Add support for conditional shifts

Add support for conditional shifts

This patch adds support for IFN_COND shifts left and shifts right.
This is mostly mechanical, but since we try to handle conditional
operations in the same way as unconditional operations in match.pd,
we need to support IFN_COND shifts by scalars as well as vectors.
E.g.:

   IFN_COND_SHL (cond, a, { 1, 1, ... }, fallback)

and:

   IFN_COND_SHL (cond, a, 1, fallback)

are the same operation, with:

   (for shiftrotate (lrotate rrotate lshift rshift)
    ...
    /* Prefer vector1 << scalar to vector1 << vector2
       if vector2 is uniform.  */
    (for vec (VECTOR_CST CONSTRUCTOR)
     (simplify
      (shiftrotate @0 vec@1)
      (with { tree tem = uniform_vector_p (@1); }
       (if (tem)
	(shiftrotate @0 { tem; }))))))

preferring the latter.  The patch copes with this by extending
create_convert_operand_from to handle scalar-to-vector conversions.

2019-08-15  Richard Sandiford  <richard.sandiford@arm.com>
	    Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>

gcc/
	* internal-fn.def (IFN_COND_SHL, IFN_COND_SHR): New internal functions.
	* internal-fn.c (FOR_EACH_CODE_MAPPING): Handle shifts.
	* match.pd (UNCOND_BINARY, COND_BINARY): Likewise.
	* optabs.def (cond_ashl_optab, cond_ashr_optab, cond_lshr_optab): New
	optabs.
	* optabs.h (create_convert_operand_from): Expand comment.
	* optabs.c (maybe_legitimize_operand): Allow implicit broadcasts
	when mapping scalar rtxes to vector operands.
	* config/aarch64/iterators.md (SVE_INT_BINARY): Add ashift,
	ashiftrt and lshiftrt.
	(sve_int_op, sve_int_op_rev, sve_pred_int_rhs2_operand): Handle them.
	* config/aarch64/aarch64-sve.md (*cond_<optab><mode>_2_const)
	(*cond_<optab><mode>_any_const): New patterns.

gcc/testsuite/
	* gcc.target/aarch64/sve/cond_shift_1.c: New test.
	* gcc.target/aarch64/sve/cond_shift_1_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_2.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_2_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_3.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_3_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_4.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_4_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_5.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_5_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_6.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_6_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_7.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_7_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_8.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_8_run.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_9.c: Likewise.
	* gcc.target/aarch64/sve/cond_shift_9_run.c: Likewise.

Co-Authored-By: Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org>
From-SVN: r274505