From: Aaron Sawdey <acsaw...@linux.ibm.com>

This patch implements a RTL pass that looks for pc-relative loads of the
address of an external variable using the PCREL_GOT relocation and a
single load or store that uses that external address.

Produced by a cast of thousands:
 * Michael Meissner
 * Peter Bergner
 * Bill Schmidt
 * Alan Modra
 * Segher Boessenkool
 * Aaron Sawdey

This incorporates the changes requested in Segher's review. A few things I
did not change were the insn-at-a-time scan that could be done with DF, and
I did not change to using statistics.[ch] for the counters struct. I did try
to improve the naming, and rewrote a number of comments to make them consistent
with the code, and generally tried to make things more readable.

OK for trunk if bootstrap/regtest passes?

Thanks!
   Aaron

gcc/ChangeLog:

        * config.gcc: Add pcrel-opt.o.
        * config/rs6000/pcrel-opt.c: New file.
        * config/rs6000/pcrel-opt.md: New file.
        * config/rs6000/predicates.md: Add d_form_memory predicate.
        * config/rs6000/rs6000-cpus.def: Add OPTION_MASK_PCREL_OPT.
        * config/rs6000/rs6000-passes.def: Add pass_pcrel_opt.
        * config/rs6000/rs6000-protos.h: Add reg_to_non_prefixed(),
        pcrel_opt_valid_mem_p(), output_pcrel_opt_reloc(),
        and make_pass_pcrel_opt().
        * config/rs6000/rs6000.c (reg_to_non_prefixed): Make global.
        (rs6000_option_override_internal): Add pcrel-opt.
        (rs6000_delegitimize_address): Support pcrel-opt.
        (rs6000_opt_masks): Add pcrel-opt.
        (pcrel_opt_valid_mem_p): New function.
        (reg_to_non_prefixed): Make global.
        (rs6000_asm_output_opcode): Reset next_insn_prefixed_p.
        (output_pcrel_opt_reloc): New function.
        * config/rs6000/rs6000.md (loads_extern_addr): New attr.
        (pcrel_extern_addr): Set loads_extern_addr.
        Add include for pcrel-opt.md.
        * config/rs6000/rs6000.opt: Add -mpcrel-opt.
        * config/rs6000/t-rs6000: Add rules for pcrel-opt.c and
        pcrel-opt.md.

gcc/testsuite/ChangeLog:

        * gcc.target/powerpc/pcrel-opt-inc-di.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-df.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-di.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-hi.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-qi.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-sf.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-si.c: New test.
        * gcc.target/powerpc/pcrel-opt-ld-vector.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-df.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-di.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-hi.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-qi.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-sf.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-si.c: New test.
        * gcc.target/powerpc/pcrel-opt-st-vector.c: New test.
---
 gcc/config.gcc                                |   8 +-
 gcc/config/rs6000/pcrel-opt.md                | 399 ++++++++
 gcc/config/rs6000/predicates.md               |  21 +
 gcc/config/rs6000/rs6000-cpus.def             |   2 +
 gcc/config/rs6000/rs6000-passes.def           |   8 +
 gcc/config/rs6000/rs6000-pcrel-opt.c          | 924 ++++++++++++++++++
 gcc/config/rs6000/rs6000-protos.h             |   4 +
 gcc/config/rs6000/rs6000.c                    | 111 ++-
 gcc/config/rs6000/rs6000.md                   |   8 +-
 gcc/config/rs6000/rs6000.opt                  |   4 +
 gcc/config/rs6000/t-rs6000                    |   7 +-
 .../gcc.target/powerpc/pcrel-opt-inc-di.c     |  17 +
 .../gcc.target/powerpc/pcrel-opt-ld-df.c      |  36 +
 .../gcc.target/powerpc/pcrel-opt-ld-di.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-ld-hi.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-ld-qi.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-ld-sf.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-ld-si.c      |  41 +
 .../gcc.target/powerpc/pcrel-opt-ld-vector.c  |  36 +
 .../gcc.target/powerpc/pcrel-opt-st-df.c      |  36 +
 .../gcc.target/powerpc/pcrel-opt-st-di.c      |  36 +
 .../gcc.target/powerpc/pcrel-opt-st-hi.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-st-qi.c      |  42 +
 .../gcc.target/powerpc/pcrel-opt-st-sf.c      |  36 +
 .../gcc.target/powerpc/pcrel-opt-st-si.c      |  41 +
 .../gcc.target/powerpc/pcrel-opt-st-vector.c  |  36 +
 26 files changed, 2054 insertions(+), 9 deletions(-)
 create mode 100644 gcc/config/rs6000/pcrel-opt.md
 create mode 100644 gcc/config/rs6000/rs6000-pcrel-opt.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-inc-di.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-df.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-di.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-hi.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-qi.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-sf.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-si.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-vector.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-df.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-di.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-hi.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-qi.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-sf.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-si.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-vector.c

