Patchwork [rs6000] power8 patches, patch #9, power8 scheduling

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Submitter Pat Haugen
Date June 7, 2013, 7:22 p.m.
Message ID <51B232E7.9040700@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/249797/
State New
Headers show

Comments

Pat Haugen - June 7, 2013, 7:22 p.m.
This patch adds instruction scheduling support for the Power8 processor. 
Bootstrap/regression test with no new failures. Ok for trunk?


2013-06-07  Michael Meissner  <meissner@linux.vnet.ibm.com>
         Pat Haugen <pthaugen@us.ibm.com>
         Peter Bergner <bergner@vnet.ibm.com>

     * config/rs6000/power8.md: New.
     * config/rs6000/rs6000-cpus.def (RS6000_CPU table): Adjust processor
     setting for power8 entry.
     * config/rs6000/t-rs6000 (MD_INCLUDES): Add power8.md.
     * config/rs6000/rs6000.c (is_microcoded_insn, is_cracked_insn): Adjust
     test for Power4/Power5 only.
     (insn_must_be_first_in_group, insn_must_be_last_in_group): Add Power8
     support.
     (force_new_group): Adjust comment.
     * config/rs6000/rs6000.md: Include power8.md.
David Edelsohn - June 19, 2013, 1 p.m.
On Fri, Jun 7, 2013 at 3:22 PM, Pat Haugen <pthaugen@linux.vnet.ibm.com> wrote:
> This patch adds instruction scheduling support for the Power8 processor.
> Bootstrap/regression test with no new failures. Ok for trunk?
>
>
> 2013-06-07  Michael Meissner  <meissner@linux.vnet.ibm.com>
>         Pat Haugen <pthaugen@us.ibm.com>
>         Peter Bergner <bergner@vnet.ibm.com>
>
>     * config/rs6000/power8.md: New.
>     * config/rs6000/rs6000-cpus.def (RS6000_CPU table): Adjust processor
>     setting for power8 entry.
>     * config/rs6000/t-rs6000 (MD_INCLUDES): Add power8.md.
>     * config/rs6000/rs6000.c (is_microcoded_insn, is_cracked_insn): Adjust
>     test for Power4/Power5 only.
>     (insn_must_be_first_in_group, insn_must_be_last_in_group): Add Power8
>     support.
>     (force_new_group): Adjust comment.
>     * config/rs6000/rs6000.md: Include power8.md.

This patch is okay.

