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Optimize local immidiate stores

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git-svn-id: svn://svn.cc65.org/cc65/trunk@555 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz 2000-12-04 23:27:16 +00:00
parent a4fd5c7648
commit 3b18880fb1
1 changed files with 43 additions and 6 deletions
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49
src/cc65/optimize.c
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@ -1664,9 +1664,9 @@ static void OptLoads (void)
* and replace it by:
*
* lda xx
* sta zzz
* lda yy
* sta zzz+1
* lda yy
* sta zzz
*
* provided that that the X register is not used later. While this is
* no direct optimization, it helps with other optimizations.
@ -1678,10 +1678,47 @@ static void OptLoads (void)
!RegXUsed (L2[2])) {
/* Found - replace it */
NewLineAfter (L2[1], "\tlda\t%s", L->Line+5);
L2[2]->Line[3] = 'a';
FreeLine (L);
L = L2[2];
L->Line[3] = 'a';
NewLineAfter (L, "\tsta\t%s", L2[2]->Line+5);
FreeLine (L2[2]);
L = L2[1];
/* Search for:
*
* ldx xx
* lda yy
* ldy #$zz
* jsr staxysp
*
* and replace it by:
*
* lda xx
* ldy #$zz+1
* sta (sp),y
* dey
* lda yy
* sta (sp),y
*
* provided that that the X register is not used later. This code
* sequence is two 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, 3) &&
LineMatch (L2 [0], "\tlda\t") &&
LineMatch (L2 [1], "\tldy\t#$") &&
LineFullMatch (L2 [2], "\tjsr\tstaxysp") &&
!RegXUsed (L2[2])) {
/* Found - replace it */
L->Line[3] = 'a';
L = NewLineAfter (L, "\tldy\t#$%02X", GetHexNum (L2[1]->Line+7)+1);
L = NewLineAfter (L, "\tsta\t(sp),y");
L = NewLineAfter (L, "\tdey");
L = NewLineAfter (L2[0], "\tsta\t(sp),y");
/* Remove the remaining lines */
FreeLines (L2[1], L2[2]);
}