Make GCC move instructions between a multi-cycle instruction and the next instruction that depends on its result.

[Segher Boessenkool]

On Tue, Feb 22, 2022 at 03:15:55PM -0600, William Tambe via Gcc-help wrote:
[snip]
> > Without above transformation, `add %4 %7` would cause the cpu to wait
> > on `div %4 %5` when it could have executed instructions that do not
> > depend on the result of "div".
> 
> How to implement above transformation such that GCC moves instructions
> between a multi-cycle instruction and the next instruction that
> depends on its result ?

GCC has a pretty advanced instruction scheduler.  You can start looking
at <https://gcc.gnu.org/onlinedocs/gccint/Scheduling.html> for example?


Segher