| You wouldn’t have to say it. Linkers could figure it out on their own (but compilers dropping hints would make it easier) Some linkers already can merge functions that happen to compile to the same code, even though that corrupts stack frames (foo calls bar, but the linker makes it call baz instead. https://stackoverflow.com/a/61865960) It’s ‘just’ a matter of learning the build system new tricks. I found a short discussion on this at https://gcc.gnu.org/legacy-ml/gcc/2000-02/msg00575.html that contains https://gcc.gnu.org/legacy-ml/gcc/2000-02/msg00599.html, which says “The P3 SSE stuff we've done generates multiple entry points,
but it does that within the backend prologue expander. There's nothing to generate multiple regular prologues. Though it shouldn't be that hard to do. It's not impossible to believe that the bulk of the compiler
would work with them, as long as flow knows how to properly
create the CFG. LABEL_ALTERNATE_NAME was invented for this,
though it appears that the code to properly deal with it is
sitting on a branch waiting for accounting to say it has been
paid for.“ That was in February 2000. I wouldn’t know whether that comment was close to the truth or what gcc currently supports. For llvm, the thread at https://lists.llvm.org/pipermail/llvm-dev/2018-October/12715... gives some cases where this could be used, but reading it, it doesn’t look it is solved in the way I gave (see for example https://lists.llvm.org/pipermail/llvm-dev/2018-October/12717.... https://lists.llvm.org/pipermail/llvm-dev/2018-October/12715... calls it “more like separate functions with a common tail.”, so I’m not alone in that. That thread also indicates that DWARF has support for helping debuggers figure out the correct name of such a function. |