This patch adds support for vectorising SLP definitions that are
constant or external (i.e. from outside the loop) when the vectorisation
factor isn't known at compile time.  It can only handle cases where the
number of SLP statements is a power of 2.

2018-01-13  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-vect-slp.c: Include gimple-fold.h and internal-fn.h
	(can_duplicate_and_interleave_p): New function.
	(vect_get_and_check_slp_defs): Take the vector of statements
	rather than just the current one.  Remove excess parentheses.
	Restriction rejectinon of vect_constant_def and vect_external_def
	for variable-length vectors to boolean types, or types for which
	can_duplicate_and_interleave_p is false.
	(vect_build_slp_tree_2): Update call to vect_get_and_check_slp_defs.
	(duplicate_and_interleave): New function.
	(vect_get_constant_vectors): Use gimple_build_vector for
	constant-length vectors and suitable variable-length constant
	vectors.  Use duplicate_and_interleave for other variable-length
	vectors.  Don't defer the update when inserting new statements.

gcc/testsuite/
	* gcc.dg/vect/no-scevccp-slp-30.c: Don't XFAIL for vect_variable_length
	&& vect_load_lanes
	* gcc.dg/vect/slp-1.c: Likewise.
	* gcc.dg/vect/slp-10.c: Likewise.
	* gcc.dg/vect/slp-12b.c: Likewise.
	* gcc.dg/vect/slp-12c.c: Likewise.
	* gcc.dg/vect/slp-17.c: Likewise.
	* gcc.dg/vect/slp-19b.c: Likewise.
	* gcc.dg/vect/slp-20.c: Likewise.
	* gcc.dg/vect/slp-21.c: Likewise.
	* gcc.dg/vect/slp-22.c: Likewise.
	* gcc.dg/vect/slp-23.c: Likewise.
	* gcc.dg/vect/slp-24-big-array.c: Likewise.
	* gcc.dg/vect/slp-24.c: Likewise.
	* gcc.dg/vect/slp-28.c: Likewise.
	* gcc.dg/vect/slp-39.c: Likewise.
	* gcc.dg/vect/slp-6.c: Likewise.
	* gcc.dg/vect/slp-7.c: Likewise.
	* gcc.dg/vect/slp-cond-1.c: Likewise.
	* gcc.dg/vect/slp-cond-2-big-array.c: Likewise.
	* gcc.dg/vect/slp-cond-2.c: Likewise.
	* gcc.dg/vect/slp-multitypes-1.c: Likewise.
	* gcc.dg/vect/slp-multitypes-8.c: Likewise.
	* gcc.dg/vect/slp-multitypes-9.c: Likewise.
	* gcc.dg/vect/slp-multitypes-10.c: Likewise.
	* gcc.dg/vect/slp-multitypes-12.c: Likewise.
	* gcc.dg/vect/slp-perm-6.c: Likewise.
	* gcc.dg/vect/slp-widen-mult-half.c: Likewise.
	* gcc.dg/vect/vect-live-slp-1.c: Likewise.
	* gcc.dg/vect/vect-live-slp-2.c: Likewise.
	* gcc.dg/vect/pr33953.c: Don't XFAIL for vect_variable_length.
	* gcc.dg/vect/slp-12a.c: Likewise.
	* gcc.dg/vect/slp-14.c: Likewise.
	* gcc.dg/vect/slp-15.c: Likewise.
	* gcc.dg/vect/slp-multitypes-2.c: Likewise.
	* gcc.dg/vect/slp-multitypes-4.c: Likewise.
	* gcc.dg/vect/slp-multitypes-5.c: Likewise.
	* gcc.target/aarch64/sve/slp_1.c: New test.
	* gcc.target/aarch64/sve/slp_1_run.c: Likewise.
	* gcc.target/aarch64/sve/slp_2.c: Likewise.
	* gcc.target/aarch64/sve/slp_2_run.c: Likewise.
	* gcc.target/aarch64/sve/slp_3.c: Likewise.
	* gcc.target/aarch64/sve/slp_3_run.c: Likewise.
	* gcc.target/aarch64/sve/slp_4.c: Likewise.
	* gcc.target/aarch64/sve/slp_4_run.c: Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r256622