[Bug target/82259] missed optimization: use LEA to add 1 to flip the low bit when copying before AND with 1

peter at cordes dot ca gcc-bugzilla@gcc.gnu.org
Tue Sep 19 16:29:00 GMT 2017


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82259

--- Comment #1 from Peter Cordes <peter at cordes dot ca> ---
More generally, you can flip a higher bit while copying with

    lea  64(%rdi), %eax

That leaves the bits above that position munged by carry-out, but that isn't
always a problem.


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