This is a resubmittal of an earlier patch
(https://gcc.gnu.org/ml/gcc-patches/2017-02/msg00203.html) to improve the
use of ccmp (conditional compare) on aarch64.  I made a couple of tweaks
after the first submittal and retested now that we are back in stage 1.

Most of the changes are restructuring the code to allow the change and do
not affect the actual output.  The actual behavour change is in
ccmp_tree_comparison_p where we recoginize a boolean variable as well
as a compare expression as code that can be done with a conditionial
compare and in get_compare_parts where we treat a boolean variable X
as 'X != 0' and generate that comparision.

Since the code in ccmp.c is ony used when TARGET_GEN_CCMP_FIRST is set
and TARGET_GEN_CCMP_FIRST is only set for aarch64 this change will only
affect aarch64.

Tested with no regressions and a new test is added to verify that we
generate a ccmp instruction with the change.  I ran the SPEC2006 int
tests and got a .02 increase in the SPECmark on a ThunderX box. The
biggest increases were in mcf and astar.  One test, xlancbmk, did slow
down but the overall SPEC result was a speedup.

OK for checkin?

Steve Ellcey
sellcey@cavium.com


GCC ChangeLog:

2017-05-01  Steve Ellcey  <sellcey@cavium.com>

	* ccmp.c (ccmp_tree_comparison_p): New function.
	(ccmp_candidate_p): Update to use above function.
	(get_compare_parts): New function.
	(expand_ccmp_next): Update to use new functions.
	(expand_ccmp_expr_1): Take tree arg instead of gimple, update to use
	new functions.
	(expand_ccmp_expr): Pass tree instead of gimple to expand_ccmp_expr_1,
	take mode as argument.
	* ccmp.h (expand_ccmp_expr): Add mode as argument.
	* expr.c (expand_expr_real_1): Pass mode as argument.

GCC Testsuite ChangeLog:


2017-05-01  Steve Ellcey  <sellcey@cavium.com>

	* gcc.target/aarch64/ccmp_2.c: New test.