Remove vec_perm_const optab

Remove vec_perm_const optab

One of the changes needed for variable-length VEC_PERM_EXPRs -- and for
long fixed-length VEC_PERM_EXPRs -- is the ability to use constant
selectors that wouldn't fit in the vectors being permuted.  E.g. a
permute on two V256QIs can't be done using a V256QI selector.

At the moment constant permutes use two interfaces:
targetm.vectorizer.vec_perm_const_ok for testing whether a permute is
valid and the vec_perm_const optab for actually emitting the permute.
The former gets passed a vec<> selector and the latter an rtx selector.
Most ports share a lot of code between the hook and the optab, with a
wrapper function for each interface.

We could try to keep that interface and require ports to define wider
vector modes that could be attached to the CONST_VECTOR (e.g. V256HI or
V256SI in the example above).  But building a CONST_VECTOR rtx seems a bit
pointless here, since the expand code only creates the CONST_VECTOR in
order to call the optab, and the first thing the target does is take
the CONST_VECTOR apart again.

The easiest approach therefore seemed to be to remove the optab and
reuse the target hook to emit the code.  One potential drawback is that
it's no longer possible to use match_operand predicates to force
operands into the required form, but in practice all targets want
register operands anyway.

The patch also changes vec_perm_indices into a class that provides
some simple routines for handling permutations.  A later patch will
flesh this out and get rid of auto_vec_perm_indices, but I didn't
want to do all that in this patch and make it more complicated than
it already is.

