PR tree-optimization/78005
	* tree-vect-loop-manip.c (vect_gen_prolog_loop_niters): Compute
	upper (included) bound for niters of prolog loop.
	(vect_gen_scalar_loop_niters): Change parameter VF to VFM1.
	Compute niters of scalar loop above which vectorized loop is
	preferred, as well as the upper (included) bound for the niters.
	(vect_do_peeling): Record niter bound for loops accordingly.

	gcc/testsuite
	PR tree-optimization/78005
	* gcc.dg/vect/pr78005.c: New.
	* gcc.target/i386/l_fma_float_1.c: Revise test.
	* gcc.target/i386/l_fma_float_2.c: Ditto.
	* gcc.target/i386/l_fma_float_3.c: Ditto.
	* gcc.target/i386/l_fma_float_4.c: Ditto.
	* gcc.target/i386/l_fma_float_5.c: Ditto.
	* gcc.target/i386/l_fma_float_6.c: Ditto.
	* gcc.target/i386/l_fma_double_1.c: Ditto.
	* gcc.target/i386/l_fma_double_2.c: Ditto.
	* gcc.target/i386/l_fma_double_3.c: Ditto.
	* gcc.target/i386/l_fma_double_4.c: Ditto.
	* gcc.target/i386/l_fma_double_5.c: Ditto.
	* gcc.target/i386/l_fma_double_6.c: Ditto.

From-SVN: r241339