9beb467d92
Moved `Contents` and `Fixups` SmallVector storage to MCSection, enabling trivial destructors for most fragment subclasses and eliminating the need for MCFragment::destroy in ~MCSection. For appending content to the current section, use getContentsForAppending. During assembler relaxation, prefer setContents/setFixups, which may involve copying and reduce the benefits of https://reviews.llvm.org/D145791. Moving only Contents out-of-line caused a slight performance regression (Alexis Engelke's 2024 prototype). By also moving Fragments out-of-line, fragment destructors become trivial, resulting in neglgible instructions:u increase for "stage2-O0-g" and [large max-rss decrease](https://llvm-compile-time-tracker.com/compare.php?from=84e82746c3ff63ec23a8b85e9efd4f7fccf92590&to=555a28c0b2f8250a9cf86fd267a04b0460283e15&stat=max-rss&linkStats=on) for the "stage1-ReleaseLTO-g (link only)" benchmark. ( An older version using fewer inline functions: https://llvm-compile-time-tracker.com/compare.php?from=bb982e733cfcda7e4cfb0583544f68af65211ed1&to=f12d55f97c47717d438951ecddecf8ebd28c296b&linkStats=on ) Now using plain SmallVector in MCSection for storage, with potential for future allocator optimizations, such as allocating `Contents` as the trailing object of MCDataFragment. (GNU Assembler uses gnulib's obstack for fragment management.) Co-authored-by: Alexis Engelke <engelke@in.tum.de> Pull Request: https://github.com/llvm/llvm-project/pull/146307
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