osprey/ipa/main/optimize/ipo_dce.cxx

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/*
 * Copyright 2003, 2004, 2005, 2006 PathScale, Inc.  All Rights Reserved.
 */

/*

  Copyright (C) 2000, 2001 Silicon Graphics, Inc.  All Rights Reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of version 2 of the GNU General Public License as
  published by the Free Software Foundation.

  This program is distributed in the hope that it would be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

  Further, this software is distributed without any warranty that it is
  free of the rightful claim of any third person regarding infringement 
  or the like.  Any license provided herein, whether implied or 
  otherwise, applies only to this software file.  Patent licenses, if 
  any, provided herein do not apply to combinations of this program with 
  other software, or any other product whatsoever.  

  You should have received a copy of the GNU General Public License along
  with this program; if not, write the Free Software Foundation, Inc., 59
  Temple Place - Suite 330, Boston MA 02111-1307, USA.

  Contact information:  Silicon Graphics, Inc., 1600 Amphitheatre Pky,
  Mountain View, CA 94043, or:

  http://www.sgi.com

  For further information regarding this notice, see:

  http://oss.sgi.com/projects/GenInfo/NoticeExplan

*/


//* -*-Mode: c++;-*- (Tell emacs to use c++ mode) */

#define __STDC_LIMIT_MACROS
#include <stdint.h>
#include "defs.h"
#include "symtab.h"     // symbol table
#include "targ_sim.h"     // Get_Return_Mtypes ()
#include "lwn_util.h"     // WN_EXTRACE_FromBlock ()

#include "ipa_option.h"     // Trace_IPA
#include "ipa_cg.h"     // call graphs
#include "ipo_defs.h"     // IPA_NODE_CONTEXT
#include "ipo_parent.h"     // WN_Get_Parent()
#include "ipo_dce.h"

//--------------------------------------------------------------
// figure out the stid preg's that we need to be looking for
//--------------------------------------------------------------
static UINT32 
Compute_Return_Pregs(TY_IDX callee_ty)
{
    PREG_NUM Reg1, Reg2;
    TYPE_ID ty1, ty2;
    TY_IDX typ;

#ifdef KEY
    BOOL ret_via_first_arg = FALSE;
#endif

    // get the return type from the callee's opcode
    if (typ = Tylist_Table[TY_tylist(Ty_Table[callee_ty])])
  if (TY_kind(typ) != KIND_VOID) {

      if (WHIRL_Return_Info_On) {

    RETURN_INFO return_info = Get_Return_Info (typ, Use_Simulated);

    if (RETURN_INFO_count(return_info) <= 2) {

        ty1 = RETURN_INFO_mtype (return_info, 0);
        ty2 = RETURN_INFO_mtype (return_info, 1);
        Reg1 = RETURN_INFO_preg (return_info, 0);
        Reg2 = RETURN_INFO_preg (return_info, 1);
#ifdef KEY
        ret_via_first_arg = RETURN_INFO_return_via_first_arg (return_info);
#endif
    }

    else
        Fail_FmtAssertion ("Compute_Return_Pregs: more than 2 return registers");
      }

      else {
    Get_Return_Mtypes(typ, Use_Simulated, &ty1, &ty2);
    Get_Return_Pregs(ty1, ty2, &Reg1, &Reg2);
      }
      
      if (Reg1 && Reg2)
    return 2;
      else if (Reg1 || Reg2
#ifdef KEY
               || ret_via_first_arg
#endif
              )
    return 1;
  }

    return 0;
}

//--------------------------------------------------------------
// delete the call whirl node
//--------------------------------------------------------------
BOOL
Delete_Call (IPA_NODE *caller, const IPA_NODE *callee, IPA_EDGE *edge,
       IPA_CALL_GRAPH* cg)
{
    IPA_NODE_CONTEXT context (caller);
    cg->Map_Callsites (caller);           // map callsites to WN nodes
    WN* call = edge->Whirl_Node();
    WN* b = WN_Get_Parent(call, Parent_Map, Current_Map_Tab);

    if ((WN_operator(b) != OPR_BLOCK))
  return FALSE;

    UINT32 Reg_count = (WN_operator (call) == OPR_ICALL) ?
  Compute_Return_Pregs (WN_ty (call)) :
  Compute_Return_Pregs (ST_pu_type (WN_st (call)));

    if (Reg_count) {
  for (INT i = 0; i < Reg_count; ++i) {
      WN* stid = WN_next(call);
      if (stid && (WN_operator(stid) == OPR_STID)) {
    if ((WN_operator(WN_kid0(stid)) == OPR_LDID) && 
        (ST_sclass(WN_st(WN_kid0(stid))) == SCLASS_REG) &&
        Preg_Is_Dedicated(WN_offset(WN_kid0(stid)))) {
        WN_EXTRACT_FromBlock(b, stid);
    }
      }
  }
    }
    WN_EXTRACT_FromBlock(b, call);
    if (Trace_IPA || Trace_Perf) {
  fprintf (TFile, "%s called from ", DEMANGLE(ST_name(callee->Func_ST())));
  fprintf (TFile, "%s deleted\n", DEMANGLE(ST_name(caller->Func_ST())));
    }
    return TRUE;
} // Delete_Call

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