isel: Move duplicate comparisons to its own function

isel: Move duplicate comparisons to its own function

This is just a small cleanup to isel and no functional changes just.
The loop inside pass_gimple_isel::execute looked was getting too
deap so let's fix that by moving it to its own function.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	* gimple-isel.cc (pass_gimple_isel::execute): Factor out
	duplicate comparisons out to ...
	(duplicate_comparison): New function.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>