Thanks, David

Patch

Index: gcc/config/rs6000/power8.md
===================================================================
--- gcc/config/rs6000/power8.md	(revision 0)
+++ gcc/config/rs6000/power8.md	(revision 0)
@@ -0,0 +1,373 @@ 
+;; Scheduling description for IBM POWER8 processor.
+;; Copyright (C) 2013 Free Software Foundation, Inc.
+;;
+;; Contributed by Pat Haugen (pthaugen@us.ibm.com).
+
+;; This file is part of GCC.
+;;
+;; GCC is free software; you can redistribute it and/or modify it
+;; under the terms of the GNU General Public License as published
+;; by the Free Software Foundation; either version 3, or (at your
+;; option) any later version.
+;;
+;; GCC is distributed in the hope that it will be useful, but WITHOUT
+;; ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+;; or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+;; License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with GCC; see the file COPYING3.  If not see
+;; <http://www.gnu.org/licenses/>.
+
+(define_automaton "power8fxu,power8lsu,power8vsu,power8misc")
+
+(define_cpu_unit "fxu0_power8,fxu1_power8" "power8fxu")
+(define_cpu_unit "lu0_power8,lu1_power8" "power8lsu")
+(define_cpu_unit "lsu0_power8,lsu1_power8" "power8lsu")
+(define_cpu_unit "vsu0_power8,vsu1_power8" "power8vsu")
+(define_cpu_unit "bpu_power8,cru_power8" "power8misc")
+(define_cpu_unit "du0_power8,du1_power8,du2_power8,du3_power8,du4_power8,\
+		  du5_power8,du6_power8"  "power8misc")
+
+
+; Dispatch group reservations
+(define_reservation "DU_any_power8"
+		    "du0_power8|du1_power8|du2_power8|du3_power8|du4_power8|\
+		     du5_power8")
+
+; 2-way Cracked instructions go in slots 0-1
+;   (can also have a second in slots 3-4 if insns are adjacent)
+(define_reservation "DU_cracked_power8"
+		    "du0_power8+du1_power8")
+
+; Insns that are first in group
+(define_reservation "DU_first_power8"
+		    "du0_power8")
+
+; Insns that are first and last in group
+(define_reservation "DU_both_power8"
+		    "du0_power8+du1_power8+du2_power8+du3_power8+du4_power8+\
+		     du5_power8+du6_power8")
+
+; Dispatch slots are allocated in order conforming to program order.
+(absence_set "du0_power8" "du1_power8,du2_power8,du3_power8,du4_power8,\
+	      du5_power8,du6_power8")
+(absence_set "du1_power8" "du2_power8,du3_power8,du4_power8,du5_power8,\
+	      du6_power8")
+(absence_set "du2_power8" "du3_power8,du4_power8,du5_power8,du6_power8")
+(absence_set "du3_power8" "du4_power8,du5_power8,du6_power8")
+(absence_set "du4_power8" "du5_power8,du6_power8")
+(absence_set "du5_power8" "du6_power8")
+
+
+; Execution unit reservations
+(define_reservation "FXU_power8"
+                    "fxu0_power8|fxu1_power8")
+
+(define_reservation "LU_power8"
+                    "lu0_power8|lu1_power8")
+
+(define_reservation "LSU_power8"
+                    "lsu0_power8|lsu1_power8")
+
+(define_reservation "LU_or_LSU_power8"
+                    "lu0_power8|lu1_power8|lsu0_power8|lsu1_power8")
+
+(define_reservation "VSU_power8"
+                    "vsu0_power8|vsu1_power8")
+
+
+; LS Unit
+(define_insn_reservation "power8-load" 3
+  (and (eq_attr "type" "load")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,LU_or_LSU_power8")
+
+(define_insn_reservation "power8-load-update" 3
+  (and (eq_attr "type" "load_u,load_ux")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,LU_or_LSU_power8+FXU_power8")
+
+(define_insn_reservation "power8-load-ext" 3
+  (and (eq_attr "type" "load_ext")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,LU_or_LSU_power8,FXU_power8")
+
+(define_insn_reservation "power8-load-ext-update" 3
+  (and (eq_attr "type" "load_ext_u,load_ext_ux")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,LU_or_LSU_power8+FXU_power8,FXU_power8")
+
+(define_insn_reservation "power8-fpload" 5
+  (and (eq_attr "type" "fpload,vecload")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,LU_power8")
+
+(define_insn_reservation "power8-fpload-update" 5
+  (and (eq_attr "type" "fpload_u,fpload_ux")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,LU_power8+FXU_power8")
+
+(define_insn_reservation "power8-store" 5 ; store-forwarding latency
+  (and (eq_attr "type" "store,store_u")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,LSU_power8+LU_power8")
+
+(define_insn_reservation "power8-store-update-indexed" 5
+  (and (eq_attr "type" "store_ux")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,LSU_power8+LU_power8")
+
+(define_insn_reservation "power8-fpstore" 5
+  (and (eq_attr "type" "fpstore")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,LSU_power8+VSU_power8")