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 17fea83b2e4..c8853009e55 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -509,7 +509,8 @@ or1k*-*-*)
        ;;
 powerpc*-*-*)
        cpu_type=rs6000
-       extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o 
rs6000-call.o"
+       extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o"
+       extra_objs="${extra_objs} rs6000-call.o rs6000-pcrel-opt.o"
        extra_headers="ppc-asm.h altivec.h htmintrin.h htmxlintrin.h"
        extra_headers="${extra_headers} bmi2intrin.h bmiintrin.h"
        extra_headers="${extra_headers} xmmintrin.h mm_malloc.h emmintrin.h"
@@ -524,6 +525,7 @@ powerpc*-*-*)
        esac
        extra_options="${extra_options} g.opt fused-madd.opt 
rs6000/rs6000-tables.opt"
        target_gtfiles="$target_gtfiles \$(srcdir)/config/rs6000/rs6000-logue.c 
\$(srcdir)/config/rs6000/rs6000-call.c"
+       target_gtfiles="$target_gtfiles 
\$(srcdir)/config/rs6000/rs6000-pcrel-opt.c"
        ;;
 pru-*-*)
        cpu_type=pru
@@ -535,8 +537,10 @@ riscv*)
        ;;
 rs6000*-*-*)
        extra_options="${extra_options} g.opt fused-madd.opt 
rs6000/rs6000-tables.opt"
-       extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o 
rs6000-call.o"
+       extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o"
+       extra_objs="${extra_objs} rs6000-call.o rs6000-pcrel-opt.o"
        target_gtfiles="$target_gtfiles \$(srcdir)/config/rs6000/rs6000-logue.c 
\$(srcdir)/config/rs6000/rs6000-call.c"
+       target_gtfiles="$target_gtfiles 
\$(srcdir)/config/rs6000/rs6000-pcrel-opt.c"
        ;;
 sparc*-*-*)
        cpu_type=sparc
diff --git a/gcc/config/rs6000/pcrel-opt.md b/gcc/config/rs6000/pcrel-opt.md
new file mode 100644
index 00000000000..33428613acd
--- /dev/null
+++ b/gcc/config/rs6000/pcrel-opt.md
@@ -0,0 +1,399 @@
+;; Machine description for the PCREL_OPT optimization.
+;; Copyright (C) 2020-2021 Free Software Foundation, Inc.
+;; Contributed by Michael Meissner (meiss...@linux.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/>.
+
+;; Support for the PCREL_OPT optimization.  PCREL_OPT looks for instances where
+;; an external variable is used only once, either for reading or for writing.
+;;
+;; If we are optimizing a single read, normally the code would look like:
+;;
+;;     (set (reg:DI <ptr>)
+;;          (symbol_ref:DI "<extern_addr>"))   # <data> is currently dead
+;;
+;;             ...     # insns do not need to be adjacent
+;;
+;;     (set (reg:SI <data>)
+;;          (mem:SI (reg:DI <xxx>)))           # <ptr> dies with this insn
+;;
+;; We transform this into:
+;;
+;;     (parallel [(set (reg:DI <ptr>)
+;;                     (unspec:SI [(symbol_ref:DI <extern_addr>)
+;;                                 (const_int <marker>)]
+;;                                UNSPEC_PCREL_OPT_LD_ADDR))
+;;                (set (reg:DI <data>)
+;;                     (unspec:DI [(const_int 0)]
+;;                                UNSPEC_PCREL_OPT_LD_DATA))])
+;;
+;;     ...
+;;
+;;     (parallel [(set (reg:SI <data>)
+;;                (unspec:SI [(mem:SI (reg:DI <ptr>))
+;;                            (reg:DI <data>)
+;;                            (const_int <marker>)]
+;;                           UNSPEC_PCREL_OPT_LD_RELOC))
+;;                (clobber (reg:DI <ptr>))])
+;;
+;; The marker is an integer constant that links the load of the external
+;; address to the load of the actual variable.
+;;
+;; In the first insn, we set both the address of the external variable, and
+;; mark that the variable being loaded both are created in that insn, and are
+;; consumed in the second insn.         It doesn't matter what mode the 
register that
+;; we will ultimately do the load into, so we use DImode.  We just need to mark
+;; that both registers may be set in the first insn, and will be used in the
+;; second insn.
+;;
+;; Since we use UNSPEC's and link both the the register holding the external
+;; address and the value being loaded, it should prevent other passes from
+;; modifying it.
+;;
+;; If the register being loaded is the same as the base register, we use an
+;; alternate form of the insns.
+;;
+;;     (set (reg:DI <data_ptr>)
+;;          (unspec:DI [(symbol_ref:DI <extern_addr>)
+;;                      (const_int <marker>)]
+;;                     UNSPEC_PCREL_OPT_LD_SAME_REG))
+;;
+;;     ...
+;;
+;;     (parallel [(set (reg:SI <data>)
+;;                (unspec:SI [(mem:SI (reg:DI <ptr>))
+;;                            (reg:DI <data>)
+;;                            (const_int <marker>)]
+;;                           UNSPEC_PCREL_OPT_LD_RELOC))
+;;                (clobber (reg:DI <ptr>))])
+
+(define_c_enum "unspec"
+  [UNSPEC_PCREL_OPT_LD_ADDR
+   UNSPEC_PCREL_OPT_LD_DATA
+   UNSPEC_PCREL_OPT_LD_SAME_REG
+   UNSPEC_PCREL_OPT_LD_RELOC
+   UNSPEC_PCREL_OPT_ST_ADDR
+   UNSPEC_PCREL_OPT_ST_RELOC])
+
+;; Modes that are supported for PCREL_OPT
+(define_mode_iterator PCRELOPT [QI HI SI DI TI SF DF KF
+                         V1TI V2DI V4SI V8HI V16QI V2DF V4SF
+                         (TF "TARGET_FLOAT128_TYPE && TARGET_IEEEQUAD")])
+
+;; Vector modes for PCREL_OPT
+(define_mode_iterator PCRELOPT_VECT [TI KF V1TI V2DI V4SI V8HI V16QI V2DF V4SF
+                              (TF "TARGET_FLOAT128_TYPE && TARGET_IEEEQUAD")])
+
+;; Insn for loading the external address, where the register being loaded is 
not
+;; the same as the register being loaded with the data.
+(define_insn "pcrel_opt_ld_addr"
+  [(set (match_operand:DI 0 "base_reg_operand" "=&b,&b")
+       (unspec:DI [(match_operand:DI 1 "pcrel_external_address")
+                   (match_operand 2 "const_int_operand" "n,n")]
+                  UNSPEC_PCREL_OPT_LD_ADDR))
+   (set (match_operand:DI 3 "gpc_reg_operand" "=r,wa")
+       (unspec:DI [(const_int 0)]
+                  UNSPEC_PCREL_OPT_LD_DATA))]
+  "TARGET_PCREL_OPT
+   && reg_or_subregno (operands[0]) != reg_or_subregno (operands[3])"
+  "ld %0,%a1\n.Lpcrel%2:"
+  [(set_attr "prefixed" "yes")
+   (set_attr "type" "load")
+   (set_attr "loads_external_address" "yes")])
+
+;; Alternate form of loading up the external address that is the same register
+;; as the final load.
+(define_insn "pcrel_opt_ld_addr_same_reg"
+  [(set (match_operand:DI 0 "base_reg_operand" "=b")
+       (unspec:DI [(match_operand:DI 1 "pcrel_external_address")
+                   (match_operand 2 "const_int_operand" "n")]
+                  UNSPEC_PCREL_OPT_LD_SAME_REG))]
+  "TARGET_PCREL_OPT"
+  "ld %0,%a1\n.Lpcrel%2:"
+  [(set_attr "prefixed" "yes")
+   (set_attr "type" "load")
+   (set_attr "loads_external_address" "yes")])
+
+;; PCREL_OPT modes that are optimized for loading or storing GPRs.
+(define_mode_iterator PCRELOPT_GPR [QI HI SI DI SF DF])
+
+(define_mode_attr PCRELOPT_GPR_LD [(QI "lbz")
+                            (HI "lhz")
+                            (SI "lwz")
+                            (SF "lwz")
+                            (DI "ld")
+                            (DF "ld")])
+
+;; PCREL_OPT load operation of GPRs.  Operand 4 (the register used to hold the
+;; address of the external symbol) is SCRATCH if the same register is used for
+;; the normal load.
+(define_insn "*pcrel_opt_ld<mode>_gpr"
+  [(parallel [(set (match_operand:PCRELOPT_GPR 0 "int_reg_operand" "+r")
+                  (unspec:PCRELOPT_GPR [(match_operand:PCRELOPT_GPR 1 
"d_form_memory" "m")
+                                  (match_operand:DI 2 "int_reg_operand" "0")
+                                  (match_operand 3 "const_int_operand" "n")]
+                                 UNSPEC_PCREL_OPT_LD_RELOC))
+             (clobber (match_scratch:DI 4 "=bX"))])]
+  "TARGET_PCREL_OPT
+   && (GET_CODE (operands[4]) == SCRATCH
+       || reg_mentioned_p (operands[4], operands[1]))"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return "<PCRELOPT_GPR_LD> %0,%1";
+}
+  [(set_attr "type" "load")])
+
+;; PCREL_OPT load with sign/zero extension
+(define_insn "*pcrel_opt_ldsi_<u><mode>_gpr"
+  [(set (match_operand:EXTSI 0 "int_reg_operand" "+r")
+       (any_extend:EXTSI
+        (unspec:SI [(match_operand:SI 1 "d_form_memory" "m")
+                    (match_operand:DI 2 "int_reg_operand" "0")
+                    (match_operand 3 "const_int_operand" "n")]
+                    UNSPEC_PCREL_OPT_LD_RELOC)))
+   (clobber (match_scratch:DI 4 "=bX"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return "lw<az> %0,%1";
+}
+  [(set_attr "type" "load")])
+
+(define_insn "*pcrel_opt_ldhi_<u><mode>_gpr"
+  [(set (match_operand:EXTHI 0 "int_reg_operand" "+r")
+       (any_extend:EXTHI
+        (unspec:HI [(match_operand:HI 1 "d_form_memory" "m")
+                    (match_operand:DI 2 "int_reg_operand" "0")
+                    (match_operand 3 "const_int_operand" "n")]
+                    UNSPEC_PCREL_OPT_LD_RELOC)))
+   (clobber (match_scratch:DI 4 "=bX"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return "lh<az> %0,%1";
+}
+  [(set_attr "type" "load")])
+
+(define_insn "*pcrel_opt_ldqi_u<mode>_gpr"
