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Optimize local immidiate stores

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git-svn-id: svn://svn.cc65.org/cc65/trunk@556 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz 2000-12-04 23:34:28 +00:00
parent 3b18880fb1
commit eed3723502
1 changed files with 35 additions and 1 deletions
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36
src/cc65/optimize.c
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@ -1719,8 +1719,42 @@ static void OptLoads (void)
/* Remove the remaining lines */
FreeLines (L2[1], L2[2]);
}
/* Search for:
*
* ldx xx
* lda yy
* jsr stax0sp
*
* and replace it by:
*
* lda xx
* ldy #$01
* sta (sp),y
* dey
* lda yy
* sta (sp),y
*
* provided that that the X register is not used later. This code
* sequence is four bytes longer, but a lot faster and it does not
* use the X register, so other loads may get removed later.
*/
} else if (LineMatch (L, "\tldx\t") &&
GetNextCodeLines (L, L2, 2) &&
LineMatch (L2 [0], "\tlda\t") &&
LineFullMatch (L2 [1], "\tjsr\tstax0sp") &&
!RegXUsed (L2[1])) {
/* Found - replace it */
L->Line[3] = 'a';
L = NewLineAfter (L, "\tldy\t#$01");
L = NewLineAfter (L, "\tsta\t(sp),y");
L = NewLineAfter (L, "\tdey");
L = NewLineAfter (L2[0], "\tsta\t(sp),y");
/* Remove the remaining line */
FreeLine (L2[1]);
}
/* All other patterns start with this one: */
if (!LineFullMatch (L, "\tldx\t#$00")) {