This patch makes fold-const.c operate directly on the VECTOR_CST
encoding when folding an operation that has a single VECTOR_CST input.
2017-12-07 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
* fold-const.c (fold_negate_expr_1): Use tree_vector_builder and
new_unary_operation, operating only on the encoded elements.
(const_unop): Likewise.
(exact_inverse): Likewise.
(distributes_over_addition_p): New function.
(const_binop): Use tree_vector_builder and new_unary_operation
for combinations of VECTOR_CST and INTEGER_CST. Operate only
on the encoded elements unless the encoding is strided and the
operation does not distribute over addition.
(fold_convert_const): Use tree_vector_builder and
new_unary_operation. Operate only on the encoded elements
for truncating integer conversions, or for non-stepped encodings.
From-SVN: r255476
