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) 2013-2014 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 "basic-block.h"
  31 #include "tree-ssa-alias.h"
  32 #include "internal-fn.h"
  33 #include "tree-eh.h"
  34 #include "gimple-expr.h"
  35 #include "is-a.h"
  36 #include "gimple.h"
  37 #include "gimple-iterator.h"
  38 #include "gimplify.h"
  39 #include "gimplify-me.h"
  40 #include "gimple-ssa.h"
  41 #include "stringpool.h"
  42 #include "tree-ssanames.h"
  43
  44
  45 /* Expand EXPR to list of gimple statements STMTS.  GIMPLE_TEST_F specifies
  46    the predicate that will hold for the result.  If VAR is not NULL, make the
  47    base variable of the final destination be VAR if suitable.  */
  48
  49 tree
  50 force_gimple_operand_1 (tree expr, gimple_seq *stmts,
  51                         gimple_predicate gimple_test_f, tree var)
  52 {
  53   enum gimplify_status ret;
  54   location_t saved_location;
  55
  56   *stmts = NULL;
  57
  58   /* gimple_test_f might be more strict than is_gimple_val, make
  59      sure we pass both.  Just checking gimple_test_f doesn't work
  60      because most gimple predicates do not work recursively.  */
  61   if (is_gimple_val (expr)
  62       && (*gimple_test_f) (expr))
  63     return expr;
  64
  65   push_gimplify_context (gimple_in_ssa_p (cfun), true);
  66   saved_location = input_location;
  67   input_location = UNKNOWN_LOCATION;
  68
  69   if (var)
  70     {
  71       if (gimple_in_ssa_p (cfun) && is_gimple_reg (var))
  72         var = make_ssa_name (var, NULL);
  73       expr = build2 (MODIFY_EXPR, TREE_TYPE (var), var, expr);
  74     }
  75
  76   if (TREE_CODE (expr) != MODIFY_EXPR
  77       && TREE_TYPE (expr) == void_type_node)
  78     {
  79       gimplify_and_add (expr, stmts);
  80       expr = NULL_TREE;
  81     }
  82   else
  83     {
  84       ret = gimplify_expr (&expr, stmts, NULL, gimple_test_f, fb_rvalue);
  85       gcc_assert (ret != GS_ERROR);
  86     }
  87
  88   input_location = saved_location;
  89   pop_gimplify_context (NULL);
  90
  91   return expr;
  92 }
  93
  94 /* Expand EXPR to list of gimple statements STMTS.  If SIMPLE is true,
  95    force the result to be either ssa_name or an invariant, otherwise
  96    just force it to be a rhs expression.  If VAR is not NULL, make the
  97    base variable of the final destination be VAR if suitable.  */
  98
  99 tree
 100 force_gimple_operand (tree expr, gimple_seq *stmts, bool simple, tree var)
 101 {
 102   return force_gimple_operand_1 (expr, stmts,
 103                                  simple ? is_gimple_val : is_gimple_reg_rhs,
 104                                  var);
 105 }
 106
 107 /* Invoke force_gimple_operand_1 for EXPR with parameters GIMPLE_TEST_F
 108    and VAR.  If some statements are produced, emits them at GSI.
 109    If BEFORE is true.  the statements are appended before GSI, otherwise
 110    they are appended after it.  M specifies the way GSI moves after
 111    insertion (GSI_SAME_STMT or GSI_CONTINUE_LINKING are the usual values).  */
 112
 113 tree
 114 force_gimple_operand_gsi_1 (gimple_stmt_iterator *gsi, tree expr,
 115                             gimple_predicate gimple_test_f,
 116                             tree var, bool before,
 117                             enum gsi_iterator_update m)
 118 {
 119   gimple_seq stmts;
 120
 121   expr = force_gimple_operand_1 (expr, &stmts, gimple_test_f, var);
 122
 123   if (!gimple_seq_empty_p (stmts))
 124     {
 125       if (before)
 126         gsi_insert_seq_before (gsi, stmts, m);
 127       else
 128         gsi_insert_seq_after (gsi, stmts, m);
 129     }
 130
 131   return expr;
 132 }
 133
 134 /* Invoke force_gimple_operand_1 for EXPR with parameter VAR.
