match.pd: Improve fneg/fadd optimization [PR109240]

match.pd has mostly for AArch64 an optimization in which it optimizes
certain forms of __builtin_shuffle of x + y and x - y vectors into
fneg using twice as wide element type so that every other sign is changed,
followed by fadd.

The following patch extends that optimization, so that it can handle
other forms as well, using the same fneg but fsub instead of fadd.

As the plus is commutative and minus is not and I want to handle
vec_perm with plus minus and minus plus order preferrably in one
pattern, I had to do the matching operand checks by hand.

2023-04-18  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/109240
	* match.pd (fneg/fadd): Rewrite such that it handles both plus as
	first vec_perm operand and minus as second using fneg/fadd and
	minus as first vec_perm operand and plus as second using fneg/fsub.

	* gcc.target/aarch64/simd/addsub_2.c: New test.
	* gcc.target/aarch64/sve/addsub_2.c: New test.

3 files changed, 175 insertions, 54 deletions

diff --git a/gcc/match.pd b/gcc/match.pd
index c5d2c36..b7d7a5d 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -8074,63 +8074,76 @@ and,
    under IEEE 754 the fneg of the wider type will negate every even entry
    and when doing an add we get a sub of the even and add of every odd
    elements.  */
-(simplify
- (vec_perm (plus:c @0 @1) (minus @0 @1) VECTOR_CST@2)
- (if (!VECTOR_INTEGER_TYPE_P (type)
-      && !FLOAT_WORDS_BIG_ENDIAN)
-  (with
-   {
-     /* Build a vector of integers from the tree mask.  */
-     vec_perm_builder builder;
-   }
-   (if (tree_to_vec_perm_builder (&builder, @2))
-    (with
-     {
-       /* Create a vec_perm_indices for the integer vector.  */
-       poly_uint64 nelts = TYPE_VECTOR_SUBPARTS (type);
-       vec_perm_indices sel (builder, 2, nelts);
-       machine_mode vec_mode = TYPE_MODE (type);
-       machine_mode wide_mode;
-       scalar_mode wide_elt_mode;
-       poly_uint64 wide_nunits;
-       scalar_mode inner_mode = GET_MODE_INNER (vec_mode);
-     }
-     (if (sel.series_p (0, 2, 0, 2)
-	  && sel.series_p (1, 2, nelts + 1, 2)
-	  && GET_MODE_2XWIDER_MODE (inner_mode).exists (&wide_elt_mode)
-	  && multiple_p (GET_MODE_NUNITS (vec_mode), 2, &wide_nunits)
-	  && related_vector_mode (vec_mode, wide_elt_mode,
-				  wide_nunits).exists (&wide_mode))
-	(with
-	 {
-	   tree stype
-	     = lang_hooks.types.type_for_mode (GET_MODE_INNER (wide_mode),
-					       TYPE_UNSIGNED (type));
-	   tree ntype = build_vector_type_for_mode (stype, wide_mode);
-
-	   /* The format has to be a non-extended ieee format.  */
-	   const struct real_format *fmt_old = FLOAT_MODE_FORMAT (vec_mode);
-	   const struct real_format *fmt_new = FLOAT_MODE_FORMAT (wide_mode);
-	 }
-	 (if (TYPE_MODE (stype) != BLKmode
-	      && VECTOR_TYPE_P (ntype)
-	      && fmt_old != NULL
-	      && fmt_new != NULL)
-	  (with
-	   {
-	     /* If the target doesn't support v1xx vectors, try using
-		scalar mode xx instead.  */
+(for plusminus (plus minus)
+     minusplus (minus plus)
+ (simplify
+  (vec_perm (plusminus @0 @1) (minusplus @2 @3) VECTOR_CST@4)
+   (if (!VECTOR_INTEGER_TYPE_P (type)
+	&& !FLOAT_WORDS_BIG_ENDIAN
+        /* plus is commutative, while minus is not, so :c can't be used.
+	   Do equality comparisons by hand and at the end pick the operands
+	   from the minus.  */
+	&& (operand_equal_p (@0, @2, 0)
+	    ? operand_equal_p (@1, @3, 0)
+	    : operand_equal_p (@0, @3, 0) && operand_equal_p (@1, @2, 0)))
+   (with
+    {
+      /* Build a vector of integers from the tree mask.  */
+      vec_perm_builder builder;
+    }
+    (if (tree_to_vec_perm_builder (&builder, @4))
+     (with
+      {
+	/* Create a vec_perm_indices for the integer vector.  */
+	poly_uint64 nelts = TYPE_VECTOR_SUBPARTS (type);
+	vec_perm_indices sel (builder, 2, nelts);
+	machine_mode vec_mode = TYPE_MODE (type);
+	machine_mode wide_mode;
+	scalar_mode wide_elt_mode;
+	poly_uint64 wide_nunits;
+	scalar_mode inner_mode = GET_MODE_INNER (vec_mode);
+      }
+      (if (sel.series_p (0, 2, 0, 2)
+	   && sel.series_p (1, 2, nelts + 1, 2)
+	   && GET_MODE_2XWIDER_MODE (inner_mode).exists (&wide_elt_mode)
+	   && multiple_p (GET_MODE_NUNITS (vec_mode), 2, &wide_nunits)
+	   && related_vector_mode (vec_mode, wide_elt_mode,
+				   wide_nunits).exists (&wide_mode))
+       (with
+	{
+	  tree stype
+	    = lang_hooks.types.type_for_mode (GET_MODE_INNER (wide_mode),
+					      TYPE_UNSIGNED (type));
+	  tree ntype = build_vector_type_for_mode (stype, wide_mode);
+
+	  /* The format has to be a non-extended ieee format.  */
+	  const struct real_format *fmt_old = FLOAT_MODE_FORMAT (vec_mode);
+	  const struct real_format *fmt_new = FLOAT_MODE_FORMAT (wide_mode);
+	}
+	(if (TYPE_MODE (stype) != BLKmode
+	     && VECTOR_TYPE_P (ntype)
+	     && fmt_old != NULL
+	     && fmt_new != NULL)
+	 (with
+	  {
+	    /* If the target doesn't support v1xx vectors, try using
+	       scalar mode xx instead.  */
 	    if (known_eq (GET_MODE_NUNITS (wide_mode), 1)
 		&& !target_supports_op_p (ntype, NEGATE_EXPR, optab_vector))
 	      ntype = stype;
-	   }
-	   (if (fmt_new->signbit_rw
-	        == fmt_old->signbit_rw + GET_MODE_UNIT_BITSIZE (vec_mode)
-		&& fmt_new->signbit_rw == fmt_new->signbit_ro
-		&& targetm.can_change_mode_class (TYPE_MODE (ntype), TYPE_MODE (type), ALL_REGS)
-		&& ((optimize_vectors_before_lowering_p () && VECTOR_TYPE_P (ntype))
-		    || target_supports_op_p (ntype, NEGATE_EXPR, optab_vector)))
-	    (plus (view_convert:type (negate (view_convert:ntype @1))) @0)))))))))))
+	  }
+	  (if (fmt_new->signbit_rw
+	       == fmt_old->signbit_rw + GET_MODE_UNIT_BITSIZE (vec_mode)
+	       && fmt_new->signbit_rw == fmt_new->signbit_ro
+	       && targetm.can_change_mode_class (TYPE_MODE (ntype),
+						 TYPE_MODE (type), ALL_REGS)
+	       && ((optimize_vectors_before_lowering_p ()
+		    && VECTOR_TYPE_P (ntype))
+		   || target_supports_op_p (ntype, NEGATE_EXPR, optab_vector)))
+	   (if (plusminus == PLUS_EXPR)
+	    (plus (view_convert:type (negate (view_convert:ntype @3))) @2)
+	    (minus @0 (view_convert:type
+			(negate (view_convert:ntype @1))))))))))))))))
 