+  [(set (match_operand:EXTQI 0 "int_reg_operand" "+r")
+       (zero_extend:EXTQI
+        (unspec:QI [(match_operand:QI 1 "d_form_memory" "m")
+                    (match_operand:DI 2 "int_reg_operand" "0")
+                    (match_operand 3 "const_int_operand" "n")]
+                    UNSPEC_PCREL_OPT_LD_RELOC)))
+   (clobber (match_scratch:DI 4 "=bX"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return "lbz %0,%1";
+}
+  [(set_attr "type" "load")])
+
+;; Scalar types that can be optimized by loading them into floating point
+;; or Altivec registers.
+(define_mode_iterator PCRELOPT_FP [DI DF SF])
+
+;; Load instructions to load up scalar floating point or 64-bit integer values
+;; into floating point registers or Altivec registers.
+(define_mode_attr PCRELOPT_FPR_LD [(DI "lfd") (DF "lfd") (SF "lfs")])
+(define_mode_attr PCRELOPT_VMX_LD [(DI "lxsd") (DF "lxsd") (SF "lxssp")])
+
+;; PCREL_OPT load operation of scalar DF/DI/SF into vector registers.
+(define_insn "*pcrel_opt_ld<mode>_vsx"
+  [(set (match_operand:PCRELOPT_FP 0 "vsx_register_operand" "+d,v")
+       (unspec:PCRELOPT_FP [(match_operand:PCRELOPT_FP 1 "d_form_memory" "m,m")
+                      (match_operand:DI 2 "vsx_register_operand" "0,0")
+                      (match_operand 3 "const_int_operand" "n,n")]
+                      UNSPEC_PCREL_OPT_LD_RELOC))
+   (clobber (match_operand:DI 4 "base_reg_operand" "=b,b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return which_alternative ? "<PCRELOPT_VMX_LD> %0,%1" : "<PCRELOPT_FPR_LD> 
%0,%1";
+}
+  [(set_attr "type" "fpload")])
+
+;; PCREL_OPT optimization extending SFmode to DFmode via a load.
+(define_insn "*pcrel_opt_ldsf_df"
+  [(set (match_operand:DF 0 "vsx_register_operand" "+d,v")
+       (float_extend:DF
+        (unspec:SF [(match_operand:SF 1 "d_form_memory" "m,m")
+                    (match_operand:DI 2 "vsx_register_operand" "0,0")
+                    (match_operand 3 "const_int_operand" "n,n")]
+                   UNSPEC_PCREL_OPT_LD_RELOC)))
+   (clobber (match_operand:DI 4 "base_reg_operand" "=b,b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return which_alternative ? "lxssp %0,%1" : "lfs %0,%1";
+}
+  [(set_attr "type" "fpload")])
+
+;; PCREL_OPT load operation of vector/float128 types into vector registers.
+(define_insn "*pcrel_opt_ld<mode>"
+  [(set (match_operand:PCRELOPT_VECT 0 "vsx_register_operand" "+wa")
+       (unspec:PCRELOPT_VECT [(match_operand:PCRELOPT_VECT 1 "d_form_memory" 
"m")
+                        (match_operand:DI 2 "vsx_register_operand" "0")
+                        (match_operand 3 "const_int_operand" "n")]
+                       UNSPEC_PCREL_OPT_LD_RELOC))
+   (clobber (match_operand:DI 4 "base_reg_operand" "=b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[3]);
+  return "lxv %x0,%1";
+}
+  [(set_attr "type" "vecload")])
+
+
+;; PCREL_OPT optimization for stores.  We need to put the label after the PLD
+;; instruction, because the assembler might insert a NOP before the PLD for
+;; alignment.
+;;
+;; If we are optimizing a single write, normally the code would look like:
+;;
+;;     (set (reg:DI <ptr>)
+;;          (symbol_ref:DI "<extern_addr>"))   # <data> must be live here
+;;
+;;         ...              # insns do not need to be adjacent
+;;
+;;     (set (mem:SI (reg:DI <xxx>))
+;;          (reg:SI <data>))                   # <ptr> dies with this insn
+;;
+;; We optimize this to be:
+;;
+;;     (parallel [(set (reg:DI <ptr>)
+;;                     (unspec:DI [(symbol_ref:DI "<extern_addr>")
+;;                                 (const_int <marker>)]
+;;                                UNSPEC_PCREL_OPT_ST_ADDR))
+;;                (use (reg:<MODE> <data>))])
+;;
+;;         ...              # insns do not need to be adjacent
+;;
+;;     (parallel [(set (mem:<MODE> (reg:DI <ptr>))
+;;                     (unspec:<MODE> [(reg:<MODE> <data>)
+;;                                     (const_int <marker>)]
+;;                                    UNSPEC_PCREL_OPT_ST_RELOC))
+;;                (clobber (reg:DI <ptr>))])
+
+(define_insn "*pcrel_opt_st_addr<mode>"
+  [(set (match_operand:DI 0 "gpc_reg_operand" "=b")
+       (unspec:DI [(match_operand:DI 1 "pcrel_external_address")
+                   (match_operand 2 "const_int_operand" "n")]
+               UNSPEC_PCREL_OPT_ST_ADDR))
+   (use (match_operand:PCRELOPT 3 "gpc_reg_operand" "rwa"))]
+  "TARGET_PCREL_OPT"
+  "ld %0,%a1\n.Lpcrel%2:"
+  [(set_attr "prefixed" "yes")
+   (set_attr "type" "load")
+   (set_attr "loads_external_address" "yes")])
+
+;; PCREL_OPT stores.
+(define_insn "*pcrel_opt_st<mode>"
+  [(set (match_operand:QHSI 0 "d_form_memory" "=m")
+       (unspec:QHSI [(match_operand:QHSI 1 "gpc_reg_operand" "r")
+                     (match_operand 2 "const_int_operand" "n")]
+                    UNSPEC_PCREL_OPT_ST_RELOC))
+   (clobber (match_operand:DI 3 "base_reg_operand" "=b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[2]);
+  return "st<wd> %1,%0";
+}
+  [(set_attr "type" "store")])
+
+(define_insn "*pcrel_opt_stdi"
+  [(set (match_operand:DI 0 "d_form_memory" "=m,m,m")
+       (unspec:DI [(match_operand:DI 1 "gpc_reg_operand" "r,d,v")
+                   (match_operand 2 "const_int_operand" "n,n,n")]
+                  UNSPEC_PCREL_OPT_ST_RELOC))
+   (clobber (match_operand:DI 3 "base_reg_operand" "=b,b,b"))]
+  "TARGET_PCREL_OPT && TARGET_POWERPC64"
+{
+  output_pcrel_opt_reloc (operands[2]);
+  switch (which_alternative)
+    {
+    case 0:
+      return "std %1,%0";
+    case 1:
+      return "stfd %1,%0";
+    case 2:
+      return "stxsd %1,%0";
+    default:
+      gcc_unreachable ();
+    }
+}
+  [(set_attr "type" "store,fpstore,fpstore")])
+
+(define_insn "*pcrel_opt_stsf"
+  [(set (match_operand:SF 0 "d_form_memory" "=m,m,m")
+       (unspec:SF [(match_operand:SF 1 "gpc_reg_operand" "d,v,r")
+                   (match_operand 2 "const_int_operand" "n,n,n")]
+                  UNSPEC_PCREL_OPT_ST_RELOC))
+   (clobber (match_operand:DI 3 "base_reg_operand" "=b,b,b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[2]);
+  switch (which_alternative)
+    {
+    case 0:
+      return "stfs %1,%0";
+    case 1:
+      return "stxssp %1,%0";
+    case 2:
+      return "stw %1,%0";
+    default:
+      gcc_unreachable ();
+    }
+}
+  [(set_attr "type" "fpstore,fpstore,store")])
+
+(define_insn "*pcrel_opt_stdf"
+  [(set (match_operand:DF 0 "d_form_memory" "=m,m,m")
+       (unspec:DF [(match_operand:DF 1 "gpc_reg_operand" "d,v,r")
+                   (match_operand 2 "const_int_operand" "n,n,n")]
+                  UNSPEC_PCREL_OPT_ST_RELOC))
+   (clobber (match_operand:DI 3 "base_reg_operand" "=b,b,b"))]
+  "TARGET_PCREL_OPT
+   && (TARGET_POWERPC64 || vsx_register_operand (operands[1], DFmode))"
+{
+  output_pcrel_opt_reloc (operands[2]);
+  switch (which_alternative)
+    {
+    case 0:
+      return "stfd %1,%0";
+    case 1:
+      return "stxsd %1,%0";
+    case 2:
+      return "std %1,%0";
+    default:
+      gcc_unreachable ();
+    }
+}
+  [(set_attr "type" "fpstore,fpstore,store")])
+
+(define_insn "*pcrel_opt_st<mode>"
+  [(set (match_operand:PCRELOPT_VECT 0 "d_form_memory" "=m")
+       (unspec:PCRELOPT_VECT [(match_operand:PCRELOPT_VECT 1 "gpc_reg_operand" 
"wa")
+                    (match_operand 2 "const_int_operand" "n")]
+                   UNSPEC_PCREL_OPT_ST_RELOC))
+   (clobber (match_operand:DI 3 "base_reg_operand" "=b"))]
+  "TARGET_PCREL_OPT"
+{
+  output_pcrel_opt_reloc (operands[2]);
+  return "stxv %x1,%0";
+}
+  [(set_attr "type" "vecstore")])
diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index bd26c62b3a4..bd6ef1e56a5 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -1904,3 +1904,24 @@ (define_predicate "prefixed_memory"
 {
   return address_is_prefixed (XEXP (op, 0), mode, NON_PREFIXED_DEFAULT);
 })
+
+;; Return true if the operand is a valid memory operand with a D-form
+;; address that could be merged with the load of a PC-relative external address
+;; with the PCREL_OPT optimization.  We don't check here whether or not the
+;; offset needs to be used in a DS-FORM (bottom 2 bits 0) or DQ-FORM (bottom 4
+;; bits 0) instruction.
+(define_predicate "d_form_memory"
+  (match_code "mem")
+{
+  if (!memory_operand (op, mode))
+    return false;
+
+  rtx addr = XEXP (op, 0);
+
+  if (REG_P (addr))
+    return true;
+  if (SUBREG_P (addr) && REG_P (SUBREG_REG (addr)))
+    return true;
+
+  return !indexed_address (addr, mode);
+})
diff --git a/gcc/config/rs6000/rs6000-cpus.def 
b/gcc/config/rs6000/rs6000-cpus.def
index f0cf79e2982..cbbb42c1b3a 100644
--- a/gcc/config/rs6000/rs6000-cpus.def
+++ b/gcc/config/rs6000/rs6000-cpus.def
@@ -77,6 +77,7 @@
 /* Flags that need to be turned off if -mno-power10.  */
 #define OTHER_POWER10_MASKS    (OPTION_MASK_MMA                        \
                                 | OPTION_MASK_PCREL                    \
+                                | OPTION_MASK_PCREL_OPT                \
                                 | OPTION_MASK_PREFIXED)
 
