gcc/gimple-laddress.c

   1 /* Lower and optimize address expressions.
   2    Copyright (C) 2015-2020 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-vrp.h"
  36 #include "tree-ssanames.h"
  37 #include "fold-const.h"
  38 #include "gimple-expr.h"
  39 #include "gimple.h"
  40 #include "gimplify.h"
  41 #include "gimple-iterator.h"
  42 #include "gimplify-me.h"
  43 #include "tree-pass.h"
  44
  45
  46 namespace {
  47
  48 const pass_data pass_data_laddress =
  49 {
  50   GIMPLE_PASS, /* type */
  51   "laddress", /* name */
  52   OPTGROUP_NONE, /* optinfo_flags */
  53   TV_GIMPLE_LADDRESS, /* tv_id */
  54   ( PROP_cfg | PROP_ssa ), /* properties_required */
  55   0, /* properties_provided */
  56   0, /* properties_destroyed */
  57   0, /* todo_flags_start */
  58   0, /* todo_flags_finish */
  59 };
  60
  61 class pass_laddress : public gimple_opt_pass
  62 {
  63 public:
  64   pass_laddress (gcc::context *ctxt)
  65     : gimple_opt_pass (pass_data_laddress, ctxt)
  66   {}
  67
  68   /* opt_pass methods: */
  69   opt_pass * clone () { return new pass_laddress (m_ctxt); }
  70   virtual bool gate (function *) { return optimize != 0; }
  71   virtual unsigned int execute (function *);
  72
  73 }; // class pass_laddress
  74
  75 unsigned int
  76 pass_laddress::execute (function *fun)
  77 {
  78   basic_block bb;
  79
  80   FOR_EACH_BB_FN (bb, fun)
  81     {
  82       for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
  83         {
  84           gimple *stmt = gsi_stmt (gsi);
  85           if (!is_gimple_assign (stmt)
  86               || gimple_assign_rhs_code (stmt) != ADDR_EXPR
  87               || is_gimple_invariant_address (gimple_assign_rhs1 (stmt)))
  88             {
  89               gsi_next (&gsi);
  90               continue;
  91             }
  92
  93           /* Lower ADDR_EXPR assignments:
  94                _4 = &b[i_9];
  95              into
  96                _1 = (sizetype) i_9;
  97                _7 = _1 * 4;
  98                _4 = &b + _7;
  99              This ought to aid the vectorizer and expose CSE opportunities.
 100           */
 101
 102           tree expr = gimple_assign_rhs1 (stmt);
 103           poly_int64 bitsize, bitpos;
 104           tree base, offset;
 105           machine_mode mode;
 106           int volatilep = 0, reversep, unsignedp = 0;
 107           base = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize,
 108                                       &bitpos, &offset, &mode, &unsignedp,
 109                                       &reversep, &volatilep);
 110           gcc_assert (base != NULL_TREE);
 111           poly_int64 bytepos = exact_div (bitpos, BITS_PER_UNIT);
 112           if (offset != NULL_TREE)
 113             {
 114               if (maybe_ne (bytepos, 0))
 115                 offset = size_binop (PLUS_EXPR, offset, size_int (bytepos));
 116               offset = force_gimple_operand_gsi (&gsi, offset, true, NULL,
 117                                                  true, GSI_SAME_STMT);
 118               base = build_fold_addr_expr (base);
 119               base = force_gimple_operand_gsi (&gsi, base, true, NULL,
 120                                                true, GSI_SAME_STMT);
 121               gimple *g = gimple_build_assign (gimple_assign_lhs (stmt),
 122                                               POINTER_PLUS_EXPR, base, offset);
 123               gsi_replace (&gsi, g, false);
 124             }
 125           gsi_next (&gsi);
 126         }
 127     }
 128
 129   return 0;
 130 }
 131
 132 } // anon namespace
 133
 134 gimple_opt_pass *
 135 make_pass_laddress (gcc::context *ctxt)
 136 {
 137   return new pass_laddress (ctxt);
 138 }