gcc/gimplify-me.c

   1 /* Tree lowering to gimple for middle end use only.
   2    This converts the GENERIC functions-as-trees tree representation into
   3    the GIMPLE form.
   4    Copyright (C) 2013 Free Software Foundation, Inc.
   5    Major work done by Sebastian Pop <s.pop@laposte.net>,
   6    Diego Novillo <dnovillo@redhat.com> and Jason Merrill <jason@redhat.com>.
   7
   8 This file is part of GCC.
   9
  10 GCC is free software; you can redistribute it and/or modify it under
  11 the terms of the GNU General Public License as published by the Free
  12 Software Foundation; either version 3, or (at your option) any later
  13 version.
  14
  15 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  16 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18 for more details.
  19
  20 You should have received a copy of the GNU General Public License
  21 along with GCC; see the file COPYING3.  If not see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "tree.h"
  28 #include "stmt.h"
  29 #include "stor-layout.h"
  30 #include "gimple.h"
  31 #include "gimple-iterator.h"
  32 #include "gimplify.h"
  33 #include "gimplify-me.h"
  34 #include "gimple-ssa.h"
  35 #include "stringpool.h"
  36 #include "tree-ssanames.h"
  37
  38
  39 /* Expand EXPR to list of gimple statements STMTS.  GIMPLE_TEST_F specifies
  40    the predicate that will hold for the result.  If VAR is not NULL, make the
  41    base variable of the final destination be VAR if suitable.  */
  42
  43 tree
  44 force_gimple_operand_1 (tree expr, gimple_seq *stmts,
  45                         gimple_predicate gimple_test_f, tree var)
  46 {
  47   enum gimplify_status ret;
  48   struct gimplify_ctx gctx;
  49   location_t saved_location;
  50
  51   *stmts = NULL;
  52
  53   /* gimple_test_f might be more strict than is_gimple_val, make
  54      sure we pass both.  Just checking gimple_test_f doesn't work
  55      because most gimple predicates do not work recursively.  */
  56   if (is_gimple_val (expr)
  57       && (*gimple_test_f) (expr))
  58     return expr;
  59
  60   push_gimplify_context (&gctx);
  61   gimplify_ctxp->into_ssa = gimple_in_ssa_p (cfun);
  62   gimplify_ctxp->allow_rhs_cond_expr = true;
  63   saved_location = input_location;
  64   input_location = UNKNOWN_LOCATION;
  65
  66   if (var)
  67     {
  68       if (gimplify_ctxp->into_ssa
  69           && is_gimple_reg (var))
  70         var = make_ssa_name (var, NULL);
  71       expr = build2 (MODIFY_EXPR, TREE_TYPE (var), var, expr);
  72     }
  73
  74   if (TREE_CODE (expr) != MODIFY_EXPR
  75       && TREE_TYPE (expr) == void_type_node)
  76     {
  77       gimplify_and_add (expr, stmts);
  78       expr = NULL_TREE;
  79     }
  80   else
  81     {
  82       ret = gimplify_expr (&expr, stmts, NULL, gimple_test_f, fb_rvalue);
  83       gcc_assert (ret != GS_ERROR);
  84     }
  85
  86   input_location = saved_location;
  87   pop_gimplify_context (NULL);
  88
  89   return expr;
  90 }
  91
  92 /* Expand EXPR to list of gimple statements STMTS.  If SIMPLE is true,
  93    force the result to be either ssa_name or an invariant, otherwise
  94    just force it to be a rhs expression.  If VAR is not NULL, make the
  95    base variable of the final destination be VAR if suitable.  */
  96
  97 tree
  98 force_gimple_operand (tree expr, gimple_seq *stmts, bool simple, tree var)
  99 {
 100   return force_gimple_operand_1 (expr, stmts,
 101                                  simple ? is_gimple_val : is_gimple_reg_rhs,
 102                                  var);
 103 }
 104
 105 /* Invoke force_gimple_operand_1 for EXPR with parameters GIMPLE_TEST_F
 106    and VAR.  If some statements are produced, emits them at GSI.