 #define ISA_3_1_MASKS_SERVER   (ISA_3_0_MASKS_SERVER                   \
@@ -147,6 +148,7 @@
                                 | OPTION_MASK_P9_MISC                  \
                                 | OPTION_MASK_P9_VECTOR                \
                                 | OPTION_MASK_PCREL                    \
+                                | OPTION_MASK_PCREL_OPT                \
                                 | OPTION_MASK_POPCNTB                  \
                                 | OPTION_MASK_POPCNTD                  \
                                 | OPTION_MASK_POWERPC64                \
diff --git a/gcc/config/rs6000/rs6000-passes.def 
b/gcc/config/rs6000/rs6000-passes.def
index 606ad3e14a2..c8e46ba6abe 100644
--- a/gcc/config/rs6000/rs6000-passes.def
+++ b/gcc/config/rs6000/rs6000-passes.def
@@ -24,4 +24,12 @@ along with GCC; see the file COPYING3.  If not see
    REPLACE_PASS (PASS, INSTANCE, TGT_PASS)
  */
 
+  /* Pass to add the appropriate vector swaps on power8 little endian systems.
+     The power8 does not have instructions that automaticaly do the byte swaps
+     for loads and stores.  */
   INSERT_PASS_BEFORE (pass_cse, 1, pass_analyze_swaps);
+
+  /* Pass to do the PCREL_OPT optimization that combines the load of an
+     external symbol's address along with a single load or store using that
+     address as a base register.  */
+  INSERT_PASS_BEFORE (pass_sched2, 1, pass_pcrel_opt);
diff --git a/gcc/config/rs6000/rs6000-pcrel-opt.c 
b/gcc/config/rs6000/rs6000-pcrel-opt.c
new file mode 100644
index 00000000000..9a3defd0478
--- /dev/null
+++ b/gcc/config/rs6000/rs6000-pcrel-opt.c
@@ -0,0 +1,924 @@
+/* Subroutines used support the pc-relative linker optimization.
+   Copyright (C) 2020-2021 Free Software Foundation, Inc.
+
+   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/>.  */
+
+/* This file implements a RTL pass that looks for pc-relative loads of the
+   address of an external variable using the PCREL_GOT relocation and a single
+   load that uses that external address.  If that is found we create the
+   PCREL_OPT relocation to possibly convert:
+
+       pld addr_reg,var@pcrel@got
+
+       <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+       lwz data_reg,0(addr_reg)
+
+   into:
+
+       plwz data_reg,var@pcrel
+
+       <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+       nop
+
+   Of course it would be nice to be able to put the plwz in this example in
+   place of the lwz but the linker cannot easily replace a 4-byte instruction
+   with an 8-byte one. 
+
+   If the variable is not defined in the main program or the code using it is
+   not in the main program, the linker puts the address in the .got section and
+   generates:
+
+               .section .got
+       .Lvar_got:
+               .dword var
+
+   At the point where it is referenced, we have:
+
+               .section .text
+               pld addr_reg,.Lvar_got@pcrel
+
+               <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+               lwz data_reg,0(addr_reg)
+
+   We look for a single usage in the basic block where this external
+   address is loaded, and convert it to a PCREL_OPT relocation so the
+   linker can convert it to a single plwz in this case.  Multiple uses
+   or references in another basic block will force us to not use the
+   PCREL_OPT relocation.
+
+   We also optimize stores to the address of an external variable using the
+   PCREL_GOT relocation and a single store that uses that external address.  If
+   that is found we create the PCREL_OPT relocation to possibly convert:
+
+       pld addr_reg,var@pcrel@got
+
+       <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+       stw data_reg,0(addr_reg)
+
+   into:
+
+       pstw data_reg,var@pcrel
+
+       <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+       nop
+
+   If the variable is not defined in the main program or the code using it is
+   not in the main program, the linker puts the address in the .got section and
+   generates:
+
+               .section .got
+       .Lvar_got:
+               .dword var
+
+   And at our point of reference we have:
+
+               .section .text
+               pld addr_reg,.Lvar_got@pcrel
+
+               <possibly other insns that do not use 'addr_reg' or 'data_reg'>
+
+               stw data_reg,0(addr_reg)
+
+   We only look for a single usage in the basic block where the external
+   address is loaded.  Multiple uses or references in another basic block will
+   force us to not use the PCREL_OPT relocation.  */
+
+#define IN_TARGET_CODE 1
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "backend.h"
+#include "rtl.h"
+#include "tree.h"
+#include "memmodel.h"
+#include "expmed.h"
+#include "optabs.h"
+#include "recog.h"
+#include "df.h"
+#include "tm_p.h"
+#include "ira.h"
+#include "print-tree.h"
+#include "varasm.h"
+#include "explow.h"
+#include "expr.h"
+#include "output.h"
+#include "tree-pass.h"
+#include "rtx-vector-builder.h"
+#include "print-rtl.h"
+#include "insn-attr.h"
+#include "insn-codes.h"
+
+/* Various counters.  */
+static struct {
+  unsigned long extern_addrs;
+  unsigned long loads;
+  unsigned long adjacent_loads;
+  unsigned long failed_loads;
+  unsigned long stores;
+  unsigned long adjacent_stores;
+  unsigned long failed_stores;
+} counters;
+
+/* Unique integer that is appended to .Lpcrel to make a pcrel_opt label. */
+static unsigned int pcrel_opt_next_num;
+
+
+/* Optimize a PC-relative load address to be used in a load. Before it calls
+   this function, pcrel_opt_address () uses DF to make sure that it is safe
+   to do the PCREL_OPT optimization on these insns.
+
+   Convert insns of the form:
+
+       (set (reg:DI addr)
+            (symbol_ref:DI "ext_symbol"))
+
+       ...
+
+       (set (reg:<MODE> value)
+            (mem:<MODE> (reg:DI addr)))
+
+   into:
+
+       (parallel [(set (reg:DI addr)
+                       (unspec:<MODE> [(symbol_ref:DI "ext_symbol")
+                                       (const_int label_num)]
+                                      UNSPEC_PCREL_OPT_LD_ADDR))
+                  (set (reg:DI data)
+                       (unspec:DI [(const_int 0)]
+                                  UNSPEC_PCREL_OPT_LD_DATA))])
+
+       ...
+
+       (parallel [(set (reg:<MODE>)
+                       (unspec:<MODE> [(mem:<MODE> (reg:DI addr))
+                                       (reg:DI data)
+                                       (const_int label_num)]
+                                      UNSPEC_PCREL_OPT_LD_RELOC))
+                  (clobber (reg:DI addr))])
+
+   Because PCREL_OPT will move the actual location of the load from the second
+   insn to the first, we need to have the register for the load data be live
+   starting at the first insn.
+
+   If the destination register for the data being loaded is the same register
+   used to hold the extern address, we generate this insn instead:
+
+       (set (reg:DI data)
+            (unspec:DI [(symbol_ref:DI "ext_symbol")
+                        (const_int label_num)]
+                       UNSPEC_PCREL_OPT_LD_SAME_REG))
+
+   In the first insn, we set both the address of the external variable, and 
mark
+   that the variable being loaded both are created in that insn, and are
+   consumed in the second insn.  The mode used in the first insn for the data
+   register that will be loaded in the second insn doesn't matter in the end so
+   we use DImode.  We just need to mark that both registers may be set in the
+   first insn, and will be used in the second insn.
+
+   The UNSPEC_PCREL_OPT_LD_ADDR insn will generate the load address plus
+   a definition of a label (.Lpcrel<n>), while the UNSPEC_PCREL_OPT_LD_RELOC
+   insn will generate the .reloc to tell the linker to tie the load address and
+   load using that address together.
+
+       pld b,ext_symbol@got@pcrel
+   .Lpcrel1:
+
+       ...
+
+       .reloc .Lpcrel1-8,R_PPC64_PCREL_OPT,.-(.Lpcrel1-8)
+       lwz r,0(b)
+
+   If ext_symbol is defined in another object file in the main program and we
+   are linking the main program, the linker will convert the above instructions
+   to:
+
+       plwz r,ext_symbol@got@pcrel
+
+       ...
+
+       nop  
+
+   ADDR_INSN is the insn that is loading the address.
+   LOAD_INSN is the insn that uses the address to load the actual data.  */
+
+static void
+pcrel_opt_load (rtx_insn *addr_insn, rtx_insn *load_insn)
+{
+  rtx addr_set = PATTERN (addr_insn);
+  gcc_assert (GET_CODE (addr_set) == SET);
+
+  rtx addr_reg = SET_DEST (addr_set);
+  gcc_assert (base_reg_operand (addr_reg, Pmode));
+
+  rtx addr_symbol = SET_SRC (addr_set);
+  gcc_assert (pcrel_external_address (addr_symbol, Pmode));
+
+  rtx load_set = PATTERN (load_insn);
+  gcc_assert (GET_CODE (load_set) == SET);
+
+  /* Make sure there are no references to the register being loaded
+     between the two insns.  */
+  rtx reg = SET_DEST (load_set);
+  if (reg_used_between_p (reg, addr_insn, load_insn)
+      || reg_set_between_p (reg, addr_insn, load_insn))
+    return;
+
+  rtx mem = SET_SRC (load_set);
+  machine_mode reg_mode = GET_MODE (reg);
+  machine_mode mem_mode = GET_MODE (mem);
+  rtx mem_inner = mem;
+  unsigned int reg_regno = reg_or_subregno (reg);
+
+  /* Handle the fact that LWA is a DS format instruction, but LWZ is a D format
+     instruction.  If the mem load is a signed SImode (i.e. LWA would be used)
+     we set mem_mode to DImode so that pcrel_opt_valid_mem_p() will check that
+     the address will work for a DS-form instruction. If it won't work, we skip
+     the optimization.  The float loads are all indexed so there are no 
problems
+     there.  */
+
+  if (GET_CODE (mem) == SIGN_EXTEND && GET_MODE (XEXP (mem, 0)) == SImode)
+    {
+      if (!INT_REGNO_P (reg_regno))
+       return;
+
+      mem_inner = XEXP (mem, 0);
+      mem_mode = DImode;
+    }
+
+  else if (GET_CODE (mem) == SIGN_EXTEND
+          || GET_CODE (mem) == ZERO_EXTEND
+          || GET_CODE (mem) == FLOAT_EXTEND)
+    {
+      mem_inner = XEXP (mem, 0);
+      mem_mode = GET_MODE (mem_inner);
+    }
+
+  if (!MEM_P (mem_inner))
+    return;
+
+  /* Can we do PCREL_OPT for this reference?  */
+  if (!pcrel_opt_valid_mem_p (reg, mem_mode, mem_inner))
+    return;
+
+  /* Allocate a new PC-relative label, and update the load external address
+     insn.
+
+     If the register being loaded is different from the address register, we
+     need to indicate both registers are set at the load of the address.
+
+       (parallel [(set (reg load)
+                       (unspec [(symbol_ref addr_symbol)
+                                (const_int label_num)]
+                               UNSPEC_PCREL_OPT_LD_ADDR))
+                  (set (reg addr)
+                       (unspec [(const_int 0)]
+                               UNSPEC_PCREL_OPT_LD_DATA))])
+