 (simplify
  (vec_perm @0 @1 VECTOR_CST@2)
diff --git a/gcc/testsuite/gcc.target/aarch64/simd/addsub_2.c b/gcc/testsuite/gcc.target/aarch64/simd/addsub_2.c
new file mode 100644
index 0000000..87424c9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/simd/addsub_2.c
@@ -0,0 +1,56 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_v8_2a_fp16_neon_ok } */
+/* { dg-options "-Ofast" } */
+/* { dg-add-options arm_v8_2a_fp16_neon } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+#pragma GCC target "+nosve"
+
+/* 
+** f1:
+** ...
+**	fneg	v[0-9]+.2d, v[0-9]+.2d
+**	fsub	v[0-9]+.4s, v[0-9]+.4s, v[0-9]+.4s
+** ...
+*/
+void f1 (float *restrict a, float *restrict b, float *res, int n)
+{
+   for (int i = 0; i < (n & -4); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}
+
+/* 
+** d1:
+** ...
+** 	fneg	v[0-9]+.4s, v[0-9]+.4s
+** 	fsub	v[0-9]+.8h, v[0-9]+.8h, v[0-9]+.8h
+** ...
+*/
+void d1 (_Float16 *restrict a, _Float16 *restrict b, _Float16 *res, int n)
+{
+   for (int i = 0; i < (n & -8); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}
+
+/* 
+** e1:
+** ...
+** 	fsub	v[0-9]+.2d, v[0-9]+.2d, v[0-9]+.2d
+** 	fadd	v[0-9]+.2d, v[0-9]+.2d, v[0-9]+.2d
+** 	ins	v[0-9]+.d\[1\], v[0-9]+.d\[1\]
+** ...
+*/
+void e1 (double *restrict a, double *restrict b, double *res, int n)
+{
+   for (int i = 0; i < (n & -4); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/addsub_2.c b/gcc/testsuite/gcc.target/aarch64/sve/addsub_2.c
new file mode 100644
index 0000000..5b9406a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/addsub_2.c
@@ -0,0 +1,52 @@
+/* { dg-do compile } */
+/* { dg-options "-Ofast" } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+/*
+** f1:
+** ...
+** 	fneg	z[0-9]+.d, p[0-9]+/m, z[0-9]+.d
+** 	fsub	z[0-9]+.s, z[0-9]+.s, z[0-9]+.s
+** ...
+*/
+void f1 (float *restrict a, float *restrict b, float *res, int n)
+{
+   for (int i = 0; i < (n & -4); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}
+
+/* 
+** d1:
+** ...
+** 	fneg	z[0-9]+.s, p[0-9]+/m, z[0-9]+.s
+** 	fsub	z[0-9]+.h, z[0-9]+.h, z[0-9]+.h
+** ...
+*/ 
+void d1 (_Float16 *restrict a, _Float16 *restrict b, _Float16 *res, int n)
+{
+   for (int i = 0; i < (n & -8); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}
+
+/*
+** e1:
+** ...
+** 	fadd	z[0-9]+.d, z[0-9]+.d, z[0-9]+.d
+** 	movprfx	z[0-9]+.d, p[0-9]+/m, z[0-9]+.d
+** 	fsub	z[0-9]+.d, p[0-9]+/m, z[0-9]+.d, z[0-9]+.d
+** ...
+*/
+void e1 (double *restrict a, double *restrict b, double *res, int n)
+{
+   for (int i = 0; i < (n & -4); i+=2)
+    {
+      res[i+0] = a[i+0] - b[i+0];
+      res[i+1] = a[i+1] + b[i+1];
+    }
+}