rs6000: Use unspec_volatile for darn (PR91481)

Every call to darn should deliver a *new* random number; such calls
should not be CSEd together.  So they should be unspec_volatile, not
plain unspec.


	PR target/91481
	* config/rs6000/rs6000.md (unspec): Delete UNSPEC_DARN, UNSPEC_DARN_32,
	and UNSPEC_DARN_RAW.
	(unspecv): New enumerator values UNSPECV_DARN, UNSPECV_DARN_32, and
	UNSPECV_DARN_RAW.
	(darn_32): Use an unspec_volatile, and UNSPECV_DARN_32.
	(darn_raw): Use an unspec_volatile, and UNSPECV_DARN_RAW.
	(darn): Use an unspec_volatile, and UNSPECV_DARN.

From-SVN: r274835

gcc/ChangeLog

 2019-08-22  Segher Boessenkool  <segher@kernel.crashing.org>
 
+	PR target/91481
+	* config/rs6000/rs6000.md (unspec): Delete UNSPEC_DARN, UNSPEC_DARN_32,
+	and UNSPEC_DARN_RAW.
+	(unspecv): New enumerator values UNSPECV_DARN, UNSPECV_DARN_32, and
+	UNSPECV_DARN_RAW.
+	(darn_32): Use an unspec_volatile, and UNSPECV_DARN_32.
+	(darn_raw): Use an unspec_volatile, and UNSPECV_DARN_RAW.
+	(darn): Use an unspec_volatile, and UNSPECV_DARN.
+
+2019-08-22  Segher Boessenkool  <segher@kernel.crashing.org>
+
 	* config/rs6000/altivec.md (unspec): Delete UNSPEC_DARN, UNSPEC_DARN_32,
 	UNSPEC_DARN_RAW, UNSPEC_CMPRB, UNSPEC_CMPRB2, UNSPEC_CMPEQB; move to...
 	* config/rs6000/rs6000.md (unspec): ... here.

gcc/config/rs6000/rs6000.md

@@ -134,9 +134,6 @@
    UNSPEC_LSQ
    UNSPEC_FUSION_GPR
    UNSPEC_STACK_CHECK
-   UNSPEC_DARN
-   UNSPEC_DARN_32
-   UNSPEC_DARN_RAW
    UNSPEC_CMPRB
    UNSPEC_CMPRB2
    UNSPEC_CMPEQB
@@ -168,6 +165,9 @@
    UNSPECV_EH_RR		; eh_reg_restore
    UNSPECV_ISYNC		; isync instruction
    UNSPECV_MFTB			; move from time base
+   UNSPECV_DARN			; darn 1 (deliver a random number)
+   UNSPECV_DARN_32		; darn 2
+   UNSPECV_DARN_RAW		; darn 0
    UNSPECV_NLGR			; non-local goto receiver
    UNSPECV_MFFS			; Move from FPSCR
    UNSPECV_MFFSL		; Move from FPSCR light instruction version
@@ -14387,21 +14387,21 @@
 
 (define_insn "darn_32"
   [(set (match_operand:SI 0 "register_operand" "=r")
-        (unspec:SI [(const_int 0)] UNSPEC_DARN_32))]
+        (unspec_volatile:SI [(const_int 0)] UNSPECV_DARN_32))]
   "TARGET_P9_MISC"
   "darn %0,0"
   [(set_attr "type" "integer")])
 
 (define_insn "darn_raw"
   [(set (match_operand:DI 0 "register_operand" "=r")
-        (unspec:DI [(const_int 0)] UNSPEC_DARN_RAW))]
+        (unspec_volatile:DI [(const_int 0)] UNSPECV_DARN_RAW))]
   "TARGET_P9_MISC && TARGET_64BIT"
   "darn %0,2"
   [(set_attr "type" "integer")])
 
 (define_insn "darn"
   [(set (match_operand:DI 0 "register_operand" "=r")
-        (unspec:DI [(const_int 0)] UNSPEC_DARN))]
+        (unspec_volatile:DI [(const_int 0)] UNSPECV_DARN))]
   "TARGET_P9_MISC && TARGET_64BIT"
   "darn %0,1"
   [(set_attr "type" "integer")])