2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* Makefile.in (OBJS): Add vec-perm-indices.o.
	* vec-perm-indices.h: New file.
	* vec-perm-indices.c: Likewise.
	* target.h (vec_perm_indices): Replace with a forward class
	declaration.
	(auto_vec_perm_indices): Move to vec-perm-indices.h.
	* optabs.h: Include vec-perm-indices.h.
	(expand_vec_perm): Delete.
	(selector_fits_mode_p, expand_vec_perm_var): Declare.
	(expand_vec_perm_const): Declare.
	* target.def (vec_perm_const_ok): Replace with...
	(vec_perm_const): ...this new hook.
	* doc/tm.texi.in (TARGET_VECTORIZE_VEC_PERM_CONST_OK): Replace with...
	(TARGET_VECTORIZE_VEC_PERM_CONST): ...this new hook.
	* doc/tm.texi: Regenerate.
	* optabs.def (vec_perm_const): Delete.
	* doc/md.texi (vec_perm_const): Likewise.
	(vec_perm): Refer to TARGET_VECTORIZE_VEC_PERM_CONST.
	* expr.c (expand_expr_real_2): Use expand_vec_perm_const rather than
	expand_vec_perm for constant permutation vectors.  Assert that
	the mode of variable permutation vectors is the integer equivalent
	of the mode that is being permuted.
	* optabs-query.h (selector_fits_mode_p): Declare.
	* optabs-query.c: Include vec-perm-indices.h.
	(selector_fits_mode_p): New function.
	(can_vec_perm_const_p): Check whether targetm.vectorize.vec_perm_const
	is defined, instead of checking whether the vec_perm_const_optab
	exists.  Use targetm.vectorize.vec_perm_const instead of
	targetm.vectorize.vec_perm_const_ok.  Check whether the indices
	fit in the vector mode before using a variable permute.
	* optabs.c (shift_amt_for_vec_perm_mask): Take a mode and a
	vec_perm_indices instead of an rtx.
	(expand_vec_perm): Replace with...
	(expand_vec_perm_const): ...this new function.  Take the selector
	as a vec_perm_indices rather than an rtx.  Also take the mode of
	the selector.  Update call to shift_amt_for_vec_perm_mask.
	Use targetm.vectorize.vec_perm_const instead of vec_perm_const_optab.
	Use vec_perm_indices::new_expanded_vector to expand the original
	selector into bytes.  Check whether the indices fit in the vector
	mode before using a variable permute.
	(expand_vec_perm_var): Make global.
	(expand_mult_highpart): Use expand_vec_perm_const.
	* fold-const.c: Includes vec-perm-indices.h.
	* tree-ssa-forwprop.c: Likewise.
	* tree-vect-data-refs.c: Likewise.
	* tree-vect-generic.c: Likewise.
	* tree-vect-loop.c: Likewise.
	* tree-vect-slp.c: Likewise.
	* tree-vect-stmts.c: Likewise.
	* config/aarch64/aarch64-protos.h (aarch64_expand_vec_perm_const):
	Delete.
	* config/aarch64/aarch64-simd.md (vec_perm_const<mode>): Delete.
	* config/aarch64/aarch64.c (aarch64_expand_vec_perm_const)
	(aarch64_vectorize_vec_perm_const_ok): Fuse into...
	(aarch64_vectorize_vec_perm_const): ...this new function.
	(TARGET_VECTORIZE_VEC_PERM_CONST_OK): Delete.
	(TARGET_VECTORIZE_VEC_PERM_CONST): Redefine.
	* config/arm/arm-protos.h (arm_expand_vec_perm_const): Delete.
	* config/arm/vec-common.md (vec_perm_const<mode>): Delete.
	* config/arm/arm.c (TARGET_VECTORIZE_VEC_PERM_CONST_OK): Delete.
	(TARGET_VECTORIZE_VEC_PERM_CONST): Redefine.
	(arm_expand_vec_perm_const, arm_vectorize_vec_perm_const_ok): Merge
	into...
	(arm_vectorize_vec_perm_const): ...this new function.  Explicitly
	check for NEON modes.
	* config/i386/i386-protos.h (ix86_expand_vec_perm_const): Delete.
	* config/i386/sse.md (VEC_PERM_CONST, vec_perm_const<mode>): Delete.
	* config/i386/i386.c (ix86_expand_vec_perm_const_1): Update comment.
	(ix86_expand_vec_perm_const, ix86_vectorize_vec_perm_const_ok): Merge
	into...
	(ix86_vectorize_vec_perm_const): ...this new function.  Incorporate
	the old VEC_PERM_CONST conditions.
	* config/ia64/ia64-protos.h (ia64_expand_vec_perm_const): Delete.
	* config/ia64/vect.md (vec_perm_const<mode>): Delete.
	* config/ia64/ia64.c (ia64_expand_vec_perm_const)
	(ia64_vectorize_vec_perm_const_ok): Merge into...
	(ia64_vectorize_vec_perm_const): ...this new function.
	* config/mips/loongson.md (vec_perm_const<mode>): Delete.
	* config/mips/mips-msa.md (vec_perm_const<mode>): Delete.
	* config/mips/mips-ps-3d.md (vec_perm_constv2sf): Delete.
	* config/mips/mips-protos.h (mips_expand_vec_perm_const): Delete.
	* config/mips/mips.c (mips_expand_vec_perm_const)
	(mips_vectorize_vec_perm_const_ok): Merge into...
	(mips_vectorize_vec_perm_const): ...this new function.
	* config/powerpcspe/altivec.md (vec_perm_constv16qi): Delete.
	* config/powerpcspe/paired.md (vec_perm_constv2sf): Delete.
	* config/powerpcspe/spe.md (vec_perm_constv2si): Delete.
	* config/powerpcspe/vsx.md (vec_perm_const<mode>): Delete.
	* config/powerpcspe/powerpcspe-protos.h (altivec_expand_vec_perm_const)
	(rs6000_expand_vec_perm_const): Delete.
	* config/powerpcspe/powerpcspe.c (TARGET_VECTORIZE_VEC_PERM_CONST_OK):
	Delete.
	(TARGET_VECTORIZE_VEC_PERM_CONST): Redefine.
	(altivec_expand_vec_perm_const_le): Take each operand individually.
	Operate on constant selectors rather than rtxes.
	(altivec_expand_vec_perm_const): Likewise.  Update call to
	altivec_expand_vec_perm_const_le.
	(rs6000_expand_vec_perm_const): Delete.
	(rs6000_vectorize_vec_perm_const_ok): Delete.
	(rs6000_vectorize_vec_perm_const): New function.
	(rs6000_do_expand_vec_perm): Take a vec_perm_builder instead of
	an element count and rtx array.
	(rs6000_expand_extract_even): Update call accordingly.
	(rs6000_expand_interleave): Likewise.
	* config/rs6000/altivec.md (vec_perm_constv16qi): Delete.
	* config/rs6000/paired.md (vec_perm_constv2sf): Delete.
	* config/rs6000/vsx.md (vec_perm_const<mode>): Delete.
	* config/rs6000/rs6000-protos.h (altivec_expand_vec_perm_const)
	(rs6000_expand_vec_perm_const): Delete.
	* config/rs6000/rs6000.c (TARGET_VECTORIZE_VEC_PERM_CONST_OK): Delete.
	(TARGET_VECTORIZE_VEC_PERM_CONST): Redefine.
	(altivec_expand_vec_perm_const_le): Take each operand individually.
	Operate on constant selectors rather than rtxes.
	(altivec_expand_vec_perm_const): Likewise.  Update call to
	altivec_expand_vec_perm_const_le.
	(rs6000_expand_vec_perm_const): Delete.
	(rs6000_vectorize_vec_perm_const_ok): Delete.
	(rs6000_vectorize_vec_perm_const): New function.  Remove stray
	reference to the SPE evmerge intructions.
	(rs6000_do_expand_vec_perm): Take a vec_perm_builder instead of
	an element count and rtx array.
	(rs6000_expand_extract_even): Update call accordingly.
	(rs6000_expand_interleave): Likewise.
	* config/sparc/sparc.md (vec_perm_constv8qi): Delete in favor of...
	* config/sparc/sparc.c (sparc_vectorize_vec_perm_const): ...this
	new function.
	(TARGET_VECTORIZE_VEC_PERM_CONST): Redefine.

From-SVN: r256093