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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [gcc/] [testsuite/] [g++.dg/] [plugin/] [selfassign.c] - Blame information for rev 705

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Line No. Rev Author Line
1 693 jeremybenn
/* This plugin contains an analysis pass that detects and warns about
2
   self-assignment statements.  */
3
/* { dg-options "-O" } */
4
 
5
#include "gcc-plugin.h"
6
#include "config.h"
7
#include "system.h"
8
#include "coretypes.h"
9
#include "tm.h"
10
#include "toplev.h"
11
#include "basic-block.h"
12
#include "gimple.h"
13
#include "tree.h"
14
#include "tree-pass.h"
15
#include "intl.h"
16
#include "plugin-version.h"
17
#include "diagnostic.h"
18
 
19
int plugin_is_GPL_compatible;
20
 
21
/* Indicate whether to check overloaded operator '=', which is performed by
22
   default. To disable it, use -fplugin-arg-NAME-no-check-operator-eq.  */
23
bool check_operator_eq = true;
24
 
25
/* Given a rhs EXPR of a gimple assign statement, if it is
26
   - SSA_NAME : returns its var decl, or, if it is a temp variable,
27
                returns the rhs of its SSA def statement.
28
   - VAR_DECL, PARM_DECL, FIELD_DECL, or a reference expression :
29
                returns EXPR itself.
30
   - any other expression : returns NULL_TREE.  */
31
 
32
static tree
33
get_real_ref_rhs (tree expr)
34
{
35
  switch (TREE_CODE (expr))
36
    {
37
      case SSA_NAME:
38
        {
39
          /* Given a self-assign statement, say foo.x = foo.x,
40
             the IR (after SSA) looks like:
41
 
42
             D.1797_14 = foo.x;
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             foo.x ={v} D.1797_14;
44
 
45
             So if the rhs EXPR is an SSA_NAME of a temp variable,
46
             e.g. D.1797_14, we need to grab the rhs of its SSA def
47
             statement (i.e. foo.x).  */
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          tree vdecl = SSA_NAME_VAR (expr);
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          if (DECL_ARTIFICIAL (vdecl)
50
              && !gimple_nop_p (SSA_NAME_DEF_STMT (expr)))
51
            {
52
              gimple def_stmt = SSA_NAME_DEF_STMT (expr);
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              /* We are only interested in an assignment with a single
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                 rhs operand because if it is not, the original assignment
55
                 will not possibly be a self-assignment.  */
56
              if (gimple_assign_single_p (def_stmt))
57
                return get_real_ref_rhs (gimple_assign_rhs1 (def_stmt));
58
              else
59
                return NULL_TREE;
60
            }
61
          else
62
            return vdecl;
63
        }
64
      case VAR_DECL:
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      case PARM_DECL:
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      case FIELD_DECL:
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      case COMPONENT_REF:
68
      case MEM_REF:
69
      case ARRAY_REF:
70
        return expr;
71
      default:
72
        return NULL_TREE;
73
    }
74
}
75
 
76
/* Given an expression tree, EXPR, that may contains SSA names, returns an
77
   equivalent tree with the SSA names converted to var/parm/field decls
78
   so that it can be used with '%E' format modifier when emitting warning
79
   messages.
80
 
81
   This function currently only supports VAR/PARM/FIELD_DECL, reference
82
   expressions (COMPONENT_REF, INDIRECT_REF, ARRAY_REF), integer constant,
83
   and SSA_NAME. If EXPR contains any other tree nodes (e.g. an arithmetic
84
   expression appears in array index), NULL_TREE is returned.  */
85
 
