Hi,
After fixing PR79347, the main problem with vectorizer is we scale down profiling counters
for vect_loop by VF, regardless of context CFG's profiling information.  This is wrong and
sometimes makes vect_loop not hot code, which may confuses following optimizers.  This
patch generates well-formed profiling information as generic tree unroller does.  It borrows
code from tree-ssa-loop-manip.c and does small refactors to existing code.  Vectorizer will
not introduce mismatch counters with it, and unroll and vrp2 are the two major passes
messing up profiling counters now.  Though it removes all mismatch in vectorizer, I am not
sure if this counts as a regression fix.
BTW, it may also help PR78116?  Hi Pat, could you please help verify this?  Thanks!

Bootstrap and test on x86_64 and AArch64 ongoing.  Is it OK if no failures?

Thanks,
bin

2017-02-16  Bin Cheng  <bin.cheng@arm.com>

	PR tree-optimization/77536
	* tree-ssa-loop-manip.c (niter_for_unrolled_loop): New function.
	(tree_transform_and_unroll_loop): Use above function to compute the
	estimated niter of unrolled loop.
	* tree-ssa-loop-manip.h niter_for_unrolled_loop(): New declaration.
	* tree-vect-loop.c (scale_profile_for_vect_loop): New function.
	(vect_transform_loop): Call above function.

gcc/testsuite/ChangeLog
2017-02-16  Bin Cheng  <bin.cheng@arm.com>

	PR tree-optimization/77536
	* gcc.dg/vect/pr79347.c: Revise testing string.