Added load/store transformation

git-svn-id: svn://svn.cc65.org/cc65/trunk@554 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/src/cc65/optimize.c b/src/cc65/optimize.c
index 1cb57894b6c2f11c7ad3c0479a37736226fd8cc1..8d24dfeacab682086a7cb714c407a8eabd72f7d1 100644 (file)
--- a/src/cc65/optimize.c
+++ b/src/cc65/optimize.c
@@ -1589,7 +1589,6 @@ static void OptLoads (void)
 
            /* Delete the remaining lines */
            FreeLines (L2 [0], L2 [3]);
-       }
 
        /* Check for
         *
@@ -1616,7 +1615,7 @@ static void OptLoads (void)
         * possible to rewrite the library routine to get rid of the additional
         * overhead.
         */
-       if (LineMatch (L, "\tldy\t#$")                  &&
+               } else if (LineMatch (L, "\tldy\t#$")           &&
            GetNextCodeLines (L, L2, 6)                 &&
            LineFullMatch (L2 [0], "\tlda\t(sp),y")     &&
            LineFullMatch (L2 [1], "\ttax")             &&
@@ -1637,7 +1636,6 @@ static void OptLoads (void)
 
            /* Delete the remaining lines */
            FreeLines (L2 [0], L2 [3]);
-       }
 
        /* Search for:
         *
@@ -1648,15 +1646,45 @@ static void OptLoads (void)
         *
                 *      jsr     pushaysp
         */
-               if (LineFullMatch (L, "\tlda\t(sp),y")          &&
+               } else if (LineFullMatch (L, "\tlda\t(sp),y")   &&
            GetNextCodeLines (L, L2, 1)                 &&
            LineFullMatch (L2 [0], "\tjsr\tpusha")) {
 
            /* Found, replace it */
            L = ReplaceLine (L, "\tjsr\tpushaysp");
            FreeLine (L2 [0]);
+
+       /* Search for:
+        *
+        *      ldx     xx
+        *      lda     yy
+        *      sta     zzz
+        *      stx     zzz+1
+        *
+        * and replace it by:
+        *
+        *      lda     xx
+        *      sta     zzz
+                *      lda     yy
+        *      sta     zzz+1
+        *
+        * provided that that the X register is not used later. While this is
+        * no direct optimization, it helps with other optimizations.
+        */
+               } else if (LineMatch (L, "\tldx\t")             &&
+                   GetNextCodeLines (L, L2, 3)                 &&
+           LineMatch (L2 [0], "\tlda\t")               &&
+           Is16BitStore (L2[1], L2[2])                 &&
+           !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]; 
        }
 
+
                /* All other patterns start with this one: */
        if (!LineFullMatch (L, "\tldx\t#$00")) {
            /* Next line */