aboutsummaryrefslogtreecommitdiff
path: root/gcc/c-gimplify.c
blob: 15d6705d744d073a7e9605b6d726a967ea9a7e0c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
/* Tree lowering pass.  This pass gimplifies the tree representation built
   by the C-based front ends.  The structure of gimplified, or
   language-independent, trees is dictated by the grammar described in this
   file.
   Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   Lowering of expressions contributed by Sebastian Pop <s.pop@laposte.net>
   Re-written to support lowering of whole function trees, documentation
   and miscellaneous cleanups by Diego Novillo <dnovillo@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "varray.h"
#include "c-tree.h"
#include "c-common.h"
#include "tree-gimple.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "tree-flow.h"
#include "tree-inline.h"
#include "diagnostic.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "flags.h"
#include "rtl.h"
#include "toplev.h"
#include "tree-dump.h"
#include "c-pretty-print.h"
#include "cgraph.h"


/*  The gimplification pass converts the language-dependent trees
    (ld-trees) emitted by the parser into language-independent trees
    (li-trees) that are the target of SSA analysis and transformations.

    Language-independent trees are based on the SIMPLE intermediate
    representation used in the McCAT compiler framework:

    "Designing the McCAT Compiler Based on a Family of Structured
    Intermediate Representations,"
    L. Hendren, C. Donawa, M. Emami, G. Gao, Justiani, and B. Sridharan,
    Proceedings of the 5th International Workshop on Languages and
    Compilers for Parallel Computing, no. 757 in Lecture Notes in
    Computer Science, New Haven, Connecticut, pp. 406-420,
    Springer-Verlag, August 3-5, 1992.

    http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html

    Basically, we walk down gimplifying the nodes that we encounter.  As we
    walk back up, we check that they fit our constraints, and copy them
    into temporaries if not.  */

/* Gimplification of statement trees.  */

/* Convert the tree representation of FNDECL from C frontend trees to
   GENERIC.  */

void
c_genericize (tree fndecl)
{
  FILE *dump_file;
  int local_dump_flags;
  struct cgraph_node *cgn;

  /* Dump the C-specific tree IR.  */
  dump_file = dump_begin (TDI_original, &local_dump_flags);
  if (dump_file)
    {
      fprintf (dump_file, "\n;; Function %s",
	       lang_hooks.decl_printable_name (fndecl, 2));
      fprintf (dump_file, " (%s)\n",
	       IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl)));
      fprintf (dump_file, ";; enabled by -%s\n", dump_flag_name (TDI_original));
      fprintf (dump_file, "\n");

      if (local_dump_flags & TDF_RAW)
	dump_node (DECL_SAVED_TREE (fndecl),
		   TDF_SLIM | local_dump_flags, dump_file);
      else
	print_c_tree (dump_file, DECL_SAVED_TREE (fndecl));
      fprintf (dump_file, "\n");

      dump_end (TDI_original, dump_file);
    }

  /* Go ahead and gimplify for now.  */
  gimplify_function_tree (fndecl);

  /* Dump the genericized tree IR.  */
  dump_function (TDI_generic, fndecl);

  /* Genericize all nested functions now.  We do things in this order so
     that items like VLA sizes are expanded properly in the context of
     the correct function.  */
  cgn = cgraph_node (fndecl);
  for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested)
    c_genericize (cgn->decl);
}

static void
add_block_to_enclosing (tree block)
{
  tree enclosing;

  for (enclosing = gimple_current_bind_expr ();
       enclosing; enclosing = TREE_CHAIN (enclosing))
    if (BIND_EXPR_BLOCK (enclosing))
      break;

  enclosing = BIND_EXPR_BLOCK (enclosing);
  BLOCK_SUBBLOCKS (enclosing) = chainon (BLOCK_SUBBLOCKS (enclosing), block);
}

/* Genericize a scope by creating a new BIND_EXPR.
   BLOCK is either a BLOCK representing the scope or a chain of _DECLs.
     In the latter case, we need to create a new BLOCK and add it to the
     BLOCK_SUBBLOCKS of the enclosing block.
   BODY is a chain of C _STMT nodes for the contents of the scope, to be
     genericized.  */

tree
c_build_bind_expr (tree block, tree body)
{
  tree decls, bind;

  if (block == NULL_TREE)
    decls = NULL_TREE;
  else if (TREE_CODE (block) == BLOCK)
    decls = BLOCK_VARS (block);
  else
    {
      decls = block;
      if (DECL_ARTIFICIAL (decls))
	block = NULL_TREE;
      else
	{
	  block = make_node (BLOCK);
	  BLOCK_VARS (block) = decls;
	  add_block_to_enclosing (block);
	}
    }

  if (!body)
    body = build_empty_stmt ();
  if (decls || block)
    {
      bind = build3 (BIND_EXPR, void_type_node, decls, body, block);
      TREE_SIDE_EFFECTS (bind) = 1;
    }
  else
    bind = body;

  return bind;
}

/* Gimplification of expression trees.  */

/* Gimplify a C99 compound literal expression.  This just means adding
   the DECL_EXPR before the current statement and using its anonymous
   decl instead.  */

static enum gimplify_status
gimplify_compound_literal_expr (tree *expr_p, tree *pre_p)
{
  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_STMT (*expr_p);
  tree decl = DECL_EXPR_DECL (decl_s);

  /* This decl isn't mentioned in the enclosing block, so add it to the
     list of temps.  FIXME it seems a bit of a kludge to say that
     anonymous artificial vars aren't pushed, but everything else is.  */
  if (DECL_NAME (decl) == NULL_TREE)
    gimple_add_tmp_var (decl);

  gimplify_and_add (decl_s, pre_p);
  *expr_p = decl;
  return GS_OK;
}

/* Do C-specific gimplification.  Args are as for gimplify_expr.  */

int
c_gimplify_expr (tree *expr_p, tree *pre_p, tree *post_p ATTRIBUTE_UNUSED)
{
  enum tree_code code = TREE_CODE (*expr_p);

  switch (code)
    {
    case DECL_EXPR:
      /* This is handled mostly by gimplify.c, but we have to deal with
	 not warning about int x = x; as it is a GCC extension to turn off
	 this warning but only if warn_init_self is zero.  */
      if (TREE_CODE (DECL_EXPR_DECL (*expr_p)) == VAR_DECL
	  && !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p))
	  && !TREE_STATIC (DECL_EXPR_DECL (*expr_p))
	  && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p))
	      == DECL_EXPR_DECL (*expr_p))
	  && !warn_init_self)
	TREE_NO_WARNING (DECL_EXPR_DECL (*expr_p)) = 1;
      return GS_UNHANDLED;
      
    case COMPOUND_LITERAL_EXPR:
      return gimplify_compound_literal_expr (expr_p, pre_p);

    default:
      return GS_UNHANDLED;
    }
}