git.sur5r.net Git - cc65/blob - src/cc65/coptpush.c

   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                coptpush.c                                 */
   4 /*                                                                           */
   5 /*                          Optimize push sequences                          */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2001      Ullrich von Bassewitz                                       */
  10 /*               Wacholderweg 14                                             */
  11 /*               D-70597 Stuttgart                                           */
  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 /* common */
  37 #include "xsprintf.h"
  38
  39 /* cc65 */
  40 #include "codeent.h"
  41 #include "codeinfo.h"
  42 #include "coptpush.h"
  43
  44
  45
  46 /*****************************************************************************/
  47 /*                                   Code                                    */
  48 /*****************************************************************************/
  49
  50
  51
  52 unsigned OptPush1 (CodeSeg* S)
  53 /* Given a sequence
  54  *
  55  *     ldy     #xx
  56  *     jsr     ldaxysp
  57  *     jsr     pushax
  58  *
  59  * If a/x are not used later, replace that by
  60  *
  61  *     ldy     #xx+2
  62  *     jsr     pushwysp
  63  *
  64  * saving 3 bytes and several cycles.
  65  */
  66 {
  67     unsigned Changes = 0;
  68
  69     /* Walk over the entries */
  70     unsigned I = 0;
  71     while (I < CS_GetEntryCount (S)) {
  72
  73         CodeEntry* L[3];
  74
  75         /* Get next entry */
  76         L[0] = CS_GetEntry (S, I);
  77
  78         /* Check for the sequence */
  79         if (L[0]->OPC == OP65_LDY               &&
  80             CE_KnownImm (L[0])                  &&
  81             L[0]->Num < 0xFE                    &&
  82             !CS_RangeHasLabel (S, I+1, 2)       &&
  83             CS_GetEntries (S, L+1, I+1, 2)      &&
  84             CE_IsCall (L[1], "ldaxysp")         &&
  85             CE_IsCall (L[2], "pushax")          &&
  86             (GetRegInfo (S, I+3, REG_AX) & REG_AX) == 0) {
  87
  88             /* Insert new code behind the pushax */
  89             char Buf [20];
  90             CodeEntry* X;
  91
  92             /* ldy     #xx+1 */
  93             xsprintf (Buf, sizeof (Buf), "$%02X", (int)(L[0]->Num+2));
  94             X = NewCodeEntry (OP65_LDY, AM65_IMM, Buf, 0, L[0]->LI);
  95             CS_InsertEntry (S, X, I+3);
  96
  97             /* jsr pushwysp */
  98             X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwysp", 0, L[2]->LI);
  99             CS_InsertEntry (S, X, I+4);
 100
 101             /* Delete the old code */
 102             CS_DelEntries (S, I, 3);
 103
 104             /* Remember, we had changes */
 105             ++Changes;
 106
 107         }
 108
 109         /* Next entry */
 110         ++I;
 111
 112     }
 113
 114     /* Return the number of changes made */
 115     return Changes;
 116 }
 117
 118
 119