r256098 - in /trunk/gcc: ChangeLog fold-const.c...

[rsandifo@gcc.gnu.org]

Author: rsandifo
Date: Tue Jan  2 18:27:15 2018
New Revision: 256098

URL: https://gcc.gnu.org/viewcvs?rev=256098&root=gcc&view=rev
Log:
Rework VEC_PERM_EXPR folding

This patch reworks the VEC_PERM_EXPR folding so that more of it
works for variable-length vectors.  E.g. it means that we can
now recognise variable-length permutes that reduce to a single
vector, or cases in which a variable-length permute only needs
one input.  There should be no functional change for fixed-length
vectors.

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

gcc/
	* selftest.h (selftest::vec_perm_indices_c_tests): Declare.
	* selftest-run-tests.c (selftest::run_tests): Call it.
	* vector-builder.h (vector_builder::operator ==): New function.
	(vector_builder::operator !=): Likewise.
	* vec-perm-indices.h (vec_perm_indices::series_p): Declare.
	(vec_perm_indices::all_from_input_p): New function.
	* vec-perm-indices.c (vec_perm_indices::series_p): Likewise.
	(test_vec_perm_12, selftest::vec_perm_indices_c_tests): Likewise.
	* fold-const.c (fold_ternary_loc): Use tree_to_vec_perm_builder
	instead of reading the VECTOR_CST directly.  Detect whether both
	vector inputs are the same before constructing the vec_perm_indices,
	and update the number of inputs argument accordingly.  Use the
	utility functions added above.  Only construct sel2 if we need to.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/fold-const.c
    trunk/gcc/selftest-run-tests.c
    trunk/gcc/selftest.h
    trunk/gcc/vec-perm-indices.c
    trunk/gcc/vec-perm-indices.h
    trunk/gcc/vector-builder.h