[2/3] [vect] Add widening add, subtract patterns

Add widening add, subtract patterns to tree-vect-patterns. Update the
widened code of patterns that detect PLUS_EXPR to also detect
WIDEN_PLUS_EXPR. These patterns take 2 vectors with N elements of size
S and perform an add/subtract on the elements, storing the results as N
elements of size 2*S (in 2 result vectors). This is implemented in the
aarch64 backend as addl,addl2 and subl,subl2 respectively. Add aarch64
tests for patterns.

gcc/ChangeLog:
	* doc/generic.texi: Document new widen_plus/minus_lo/hi tree codes.
	* doc/md.texi: Document new widenening add/subtract hi/lo optabs.
	* expr.c (expand_expr_real_2): Add widen_add, widen_subtract cases.
	* optabs-tree.c (optab_for_tree_code): Add case for widening optabs.
	* optabs.def (OPTAB_D): Define vectorized widen add, subtracts.
	* tree-cfg.c (verify_gimple_assign_binary): Add case for widening adds,
	subtracts.
	* tree-inline.c (estimate_operator_cost): Add case for widening adds,
	subtracts.
	* tree-vect-generic.c (expand_vector_operations_1): Add case for
	widening adds, subtracts
	* tree-vect-patterns.c (vect_recog_widen_add_pattern): New recog
	pattern.
	(vect_recog_widen_sub_pattern): New recog pattern.
	(vect_recog_average_pattern): Update widened add code.
	(vect_recog_average_pattern): Update widened add code.
	* tree-vect-stmts.c (vectorizable_conversion): Add case for widened add,
	subtract.
	(supportable_widening_operation): Add case for widened add, subtract.
	* tree.def
	(WIDEN_PLUS_EXPR): New tree code.
	(WIDEN_MINUS_EXPR): New tree code.
	(VEC_WIDEN_ADD_HI_EXPR): New tree code.
	(VEC_WIDEN_PLUS_LO_EXPR): New tree code.
	(VEC_WIDEN_MINUS_HI_EXPR): New tree code.
	(VEC_WIDEN_MINUS_LO_EXPR): New tree code.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/vect-widen-add.c: New test.
	* gcc.target/aarch64/vect-widen-sub.c: New test.

1 files changed, 31 insertions, 0 deletions

diff --git a/gcc/doc/generic.texi b/gcc/doc/generic.texi
index 5c1d3cd..9791f8b 100644
--- a/gcc/doc/generic.texi
+++ b/gcc/doc/generic.texi
@@ -1798,6 +1798,10 @@ a value from @code{enum annot_expr_kind}, the third is an @code{INTEGER_CST}.
 @tindex VEC_RSHIFT_EXPR
 @tindex VEC_WIDEN_MULT_HI_EXPR
 @tindex VEC_WIDEN_MULT_LO_EXPR
+@tindex VEC_WIDEN_PLUS_HI_EXPR
+@tindex VEC_WIDEN_PLUS_LO_EXPR
+@tindex VEC_WIDEN_MINUS_HI_EXPR
+@tindex VEC_WIDEN_MINUS_LO_EXPR
 @tindex VEC_UNPACK_HI_EXPR
 @tindex VEC_UNPACK_LO_EXPR
 @tindex VEC_UNPACK_FLOAT_HI_EXPR
@@ -1844,6 +1848,33 @@ vector of @code{N/2} products. In the case of @code{VEC_WIDEN_MULT_LO_EXPR} the
 low @code{N/2} elements of the two vector are multiplied to produce the
 vector of @code{N/2} products.
 
+@item VEC_WIDEN_PLUS_HI_EXPR
+@itemx VEC_WIDEN_PLUS_LO_EXPR
+These nodes represent widening vector addition of the high and low parts of
+the two input vectors, respectively.  Their operands are vectors that contain
+the same number of elements (@code{N}) of the same integral type. The result
+is a vector that contains half as many elements, of an integral type whose size
+is twice as wide.  In the case of @code{VEC_WIDEN_PLUS_HI_EXPR} the high
+@code{N/2} elements of the two vectors are added to produce the vector of
+@code{N/2} products.  In the case of @code{VEC_WIDEN_PLUS_LO_EXPR} the low
+@code{N/2} elements of the two vectors are added to produce the vector of
+@code{N/2} products.
+
+@item VEC_WIDEN_MINUS_HI_EXPR
+@itemx VEC_WIDEN_MINUS_LO_EXPR
+These nodes represent widening vector subtraction of the high and low parts of
+the two input vectors, respectively.  Their operands are vectors that contain
+the same number of elements (@code{N}) of the same integral type. The high/low
+elements of the second vector are subtracted from the high/low elements of the
+first. The result is a vector that contains half as many elements, of an
+integral type whose size is twice as wide.  In the case of
+@code{VEC_WIDEN_MINUS_HI_EXPR} the high @code{N/2} elements of the second
+vector are subtracted from the high @code{N/2} of the first to produce the
+vector of @code{N/2} products.  In the case of
+@code{VEC_WIDEN_MINUS_LO_EXPR} the low @code{N/2} elements of the second
+vector are subtracted from the low @code{N/2} of the first to produce the
+vector of @code{N/2} products.
+
 @item VEC_UNPACK_HI_EXPR
 @itemx VEC_UNPACK_LO_EXPR
 These nodes represent unpacking of the high and low parts of the input vector,