[PATCH, PR61776] verify_flow_info failed: control flow in the middle of basic block with -fprofile-generate

[Wei Mi]

By the way, the resetting of const/pure flags loop is also executed
during profile-use， but if there is no instrumentation, the reset is
unnecessary. The flags are kept until pass_ipa_pure_const fixes them.
And because of non-instantaneous ssa update,  the fixes are reflected
on ssa only after ipa passes finish.

If it is agreed that this is a problem, I will address the
conservativeness in a separate patch.

Regards,
Wei.