;; ARM ldrd/strd peephole optimizations.
;;
;; Copyright (C) 2013-2018 Free Software Foundation, Inc.
;;
;; Written by Greta Yorsh <greta.yorsh@arm.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/>.

;; The following peephole optimizations identify consecutive memory
;; accesses, and try to rearrange the operands to enable generation of
;; ldrd/strd.

(define_peephole2 ; ldrd
  [(set (match_operand:SI 0 "arm_general_register_operand" "")
        (match_operand:SI 2 "memory_operand" ""))
   (set (match_operand:SI 1 "arm_general_register_operand" "")
        (match_operand:SI 3 "memory_operand" ""))]
  "TARGET_LDRD"
  [(const_int 0)]
{
  if (!gen_operands_ldrd_strd (operands, true, false, false))
    FAIL;
  else if (TARGET_ARM)
  {
    /* In ARM state, the destination registers of LDRD/STRD must be
       consecutive. We emit DImode access.  */
    operands[0] = gen_rtx_REG (DImode, REGNO (operands[0]));
    operands[2] = adjust_address (operands[2], DImode, 0);
    /* Emit [(set (match_dup 0) (match_dup 2))] */
    emit_insn (gen_rtx_SET (operands[0], operands[2]));
    DONE;
  }
  else if (TARGET_THUMB2)
  {
    /* Emit the pattern:
       [(parallel [(set (match_dup 0) (match_dup 2))
                   (set (match_dup 1) (match_dup 3))])] */
    rtx t1 = gen_rtx_SET (operands[0], operands[2]);
    rtx t2 = gen_rtx_SET (operands[1], operands[3]);
    emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, t1, t2)));
    DONE;
  }
})

(define_peephole2 ; strd
  [(set (match_operand:SI 2 "memory_operand" "")
	(match_operand:SI 0 "arm_general_register_operand" ""))
   (set (match_operand:SI 3 "memory_operand" "")
	(match_operand:SI 1 "arm_general_register_operand" ""))]
  "TARGET_LDRD"
  [(const_int 0)]
{
  if (!gen_operands_ldrd_strd (operands, false, false, false))
    FAIL;
  else if (TARGET_ARM)
  {
    /* In ARM state, the destination registers of LDRD/STRD must be
       consecutive. We emit DImode access.  */
    operands[0] = gen_rtx_REG (DImode, REGNO (operands[0]));
    operands[2] = adjust_address (operands[2], DImode, 0);
    /* Emit [(set (match_dup 2) (match_dup 0))]  */
    emit_insn (gen_rtx_SET (operands[2], operands[0]));
    DONE;
  }
  else if (TARGET_THUMB2)
  {
    /* Emit the pattern:
       [(parallel [(set (match_dup 2) (match_dup 0))
                   (set (match_dup 3) (match_dup 1))])]  */
    rtx t1 = gen_rtx_SET (operands[2], operands[0]);
    rtx t2 = gen_rtx_SET (operands[3], operands[1]);
    emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, t1, t2)));
    DONE;
  }
})

;; The following peepholes reorder registers to enable LDRD/STRD.
(define_peephole2 ; strd of constants
  [(set (match_operand:SI 0 "arm_general_register_operand" "")
        (match_operand:SI 4 "const_int_operand" ""))
   (set (match_operand:SI 2 "memory_operand" "")
        (match_dup 0))
   (set (match_operand:SI 1 "arm_general_register_operand" "")
        (match_operand:SI 5 "const_int_operand" ""))
   (set (match_operand:SI 3 "memory_operand" "")
        (match_dup 1))]
  "TARGET_LDRD"
  [(const_int 0)]
{
  if (!gen_operands_ldrd_strd (operands, false, true, false))
    FAIL;
  else if (TARGET_ARM)
  {
   rtx tmp = gen_rtx_REG (DImode, REGNO (operands[0]));
   operands[2] = adjust_address (operands[2], DImode, 0);
   /* Emit the pattern:
      [(set (match_dup 0) (match_dup 4))
      (set (match_dup 1) (match_dup 5))
      (set (match_dup 2) tmp)]  */
   emit_insn (gen_rtx_SET (operands[0], operands[4]));
   emit_insn (gen_rtx_SET (operands[1], operands[5]));
   emit_insn (gen_rtx_SET (operands[2], tmp));
   DONE;
  }
  else if (TARGET_THUMB2)
  {
    /* Emit the pattern:
       [(set (match_dup 0) (match_dup 4))
        (set (match_dup 1) (match_dup 5))
        (parallel [(set (match_dup 2) (match_dup 0))
                   (set (match_dup 3) (match_dup 1))])]  */
    emit_insn (gen_rtx_SET (operands[0], operands[4]));
    emit_insn (gen_rtx_SET (operands[1], operands[5]));
    rtx t1 = gen_rtx_SET (operands[2], operands[0]);
    rtx t2 = gen_rtx_SET (operands[3], operands[1]);
    emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, t1, t2)));
    DONE;
  }
})

