rs6000: Give names to cbranch/creturn patterns

This gives a name to the conditional branch and conditional return
patterns, so that it looks neater in dumps and verbose asm.  Also, the
comment for conditional branch was out of date; this fixes it.


	* config/rs6000/rs6000.md (*cbranch, *creturn): Name these patterns
	(they were unnamed before).  Fix comments.

From-SVN: r263623

gcc/ChangeLog

+2018-08-17  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* config/rs6000/rs6000.md (*cbranch, *creturn): Name these patterns
+	(they were unnamed before).  Fix comments.
+
 2018-08-17  Nathan Sidwell  <nathan@acm.org>
 
 	* cppbuiltin.c: Include "cpplib.h", not "cpp-id-data.h".

gcc/config/rs6000/rs6000.md

@@ -12254,11 +12254,10 @@
 		      (const_string "12")
 		      (const_string "16")))])
 
-;; Define both directions of branch and return.  If we need a reload
-;; register, we'd rather use CR0 since it is much easier to copy a
-;; register CC value to there.
+;; Conditional branches.
+;; These either are a single bc insn, or a bc around a b.
 
-(define_insn ""
+(define_insn "*cbranch"
   [(set (pc)
 	(if_then_else (match_operator 1 "branch_comparison_operator"
 				      [(match_operand 2 "cc_reg_operand" "y")
@@ -12278,7 +12277,8 @@
 		      (const_int 4)
 		      (const_int 8)))])
 
-(define_insn ""
+;; Conditional return.
+(define_insn "*creturn"
   [(set (pc)
 	(if_then_else (match_operator 0 "branch_comparison_operator"
 				      [(match_operand 1 "cc_reg_operand" "y")