On Sat, Nov 05, 2016 at 12:15:25AM +0100, Ludovic Courtès wrote: > I’ve fiddled a bit with GCC and read some code. No success yet, but > here’s a status update.
Thanks for writing this out! > Instead, the knobs we have are (1) global flag to enable/disable each > built-in function (like -fno-builtin-… does), and (2) an x86-specific > knob to determine whether to use ‘movabs’ or not (‘-mmemcpy-strategy’ > supposedly controls that, but ‘-mmemcpy-strategy=libcall:-1:noalign’ > doesn’t seem to have any effect for instance.) Please correct me if I paraphrase the choices incorrectly: (1) Completely disable the strcpy optimization for all architectures (2) Ostensibly change how strcpy is optimized on x86, except the knob seems to have no effect > These knobs are not great because that would lead us to disable the > optimization wholesale, which is not desirable. What are the costs of (1)? Should we report (2) upstream?
