> I think you are asking for per-function constant pool sections. Because > we generally cannot avoid the need of a constant pool and dependent > on the target that is always global. Note with per-function constant > pools you will not benefit from constant pool entry merging across > functions. I'm also not aware of any non-target-specific (and thus not > implemented on some targets) option to get these.
Thanks, yeah, that sounds like what I need. Is there any way to get that behavior today, even for a specific target? (I'm mostly interested in x86_64, armv7 and aarch64.) And are you saying that there are some targets for which it would be impossible to provide this behavior? Or just that it's not implemented for all targets today? Are constant pool entries merged at compile time or at link time? I would presume it should be done at link time because otherwise you're only merging entries within a single compilation unit (which doesn't sound that useful in a big project with hundreds of source files), right? So if they're merged at link time, shouldn't it be possible to do that merging after a linker script condensed all the per-function input sections that are left after --gc-sections back into a single big .rodata output section? (In my case, the linker script would instead condense all the constant pool sections for marked functions into .special_area.rodata and all the others into .rodata, and then it should be merging internally within those two output sections.) > Does it work better if you make this "static const"? Yes, then I can declare an __attribute__((section)) for that specific variable. However, that doesn't really seem like a safe and scalable approach, especially since it's hard to notice when you missed a variable. I'd like to have a way that I can annotate a function and that whole function (with everything it needs, except for globals) gets put into a special section (or a set of special sections with a common prefix or suffix), without having to rewrite the source to accommodate for this every time.
