[RS6000] Don't allow combine to form doloop pattern

	* config/rs6000/rs6000.md (UNSPEC_DOLOOP): New unspec.
	(ctr<mode>): Add unspec.
	(ctr<mode>_internal*): Likewise.

From-SVN: r238207

gcc/ChangeLog

+2016-07-11  Alan Modra  <amodra@gmail.com>
+
+	* config/rs6000/rs6000.md (UNSPEC_DOLOOP): New unspec.
+	(ctr<mode>): Add unspec.
+	(ctr<mode>_internal*): Likewise.
+
 2016-07-08  James Bowman  <james.bowman@ftdichip.com>
 
 	* config/ft32/ft32.c (ft32_elf_encode_section_info): New function.

gcc/config/rs6000/rs6000.md

@@ -148,6 +148,7 @@
    UNSPEC_IEEE128_MOVE
    UNSPEC_IEEE128_CONVERT
    UNSPEC_SIGNBIT
+   UNSPEC_DOLOOP
   ])
 
 ;;
@@ -12185,6 +12186,7 @@
 	      (set (match_dup 0)
 		   (plus:P (match_dup 0)
 			    (const_int -1)))
+	      (unspec [(const_int 0)] UNSPEC_DOLOOP)
 	      (clobber (match_scratch:CC 2 ""))
 	      (clobber (match_scratch:P 3 ""))])]
   ""
@@ -12195,6 +12197,7 @@
 ;; JUMP_INSNs.
 ;; For the length attribute to be calculated correctly, the
 ;; label MUST be operand 0.
+;; The UNSPEC is present to prevent combine creating this pattern.
 
 (define_insn "*ctr<mode>_internal1"
   [(set (pc)
@@ -12205,6 +12208,7 @@
    (set (match_operand:P 2 "nonimmediate_operand" "=1,*r,m,*d*wi*c*l")
 	(plus:P (match_dup 1)
 		 (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 "=X,&x,&x,&x"))
    (clobber (match_scratch:P 4 "=X,X,&r,r"))]
   ""
@@ -12229,6 +12233,7 @@
    (set (match_operand:P 2 "nonimmediate_operand" "=1,*r,m,*d*wi*c*l")
 	(plus:P (match_dup 1)
 		 (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 "=X,&x,&x,&x"))
    (clobber (match_scratch:P 4 "=X,X,&r,r"))]
   ""
@@ -12255,6 +12260,7 @@
    (set (match_operand:P 2 "nonimmediate_operand" "=1,*r,m,*d*wi*c*l")
 	(plus:P (match_dup 1)
 		 (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 "=X,&x,&x,&x"))
    (clobber (match_scratch:P 4 "=X,X,&r,r"))]
   ""
@@ -12279,6 +12285,7 @@
    (set (match_operand:P 2 "nonimmediate_operand" "=1,*r,m,*d*wi*c*l")
 	(plus:P (match_dup 1)
 		 (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 "=X,&x,&x,&x"))
    (clobber (match_scratch:P 4 "=X,X,&r,r"))]
   ""
@@ -12305,6 +12312,7 @@
 		      (match_operand 6 "" "")))
    (set (match_operand:P 0 "int_reg_operand" "")
 	(plus:P (match_dup 1) (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 ""))
    (clobber (match_scratch:P 4 ""))]
   "reload_completed"
@@ -12330,6 +12338,7 @@
 		      (match_operand 6 "" "")))
    (set (match_operand:P 0 "nonimmediate_operand" "")
 	(plus:P (match_dup 1) (const_int -1)))
+   (unspec [(const_int 0)] UNSPEC_DOLOOP)
    (clobber (match_scratch:CC 3 ""))
    (clobber (match_scratch:P 4 ""))]
   "reload_completed && ! gpc_reg_operand (operands[0], SImode)"