gcc/java/java-gimplify.c

   1 /* Java(TM) language-specific gimplification routines.
   2    Copyright (C) 2003, 2004, 2006, 2007, 2007 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.
  19
  20 Java and all Java-based marks are trademarks or registered trademarks
  21 of Sun Microsystems, Inc. in the United States and other countries.
  22 The Free Software Foundation is independent of Sun Microsystems, Inc.  */
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "coretypes.h"
  27 #include "tm.h"
  28 #include "tree.h"
  29 #include "java-tree.h"
  30 #include "tree-dump.h"
  31 #include "gimple.h"
  32 #include "toplev.h"
  33
  34 static tree java_gimplify_block (tree);
  35 static enum gimplify_status java_gimplify_modify_expr (tree *);
  36 static enum gimplify_status java_gimplify_self_mod_expr (tree *, gimple_seq *,
  37                                                          gimple_seq *);
  38
  39 static void dump_java_tree (enum tree_dump_index, tree);
  40
  41 /* Convert a Java tree to GENERIC.  */
  42
  43 void
  44 java_genericize (tree fndecl)
  45 {
  46   dump_java_tree (TDI_original, fndecl);
  47
  48   /* Genericize with the gimplifier.  */
  49   gimplify_function_tree (fndecl);
  50
  51   dump_function (TDI_generic, fndecl);
  52 }
  53
  54 /* Gimplify a Java tree.  */
  55
  56 int
  57 java_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
  58 {
  59   enum tree_code code = TREE_CODE (*expr_p);
  60
  61   switch (code)
  62     {
  63     case BLOCK:
  64       *expr_p = java_gimplify_block (*expr_p);
  65       break;
  66
  67     case VAR_DECL:
  68       *expr_p = java_replace_reference (*expr_p, /* want_lvalue */ false);
  69       return GS_UNHANDLED;
  70
  71     case MODIFY_EXPR:
  72       return java_gimplify_modify_expr (expr_p);
  73
  74     case SAVE_EXPR:
  75       /* Note that we can see <save_expr NULL> if the save_expr was
  76          already handled by gimplify_save_expr.  */
  77       if (TREE_OPERAND (*expr_p, 0) != NULL_TREE
  78           && TREE_CODE (TREE_OPERAND (*expr_p, 0)) == VAR_DECL)
  79         TREE_OPERAND (*expr_p, 0)
  80           = java_replace_reference (TREE_OPERAND (*expr_p, 0),
  81                                /* want_lvalue */ false);
  82       return GS_UNHANDLED;
  83
  84     case POSTINCREMENT_EXPR:
  85     case POSTDECREMENT_EXPR:
  86     case PREINCREMENT_EXPR:
  87     case PREDECREMENT_EXPR:
  88       return java_gimplify_self_mod_expr (expr_p, pre_p, post_p);
  89
  90     /* These should already be lowered before we get here.  */
  91     case URSHIFT_EXPR:
  92     case COMPARE_EXPR:
  93     case COMPARE_L_EXPR:
  94     case COMPARE_G_EXPR:
  95       gcc_unreachable ();
  96
  97     default:
  98       /* Java insists on strict left-to-right evaluation of expressions.