+     If the register being loaded is the same as the address register, we use
+     an alternate form:
+
+       (set (reg load)
+            (unspec [(symbol_ref addr_symbol)
+                     (const_int label_num)]
+                    UNSPEC_PCREL_OPT_LD_SAME_REG))  */
+  unsigned int addr_regno = reg_or_subregno (addr_reg);
+  rtx label_num = GEN_INT (++pcrel_opt_next_num);
+  rtx reg_di = gen_rtx_REG (DImode, reg_regno);
+  rtx addr_pattern;
+
+  /* Create the load address, either using the pattern with an explicit clobber
+     if the address register is not the same as the register being loaded, or
+     using the pattern that requires the address register to be the address
+     loaded.  */
+  if (addr_regno != reg_regno)
+    addr_pattern = gen_pcrel_opt_ld_addr (addr_reg, addr_symbol, label_num,
+                                         reg_di);
+  else
+    addr_pattern = gen_pcrel_opt_ld_addr_same_reg (addr_reg, addr_symbol,
+                                                  label_num);
+
+  validate_change (addr_insn, &PATTERN (addr_insn), addr_pattern, false);
+
+  /* Update the load insn.  If the mem had a sign/zero/float extend, add that
+     also after doing the UNSPEC.  Add an explicit clobber of the external
+     address register just to make it clear that the address register dies.
+
+       (parallel [(set (reg:<MODE> data)
+                       (unspec:<MODE> [(mem (addr_reg)
+                                       (reg:DI data)
+                                       (const_int label_num)]
+                                      UNSPEC_PCREL_OPT_LD_RELOC))
+                  (clobber (reg:DI addr_reg))])  */
+  rtvec v_load = gen_rtvec (3, mem_inner, reg_di, label_num);
+  rtx new_load = gen_rtx_UNSPEC (GET_MODE (mem_inner), v_load,
+                                UNSPEC_PCREL_OPT_LD_RELOC);
+
+  if (GET_CODE (mem) != GET_CODE (mem_inner))
+    new_load = gen_rtx_fmt_e (GET_CODE (mem), reg_mode, new_load);
+
+  rtx new_load_set = gen_rtx_SET (reg, new_load);
+  rtx load_clobber = gen_rtx_CLOBBER (VOIDmode,
+                                     (addr_regno == reg_regno
+                                      ? gen_rtx_SCRATCH (Pmode)
+                                      : addr_reg));
+  rtx new_load_pattern
+    = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, new_load_set, load_clobber));
+
+  validate_change (load_insn, &PATTERN (load_insn), new_load_pattern, false);
+
+  /* Attempt to apply the changes:  */
+  if (!apply_change_group ())
+    {
+      /* PCREL_OPT load optimization did not succeed.  */
+      counters.failed_loads++;
+      if (dump_file)
+       fprintf (dump_file,
+                "PCREL_OPT load failed (addr insn = %d, use insn = %d).\n",
+                INSN_UID (addr_insn),
+                INSN_UID (load_insn));
+      return;
+    }
+
+  /* PCREL_OPT load optimization succeeded.  */
+  counters.loads++;
+  if (next_nonnote_insn (addr_insn) == load_insn)
+    counters.adjacent_loads++;
+  
+  if (dump_file)
+    fprintf (dump_file,
+            "PCREL_OPT load (addr insn = %d, use insn = %d).\n",
+            INSN_UID (addr_insn),
+            INSN_UID (load_insn));
+  
+  /* Because we have set DF_DEFER_INSN_RESCAN, we have to explicitly do it
+     after we have made changes to the insns.  */
+  df_analyze ();
+
+}
+
+/* Optimize a PC-relative load address to be used in a store. Before calling
+   this function, pcrel_opt_address () uses DF to make sure it is safe to do 
+   the PCREL_OPT optimization.
+
+   Convert insns of the form:
+
+       (set (reg:DI addr)
+            (symbol_ref:DI "ext_symbol"))
+
+       ...
+
+       (set (mem:<MODE> (reg:DI addr))
+            (reg:<MODE> value))
+
+   into:
+
+       (parallel [(set (reg:DI addr)
+                       (unspec:DI [(symbol_ref:DI "ext_symbol")
+                                   (const_int label_num)]
+                                 UNSPEC_PCREL_OPT_ST_ADDR))
+                 (use (reg:<MODE> value))])
+
+       ...
+
+       (parallel [(set (mem:<MODE> (reg:DI addr))
+                       (unspec:<MODE> [(reg:<MODE>)
+                                       (const_int label_num)]
+                                      UNSPEC_PCREL_OPT_ST_RELOC))
+                  (clobber (reg:DI addr))])
+
+   The UNSPEC_PCREL_OPT_ST_ADDR insn will generate the load address plus a
+   definition of a label (.Lpcrel<n>), while the UNSPEC_PCREL_OPT_ST_RELOC insn
+   will generate the .reloc to tell the linker to tie the load address and load
+   using that address together.
+
+       pld b,ext_symbol@got@pcrel
+   .Lpcrel1:
+
+       ...
+
+       .reloc .Lpcrel1-8,R_PPC64_PCREL_OPT,.-(.Lpcrel1-8)
+       stw r,0(b)
+
+   If ext_symbol is defined in another object file in the main program and we
+   are linking the main program, the linker will convert the above instructions
+   to:
+
+       pstwz r,ext_symbol@got@pcrel
+
+       ...
+
+       nop  */
+
+static void
+pcrel_opt_store (rtx_insn *addr_insn,          /* insn loading address.  */
+                rtx_insn *store_insn)          /* insn using address.  */
+{
+  rtx addr_old_set = PATTERN (addr_insn);
+  gcc_assert (GET_CODE (addr_old_set) == SET);
+
+  rtx addr_reg = SET_DEST (addr_old_set);
+  gcc_assert (base_reg_operand (addr_reg, Pmode));
+
+  rtx addr_symbol = SET_SRC (addr_old_set);
+  gcc_assert (pcrel_external_address (addr_symbol, Pmode));
+
+  rtx store_set = PATTERN (store_insn);
+  gcc_assert (GET_CODE (store_set) == SET);
+
+  rtx mem = SET_DEST (store_set);
+  if (!MEM_P (mem))
+    return;
+
+  machine_mode mem_mode = GET_MODE (mem);
+  rtx reg = SET_SRC (store_set);
+
+  /* Don't allow storing the address of the external variable.  */
+  if (reg_or_subregno (reg) == reg_or_subregno (addr_reg))
+    return;
+
+  /* Can we do PCREL_OPT for this reference?  */
+  if (!pcrel_opt_valid_mem_p (reg, mem_mode, mem))
+    return;
+
+  /* Allocate a new PC-relative label, and update the load address insn.
+
+       (parallel [(set (reg addr)
+                      (unspec [(symbol_ref symbol)
+                                (const_int label_num)]
+                               UNSPEC_PCREL_OPT_ST_ADDR))
+                 (use (reg store))])  
+  */
+  rtx label_num = GEN_INT (++pcrel_opt_next_num);
+  rtvec v_addr = gen_rtvec (2, addr_symbol, label_num);
+  rtx addr_unspec = gen_rtx_UNSPEC (Pmode, v_addr,
+                                  UNSPEC_PCREL_OPT_ST_ADDR);
+  rtx addr_new_set = gen_rtx_SET (addr_reg, addr_unspec);
+  rtx addr_use = gen_rtx_USE (VOIDmode, reg);
+  rtx addr_new_pattern
+    = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, addr_new_set, addr_use));
+
+  validate_change (addr_insn, &PATTERN (addr_insn), addr_new_pattern, false);
+
+  /* Update the store insn.  Add an explicit clobber of the external address
+     register just to be sure there are no additional uses of the address
+     register.
+
+       (parallel [(set (mem (addr_reg)
+                       (unspec:<MODE> [(reg)
+                                       (const_int label_num)]
+                                      UNSPEC_PCREL_OPT_ST_RELOC))
+                 (clobber (reg:DI addr_reg))])  */
+  rtvec v_store = gen_rtvec (2, reg, label_num);
+  rtx new_store = gen_rtx_UNSPEC (mem_mode, v_store,
+                                 UNSPEC_PCREL_OPT_ST_RELOC);
+
+  rtx new_store_set = gen_rtx_SET (mem, new_store);
+  rtx store_clobber = gen_rtx_CLOBBER (VOIDmode, addr_reg);
+  rtx new_store_pattern
+    = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, new_store_set, store_clobber));
+
+  validate_change (store_insn, &PATTERN (store_insn), new_store_pattern, 
false);
+
+  /* Attempt to apply the changes:  */
+  if (!apply_change_group ())
+    {
+      /* PCREL_OPT store failed.  */
+      counters.failed_stores++;
+      if (dump_file)
+       fprintf (dump_file,
+                "PCREL_OPT store failed (addr insn = %d, use insn = %d).\n",
+                INSN_UID (addr_insn),
+                INSN_UID (store_insn));
+      return;
+    }
+
+  /* PCREL_OPT store succeeded.  */
+  counters.stores++;
+  if (next_nonnote_insn (addr_insn) == store_insn)
+    counters.adjacent_stores++;
+  
+  if (dump_file)
+    fprintf (dump_file,
+            "PCREL_OPT store (addr insn = %d, use insn = %d).\n",
+            INSN_UID (addr_insn),
+            INSN_UID (store_insn));
+  
+  /* Because we have set DF_DEFER_INSN_RESCAN, we have to explicitly do it
+     after we have made changes to the insns.  */
+  df_analyze();
+
+}
+
+/* Return the register used as the base register of MEM, if the instruction has
+   a pc-relative form.  We look for BSWAP to rule out LFIWAX/LFIWZX/STFIWX, and
+   ROTATE/VEC_SELECT are RTX_EXTRA not RTX_UNARY which rules out lxvd2x. This
+   excludes instructions that do not have a pc-relative form.  */
+
+static rtx
+get_mem_base_reg (rtx mem)
+{
+  const char * fmt;
+
+  while (!MEM_P (mem))
+    {
+      switch (GET_CODE (mem))
+       {
+       case BSWAP:            /* LFIWAX/LFIWZX/STFIWX.  */
+       case UNSPEC:
+       case UNSPEC_VOLATILE:   /* Leave this alone for obvious reasons.  */
+       case ROTATE:           /* lxvd2x.  */
+       case VEC_SELECT:
+         return NULL_RTX;
+       default: ;
+       }
+      if (GET_RTX_CLASS (GET_CODE (mem)) != RTX_UNARY)
+       return NULL_RTX;
+      /* Rule out LFIWAX/LFIWZX/STFIWX.  */
+      if (GET_CODE (mem) == BSWAP)
+       return NULL_RTX;
+      fmt = GET_RTX_FORMAT (GET_CODE (mem));
+      if (fmt[0] != 'e')
+       return NULL_RTX;
+      mem = XEXP (mem, 0);
+      if (mem == NULL_RTX )
+       return NULL_RTX;
+    }
+
+  if (!MEM_SIZE_KNOWN_P (mem))
+    return NULL_RTX;
+
+  rtx addr_rtx = (XEXP (mem, 0));
+  if (GET_CODE (addr_rtx) == PRE_MODIFY)
+    addr_rtx = XEXP (addr_rtx, 1);
+
+  while (GET_CODE (addr_rtx) == PLUS
+        && CONST_INT_P (XEXP (addr_rtx, 1)))
+    addr_rtx = XEXP (addr_rtx, 0);
+
+  if (!REG_P (addr_rtx))
+    return NULL_RTX;
+
+  return addr_rtx;
+}
+
+/* Check whether INSN contains a reference to REGNO that will inhibit the
+   PCREL_OPT optimization.  If TYPE is a load or store instruction, return true
+   if there is a definition of REGNO.  If TYPE is a load instruction, then
+   return true of there is a use of REGNO.  */
+
+static bool
+insn_references_regno_p (rtx_insn *insn, unsigned int regno,
+                      enum attr_type type)
+{
+  struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+  /* If we don't have the insn_info for some reason, do not attempt to optimize
+     this reference.  */
+  if (!insn_info)
+    return true;
+
+  df_ref ref;
+
+  /* Return true if there is a definition of REGNO.  */
+  for (ref = DF_INSN_INFO_DEFS (insn_info); ref; ref = DF_REF_NEXT_LOC (ref))
+    if (DF_REF_REGNO (ref) == regno)
+      return true;
+
+  /* If type is a load, return true if there is a use of REGNO.  */
