tree-optimization/67196 - normalize use predicates earlier
The following makes sure to have use predicates simplified and
normalized before doing uninit_analysis::overlap because that
otherwise cannot pick up all flag setting cases. This fixes
half of the issue in PR67196 and conveniently resolves the
XFAIL in gcc.dg/uninit-pred-7_a.c.
PR tree-optimization/67196
* gimple-predicate-analysis.cc (uninit_analysis::is_use_guarded):
Simplify and normalize use prediates before first use.
* gcc.dg/uninit-pred-7_a.c: Un-XFAIL.