 135    If SIMPLE is true, force the result to be either ssa_name or an invariant,
 136    otherwise just force it to be a rhs expression.  If some statements are
 137    produced, emits them at GSI.  If BEFORE is true, the statements are
 138    appended before GSI, otherwise they are appended after it.  M specifies
 139    the way GSI moves after insertion (GSI_SAME_STMT or GSI_CONTINUE_LINKING
 140    are the usual values).  */
 141
 142 tree
 143 force_gimple_operand_gsi (gimple_stmt_iterator *gsi, tree expr,
 144                           bool simple_p, tree var, bool before,
 145                           enum gsi_iterator_update m)
 146 {
 147   return force_gimple_operand_gsi_1 (gsi, expr,
 148                                      simple_p
 149                                      ? is_gimple_val : is_gimple_reg_rhs,
 150                                      var, before, m);
 151 }
 152
 153 /* Some transformations like inlining may invalidate the GIMPLE form
 154    for operands.  This function traverses all the operands in STMT and
 155    gimplifies anything that is not a valid gimple operand.  Any new
 156    GIMPLE statements are inserted before *GSI_P.  */
 157
 158 void
 159 gimple_regimplify_operands (gimple stmt, gimple_stmt_iterator *gsi_p)
 160 {
 161   size_t i, num_ops;
 162   tree lhs;
 163   gimple_seq pre = NULL;
 164   gimple post_stmt = NULL;
 165
 166   push_gimplify_context (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 (
 182                        as_a <gimple_omp_atomic_load> (stmt)),
 183                      &pre, NULL, is_gimple_val, fb_rvalue);
 184       break;
 185     case GIMPLE_ASM:
 186       {
 187         gimple_asm asm_stmt = as_a <gimple_asm> (stmt);
 188         size_t i, noutputs = gimple_asm_noutputs (asm_stmt);
 189         const char *constraint, **oconstraints;
 190         bool allows_mem, allows_reg, is_inout;
 191
 192         oconstraints
 193           = (const char **) alloca ((noutputs) * sizeof (const char *));
 194         for (i = 0; i < noutputs; i++)
 195           {
 196             tree op = gimple_asm_output_op (asm_stmt, i);
 197             constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (op)));
 198             oconstraints[i] = constraint;
 199             parse_output_constraint (&constraint, i, 0, 0, &allows_mem,
 200                                      &allows_reg, &is_inout);
 201             gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 202                            is_inout ? is_gimple_min_lval : is_gimple_lvalue,
 203                            fb_lvalue | fb_mayfail);
 204           }
 205         for (i = 0; i < gimple_asm_ninputs (asm_stmt); i++)
 206           {
 207             tree op = gimple_asm_input_op (asm_stmt, i);
 208             constraint = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (op)));
 209             parse_input_constraint (&constraint, 0, 0, noutputs, 0,
 210                                     oconstraints, &allows_mem, &allows_reg);
 211             if (TREE_ADDRESSABLE (TREE_TYPE (TREE_VALUE (op))) && allows_mem)
 212               allows_reg = 0;
 213             if (!allows_reg && allows_mem)
 214               gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 215                              is_gimple_lvalue, fb_lvalue | fb_mayfail);
 216             else
 217               gimplify_expr (&TREE_VALUE (op), &pre, NULL,
 218                              is_gimple_asm_val, fb_rvalue);
 219           }
 220       }
 221       break;
 222     default:
 223       /* NOTE: We start gimplifying operands from last to first to
 224          make sure that side-effects on the RHS of calls, assignments
 225          and ASMs are executed before the LHS.  The ordering is not
 226          important for other statements.  */
 227       num_ops = gimple_num_ops (stmt);
