/*****************************************************************************/
/*                                                                           */
/*				  coptpush.c                                 */
/*                                                                           */
/*			    Optimize push sequences                          */
/*                                                                           */
/*                                                                           */
/*                                                                           */
/* (C) 2001-2002 Ullrich von Bassewitz                                       */
/*               Wacholderweg 14                                             */
/*               D-70597 Stuttgart                                           */
/* EMail:        uz@cc65.org                                                 */
/*                                                                           */
/*                                                                           */
/* This software is provided 'as-is', without any expressed or implied       */
/* warranty.  In no event will the authors be held liable for any damages    */
/* arising from the use of this software.                                    */
/*                                                                           */
/* Permission is granted to anyone to use this software for any purpose,     */
/* including commercial applications, and to alter it and redistribute it    */
/* freely, subject to the following restrictions:                            */
/*                                                                           */
/* 1. The origin of this software must not be misrepresented; you must not   */
/*    claim that you wrote the original software. If you use this software   */
/*    in a product, an acknowledgment in the product documentation would be  */
/*    appreciated but is not required.                                       */
/* 2. Altered source versions must be plainly marked as such, and must not   */
/*    be misrepresented as being the original software.                      */
/* 3. This notice may not be removed or altered from any source              */
/*    distribution.                                                          */
/*                                                                           */
/*****************************************************************************/



/* cc65 */
#include "codeent.h"
#include "codeinfo.h"
#include "coptpush.h"



/*****************************************************************************/
/*				     Code                                    */
/*****************************************************************************/



unsigned OptPush1 (CodeSeg* S)
/* Given a sequence
 *
 *     jsr     ldaxysp
 *     jsr     pushax
 *
 * If a/x are not used later, and Y is known, replace that by
 *
 *     ldy     #xx+2
 *     jsr     pushwysp
 *
 * saving 3 bytes and several cycles.
 */
{
    unsigned I;
    unsigned Changes = 0;

    /* Generate register info */
    CS_GenRegInfo (S);

    /* Walk over the entries */
    I = 0;
    while (I < CS_GetEntryCount (S)) {

     	CodeEntry* L[2];

      	/* Get next entry */
       	L[0] = CS_GetEntry (S, I);

     	/* Check for the sequence */
       	if (CE_IsCallTo (L[0], "ldaxysp")               &&
            RegValIsKnown (L[0]->RI->In.RegY)           &&
            L[0]->RI->In.RegY < 0xFE                    &&
            (L[1] = CS_GetNextEntry (S, I)) != 0        &&
            !CE_HasLabel (L[1])                         &&
       	    CE_IsCallTo (L[1], "pushax")                &&
       	    !RegAXUsed (S, I+2)) {

	    /* Insert new code behind the pushax */
	    const char* Arg;
	    CodeEntry* X;

	    /* ldy     #xx+1 */
	    Arg = MakeHexArg (L[0]->RI->In.RegY+2);
	    X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, L[0]->LI);
	    CS_InsertEntry (S, X, I+2);

	    /* jsr pushwysp */
	    X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwysp", 0, L[1]->LI);
	    CS_InsertEntry (S, X, I+3);

	    /* Delete the old code */
	    CS_DelEntries (S, I, 2);

	    /* Remember, we had changes */
	    ++Changes;

	}

	/* Next entry */
	++I;

    }

    /* Free the register info */
    CS_FreeRegInfo (S);

    /* Return the number of changes made */
    return Changes;
}



unsigned OptPush2 (CodeSeg* S)
/* A sequence
 *
 *     jsr     ldaxidx
 *     jsr     pushax
 *
 * may get replaced by
 *
 *     jsr     pushwidx
 *
 */
{
    unsigned I;
    unsigned Changes = 0;

    /* Generate register info */
    CS_GenRegInfo (S);

    /* Walk over the entries */
    I = 0;
    while (I < CS_GetEntryCount (S)) {

     	CodeEntry* L[2];

      	/* Get next entry */
       	L[0] = CS_GetEntry (S, I);

     	/* Check for the sequence */
       	if (CE_IsCallTo (L[0], "ldaxidx")               &&
            (L[1] = CS_GetNextEntry (S, I)) != 0        &&
            !CE_HasLabel (L[1])                         &&
       	    CE_IsCallTo (L[1], "pushax")) {

	    /* Insert new code behind the pushax */
	    CodeEntry* X;

	    /* jsr pushwidx */
	    X = NewCodeEntry (OP65_JSR, AM65_ABS, "pushwidx", 0, L[1]->LI);
	    CS_InsertEntry (S, X, I+2);

	    /* Delete the old code */
	    CS_DelEntries (S, I, 2);

	    /* Remember, we had changes */
	    ++Changes;

	}

	/* Next entry */
	++I;

    }

    /* Free the register info */
    CS_FreeRegInfo (S);

    /* Return the number of changes made */
    return Changes;
}