+  if (type == TYPE_LOAD
+      || type == TYPE_FPLOAD
+      || type == TYPE_VECLOAD)
+    for (ref = DF_INSN_INFO_USES (insn_info); ref; ref = DF_REF_NEXT_LOC (ref))
+      if (DF_REF_REGNO (ref) == regno)
+       return true;
+
+  return false;
+}
+
+/* Given an insn that loads up a base register with the address of an
+   external symbol, see if we can optimize it with the PCREL_OPT
+   optimization.
+
+   DF is used to make sure that there is exactly one definition and one
+   non-debug use of the address register defined by the insn. The use insn must
+   be a non-prefix insn, and must also be in the same basic block as the 
address
+   insn.
+
+   ADDR_INSN is the insn that loads the external symbol address.  */
+
+static void
+pcrel_opt_address (rtx_insn *addr_insn)
+{
+  counters.extern_addrs++;
+
+  /* Do some basic validation.  */
+  rtx addr_set = PATTERN (addr_insn);
+  if (GET_CODE (addr_set) != SET)
+    return;
+
+  rtx addr_reg = SET_DEST (addr_set);
+  rtx addr_symbol = SET_SRC (addr_set);
+
+  if (!base_reg_operand (addr_reg, Pmode)
+      || !pcrel_external_address (addr_symbol, Pmode))
+    return;
+
+  /* The address register must have exactly one definition.  */
+  struct df_insn_info *insn_info = DF_INSN_INFO_GET (addr_insn);
+  if (!insn_info)
+    return;
+
+  df_ref def = df_single_def (insn_info);
+  if (!def)
+    return;
+
+  /* Make sure there is at least one use.  */
+  df_link *chain = DF_REF_CHAIN (def);
+  if (!chain || !chain->ref)
+    return;
+
+  /* Get the insn of the possible load or store.  */
+  rtx_insn *use_insn = DF_REF_INSN (chain->ref);
+
+  /* Ensure there are no other uses.  */
+  for (chain = chain->next; chain; chain = chain->next)
+    if (chain->ref && DF_REF_INSN_INFO (chain->ref))
+      {
+       gcc_assert (DF_REF_INSN (chain->ref));
+       if (NONDEBUG_INSN_P (DF_REF_INSN (chain->ref)))
+         return;
+      }
+
+  /* The use instruction must be a single non-prefixed instruction.  */
+  if (get_attr_length (use_insn) != 4)
+    return;
+
+  /* The address and the memory operation must be in the same basic block.  */
+  if (BLOCK_FOR_INSN (use_insn) != BLOCK_FOR_INSN (addr_insn))
+    return;
+
+  /* If this isn't a simple SET, skip doing the optimization.  */
+  if (GET_CODE (PATTERN (use_insn)) != SET)
+    return;
+
+  enum attr_type use_insn_type = get_attr_type (use_insn);
+  unsigned int use_regno;
+
+  /* Make sure the use_insn is using addr_reg as its base register 
+     for the load or store, and determine the regno for the register
+     used in the use_insn.  */
+  rtx use_dest, use_src;
+  switch (use_insn_type)
+    {
+    case TYPE_LOAD:
+    case TYPE_FPLOAD:
+    case TYPE_VECLOAD:
+      /* Make sure our address register is the same register used in the
+        base address of the load.  */
+      if (addr_reg != get_mem_base_reg (SET_SRC (PATTERN (use_insn))))
+       return;
+      /* Make sure we are setting a register before we look at REGNO.  */
+      use_dest = SET_DEST (PATTERN (use_insn));
+      if (!register_operand (use_dest, GET_MODE (use_dest)))
+       return;
+      use_regno = REGNO (use_dest);
+      break;
+    case TYPE_STORE:
+    case TYPE_FPSTORE:
+    case TYPE_VECSTORE:
+      /* Make sure our address register is the same register used in the
+        base address of the store.  */
+      if (addr_reg != get_mem_base_reg (SET_DEST (PATTERN (use_insn))))
+       return;
+      /* Make sure this is a register before we look at REGNO.  */
+      use_src = SET_SRC (PATTERN (use_insn));
+      if (!register_operand (use_src, GET_MODE (use_src)))
+       return;
+      use_regno = REGNO (use_src);
+      break;
+    default:
+      /* We can only optimize loads and stores.  Ignore everything else.  */
+      return;
+    }
+
+  rtx_insn *insn;
+  for (insn = NEXT_INSN (addr_insn);
+       insn != use_insn;
+       insn = NEXT_INSN (insn))
+    {
+      /* If we see a call, do not do the PCREL_OPT optimization.  */
+      if (CALL_P (insn))
+       return;
+
+      /* For a normal insn, see if it is a load or store.  */
+      if (NONDEBUG_INSN_P (insn)
+         && GET_CODE (PATTERN (insn)) != USE
+         && GET_CODE (PATTERN (insn)) != CLOBBER)
+       {
+         switch (get_attr_type (insn))
+           {
+           case TYPE_LOAD:
+             /* While load of the external address is a 'load' for scheduling
+                purposes, it should be safe to allow loading other external
+                addresses between the load of the external address we are
+                currently looking at and the load or store using that
+                address.  */
+             if (get_attr_loads_external_address (insn)
+                 == LOADS_EXTERNAL_ADDRESS_YES)
+               break;
+             /* fall through */
+
+           case TYPE_FPLOAD:
+           case TYPE_VECLOAD:
+             /* Don't do the PCREL_OPT store optimization if there is a load
+                operation.  For example, the load might be trying to load the
+                value being stored in between getting the address and doing
+                the store.  */
+             if (use_insn_type == TYPE_STORE
+                 || use_insn_type == TYPE_FPSTORE
+                 || use_insn_type == TYPE_VECSTORE)
+               return;
+             break;
+
+           case TYPE_STORE:
+           case TYPE_FPSTORE:
+           case TYPE_VECSTORE:
+             /* Don't do the PCREL_OPT load optimization if there is a store
+                operation.  Perhaps the store might be to the global variable
+                through a pointer.  */
+             return;
+
+           case TYPE_LOAD_L:
+           case TYPE_STORE_C:
+           case TYPE_HTM:
+           case TYPE_HTMSIMPLE:
+             /* Don't do the optimization through atomic operations.  */
+             return;
+
+           default:
+             break;
+           }
+       }
+
+      /* Check for invalid references of the non-address register that is
+        used in the load or store instruction.  */
+      if (insn_references_regno_p (insn, use_regno, use_insn_type))
+       return;
+    }
+
+  /* Is this a load or a store?  */
+  switch (use_insn_type)
+    {
+    case TYPE_LOAD:
+    case TYPE_FPLOAD:
+    case TYPE_VECLOAD:
+      pcrel_opt_load (addr_insn, use_insn);
+      break;
+
+    case TYPE_STORE:
+    case TYPE_FPSTORE:
+    case TYPE_VECSTORE:
+      pcrel_opt_store (addr_insn, use_insn);
+      break;
+
+    default:
+      gcc_unreachable ();
+    }
+}
+
+/* Optimize pcrel external variable references.  */
+
+static unsigned int
+pcrel_opt_pass (function *fun)
+{
+  basic_block bb;
+  rtx_insn *insn, *curr_insn = 0;
+
+  memset (&counters, 0, sizeof (counters));
+
+  /* Dataflow analysis for use-def chains.  However we have to specify both UD
+   and DU as otherwise when we make changes to insns for the PCREL_OPT there
+   will be dangling references.  */
+  df_set_flags (DF_RD_PRUNE_DEAD_DEFS);
+  df_chain_add_problem (DF_DU_CHAIN + DF_UD_CHAIN);
+  df_note_add_problem ();
+  df_analyze ();
+
+  /* Set the defer flag as our pattern of operation will be to modify two 
insns,
+     then call df_analyze ().  */
+  df_set_flags (DF_DEFER_INSN_RESCAN | DF_LR_RUN_DCE);
+
+  if (dump_file)
+    fprintf (dump_file, "\n");
+
+  /* Look at each basic block to see if there is a load of an external
+     variable's external address, and a single load/store using that external
+     address.  */
+  FOR_ALL_BB_FN (bb, fun)
+    {
+      FOR_BB_INSNS_SAFE (bb, insn, curr_insn)
+       {
+         if (NONJUMP_INSN_P (insn)
+             && single_set (insn)
+             && get_attr_loads_external_address (insn)
+             == LOADS_EXTERNAL_ADDRESS_YES)
+           pcrel_opt_address (insn);
+       }
+    }
+
+  if (dump_file)
+    {
+      fprintf (dump_file,
+              "\n# of loads of an address of an external symbol = %lu\n",
+              counters.extern_addrs);
+
+      fprintf (dump_file, "# of PCREL_OPT loads = %lu (adjacent %lu)\n",
+              counters.loads, counters.adjacent_loads);
+
+      if (counters.failed_loads)
+       fprintf (dump_file, "# of failed PCREL_OPT loads = %lu\n",
+                counters.failed_loads);
+
+      fprintf (dump_file, "# of PCREL_OPT stores = %lu (adjacent %lu)\n",
+              counters.stores, counters.adjacent_stores);
+
+      if (counters.failed_stores)
+       fprintf (dump_file, "# of failed PCREL_OPT stores = %lu\n",
+                counters.failed_stores);
+
+      fprintf (dump_file, "\n");
+    }
+
+  df_remove_problem (df_chain);
+  df_process_deferred_rescans ();
+  df_set_flags (DF_RD_PRUNE_DEAD_DEFS | DF_LR_RUN_DCE);
+  df_analyze ();
+  return 0;
+}
+
+/* Optimize pc-relative references for the new PCREL_OPT pass.  */
+const pass_data pass_data_pcrel_opt =
+{
+  RTL_PASS,                    /* type.  */
+  "pcrel_opt",                 /* name.  */
+  OPTGROUP_NONE,               /* optinfo_flags.  */
+  TV_NONE,                     /* tv_id.  */
+  0,                           /* properties_required.  */
+  0,                           /* properties_provided.  */
+  0,                           /* properties_destroyed.  */
+  0,                           /* todo_flags_start.  */
+  TODO_df_finish,              /* todo_flags_finish.  */
+};
+
+/* Pass data structures.  */
+class pcrel_opt : public rtl_opt_pass
+{
+public:
+  pcrel_opt (gcc::context *ctxt)
+  : rtl_opt_pass (pass_data_pcrel_opt, ctxt)
+  {}
+
+  ~pcrel_opt (void)
+  {}
+
+  /* opt_pass methods:  */
+  virtual bool gate (function *)
+  {
+    return (TARGET_PCREL && TARGET_PCREL_OPT && optimize);
+  }
+
+  virtual unsigned int execute (function *fun)
+  {
+    return pcrel_opt_pass (fun);
+  }
+
+  opt_pass *clone ()
+  {
+    return new pcrel_opt (m_ctxt);
+  }
+};
+
+rtl_opt_pass *
+make_pass_pcrel_opt (gcc::context *ctxt)
+{
+  return new pcrel_opt (ctxt);
+}
diff --git a/gcc/config/rs6000/rs6000-protos.h 
b/gcc/config/rs6000/rs6000-protos.h
index d9d44fe9821..203660b0a78 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -193,10 +193,13 @@ extern enum insn_form address_to_insn_form (rtx, 
machine_mode,
                                            enum non_prefixed_form);
 extern bool address_is_non_pfx_d_or_x (rtx addr, machine_mode mode,
                                       enum non_prefixed_form 
non_prefix_format);
+extern bool pcrel_opt_valid_mem_p (rtx, machine_mode, rtx);
+enum non_prefixed_form reg_to_non_prefixed (rtx reg, machine_mode mode);
 extern bool prefixed_load_p (rtx_insn *);
 extern bool prefixed_store_p (rtx_insn *);
 extern bool prefixed_paddi_p (rtx_insn *);
 extern void rs6000_asm_output_opcode (FILE *);
+extern void output_pcrel_opt_reloc (rtx);
 extern void rs6000_final_prescan_insn (rtx_insn *, rtx [], int);
 extern int rs6000_adjust_insn_length (rtx_insn *, int);
 