+
+(define_insn_reservation "power8-fpstore-update" 5
+  (and (eq_attr "type" "fpstore_u,fpstore_ux")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,LSU_power8+VSU_power8")
+
+(define_insn_reservation "power8-vecstore" 5
+  (and (eq_attr "type" "vecstore")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,LSU_power8+VSU_power8")
+
+(define_insn_reservation "power8-larx" 3
+  (and (eq_attr "type" "load_l")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,LU_or_LSU_power8")
+
+(define_insn_reservation "power8-stcx" 10
+  (and (eq_attr "type" "store_c")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,LSU_power8+LU_power8")
+
+(define_insn_reservation "power8-sync" 1
+  (and (eq_attr "type" "sync,isync")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,LSU_power8")
+
+
+; FX Unit
+(define_insn_reservation "power8-1cyc" 1
+  (and (eq_attr "type" "integer,insert_word,insert_dword,shift,trap,\
+                        var_shift_rotate,exts,isel")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,FXU_power8")
+
+; Extra cycle to LU/LSU
+(define_bypass 2 "power8-1cyc"
+		 "power8-load*,power8-fpload*,power8-store*,power8-fpstore*,\
+		  power8-vecstore,power8-larx,power8-stcx")
+;		 "power8-load,power8-load-update,power8-load-ext,\
+;		  power8-load-ext-update,power8-fpload,power8-fpload-update,\
+;		  power8-store,power8-store-update,power8-store-update-indexed,\
+;		  power8-fpstore,power8-fpstore-update,power8-vecstore,\
+;		  power8-larx,power8-stcx")
+
+(define_insn_reservation "power8-2cyc" 2
+  (and (eq_attr "type" "cntlz,popcnt")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,FXU_power8")
+
+(define_insn_reservation "power8-two" 2
+  (and (eq_attr "type" "two")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8+DU_any_power8,FXU_power8,FXU_power8")
+
+(define_insn_reservation "power8-three" 3
+  (and (eq_attr "type" "three")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8+DU_any_power8+DU_any_power8,FXU_power8,FXU_power8,FXU_power8")
+
+; cmp - Normal compare insns
+(define_insn_reservation "power8-cmp" 2
+  (and (eq_attr "type" "cmp")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,FXU_power8")
+
+; fast_compare : add./and./nor./etc
+(define_insn_reservation "power8-fast-compare" 2
+  (and (eq_attr "type" "fast_compare")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,FXU_power8")
+
+; compare : rldicl./exts./etc
+; delayed_compare : rlwinm./slwi./etc
+; var_delayed_compare : rlwnm./slw./etc
+(define_insn_reservation "power8-compare" 2
+  (and (eq_attr "type" "compare,delayed_compare,var_delayed_compare")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,FXU_power8,FXU_power8")
+
+; Extra cycle to LU/LSU
+(define_bypass 3 "power8-fast-compare,power8-compare"
+		 "power8-load*,power8-fpload*,power8-store*,power8-fpstore*,\
+		  power8-vecstore,power8-larx,power8-stcx")
+
+; 5 cycle CR latency 
+(define_bypass 5 "power8-fast-compare,power8-compare"
+		 "power8-crlogical,power8-mfcr,power8-mfcrf,power8-branch")
+
+(define_insn_reservation "power8-mul" 4
+  (and (eq_attr "type" "imul,imul2,imul3,lmul")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,FXU_power8")
+
+(define_insn_reservation "power8-mul-compare" 4
+  (and (eq_attr "type" "imul_compare,lmul_compare")
+       (eq_attr "cpu" "power8"))
+  "DU_cracked_power8,FXU_power8")
+
+; Extra cycle to LU/LSU
+(define_bypass 5 "power8-mul,power8-mul-compare"
+		 "power8-load*,power8-fpload*,power8-store*,power8-fpstore*,\
+		  power8-vecstore,power8-larx,power8-stcx")
+
+; 7 cycle CR latency 
+(define_bypass 7 "power8-mul,power8-mul-compare"
+		 "power8-crlogical,power8-mfcr,power8-mfcrf,power8-branch")
+
+; FXU divides are not pipelined
+(define_insn_reservation "power8-idiv" 37
+  (and (eq_attr "type" "idiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,fxu0_power8*37|fxu1_power8*37")
+
+(define_insn_reservation "power8-ldiv" 68
+  (and (eq_attr "type" "ldiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,fxu0_power8*68|fxu1_power8*68")
+
+(define_insn_reservation "power8-mtjmpr" 5
+  (and (eq_attr "type" "mtjmpr")
+       (eq_attr "cpu" "power8"))
+  "DU_first_power8,FXU_power8")
+
+; Should differentiate between 1 cr field and > 1 since mtocrf is not microcode
+(define_insn_reservation "power8-mtcr" 3
+  (and (eq_attr "type" "mtcr")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,FXU_power8")
+
+
+; CR Unit
+(define_insn_reservation "power8-mfjmpr" 5
+  (and (eq_attr "type" "mfjmpr")
+       (eq_attr "cpu" "power8"))
+  "DU_first_power8,cru_power8+FXU_power8")
+
+(define_insn_reservation "power8-crlogical" 3