86
static tree
87
get_non_ssa_expr (tree expr)
88
{
89
  switch (TREE_CODE (expr))
90
    {
91
      case VAR_DECL:
92
      case PARM_DECL:
93
      case FIELD_DECL:
94
        {
95
          if (DECL_NAME (expr))
96
            return expr;
97
          else
98
            return NULL_TREE;
99
        }
100
      case COMPONENT_REF:
101
        {
102
          tree base, orig_base = TREE_OPERAND (expr, 0);
103
          tree component, orig_component = TREE_OPERAND (expr, 1);
104
          base = get_non_ssa_expr (orig_base);
105
          if (!base)
106
            return NULL_TREE;
107
          component = get_non_ssa_expr (orig_component);
108
          if (!component)
109
            return NULL_TREE;
110
          /* If either BASE or COMPONENT is converted, build a new
111
             component reference tree.  */
112
          if (base != orig_base || component != orig_component)
113
            return build3 (COMPONENT_REF, TREE_TYPE (component),
114
                           base, component, NULL_TREE);
115
          else
116
            return expr;
117
        }
118
      case MEM_REF:
119
        {
120
          tree orig_base = TREE_OPERAND (expr, 0);
121
          if (TREE_CODE (orig_base) == SSA_NAME)
122
            {
123
              tree base = get_non_ssa_expr (orig_base);
124
              if (!base)
125
                return NULL_TREE;
126
              return fold_build2 (MEM_REF, TREE_TYPE (expr),
127
                                  base, TREE_OPERAND (expr, 1));
128
            }
129
          return expr;
130
        }
131
      case ARRAY_REF:
132
        {
133
          tree array, orig_array = TREE_OPERAND (expr, 0);
134
          tree index, orig_index = TREE_OPERAND (expr, 1);
135
          array = get_non_ssa_expr (orig_array);
136
          if (!array)
137
            return NULL_TREE;
138
          index = get_non_ssa_expr (orig_index);
139
          if (!index)
140
            return NULL_TREE;
141
          /* If either ARRAY or INDEX is converted, build a new array
142
             reference tree.  */
143
          if (array != orig_array || index != orig_index)
144
            return build4 (ARRAY_REF, TREE_TYPE (expr), array, index,
145
                           TREE_OPERAND (expr, 2), TREE_OPERAND (expr, 3));
146
          else
147
            return expr;
148
        }
149
      case SSA_NAME:
150
        {
151
          tree vdecl = SSA_NAME_VAR (expr);
152
          if (DECL_ARTIFICIAL (vdecl)
153
              && !gimple_nop_p (SSA_NAME_DEF_STMT (expr)))
154
            {
155
              gimple def_stmt = SSA_NAME_DEF_STMT (expr);
156
              if (gimple_assign_single_p (def_stmt))
157
                vdecl = gimple_assign_rhs1 (def_stmt);
158
            }
159
          return get_non_ssa_expr (vdecl);
160
        }
161
      case INTEGER_CST:
162
        return expr;
163
      default:
164
        /* Return NULL_TREE for any other kind of tree nodes.  */
165
        return NULL_TREE;
166
    }
167
}
168
 
169
/* Given the LHS and (real) RHS of a gimple assign statement, STMT, check if
170
   they are the same. If so, print a warning message about self-assignment.  */
171
 
172
static void
173
compare_and_warn (gimple stmt, tree lhs, tree rhs)
174
{
175
  if (operand_equal_p (lhs, rhs, OEP_PURE_SAME))
176
    {
177
      location_t location;
178
      location = (gimple_has_location (stmt)
179
                  ? gimple_location (stmt)
180
                  : (DECL_P (lhs)
181
                     ? DECL_SOURCE_LOCATION (lhs)
182
                     : input_location));
183
      /* If LHS contains any tree node not currently supported by
184
         get_non_ssa_expr, simply emit a generic warning without
185
         specifying LHS in the message.  */
186
      lhs = get_non_ssa_expr (lhs);
187
      if (lhs)
188
        warning_at (location, 0, G_("%qE is assigned to itself"), lhs);
189
      else
190
        warning_at (location, 0, G_("self-assignment detected"));
191
    }
192
}
193
 
194
/* Check and warn if STMT is a self-assign statement.  */
195
 
196
static void
197
warn_self_assign (gimple stmt)
198
{
199
  tree rhs, lhs;
200
 
201
  /* Check assigment statement.  */
202
  if (gimple_assign_single_p (stmt))
203
    {
204
      rhs = get_real_ref_rhs (gimple_assign_rhs1 (stmt));
205
      if (!rhs)
206
        return;
207
 
208
      lhs = gimple_assign_lhs (stmt);
209
      if (TREE_CODE (lhs) == SSA_NAME)
210
        {
211
          lhs = SSA_NAME_VAR (lhs);
212
          if (DECL_ARTIFICIAL (lhs))
213
            return;
214
        }
215
 