(define_peephole2 ; strd of constants
  [(set (match_operand:SI 0 "arm_general_register_operand" "")
        (match_operand:SI 4 "const_int_operand" ""))
   (set (match_operand:SI 1 "arm_general_register_operand" "")
        (match_operand:SI 5 "const_int_operand" ""))
   (set (match_operand:SI 2 "memory_operand" "")
        (match_dup 0))
   (set (match_operand:SI 3 "memory_operand" "")
        (match_dup 1))]
  "TARGET_LDRD"
  [(const_int 0)]
{
  if (!gen_operands_ldrd_strd (operands, false, true, false))
     FAIL;
  else if (TARGET_ARM)
  {
   rtx tmp = gen_rtx_REG (DImode, REGNO (operands[0]));
   operands[2] = adjust_address (operands[2], DImode, 0);
   /* Emit the pattern
      [(set (match_dup 0) (match_dup 4))
       (set (match_dup 1) (match_dup 5))
       (set (match_dup 2) tmp)]  */
   emit_insn (gen_rtx_SET (operands[0], operands[4]));
   emit_insn (gen_rtx_SET (operands[1], operands[5]));
   emit_insn (gen_rtx_SET (operands[2], tmp));
   DONE;
  }
  else if (TARGET_THUMB2)
  {
    /*  Emit the pattern:
        [(set (match_dup 0) (match_dup 4))
         (set (match_dup 1) (match_dup 5))
         (parallel [(set (match_dup 2) (match_dup 0))
                    (set (match_dup 3) (match_dup 1))])]  */
    emit_insn (gen_rtx_SET (operands[0], operands[4]));
    emit_insn (gen_rtx_SET (operands[1], operands[5]));
    rtx t1 = gen_rtx_SET (operands[2], operands[0]);
    rtx t2 = gen_rtx_SET (operands[3], operands[1]);
    emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, t1, t2)));
    DONE;
  }
})

;; The following two peephole optimizations are only relevant for ARM
;; mode where LDRD/STRD require consecutive registers.

(define_peephole2 ; swap the destination registers of two loads
		  ; before a commutative operation.
  [(set (match_operand:SI 0 "arm_general_register_operand" "")
        (match_operand:SI 2 "memory_operand" ""))
   (set (match_operand:SI 1 "arm_general_register_operand" "")
        (match_operand:SI 3 "memory_operand" ""))
   (set (match_operand:SI 4 "arm_general_register_operand" "")
        (match_operator:SI 5 "commutative_binary_operator"
			   [(match_operand 6 "arm_general_register_operand" "")
			    (match_operand 7 "arm_general_register_operand" "") ]))]
  "TARGET_LDRD && TARGET_ARM
   && (  ((rtx_equal_p(operands[0], operands[6])) && (rtx_equal_p(operands[1], operands[7])))
        ||((rtx_equal_p(operands[0], operands[7])) && (rtx_equal_p(operands[1], operands[6]))))
   && (peep2_reg_dead_p (3, operands[0]) || rtx_equal_p (operands[0], operands[4]))
   && (peep2_reg_dead_p (3, operands[1]) || rtx_equal_p (operands[1], operands[4]))"
  [(set (match_dup 0) (match_dup 2))
   (set (match_dup 4) (match_op_dup 5 [(match_dup 6) (match_dup 7)]))]
  {
    if (!gen_operands_ldrd_strd (operands, true, false, true))
     {
        FAIL;
     }
    else
     {
        operands[0] = gen_rtx_REG (DImode, REGNO (operands[0]));
        operands[2] = adjust_address (operands[2], DImode, 0);
     }
   }
)

(define_peephole2 ; swap the destination registers of two loads
		  ; before a commutative operation that sets the flags.
  [(set (match_operand:SI 0 "arm_general_register_operand" "")
        (match_operand:SI 2 "memory_operand" ""))
   (set (match_operand:SI 1 "arm_general_register_operand" "")
        (match_operand:SI 3 "memory_operand" ""))
   (parallel
      [(set (match_operand:SI 4 "arm_general_register_operand" "")
	    (match_operator:SI 5 "commutative_binary_operator"
			       [(match_operand 6 "arm_general_register_operand" "")
				(match_operand 7 "arm_general_register_operand" "") ]))
       (clobber (reg:CC CC_REGNUM))])]
  "TARGET_LDRD && TARGET_ARM
   && (  ((rtx_equal_p(operands[0], operands[6])) && (rtx_equal_p(operands[1], operands[7])))
       ||((rtx_equal_p(operands[0], operands[7])) && (rtx_equal_p(operands[1], operands[6]))))
   && (peep2_reg_dead_p (3, operands[0]) || rtx_equal_p (operands[0], operands[4]))
   && (peep2_reg_dead_p (3, operands[1]) || rtx_equal_p (operands[1], operands[4]))"
  [(set (match_dup 0) (match_dup 2))
   (parallel
      [(set (match_dup 4)
	    (match_op_dup 5 [(match_dup 6) (match_dup 7)]))
       (clobber (reg:CC CC_REGNUM))])]
  {
    if (!gen_operands_ldrd_strd (operands, true, false, true))
     {
        FAIL;
     }
    else
     {
        operands[0] = gen_rtx_REG (DImode, REGNO (operands[0]));
        operands[2] = adjust_address (operands[2], DImode, 0);
     }
   }
)

;; TODO: Handle LDRD/STRD with writeback:
;; (a) memory operands can be POST_INC, POST_DEC, PRE_MODIFY, POST_MODIFY
;; (b) Patterns may be followed by an update of the base address.