+  (and (eq_attr "type" "cr_logical,delayed_cr")
+       (eq_attr "cpu" "power8"))
+  "DU_first_power8,cru_power8")
+
+(define_insn_reservation "power8-mfcr" 5
+  (and (eq_attr "type" "mfcr")
+       (eq_attr "cpu" "power8"))
+  "DU_both_power8,cru_power8")
+
+(define_insn_reservation "power8-mfcrf" 3
+  (and (eq_attr "type" "mfcrf")
+       (eq_attr "cpu" "power8"))
+  "DU_first_power8,cru_power8")
+
+
+; BR Unit
+; Branches take dispatch slot 7, but reserve any remaining prior slots to
+; prevent other insns from grabbing them once this is assigned.
+(define_insn_reservation "power8-branch" 3
+  (and (eq_attr "type" "jmpreg,branch")
+       (eq_attr "cpu" "power8"))
+  "(du6_power8\
+   |du5_power8+du6_power8\
+   |du4_power8+du5_power8+du6_power8\
+   |du3_power8+du4_power8+du5_power8+du6_power8\
+   |du2_power8+du3_power8+du4_power8+du5_power8+du6_power8\
+   |du1_power8+du2_power8+du3_power8+du4_power8+du5_power8+du6_power8\
+   |du0_power8+du1_power8+du2_power8+du3_power8+du4_power8+du5_power8+\
+    du6_power8),bpu_power8")
+
+; Branch updating LR/CTR feeding mf[lr|ctr]
+(define_bypass 4 "power8-branch" "power8-mfjmpr")
+
+
+; VS Unit (includes FP/VSX/VMX/DFP/Crypto)
+(define_insn_reservation "power8-fp" 6
+  (and (eq_attr "type" "fp,dmul")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+; Additional 3 cycles for any CR result
+(define_bypass 9 "power8-fp" "power8-crlogical,power8-mfcr*,power8-branch")
+
+(define_insn_reservation "power8-fpcompare" 8
+  (and (eq_attr "type" "fpcompare")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-sdiv" 27
+  (and (eq_attr "type" "sdiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-ddiv" 33
+  (and (eq_attr "type" "ddiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-sqrt" 32
+  (and (eq_attr "type" "ssqrt")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-dsqrt" 44
+  (and (eq_attr "type" "dsqrt")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-vecsimple" 2
+  (and (eq_attr "type" "vecperm,vecsimple,veccmp")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-vecnormal" 6
+  (and (eq_attr "type" "vecfloat,vecdouble")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_bypass 7 "power8-vecnormal"
+		 "power8-vecsimple,power8-veccomplex,power8-fpstore*,\
+		  power8-vecstore")
+
+(define_insn_reservation "power8-veccomplex" 7
+  (and (eq_attr "type" "veccomplex")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-vecfdiv" 25
+  (and (eq_attr "type" "vecfdiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-vecdiv" 31
+  (and (eq_attr "type" "vecdiv")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-mffgpr" 5
+  (and (eq_attr "type" "mffgpr")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-mftgpr" 6
+  (and (eq_attr "type" "mftgpr")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
+(define_insn_reservation "power8-crypto" 7
+  (and (eq_attr "type" "crypto")
+       (eq_attr "cpu" "power8"))
+  "DU_any_power8,VSU_power8")
+
Index: gcc/config/rs6000/rs6000-cpus.def
===================================================================
--- gcc/config/rs6000/rs6000-cpus.def	(revision 199674)
+++ gcc/config/rs6000/rs6000-cpus.def	(working copy)
@@ -181,7 +181,7 @@  RS6000_CPU ("power7", PROCESSOR_POWER7, 
 	    POWERPC_7400_MASK | MASK_POWERPC64 | MASK_PPC_GPOPT | MASK_MFCRF
 	    | MASK_POPCNTB | MASK_FPRND | MASK_CMPB | MASK_DFP | MASK_POPCNTD
 	    | MASK_VSX | MASK_RECIP_PRECISION | MASK_VSX_TIMODE)
-RS6000_CPU ("power8", PROCESSOR_POWER7, MASK_POWERPC64 | ISA_2_7_MASKS_SERVER)
+RS6000_CPU ("power8", PROCESSOR_POWER8, MASK_POWERPC64 | ISA_2_7_MASKS_SERVER)
 RS6000_CPU ("powerpc", PROCESSOR_POWERPC, 0)
 RS6000_CPU ("powerpc64", PROCESSOR_POWERPC64, MASK_PPC_GFXOPT | MASK_POWERPC64)
 RS6000_CPU ("rs64", PROCESSOR_RS64A, MASK_PPC_GFXOPT | MASK_POWERPC64)
Index: gcc/config/rs6000/t-rs6000
===================================================================
--- gcc/config/rs6000/t-rs6000	(revision 199674)
+++ gcc/config/rs6000/t-rs6000	(working copy)
@@ -60,6 +60,7 @@  MD_INCLUDES = $(srcdir)/config/rs6000/rs
 	$(srcdir)/config/rs6000/power5.md \
 	$(srcdir)/config/rs6000/power6.md \
 	$(srcdir)/config/rs6000/power7.md \
+	$(srcdir)/config/rs6000/power8.md \
 	$(srcdir)/config/rs6000/cell.md \
 	$(srcdir)/config/rs6000/xfpu.md \
 	$(srcdir)/config/rs6000/a2.md \
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 199674)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -23451,7 +23451,8 @@  is_microcoded_insn (rtx insn)
   if (rs6000_cpu_attr == CPU_CELL)
     return get_attr_cell_micro (insn) == CELL_MICRO_ALWAYS;
 
