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   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                 coptneg.h                                 */
   4 /*                                                                           */
   5 /*                        Optimize negation sequences                        */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2001-2012, Ullrich von Bassewitz                                      */
  10 /*                Roemerstrasse 52                                           */
  11 /*                D-70794 Filderstadt                                        */
  12 /* EMail:         uz@cc65.org                                                */
  13 /*                                                                           */
  14 /*                                                                           */
  15 /* This software is provided 'as-is', without any expressed or implied       */
  16 /* warranty.  In no event will the authors be held liable for any damages    */
  17 /* arising from the use of this software.                                    */
  18 /*                                                                           */
  19 /* Permission is granted to anyone to use this software for any purpose,     */
  20 /* including commercial applications, and to alter it and redistribute it    */
  21 /* freely, subject to the following restrictions:                            */
  22 /*                                                                           */
  23 /* 1. The origin of this software must not be misrepresented; you must not   */
  24 /*    claim that you wrote the original software. If you use this software   */
  25 /*    in a product, an acknowledgment in the product documentation would be  */
  26 /*    appreciated but is not required.                                       */
  27 /* 2. Altered source versions must be plainly marked as such, and must not   */
  28 /*    be misrepresented as being the original software.                      */
  29 /* 3. This notice may not be removed or altered from any source              */
  30 /*    distribution.                                                          */
  31 /*                                                                           */
  32 /*****************************************************************************/
  33
  34
  35
  36 #ifndef COPTNEG_H
  37 #define COPTNEG_H
  38
  39
  40
  41 /* cc65 */
  42 #include "codeseg.h"
  43
  44
  45
  46 /*****************************************************************************/
  47 /*                            bnega optimizations                            */
  48 /*****************************************************************************/
  49
  50
  51
  52 unsigned OptBNegA1 (CodeSeg* S);
  53 /* Check for
  54 **
  55 **      ldx     #$00
  56 **      lda     ..
  57 **      jsr     bnega
  58 **
  59 ** Remove the ldx if the lda does not use it.
  60 */
  61
  62 unsigned OptBNegA2 (CodeSeg* S);
  63 /* Check for
  64 **
  65 **      lda     ..
  66 **      jsr     bnega
  67 **      jeq/jne ..
  68 **
  69 ** Adjust the conditional branch and remove the call to the subroutine.
  70 */
  71
  72
  73
  74 /*****************************************************************************/
  75 /*                            bnegax optimizations                           */
  76 /*****************************************************************************/
  77
  78
  79
  80 unsigned OptBNegAX1 (CodeSeg* S);
  81 /* On a call to bnegax, if X is zero, the result depends only on the value in
  82 ** A, so change the call to a call to bnega. This will get further optimized
  83 ** later if possible.
  84 */
  85
  86 unsigned OptBNegAX2 (CodeSeg* S);
  87 /* Search for the sequence:
  88 **
  89 **      lda     (xx),y
  90 **      tax
  91 **      dey
  92 **      lda     (xx),y
  93 **      jsr     bnegax
  94 **      jne/jeq ...
  95 **
  96 ** and replace it by
  97 **
  98 **      lda     (xx),y
  99 **      dey
 100 **      ora     (xx),y
 101 **      jeq/jne ...
 102 */
 103
 104 unsigned OptBNegAX3 (CodeSeg* S);
 105 /* Search for the sequence:
 106 **
 107 **      lda     xx
 108 **      ldx     yy
 109 **      jsr     bnegax
 110 **      jne/jeq ...
 111 **
 112 ** and replace it by
 113 **
 114 **      lda     xx
 115 **      ora     xx+1
 116 **      jeq/jne ...
 117 */
 118
 119 unsigned OptBNegAX4 (CodeSeg* S);
 120 /* Search for the sequence:
 121 **
 122 **      jsr     xxx
 123 **      jsr     bnega(x)
 124 **      jeq/jne ...
 125 **
 126 ** and replace it by:
 127 **
 128 **      jsr     xxx
 129 **      <boolean test>
 130 **      jne/jeq ...
 131 */
 132
 133
 134
 135 /*****************************************************************************/
 136 /*                            negax optimizations                            */
 137 /*****************************************************************************/
 138
 139
 140
 141 unsigned OptNegAX1 (CodeSeg* S);
 142 /* Search for a call to negax and replace it by
 143 **
 144 **      eor     #$FF
 145 **      clc
 146 **      adc     #$01
 147 **
 148 ** if X isn't used later.
 149 */
 150
 151 unsigned OptNegAX2 (CodeSeg* S);
 152 /* Search for a call to negax and replace it by
 153 **
 154 **      ldx     #$FF
 155 **      eor     #$FF
 156 **      clc
 157 **      adc     #$01
 158 **      bne     L1
 159 **      inx
 160 ** L1:
 161 **
 162 ** if X is known and zero on entry.
 163 */
 164
 165
 166
 167 /*****************************************************************************/
 168 /*                           complax optimizations                           */
 169 /*****************************************************************************/
 170
 171
 172
 173 unsigned OptComplAX1 (CodeSeg* S);
 174 /* Search for a call to complax and replace it by
 175 **
 176 **      eor     #$FF
 177 **
 178 ** if X isn't used later.
 179 */
 180
 181
 182
 183 /* End of coptneg.h */
 184
 185 #endif