  99          A problem may arise if a variable used in the LHS of a binary
 100          operation is altered by an assignment to that value in the RHS
 101          before we've performed the operation.  So, we always copy every
 102          LHS to a temporary variable.
 103
 104          FIXME: Are there any other cases where we should do this?
 105          Parameter lists, maybe?  Or perhaps that's unnecessary because
 106          the front end already generates SAVE_EXPRs.  */
 107
 108       if (TREE_CODE_CLASS (code) == tcc_binary
 109           || TREE_CODE_CLASS (code) == tcc_comparison)
 110         {
 111           enum gimplify_status stat
 112             = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
 113                              is_gimple_formal_tmp_var, fb_rvalue);
 114           if (stat == GS_ERROR)
 115             return stat;
 116         }
 117
 118       return GS_UNHANDLED;
 119     }
 120
 121   return GS_OK;
 122 }
 123
 124 static enum gimplify_status
 125 java_gimplify_modify_expr (tree *modify_expr_p)
 126 {
 127   tree modify_expr = *modify_expr_p;
 128   tree lhs = TREE_OPERAND (modify_expr, 0);
 129   tree rhs = TREE_OPERAND (modify_expr, 1);
 130   tree lhs_type = TREE_TYPE (lhs);
 131
 132   /* This is specific to the bytecode compiler.  If a variable has
 133      LOCAL_SLOT_P set, replace an assignment to it with an assignment
 134      to the corresponding variable that holds all its aliases.  */
 135   if (TREE_CODE (lhs) == VAR_DECL
 136       && DECL_LANG_SPECIFIC (lhs)
 137       && LOCAL_SLOT_P (lhs)
 138       && TREE_CODE (lhs_type) == POINTER_TYPE)
 139     {
 140       tree new_lhs = java_replace_reference (lhs, /* want_lvalue */ true);
 141       tree new_rhs = build1 (NOP_EXPR, TREE_TYPE (new_lhs), rhs);
 142       modify_expr = build2 (MODIFY_EXPR, TREE_TYPE (new_lhs),
 143                             new_lhs, new_rhs);
 144       modify_expr = build1 (NOP_EXPR, lhs_type, modify_expr);
 145     }
 146   else if (lhs_type != TREE_TYPE (rhs))
 147     /* Fix up type mismatches to make legal GIMPLE.  These are
 148        generated in several places, in particular null pointer
 149        assignment and subclass assignment.  */
 150     TREE_OPERAND (modify_expr, 1) = convert (lhs_type, rhs);
 151
 152   *modify_expr_p = modify_expr;
 153   return GS_UNHANDLED;
 154 }
 155
 156 /*  Special case handling for volatiles: we need to generate a barrier
 157     between the reading and the writing.  */
 158
 159 static enum gimplify_status
 160 java_gimplify_self_mod_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
 161                              gimple_seq *post_p ATTRIBUTE_UNUSED)
 162 {
 163   tree lhs = TREE_OPERAND (*expr_p, 0);
 164
 165   if (TREE_CODE (lhs) == COMPONENT_REF
 166       && TREE_THIS_VOLATILE (TREE_OPERAND (lhs, 1)))
 167     TREE_THIS_VOLATILE (lhs) = 1;
 168
 169   return GS_UNHANDLED;
 170 }
 171
 172
 173 /* Gimplify BLOCK into a BIND_EXPR.  */
 174
 175 static tree
 176 java_gimplify_block (tree java_block)
 177 {
 178   tree decls = BLOCK_VARS (java_block);
 179   tree body = BLOCK_EXPR_BODY (java_block);
 180   gimple outer = gimple_current_bind_expr ();
 181   tree block;
 182
 183   /* Don't bother with empty blocks.  */
 184   if (! body)
 185     return build_empty_stmt ();
 186
 187   if (IS_EMPTY_STMT (body))
 188     return body;
 189
 190   /* Make a proper block.  Java blocks are unsuitable for BIND_EXPR
 191      because they use BLOCK_SUBBLOCKS for another purpose.  */
 192   block = make_node (BLOCK);
 193   BLOCK_VARS (block) = decls;
 194
 195   /* The TREE_USED flag on a block determines whether the debug output
 196      routines generate info for the variables in that block.  */
 197   TREE_USED (block) = 1;
 198
 199   if (outer != NULL)
 200     {
 201       tree b = gimple_bind_block (outer);
 202       BLOCK_SUBBLOCKS (b) = chainon (BLOCK_SUBBLOCKS (b), block);
 203     }
 204   BLOCK_EXPR_BODY (java_block) = NULL_TREE;
 205
 206   return build3 (BIND_EXPR, TREE_TYPE (java_block), decls, body, block);
 207 }
 208
 209 /* Dump a tree of some kind.  This is a convenience wrapper for the
 210    dump_* functions in tree-dump.c.  */
 211 static void
 212 dump_java_tree (enum tree_dump_index phase, tree t)
 213 {
 214   FILE *stream;
 215   int flags;
 216
 217   stream = dump_begin (phase, &flags);
 218   flags |= TDF_SLIM;
 219   if (stream)
 220     {
 221       dump_node (t, flags, stream);
 222       dump_end (phase, stream);
 223     }
 224 }