-  if (rs6000_sched_groups)
+  if (rs6000_sched_groups
+      && (rs6000_cpu == PROCESSOR_POWER4 || rs6000_cpu == PROCESSOR_POWER5))
     {
       enum attr_type type = get_attr_type (insn);
       if (type == TYPE_LOAD_EXT_U
@@ -23476,7 +23477,8 @@  is_cracked_insn (rtx insn)
       || GET_CODE (PATTERN (insn)) == CLOBBER)
     return false;
 
-  if (rs6000_sched_groups)
+  if (rs6000_sched_groups
+      && (rs6000_cpu == PROCESSOR_POWER4 || rs6000_cpu == PROCESSOR_POWER5))
     {
       enum attr_type type = get_attr_type (insn);
       if (type == TYPE_LOAD_U || type == TYPE_STORE_U
@@ -24350,7 +24352,6 @@  insn_must_be_first_in_group (rtx insn)
         }
       break;
     case PROCESSOR_POWER7:
-    case PROCESSOR_POWER8:	/* FIXME */
       type = get_attr_type (insn);
 
       switch (type)
@@ -24385,6 +24386,39 @@  insn_must_be_first_in_group (rtx insn)
           break;
         }
       break;
+    case PROCESSOR_POWER8:
+      type = get_attr_type (insn);
+
+      switch (type)
+        {
+        case TYPE_CR_LOGICAL:
+        case TYPE_DELAYED_CR:
+        case TYPE_MFCR:
+        case TYPE_MFCRF:
+        case TYPE_MTCR:
+        case TYPE_COMPARE:
+        case TYPE_DELAYED_COMPARE:
+        case TYPE_VAR_DELAYED_COMPARE:
+        case TYPE_IMUL_COMPARE:
+        case TYPE_LMUL_COMPARE:
+        case TYPE_SYNC:
+        case TYPE_ISYNC:
+        case TYPE_LOAD_L:
+        case TYPE_STORE_C:
+        case TYPE_LOAD_U:
+        case TYPE_LOAD_UX:
+        case TYPE_LOAD_EXT:
+        case TYPE_LOAD_EXT_U:
+        case TYPE_LOAD_EXT_UX:
+        case TYPE_STORE_UX:
+        case TYPE_VECSTORE:
+        case TYPE_MFJMPR:
+        case TYPE_MTJMPR:
+          return true;
+        default:
+          break;
+        }
+      break;
     default:
       break;
     }
@@ -24447,7 +24481,6 @@  insn_must_be_last_in_group (rtx insn)
     }
     break;
   case PROCESSOR_POWER7:
-  case PROCESSOR_POWER8:	/* FIXME */
     type = get_attr_type (insn);
 
     switch (type)
@@ -24464,6 +24497,25 @@  insn_must_be_last_in_group (rtx insn)
         break;
     }
     break;
+  case PROCESSOR_POWER8:
+    type = get_attr_type (insn);
+
+    switch (type)
+      {
+      case TYPE_MFCR:
+      case TYPE_MTCR:
+      case TYPE_ISYNC:
+      case TYPE_SYNC:
+      case TYPE_LOAD_L:
+      case TYPE_STORE_C:
+      case TYPE_LOAD_EXT_U:
+      case TYPE_LOAD_EXT_UX:
+      case TYPE_STORE_UX:
+        return true;
+      default:
+        break;
+    }
+    break;
   default:
     break;
   }
@@ -24553,7 +24605,7 @@  force_new_group (int sched_verbose, FILE
       if (can_issue_more && !is_branch_slot_insn (next_insn))
 	can_issue_more--;
 
-      /* Power6 and Power7 have special group ending nop. */
+      /* Do we have a special group ending nop? */
       if (rs6000_cpu_attr == CPU_POWER6 || rs6000_cpu_attr == CPU_POWER7
 	  || rs6000_cpu_attr == CPU_POWER8)
 	{
Index: gcc/config/rs6000/rs6000.md
===================================================================
--- gcc/config/rs6000/rs6000.md	(revision 199674)
+++ gcc/config/rs6000/rs6000.md	(working copy)
@@ -206,6 +206,7 @@  (define_attr "cell_micro" "not,condition
 (include "power5.md")
 (include "power6.md")
 (include "power7.md")
+(include "power8.md")
 (include "cell.md")
 (include "xfpu.md")
 (include "a2.md")