 107    If BEFORE is true.  the statements are appended before GSI, otherwise
 108    they are appended after it.  M specifies the way GSI moves after
 109    insertion (GSI_SAME_STMT or GSI_CONTINUE_LINKING are the usual values).  */
 110
 111 tree
 112 force_gimple_operand_gsi_1 (gimple_stmt_iterator *gsi, tree expr,
 113                             gimple_predicate gimple_test_f,
 114                             tree var, bool before,
 115                             enum gsi_iterator_update m)
 116 {
 117   gimple_seq stmts;
 118
 119   expr = force_gimple_operand_1 (expr, &stmts, gimple_test_f, var);
 120
 121   if (!gimple_seq_empty_p (stmts))
 122     {
 123       if (before)
 124         gsi_insert_seq_before (gsi, stmts, m);
 125       else
 126         gsi_insert_seq_after (gsi, stmts, m);
 127     }
 128
 129   return expr;
 130 }
 131
 132 /* Invoke force_gimple_operand_1 for EXPR with parameter VAR.
 133    If SIMPLE is true, force the result to be either ssa_name or an invariant,
 134    otherwise just force it to be a rhs expression.  If some statements are
 135    produced, emits them at GSI.  If BEFORE is true, the statements are
 136    appended before GSI, otherwise they are appended after it.  M specifies
 137    the way GSI moves after insertion (GSI_SAME_STMT or GSI_CONTINUE_LINKING
 138    are the usual values).  */
 139
 140 tree
 141 force_gimple_operand_gsi (gimple_stmt_iterator *gsi, tree expr,
 142                           bool simple_p, tree var, bool before,
 143                           enum gsi_iterator_update m)
 144 {
 145   return force_gimple_operand_gsi_1 (gsi, expr,
 146                                      simple_p
 147                                      ? is_gimple_val : is_gimple_reg_rhs,
 148                                      var, before, m);
 149 }
 150
 151 /* Some transformations like inlining may invalidate the GIMPLE form
 152    for operands.  This function traverses all the operands in STMT and
 153    gimplifies anything that is not a valid gimple operand.  Any new
 154    GIMPLE statements are inserted before *GSI_P.  */
 155
 156 void
 157 gimple_regimplify_operands (gimple stmt, gimple_stmt_iterator *gsi_p)
 158 {
 159   size_t i, num_ops;
 160   tree lhs;
 161   gimple_seq pre = NULL;
 162   gimple post_stmt = NULL;
 163   struct gimplify_ctx gctx;
 164
 165   push_gimplify_context (&gctx);
 166   gimplify_ctxp->into_ssa = gimple_in_ssa_p (cfun);
 167
 168   switch (gimple_code (stmt))
 169     {
 170     case GIMPLE_COND:
 171       gimplify_expr (gimple_cond_lhs_ptr (stmt), &pre, NULL,
 172                      is_gimple_val, fb_rvalue);
 173       gimplify_expr (gimple_cond_rhs_ptr (stmt), &pre, NULL,
 174                      is_gimple_val, fb_rvalue);
 175       break;
 176     case GIMPLE_SWITCH:
 177       gimplify_expr (gimple_switch_index_ptr (stmt), &pre, NULL,
 178                      is_gimple_val, fb_rvalue);
 179       break;
 180     case GIMPLE_OMP_ATOMIC_LOAD:
 181       gimplify_expr (gimple_omp_atomic_load_rhs_ptr (stmt), &pre, NULL,
 182                      is_gimple_val, fb_rvalue);
 183       break;
 184     case GIMPLE_ASM:
 185       {
 186         size_t i, noutputs = gimple_asm_noutputs (stmt);
 187         const char *constraint, **oconstraints;
 188         bool allows_mem, allows_reg, is_inout;
 189
 190         oconstraints
 191           = (const char **) alloca ((noutputs) * sizeof (const char *));
 192         for (i = 0; i < noutputs; i++)
 193           {
 194             tree op = gimple_asm_output_op (stmt, i);
 195             constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (op)));
 196             oconstraints[i] = constraint;
 197             parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
 198                                      &allows_reg, &is_inout);
 199             gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 200                            is_inout ? is_gimple_min_lval : is_gimple_lvalue,
 201                            fb_lvalue | fb_mayfail);
 202           }
 203         for (i = 0; i < gimple_asm_ninputs (stmt); i++)
 204           {
 205             tree op = gimple_asm_input_op (stmt, i);
 206             constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (op)));
 207             parse_input_constraint (&constraint, 0, 0, noutputs, 0,
 208                                     oconstraints, &allows_mem, &allows_reg);
 209             if (TREE_ADDRESSABLE (TREE_TYPE (TREE_VALUE (op))) && allows_mem)
 210               allows_reg = 0;