@@ -309,6 +312,7 @@ namespace gcc { class context; }
 class rtl_opt_pass;
 
 extern rtl_opt_pass *make_pass_analyze_swaps (gcc::context *);
+extern rtl_opt_pass *make_pass_pcrel_opt (gcc::context *);
 extern bool rs6000_sum_of_two_registers_p (const_rtx expr);
 extern bool rs6000_quadword_masked_address_p (const_rtx exp);
 extern rtx rs6000_gen_lvx (enum machine_mode, rtx, rtx);
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index ec068c58aa5..5edbe3293c6 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -1173,7 +1173,6 @@ static bool rs6000_secondary_reload_move (enum 
rs6000_reg_type,
                                          machine_mode,
                                          secondary_reload_info *,
                                          bool);
-static enum non_prefixed_form reg_to_non_prefixed (rtx reg, machine_mode mode);
 rtl_opt_pass *make_pass_analyze_swaps (gcc::context*);
 
 /* Hash table stuff for keeping track of TOC entries.  */
@@ -4452,6 +4451,9 @@ rs6000_option_override_internal (bool global_init_p)
       rs6000_isa_flags &= ~OPTION_MASK_MMA;
     }
 
+  if (!TARGET_PCREL && TARGET_PCREL_OPT)
+    rs6000_isa_flags &= ~OPTION_MASK_PCREL_OPT;
+
   if (TARGET_DEBUG_REG || TARGET_DEBUG_TARGET)
     rs6000_print_isa_options (stderr, 0, "after subtarget", rs6000_isa_flags);
 
@@ -8985,8 +8987,57 @@ rs6000_delegitimize_address (rtx orig_x)
 {
   rtx x, y, offset;
 
-  if (GET_CODE (orig_x) == UNSPEC && XINT (orig_x, 1) == UNSPEC_FUSION_GPR)
-    orig_x = XVECEXP (orig_x, 0, 0);
+  /* UNSPEC_FUSION_GPR is created by the peephole2 for power8 fusion.  It
+     encodes loading up the high part of the address of a TOC reference along
+     with a load of a GPR using the same base register used for the load.  We
+     return the original SYMBOL_REF.
+
+       (set (reg:INT1 <reg>
+            (unspec:INT1 [<combined-address>] UNSPEC_FUSION_GPR)))
+
+     UNSPEC_PCREL_OPT_LD_ADDR is used by the power10 PCREL_OPT pass.  These
+     UNSPECs include the external SYMBOL_REF along with the value being loaded.
+     We return the original SYMBOL_REF.
+
+       (parallel [(set (reg:DI <base-reg>)
+                       (unspec:DI [(symbol_ref <symbol>)
+                                   (const_int <marker>)]
+                                  UNSPEC_PCREL_OPT_LD_ADDR))
+                  (set (reg:DI <load-reg>)
+                       (unspec:DI [(const_int 0)]
+                                  UNSPEC_PCREL_OPT_LD_DATA))])
+
+     UNSPEC_PCREL_OPT_LD_SAME_REG is an alternative that is used if the
+     GPR being loaded is the same as the GPR used to hold the external address.
+
+       (set (reg:DI <base-reg>)
+            (unspec:DI [(symbol_ref <symbol>)
+                        (const_int <marker>)]
+                       UNSPEC_PCREL_OPT_LD_SAME_REG))
+
+     UNSPEC_PCREL_OPT_ST_ADDR is used by the power10 PCREL_OPT pass.  This
+     UNSPEC include the external SYMBOL_REF along with the value being loaded.
+     We return the original SYMBOL_REF.
+
+       (parallel [(set (reg:DI <base-reg>)
+                       (unspec:DI [(symbol_ref <symbol>)
+                                   (const_int <marker>)]
+                                  UNSPEC_PCREL_OPT_ST_ADDR))
+                  (use (reg <store-reg>))])  */
+
+  if (GET_CODE (orig_x) == UNSPEC)
+    switch (XINT (orig_x, 1))
+      {
+      case UNSPEC_FUSION_GPR:
+      case UNSPEC_PCREL_OPT_LD_ADDR:
+      case UNSPEC_PCREL_OPT_LD_SAME_REG:
+      case UNSPEC_PCREL_OPT_ST_ADDR:
+       orig_x = XVECEXP (orig_x, 0, 0);
+       break;
+
+      default:
+       break;
+      }
 
   orig_x = delegitimize_mem_from_attrs (orig_x);
 
@@ -23788,6 +23839,7 @@ static struct rs6000_opt_mask const rs6000_opt_masks[] =
   { "mulhw",                   OPTION_MASK_MULHW,              false, true  },
   { "multiple",                        OPTION_MASK_MULTIPLE,           false, 
true  },
   { "pcrel",                   OPTION_MASK_PCREL,              false, true  },
+  { "pcrel-opt",               OPTION_MASK_PCREL_OPT,          false, true  },
   { "popcntb",                 OPTION_MASK_POPCNTB,            false, true  },
   { "popcntd",                 OPTION_MASK_POPCNTD,            false, true  },
   { "power8-fusion",           OPTION_MASK_P8_FUSION,          false, true  },
@@ -25932,6 +25984,32 @@ address_is_non_pfx_d_or_x (rtx addr, machine_mode mode,
   return false;
 }
 
+/* Return true if an REG with a given MODE is loaded from or stored into a MEM
+   location uses a non-prefixed D/DS/DQ-form address.  This is used to validate
+   the load or store with the PCREL_OPT optimization to make sure it is an
+   instruction that can be optimized.
+
+   We need to specify the MODE separately from the REG to allow for loads that
+   include zero/sign/float extension.  */
+
+bool
+pcrel_opt_valid_mem_p (rtx reg, machine_mode mode, rtx mem)
+{
+  /* If the instruction is indexed only like LFIWAX/LXSIWAX we cannot do the
+     PCREL_OPT optimization.  */
+  enum non_prefixed_form non_prefixed = reg_to_non_prefixed (reg, mode);
+  if (non_prefixed == NON_PREFIXED_X)
+    return false;
+
+  /* Check if this is a non-prefixed D/DS/DQ-form instruction.  */
+  rtx addr = XEXP (mem, 0);
+  enum insn_form iform = address_to_insn_form (addr, mode, non_prefixed);
+  return (iform == INSN_FORM_BASE_REG
+         || iform == INSN_FORM_D
+         || iform == INSN_FORM_DS
+         || iform == INSN_FORM_DQ);
+}
+
 /* Helper function to see if we're potentially looking at lfs/stfs.
    - PARALLEL containing a SET and a CLOBBER
    - stfs:
@@ -25990,7 +26068,7 @@ is_lfs_stfs_insn (rtx_insn *insn)
 /* Helper function to take a REG and a MODE and turn it into the non-prefixed
    instruction format (D/DS/DQ) used for offset memory.  */
 
