gcc/gimple-laddress.c

   1 /* Lower and optimize address expressions.
   2    Copyright (C) 2015 Free Software Foundation, Inc.
   3    Contributed by Marek Polacek <polacek@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "alias.h"
  25 #include "predict.h"
  26 #include "tm.h"
  27 #include "function.h"
  28 #include "dominance.h"
  29 #include "cfg.h"
  30 #include "basic-block.h"
  31 #include "tree-ssa-alias.h"
  32 #include "symtab.h"
  33 #include "tree.h"
  34 #include "stringpool.h"
  35 #include "tree-ssanames.h"
  36 #include "fold-const.h"
  37 #include "gimple-expr.h"
  38 #include "gimple.h"
  39 #include "gimplify.h"
  40 #include "gimple-iterator.h"
  41 #include "gimplify-me.h"
  42 #include "tree-pass.h"
  43
  44
  45 namespace {
  46
  47 const pass_data pass_data_laddress =
  48 {
  49   GIMPLE_PASS, /* type */
  50   "laddress", /* name */
  51   OPTGROUP_NONE, /* optinfo_flags */
  52   TV_GIMPLE_LADDRESS, /* tv_id */
  53   ( PROP_cfg | PROP_ssa ), /* properties_required */
  54   0, /* properties_provided */
  55   0, /* properties_destroyed */
  56   0, /* todo_flags_start */
  57   0, /* todo_flags_finish */
  58 };
  59
  60 class pass_laddress : public gimple_opt_pass
  61 {
  62 public:
  63   pass_laddress (gcc::context *ctxt)
  64     : gimple_opt_pass (pass_data_laddress, ctxt)
  65   {}
  66
  67   /* opt_pass methods: */
  68   opt_pass * clone () { return new pass_laddress (m_ctxt); }
  69   virtual bool gate (function *) { return optimize != 0; }
  70   virtual unsigned int execute (function *);
  71
  72 }; // class pass_laddress
  73
  74 unsigned int
  75 pass_laddress::execute (function *fun)
  76 {
  77   basic_block bb;
  78
  79   FOR_EACH_BB_FN (bb, fun)
  80     {
  81       for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
  82         {
  83           gimple stmt = gsi_stmt (gsi);
  84           if (!is_gimple_assign (stmt)
  85               || gimple_assign_rhs_code (stmt) != ADDR_EXPR
  86               || is_gimple_invariant_address (gimple_assign_rhs1 (stmt)))
  87             {
  88               gsi_next (&gsi);
  89               continue;
  90             }
  91
  92           /* Lower ADDR_EXPR assignments:
  93                _4 = &b[i_9];
  94              into
  95                _1 = (sizetype) i_9;
  96                _7 = _1 * 4;
  97                _4 = &b + _7;
  98              This ought to aid the vectorizer and expose CSE opportunities.
  99           */
 100
 101           tree expr = gimple_assign_rhs1 (stmt);
 102           HOST_WIDE_INT bitsize, bitpos;
 103           tree base, offset;
 104           machine_mode mode;
 105           int volatilep = 0, unsignedp = 0;
 106           base = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize,
 107                                       &bitpos, &offset, &mode, &unsignedp,
 108                                       &volatilep, false);
 109           gcc_assert (base != NULL_TREE && (bitpos % BITS_PER_UNIT) == 0);
 110           if (offset != NULL_TREE)
 111             {
 112               if (bitpos != 0)
 113                 offset = size_binop (PLUS_EXPR, offset,
 114                                      size_int (bitpos / BITS_PER_UNIT));
 115               offset = force_gimple_operand_gsi (&gsi, offset, true, NULL,
 116                                                  true, GSI_SAME_STMT);
 117               base = build_fold_addr_expr (base);
 118               base = force_gimple_operand_gsi (&gsi, base, true, NULL,
 119                                                true, GSI_SAME_STMT);
 120               gimple g = gimple_build_assign (gimple_assign_lhs (stmt),
 121                                               POINTER_PLUS_EXPR, base, offset);
 122               gsi_replace (&gsi, g, false);
 123             }
 124           gsi_next (&gsi);
 125         }
 126     }
 127
 128   return 0;
 129 }
 130
 131 } // anon namespace
 132
 133 gimple_opt_pass *
 134 make_pass_laddress (gcc::context *ctxt)
 135 {
 136   return new pass_laddress (ctxt);
 137 }