Optimize local immidiate stores

git-svn-id: svn://svn.cc65.org/cc65/trunk@555 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/src/cc65/optimize.c b/src/cc65/optimize.c
index 8d24dfeacab682086a7cb714c407a8eabd72f7d1..5fa0ad5612b36f0c4cd50013d686114fe92c6215 100644 (file)
--- a/src/cc65/optimize.c
+++ b/src/cc65/optimize.c
@@ -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]);
        }