[AArch64] Add a commutativity marker to the SVE [SU]ABD patterns

This will be tested by the ACLE patches, but it's really an
independent improvement.

2019-08-15  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/aarch64-sve.md (aarch64_<su>abd<mode>_3): Add
	a commutativity marker.

From-SVN: r274510

gcc/ChangeLog

 2019-08-15  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* config/aarch64/aarch64-sve.md (aarch64_<su>abd<mode>_3): Add
+	a commutativity marker.
+
+2019-08-15  Richard Sandiford  <richard.sandiford@arm.com>
 	    Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
 
 	* config/aarch64/aarch64-protos.h (aarch64_prepare_sve_int_fma)

gcc/config/aarch64/aarch64-sve.md

@@ -2060,7 +2060,7 @@
 	  [(match_operand:<VPRED> 1 "register_operand" "Upl, Upl")
 	   (minus:SVE_I
 	     (USMAX:SVE_I
-	       (match_operand:SVE_I 2 "register_operand" "0, w")
+	       (match_operand:SVE_I 2 "register_operand" "%0, w")
 	       (match_operand:SVE_I 3 "register_operand" "w, w"))
 	     (<max_opp>:SVE_I
 	       (match_dup 2)