift#84300
and swiftlang/swift#84236 to actually have an
affect. The default behavior has not changed.
The reason this is useful is because strings in different sections might
have different access patterns at runtime. By splitting these strings
into separate sections, we may reduce the number of page faults during
startup. For example, the ObjC runtime accesses all strings in
`__objc_classname` before main.
SeongjaeP
pushed a commit
to SeongjaeP/llvm-project
that referenced
this pull request
Sep 23, 2025
Add the `--{no-}separate-cstring-literal-sections` option to emit
cstring literals into sections defined by their section name. This
allows for changes like swiftlang/swift#84300
and swiftlang/swift#84236 to actually have an
affect. The default behavior has not changed.
The reason this is useful is because strings in different sections might
have different access patterns at runtime. By splitting these strings
into separate sections, we may reduce the number of page faults during
startup. For example, the ObjC runtime accesses all strings in
`__objc_classname` before main.
YixingZhang007
pushed a commit
to YixingZhang007/llvm-project
that referenced
this pull request
Sep 27, 2025
Add the `--{no-}separate-cstring-literal-sections` option to emit
cstring literals into sections defined by their section name. This
allows for changes like swiftlang/swift#84300
and swiftlang/swift#84236 to actually have an
affect. The default behavior has not changed.
The reason this is useful is because strings in different sections might
have different access patterns at runtime. By splitting these strings
into separate sections, we may reduce the number of page faults during
startup. For example, the ObjC runtime accesses all strings in
`__objc_classname` before main.
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Clang emits ObjC properties in the
__TEXT__objc_methnamesection.https://github.com/llvm/llvm-project/blob/d5e7c27d53887e6ae490d8e26193a54987728458/clang/lib/CodeGen/CGObjCMac.cpp#L4056-L4072
This change was made in llvm/llvm-project@75af694 to allow property names to be deduplicated with their method names.
This could also improve page faults during startup due to better grouping of types of strings to their specific sections. Basically, it moves method names out of the
__cstringsection so strings are more compact and thus more efficient with respect to memory pages.