https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79173
--- Comment #15 from Paweł Bylica <chfast at gmail dot com> --- For what it's worth, clang's __builtin_addc is implemented in frontend only as a pair of __builtin_add_overflow. The commit from 11 year ago does not explain why they were added. https://github.com/llvm/llvm-project/commit/54398015bf8cbdc3af54dda74807d6f3c8436164 Producing a chain of ADC instructions out of __builtin_add_overflow patterns has been done quite recently (~1 year ago). And this work is not fully finished yet. On the other hand, Go recently added "addc" like "builtins" in https://pkg.go.dev/math/bits. And they are really pleasure to use in multi-precision arithmetic.
