gcc/d/d-gimplify.cc

   1 /* D-specific tree lowering bits; see also gimple.c.
   2    Copyright (C) 2020-2021 Free Software Foundation, Inc.
   3
   4 GCC is free software; you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation; either version 3, or (at your option)
   7 any later version.
   8
   9 GCC is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with GCC; see the file COPYING3.  If not see
  16 <http://www.gnu.org/licenses/>.  */
  17
  18 #include "config.h"
  19 #include "system.h"
  20 #include "coretypes.h"
  21
  22 #include "dmd/globals.h"
  23
  24 #include "tree.h"
  25 #include "gimple-expr.h"
  26 #include "gimplify.h"
  27
  28 #include "d-tree.h"
  29
  30
  31 /* Return TRUE if an operand OP of a given TYPE being copied has no data.
  32    The middle-end does a similar check with zero sized types.  */
  33
  34 static bool
  35 empty_modify_p (tree type, tree op)
  36 {
  37   tree_code code = TREE_CODE (op);
  38   switch (code)
  39     {
  40     case COMPOUND_EXPR:
  41       return empty_modify_p (type, TREE_OPERAND (op, 1));
  42
  43     case CONSTRUCTOR:
  44       /* Non-empty construcors are valid.  */
  45       if (CONSTRUCTOR_NELTS (op) != 0 || TREE_CLOBBER_P (op))
  46         return false;
  47       break;
  48
  49     case CALL_EXPR:
  50       /* Leave nrvo alone because it isn't a copy.  */
  51       if (CALL_EXPR_RETURN_SLOT_OPT (op))
  52         return false;
  53       break;
  54
  55     default:
  56       /* If the operand doesn't have a simple form.  */
  57       if (!is_gimple_lvalue (op) && !INDIRECT_REF_P (op))
  58         return false;
  59       break;
  60     }
  61
  62   return empty_aggregate_p (type);
  63 }
  64
  65 /* Gimplify assignment from an INIT_EXPR or MODIFY_EXPR.  */
  66
  67 static gimplify_status
  68 d_gimplify_modify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
  69 {
  70   tree op0 = TREE_OPERAND (*expr_p, 0);
  71   tree op1 = TREE_OPERAND (*expr_p, 1);
  72
  73   if (error_operand_p (op0) || error_operand_p (op1))
  74     return GS_UNHANDLED;
  75
  76   /* Remove any copies of empty aggregates.  */
  77   if (empty_modify_p (TREE_TYPE (op0), op1))
  78     {
  79       gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
  80                      is_gimple_lvalue, fb_lvalue);
  81
  82       if (TREE_SIDE_EFFECTS (op1))
  83         gimplify_and_add (op1, pre_p);
  84
  85       *expr_p = TREE_OPERAND (*expr_p, 0);
  86       return GS_OK;
  87     }
  88
  89   /* If the back end isn't clever enough to know that the lhs and rhs
  90      types are the same, add an explicit conversion.  */
  91   if ((AGGREGATE_TYPE_P (TREE_TYPE (op0)) || AGGREGATE_TYPE_P (TREE_TYPE (op1)))
  92       && !useless_type_conversion_p (TREE_TYPE (op1), TREE_TYPE (op0)))
  93     {
  94       TREE_OPERAND (*expr_p, 1) = build1 (VIEW_CONVERT_EXPR,
  95                                           TREE_TYPE (op0), op1);
  96       return GS_OK;
  97     }
  98
  99   return GS_UNHANDLED;
 100 }
 101
 102 /* Gimplify an ADDR_EXPR node.  */
 103
 104 static gimplify_status
 105 d_gimplify_addr_expr (tree *expr_p)
 106 {
 107   tree op0 = TREE_OPERAND (*expr_p, 0);
 108   /* Constructors are not lvalues, so make them one.  */
 109   if (TREE_CODE (op0) == CONSTRUCTOR)