-static enum non_prefixed_form
+enum non_prefixed_form
 reg_to_non_prefixed (rtx reg, machine_mode mode)
 {
   /* If it isn't a register, use the defaults.  */
@@ -26213,11 +26291,34 @@ void
 rs6000_asm_output_opcode (FILE *stream)
 {
   if (next_insn_prefixed_p)
-    fprintf (stream, "p");
+    {
+      fprintf (stream, "p");
+
+      /* Reset the flag in the case where there are separate insn lines in the
+        sequence, so the 'p' is only emitted for the first line.  This shows up
+        when we are doing the PCREL_OPT optimization, in that the label created
+        with %r<n> would have a leading 'p' printed.  */
+      next_insn_prefixed_p = false;
+    }
 
   return;
 }
 
+/* Emit the relocation to tie the next instruction to a previous instruction
+   that loads up an external address.  This is used to do the PCREL_OPT
+   optimization.  Note, the label is generated after the PLD of the got
+   pc-relative address to allow for the assembler to insert NOPs before the PLD
+   instruction.  The operand is a constant integer that is the label
+   number.  */
+
+void
+output_pcrel_opt_reloc (rtx label_num)
+{
+  rtx operands[1] = { label_num };
+  output_asm_insn (".reloc .Lpcrel%0-8,R_PPC64_PCREL_OPT,.-(.Lpcrel%0-8)",
+                  operands);
+}
+
 /* Adjust the length of an INSN.  LENGTH is the currently-computed length and
    should be adjusted to reflect any required changes.  This macro is used when
    there is some systematic length adjustment required that would be difficult
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index a1315523fec..ccecad321f6 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -292,6 +292,10 @@ (define_attr "prefixed" "no,yes"
 
        (const_string "no")))
 
+;; Whether an insn loads an external address for the PCREL_OPT optimizaton.
+(define_attr "loads_external_address" "no,yes"
+  (const_string "no"))
+
 ;; Return the number of real hardware instructions in a combined insn.  If it
 ;; is 0, just use the length / 4.
 (define_attr "num_insns" "" (const_int 0))
@@ -10243,7 +10247,8 @@ (define_insn "*pcrel_extern_addr"
   "TARGET_PCREL"
   "ld %0,%a1"
   [(set_attr "prefixed" "yes")
-   (set_attr "type" "load")])
+   (set_attr "type" "load")
+   (set_attr "loads_external_address" "yes")])
 
 ;; TOC register handling.
 
@@ -14928,3 +14933,4 @@ (define_insn "*cmpeqb_internal"
 (include "crypto.md")
 (include "htm.md")
 (include "fusion.md")
+(include "pcrel-opt.md")
diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index ae9e91e77cc..0dbdf753673 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -609,6 +609,10 @@ mpcrel
 Target Mask(PCREL) Var(rs6000_isa_flags)
 Generate (do not generate) pc-relative memory addressing.
 
+mpcrel-opt
+Target Undocumented Mask(PCREL_OPT) Var(rs6000_isa_flags)
+Generate (do not generate) pc-relative memory optimizations for externals.
+
 mmma
 Target Mask(MMA) Var(rs6000_isa_flags)
 Generate (do not generate) MMA instructions.
diff --git a/gcc/config/rs6000/t-rs6000 b/gcc/config/rs6000/t-rs6000
index 1541a653738..44f7ffb35fe 100644
--- a/gcc/config/rs6000/t-rs6000
+++ b/gcc/config/rs6000/t-rs6000
@@ -23,6 +23,10 @@ TM_H += $(srcdir)/config/rs6000/rs6000-cpus.def
 TM_H += $(srcdir)/config/rs6000/rs6000-modes.h
 PASSES_EXTRA += $(srcdir)/config/rs6000/rs6000-passes.def
 
+rs6000-pcrel-opt.o: $(srcdir)/config/rs6000/rs6000-pcrel-opt.c
+       $(COMPILE) $<
+       $(POSTCOMPILE)
+
 rs6000-c.o: $(srcdir)/config/rs6000/rs6000-c.c
        $(COMPILE) $<
        $(POSTCOMPILE)
@@ -90,4 +94,5 @@ MD_INCLUDES = $(srcdir)/config/rs6000/rs64.md \
        $(srcdir)/config/rs6000/crypto.md \
        $(srcdir)/config/rs6000/htm.md \
        $(srcdir)/config/rs6000/dfp.md \
-       $(srcdir)/config/rs6000/fusion.md
+       $(srcdir)/config/rs6000/fusion.md \
+       $(srcdir)/config/rs6000/pcrel-opt.md
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-inc-di.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-inc-di.c
new file mode 100644
index 00000000000..c82041c9dc6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-inc-di.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   unsigned int
+
+/* Test whether using an external variable twice (doing an increment) prevents
+   the PCREL_OPT optimization.  */
+extern TYPE ext;
+
+void
+inc (void)
+{
+  ext++;               /* No PCREL_OPT (uses address twice).  */
+}
+
+/* { dg-final { scan-assembler-not "R_PPC64_PCREL_OPT" } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-df.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-df.c
new file mode 100644
index 00000000000..d35862fcb6e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-df.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   double
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   double.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-di.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-di.c
new file mode 100644
index 00000000000..7e1ff99f20e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-di.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   long long
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for long
+   long.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+double
+get_double (void)
+{
+  return (double) ext[0];      /* PCREL_OPT relocation.  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  3 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-hi.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-hi.c
new file mode 100644
index 00000000000..4143aeb7371
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-hi.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   unsigned short
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for unsigned
+   short.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+double
+get_double (void)
+{
+  return (double) ext[0];      /* No PCREL_OPT (LXSIHZX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-qi.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-qi.c
new file mode 100644
index 00000000000..30d3236f95c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-qi.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   unsigned char
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for unsigned
+   char.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+double
+get_double (void)
+{
+  return (double) ext[0];      /* No PCREL_OPT (LXSIBZX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-sf.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-sf.c
new file mode 100644
index 00000000000..9d1e2a1956f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-sf.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   float
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   float.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+double
+get_double (void)
+{
+  return (double) ext[0];      /* PCREL_OPT relocation.  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  3 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-si.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-si.c
new file mode 100644
index 00000000000..17be6fa1778
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-si.c
@@ -0,0 +1,41 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   int
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for int.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+double
+get_double (void)
+{
+  return (double) ext[0];      /* No PCREL_OPT (LFIWAX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-vector.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-vector.c
new file mode 100644
index 00000000000..8c12aea5acd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-ld-vector.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   vector double
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   vector double.  */
+extern TYPE ext[];
+
+TYPE
+get (void)
+{
+  return ext[0];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get2 (void)
+{
+  return ext[2];               /* PCREL_OPT relocation.  */
+}
+
+TYPE
+get_large (void)
+{
+  return ext[LARGE];           /* No PCREL_OPT (load is  prefixed).  */
+}
+
+TYPE
+get_variable (unsigned long n)
+{
+  return ext[n];               /* No PCREL_OPT (load is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-df.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-df.c
new file mode 100644
index 00000000000..d795d35d8de
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-df.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   double
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   double.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-di.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-di.c
new file mode 100644
index 00000000000..bf57de4b886
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-di.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   long long
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for long
+   long.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-hi.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-hi.c
new file mode 100644
index 00000000000..8822e767dfe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-hi.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   unsigned short
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for unsigned
+   short.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+void
+store_double (double a)
+{
+  ext[0] = (TYPE) a;           /* No PCREL_OPT (STXIHZX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-qi.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-qi.c
new file mode 100644
index 00000000000..2f756833717
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-qi.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   unsigned char
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for unsigned
+   char.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+void
+store_double (double a)
+{
+  ext[0] = (TYPE) a;           /* No PCREL_OPT (STXIBZX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-sf.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-sf.c
new file mode 100644
index 00000000000..3dd88aad856
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-sf.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   float
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   float.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-si.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-si.c
new file mode 100644
index 00000000000..78dc8120efe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-si.c
@@ -0,0 +1,41 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   int
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for int.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+void
+store_double (double a)
+{
+  ext[0] = (TYPE) a;           /* No PCREL_OPT (STFIWX is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-vector.c 
b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-vector.c
new file mode 100644
index 00000000000..2c602eb3103
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pcrel-opt-st-vector.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_pcrel } */
+/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
+
+#define TYPE   vector double
+#define LARGE  0x20000
+
+/* Test whether we get the right number of PCREL_OPT optimizations for
+   vector double.  */
+extern TYPE ext[];
+
+void
+store (TYPE a)
+{
+  ext[0] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store2 (TYPE a)
+{
+  ext[2] = a;                  /* PCREL_OPT relocation.  */
+}
+
+void
+store_large (TYPE a)
+{
+  ext[LARGE] = a;              /* No PCREL_OPT (store is prefixed).  */
+}
+
+void
+store_variable (TYPE a, unsigned long n)
+{
+  ext[n] = a;                  /* No PCREL_OPT (store is indexed).  */
+}
+
+/* { dg-final { scan-assembler-times "R_PPC64_PCREL_OPT"  2 } } */
-- 
2.27.0

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