122 lines
4 KiB
C
122 lines
4 KiB
C
/*-------------------------------------------------------------------------
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SDCCptropt.c - source file for pointer arithmetic Optimizations
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Written By - Sandeep Dutta . sandeep.dutta@usa.net (1998)
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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In other words, you are welcome to use, share and improve this program.
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You are forbidden to forbid anyone else to use, share and improve
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what you give them. Help stamp out software-hoarding!
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-------------------------------------------------------------------------*/
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#include "common.h"
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/*-----------------------------------------------------------------------*/
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/* findPointerGetSet - find the pointer get or set for a operand */
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/*-----------------------------------------------------------------------*/
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static iCode *
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findPointerGetSet (iCode * sic, operand * op)
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{
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iCode *ic = sic;
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for (; ic; ic = ic->next)
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{
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if ((POINTER_SET (ic) && isOperandEqual (op, IC_RESULT (ic))) ||
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(POINTER_GET (ic) && isOperandEqual (op, IC_LEFT (ic))))
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return ic;
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/* if we find any other usage or definition of op null */
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if (IC_RESULT (ic) && isOperandEqual (IC_RESULT (ic), op))
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return NULL;
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if (IC_RIGHT (ic) && isOperandEqual (IC_RIGHT (ic), op))
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return NULL;
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if (IC_LEFT (ic) && isOperandEqual (IC_LEFT (ic), op))
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return NULL;
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}
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return NULL;
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}
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/*-----------------------------------------------------------------------*/
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/* ptrPostIncDecOpts - will do some pointer post increment optimizations */
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/* this will help register allocation amongst others */
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/*-----------------------------------------------------------------------*/
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void
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ptrPostIncDecOpt (iCode * sic)
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{
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/* this is what we do. look for sequences like
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iTempX := _SOME_POINTER_;
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iTempY := _SOME_POINTER_ + nn ; nn = sizeof (pointed to object)
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_SOME_POINTER_ := iTempY;
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either
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iTempZ := @[iTempX];
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or
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*(iTempX) := ..something..
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if we find this then transform this to
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iTempX := _SOME_POINTER_;
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either
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iTempZ := @[iTempX];
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or
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*(iTempX) := ..something..
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iTempY := _SOME_POINTER_ + nn ; nn = sizeof (pointed to object)
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_SOME_POINTER_ := iTempY; */
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/* sounds simple enough so lets start , here I use -ve
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tests all the way to return if any test fails */
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iCode *pgs, *sh, *st;
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if (!(sic->next && sic->next->next && sic->next->next->next))
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return;
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if (sic->next->op != '+' && sic->next->op != '-')
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return;
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if (!(sic->next->next->op == '=' &&
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!POINTER_SET (sic->next->next)))
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return;
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if (!isOperandEqual (IC_LEFT (sic->next), IC_RIGHT (sic)) ||
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!IS_OP_LITERAL (IC_RIGHT (sic->next)))
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return;
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if (operandLitValue (IC_RIGHT (sic->next)) !=
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getSize (operandType (IC_RIGHT (sic))->next))
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return;
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if (!isOperandEqual (IC_RESULT (sic->next->next),
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IC_RIGHT (sic)))
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return;
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if (!isOperandEqual (IC_RESULT (sic->next), IC_RIGHT (sic->next->next)))
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return;
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if (!(pgs = findPointerGetSet (sic->next->next, IC_RESULT (sic))))
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return;
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/* found the patter .. now do the transformation */
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sh = sic->next;
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st = sic->next->next;
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/* take the two out of the chain */
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sic->next = st->next;
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st->next->prev = sic;
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/* and put them after the pointer get/set icode */
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if ((st->next = pgs->next))
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st->next->prev = st;
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pgs->next = sh;
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sh->prev = pgs;
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}
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