 110     {
 111       TREE_OPERAND (*expr_p, 0) = force_target_expr (op0);
 112       return GS_OK;
 113     }
 114
 115   return GS_UNHANDLED;
 116 }
 117
 118 /* Gimplify a CALL_EXPR node.  */
 119
 120 static gimplify_status
 121 d_gimplify_call_expr (tree *expr_p, gimple_seq *pre_p)
 122 {
 123   if (CALL_EXPR_ARGS_ORDERED (*expr_p))
 124     {
 125       /* Strictly evaluate all arguments from left to right.  */
 126       int nargs = call_expr_nargs (*expr_p);
 127       location_t loc = EXPR_LOC_OR_LOC (*expr_p, input_location);
 128
 129       /* No need to enforce evaluation order if only one argument.  */
 130       if (nargs < 2)
 131         return GS_UNHANDLED;
 132
 133       /* Or if all arguments are already free of side-effects.  */
 134       bool has_side_effects = false;
 135       for (int i = 0; i < nargs; i++)
 136         {
 137           if (TREE_SIDE_EFFECTS (CALL_EXPR_ARG (*expr_p, i)))
 138             {
 139               has_side_effects = true;
 140               break;
 141             }
 142         }
 143
 144       if (!has_side_effects)
 145         return GS_UNHANDLED;
 146
 147       /* Leave the last argument for gimplify_call_expr.  */
 148       for (int i = 0; i < nargs - 1; i++)
 149         {
 150           tree new_arg = CALL_EXPR_ARG (*expr_p, i);
 151
 152           /* If argument has a side-effect, gimplify_arg will handle it.  */
 153           if (gimplify_arg (&new_arg, pre_p, loc) == GS_ERROR)
 154             return GS_ERROR;
 155
 156           /* Even if an argument itself doesn't have any side-effects, it
 157              might be altered by another argument in the list.  */
 158           if (new_arg == CALL_EXPR_ARG (*expr_p, i)
 159               && !really_constant_p (new_arg))
 160             new_arg = get_formal_tmp_var (new_arg, pre_p);
 161
 162           CALL_EXPR_ARG (*expr_p, i) = new_arg;
 163         }
 164
 165       return GS_OK;
 166     }
 167
 168   return GS_UNHANDLED;
 169 }
 170
 171 /* Gimplify an UNSIGNED_RSHIFT_EXPR node.  */
 172
 173 static gimplify_status
 174 d_gimplify_unsigned_rshift_expr (tree *expr_p)
 175 {
 176   /* Convert op0 to an unsigned type.  */
 177   tree op0 = TREE_OPERAND (*expr_p, 0);
 178   tree op1 = TREE_OPERAND (*expr_p, 1);
 179   tree type = d_unsigned_type (TREE_TYPE (op0));
 180
 181   *expr_p = convert (TREE_TYPE (*expr_p),
 182                      build2 (RSHIFT_EXPR, type, convert (type, op0), op1));
 183   return GS_OK;
 184 }
 185
 186 /* Implements the lang_hooks.gimplify_expr routine for language D.
 187    Do gimplification of D specific expression trees in EXPR_P.  */
 188
 189 int
 190 d_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
 191 {
 192   switch (TREE_CODE (*expr_p))
 193     {
 194     case INIT_EXPR:
 195     case MODIFY_EXPR:
 196       return d_gimplify_modify_expr (expr_p, pre_p, post_p);
 197
 198     case ADDR_EXPR:
 199       return d_gimplify_addr_expr (expr_p);
 200
 201     case CALL_EXPR:
 202       return d_gimplify_call_expr (expr_p, pre_p);
 203
 204     case UNSIGNED_RSHIFT_EXPR:
 205       return d_gimplify_unsigned_rshift_expr (expr_p);
 206
 207     case FLOAT_MOD_EXPR:
 208       gcc_unreachable ();
 209
 210     default:
 211       break;
 212     }
 213
 214   return GS_UNHANDLED;
 215 }