 211             if (!allows_reg && allows_mem)
 212               gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 213                              is_gimple_lvalue, fb_lvalue | fb_mayfail);
 214             else
 215               gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 216                              is_gimple_asm_val, fb_rvalue);
 217           }
 218       }
 219       break;
 220     default:
 221       /* NOTE: We start gimplifying operands from last to first to
 222          make sure that side-effects on the RHS of calls, assignments
 223          and ASMs are executed before the LHS.  The ordering is not
 224          important for other statements.  */
 225       num_ops = gimple_num_ops (stmt);
 226       for (i = num_ops; i > 0; i--)
 227         {
 228           tree op = gimple_op (stmt, i - 1);
 229           if (op == NULL_TREE)
 230             continue;
 231           if (i == 1 && (is_gimple_call (stmt) || is_gimple_assign (stmt)))
 232             gimplify_expr (&op, &pre, NULL, is_gimple_lvalue, fb_lvalue);
 233           else if (i == 2
 234                    && is_gimple_assign (stmt)
 235                    && num_ops == 2
 236                    && get_gimple_rhs_class (gimple_expr_code (stmt))
 237                       == GIMPLE_SINGLE_RHS)
 238             gimplify_expr (&op, &pre, NULL,
 239                            rhs_predicate_for (gimple_assign_lhs (stmt)),
 240                            fb_rvalue);
 241           else if (i == 2 && is_gimple_call (stmt))
 242             {
 243               if (TREE_CODE (op) == FUNCTION_DECL)
 244                 continue;
 245               gimplify_expr (&op, &pre, NULL, is_gimple_call_addr, fb_rvalue);
 246             }
 247           else
 248             gimplify_expr (&op, &pre, NULL, is_gimple_val, fb_rvalue);
 249           gimple_set_op (stmt, i - 1, op);
 250         }
 251
 252       lhs = gimple_get_lhs (stmt);
 253       /* If the LHS changed it in a way that requires a simple RHS,
 254          create temporary.  */
 255       if (lhs && !is_gimple_reg (lhs))
 256         {
 257           bool need_temp = false;
 258
 259           if (is_gimple_assign (stmt)
 260               && num_ops == 2
 261               && get_gimple_rhs_class (gimple_expr_code (stmt))
 262                  == GIMPLE_SINGLE_RHS)
 263             gimplify_expr (gimple_assign_rhs1_ptr (stmt), &pre, NULL,
 264                            rhs_predicate_for (gimple_assign_lhs (stmt)),
 265                            fb_rvalue);
 266           else if (is_gimple_reg (lhs))
 267             {
 268               if (is_gimple_reg_type (TREE_TYPE (lhs)))
 269                 {
 270                   if (is_gimple_call (stmt))
 271                     {
 272                       i = gimple_call_flags (stmt);
 273                       if ((i & ECF_LOOPING_CONST_OR_PURE)
 274                           || !(i & (ECF_CONST | ECF_PURE)))
 275                         need_temp = true;
 276                     }
 277                   if (stmt_can_throw_internal (stmt))
 278                     need_temp = true;
 279                 }
 280             }
 281           else
 282             {
 283               if (is_gimple_reg_type (TREE_TYPE (lhs)))
 284                 need_temp = true;
 285               else if (TYPE_MODE (TREE_TYPE (lhs)) != BLKmode)
 286                 {
 287                   if (is_gimple_call (stmt))
 288                     {
 289                       tree fndecl = gimple_call_fndecl (stmt);
 290
 291                       if (!aggregate_value_p (TREE_TYPE (lhs), fndecl)
 292                           && !(fndecl && DECL_RESULT (fndecl)
 293                                && DECL_BY_REFERENCE (DECL_RESULT (fndecl))))
 294                         need_temp = true;
 295                     }
 296                   else
 297                     need_temp = true;
 298                 }
 299             }
 300           if (need_temp)
 301             {
 302               tree temp = create_tmp_reg (TREE_TYPE (lhs), NULL);
 303               if (gimple_in_ssa_p (cfun))
 304                 temp = make_ssa_name (temp, NULL);
 305               gimple_set_lhs (stmt, temp);
 306               post_stmt = gimple_build_assign (lhs, temp);
 307             }
 308         }
 309       break;
 310     }
 311
 312   if (!gimple_seq_empty_p (pre))
 313     gsi_insert_seq_before (gsi_p, pre, GSI_SAME_STMT);
 314   if (post_stmt)
 315     gsi_insert_after (gsi_p, post_stmt, GSI_NEW_STMT);
 316
 317   pop_gimplify_context (NULL);
 318 }
 319
 320