1 /*****************************************************************************/
5 /* Optimize push sequences */
9 /* (C) 2001-2002 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
43 /*****************************************************************************/
45 /*****************************************************************************/
49 unsigned OptPush1 (CodeSeg* S)
56 * If a/x are not used later, replace that by
61 * saving 3 bytes and several cycles.
66 /* Walk over the entries */
68 while (I < CS_GetEntryCount (S)) {
73 L[0] = CS_GetEntry (S, I);
75 /* Check for the sequence */
76 if (L[0]->OPC == OP65_LDY &&
79 !CS_RangeHasLabel (S, I+1, 2) &&
80 CS_GetEntries (S, L+1, I+1, 2) &&
81 CE_IsCallTo (L[1], "ldaxysp") &&
82 CE_IsCallTo (L[2], "pushax") &&
83 !RegAXUsed (S, I+3)) {
85 /* Insert new code behind the pushax */
90 Arg = MakeHexArg (L[0]->Num+2);
91 X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, L[0]->LI);
92 CS_InsertEntry (S, X, I+3);
95 X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwysp", 0, L[2]->LI);
96 CS_InsertEntry (S, X, I+4);
98 /* Delete the old code */
99 CS_DelEntries (S, I, 3);
101 /* Remember, we had changes */
111 /* Return the number of changes made */