 228       for (i = num_ops; i > 0; i--)
 229         {
 230           tree op = gimple_op (stmt, i - 1);
 231           if (op == NULL_TREE)
 232             continue;
 233           if (i == 1 && (is_gimple_call (stmt) || is_gimple_assign (stmt)))
 234             gimplify_expr (&op, &pre, NULL, is_gimple_lvalue, fb_lvalue);
 235           else if (i == 2
 236                    && is_gimple_assign (stmt)
 237                    && num_ops == 2
 238                    && get_gimple_rhs_class (gimple_expr_code (stmt))
 239                       == GIMPLE_SINGLE_RHS)
 240             gimplify_expr (&op, &pre, NULL,
 241                            rhs_predicate_for (gimple_assign_lhs (stmt)),
 242                            fb_rvalue);
 243           else if (i == 2 && is_gimple_call (stmt))
 244             {
 245               if (TREE_CODE (op) == FUNCTION_DECL)
 246                 continue;
 247               gimplify_expr (&op, &pre, NULL, is_gimple_call_addr, fb_rvalue);
 248             }
 249           else
 250             gimplify_expr (&op, &pre, NULL, is_gimple_val, fb_rvalue);
 251           gimple_set_op (stmt, i - 1, op);
 252         }
 253
 254       lhs = gimple_get_lhs (stmt);
 255       /* If the LHS changed it in a way that requires a simple RHS,
 256          create temporary.  */
 257       if (lhs && !is_gimple_reg (lhs))
 258         {
 259           bool need_temp = false;
 260
 261           if (is_gimple_assign (stmt)
 262               && num_ops == 2
 263               && get_gimple_rhs_class (gimple_expr_code (stmt))
 264                  == GIMPLE_SINGLE_RHS)
 265             gimplify_expr (gimple_assign_rhs1_ptr (stmt), &pre, NULL,
 266                            rhs_predicate_for (gimple_assign_lhs (stmt)),
 267                            fb_rvalue);
 268           else if (is_gimple_reg (lhs))
 269             {
 270               if (is_gimple_reg_type (TREE_TYPE (lhs)))
 271                 {
 272                   if (is_gimple_call (stmt))
 273                     {
 274                       i = gimple_call_flags (stmt);
 275                       if ((i & ECF_LOOPING_CONST_OR_PURE)
 276                           || !(i & (ECF_CONST | ECF_PURE)))
 277                         need_temp = true;
 278                     }
 279                   if (stmt_can_throw_internal (stmt))
 280                     need_temp = true;
 281                 }
 282             }
 283           else
 284             {
 285               if (is_gimple_reg_type (TREE_TYPE (lhs)))
 286                 need_temp = true;
 287               else if (TYPE_MODE (TREE_TYPE (lhs)) != BLKmode)
 288                 {
 289                   if (is_gimple_call (stmt))
 290                     {
 291                       tree fndecl = gimple_call_fndecl (stmt);
 292
 293                       if (!aggregate_value_p (TREE_TYPE (lhs), fndecl)
 294                           && !(fndecl && DECL_RESULT (fndecl)
 295                                && DECL_BY_REFERENCE (DECL_RESULT (fndecl))))
 296                         need_temp = true;
 297                     }
 298                   else
 299                     need_temp = true;
 300                 }
 301             }
 302           if (need_temp)
 303             {
 304               tree temp = create_tmp_reg (TREE_TYPE (lhs), NULL);
 305               if (gimple_in_ssa_p (cfun))
 306                 temp = make_ssa_name (temp, NULL);
 307               gimple_set_lhs (stmt, temp);
 308               post_stmt = gimple_build_assign (lhs, temp);
 309             }
 310         }
 311       break;
 312     }
 313
 314   if (!gimple_seq_empty_p (pre))
 315     gsi_insert_seq_before (gsi_p, pre, GSI_SAME_STMT);
 316   if (post_stmt)
 317     gsi_insert_after (gsi_p, post_stmt, GSI_NEW_STMT);
 318
 319   pop_gimplify_context (NULL);
 320
 321   update_stmt (stmt);
 322 }
 323
 324