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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 /* End of coptneg.h */
 168
 169 #endif
 170
 171
 172