Gimple range PHI analyzer and testcases

Gimple range PHI analyzer and testcases

Provide a PHI analyzer framework to provive better initial values for
PHI nodes which formk groups with initial values and single statements
which modify the PHI values in some predicatable way.

	PR tree-optimization/107822
	PR tree-optimization/107986
	gcc/
	* Makefile.in (OBJS): Add gimple-range-phi.o.
	* gimple-range-cache.h (ranger_cache::m_estimate): New
	phi_analyzer pointer member.
	* gimple-range-fold.cc (fold_using_range::range_of_phi): Use
	phi_analyzer if no loop info is available.
	* gimple-range-phi.cc: New file.
	* gimple-range-phi.h: New file.
	* tree-vrp.cc (execute_ranger_vrp): Utililze a phi_analyzer.

	gcc/testsuite/
	* gcc.dg/pr107822.c: New.
	* gcc.dg/pr107986-1.c: New.