From eed37235024a857b6ed957e88750ce8e57bf9120 Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Mon, 4 Dec 2000 23:34:28 +0000
Subject: [PATCH] Optimize local immidiate stores

git-svn-id: svn://svn.cc65.org/cc65/trunk@556 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 src/cc65/optimize.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/cc65/optimize.c b/src/cc65/optimize.c
index 5fa0ad561..55ebe9761 100644
--- a/src/cc65/optimize.c
+++ b/src/cc65/optimize.c
@@ -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")) {
-- 
2.39.5