216
      compare_and_warn (stmt, lhs, rhs);
217
    }
218
  /* Check overloaded operator '=' (if enabled).  */
219
  else if (check_operator_eq && is_gimple_call (stmt))
220
    {
221
      tree fdecl = gimple_call_fndecl (stmt);
222
      if (fdecl && (DECL_NAME (fdecl) == maybe_get_identifier ("operator=")))
223
        {
224
          /* If 'operator=' takes reference operands, the arguments will be
225
             ADDR_EXPR trees. In this case, just remove the address-taken
226
             operator before we compare the lhs and rhs.  */
227
          lhs = gimple_call_arg (stmt, 0);
228
          if (TREE_CODE (lhs) == ADDR_EXPR)
229
            lhs = TREE_OPERAND (lhs, 0);
230
          rhs = gimple_call_arg (stmt, 1);
231
          if (TREE_CODE (rhs) == ADDR_EXPR)
232
            rhs = TREE_OPERAND (rhs, 0);
233
 
234
          compare_and_warn (stmt, lhs, rhs);
235
        }
236
    }
237
}
238
 
239
/* Entry point for the self-assignment detection pass.  */
240
 
241
static unsigned int
242
execute_warn_self_assign (void)
243
{
244
  gimple_stmt_iterator gsi;
245
  basic_block bb;
246
 
247
  FOR_EACH_BB (bb)
248
    {
249
      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
250
        warn_self_assign (gsi_stmt (gsi));
251
    }
252
 
253
  return 0;
254
}
255
 
256
/* Pass gate function. Currently always returns true.  */
257
 
258
static bool
259
gate_warn_self_assign (void)
260
{
261
  return true;
262
}
263
 
264
static struct gimple_opt_pass pass_warn_self_assign =
265
{
266
  {
267
    GIMPLE_PASS,
268
    "warn_self_assign",                   /* name */
269
    gate_warn_self_assign,                /* gate */
270
    execute_warn_self_assign,             /* execute */
271
    NULL,                                 /* sub */
272
    NULL,                                 /* next */
273
    0,                                    /* static_pass_number */
274
    TV_NONE,                              /* tv_id */
275
    PROP_ssa,                             /* properties_required */
276
    0,                                    /* properties_provided */
277
    0,                                    /* properties_destroyed */
278
    0,                                    /* todo_flags_start */
279
    TODO_dump_func                        /* todo_flags_finish */
280
  }
281
};
282
 
283
/* The initialization routine exposed to and called by GCC. The spec of this
284
   function is defined in gcc/gcc-plugin.h.
285
 
286
   PLUGIN_NAME - name of the plugin (useful for error reporting)
287
   ARGC        - the size of the ARGV array
288
   ARGV        - an array of key-value argument pair
289
 
290
   Returns 0 if initialization finishes successfully.
291
 
292
   Note that this function needs to be named exactly "plugin_init".  */
293
 
294
int
295
plugin_init (struct plugin_name_args *plugin_info,
296
             struct plugin_gcc_version *version)
297
{
298
  struct register_pass_info pass_info;
299
  const char *plugin_name = plugin_info->base_name;
300
  int argc = plugin_info->argc;
301
  struct plugin_argument *argv = plugin_info->argv;
302
  bool enabled = true;
303
  int i;
304
 
305
  if (!plugin_default_version_check (version, &gcc_version))
306
    return 1;
307
 
308
  /* Self-assign detection should happen after SSA is constructed.  */
309
  pass_info.pass = &pass_warn_self_assign.pass;
310
  pass_info.reference_pass_name = "ssa";
311
  pass_info.ref_pass_instance_number = 1;
312
  pass_info.pos_op = PASS_POS_INSERT_AFTER;
313
 
314
  /* Process the plugin arguments. This plugin takes the following arguments:
315
     check-operator-eq, no-check-operator-eq, enable, and disable.
316
     By default, the analysis is enabled with 'operator=' checked.  */
317
  for (i = 0; i < argc; ++i)
318
    {
319
      if (!strcmp (argv[i].key, "check-operator-eq"))
320
        {
321
          if (argv[i].value)
322
            warning (0, G_("option '-fplugin-arg-%s-check-operator-eq=%s'"
323
                           " ignored (superfluous '=%s')"),
324
                     plugin_name, argv[i].value, argv[i].value);
325
          else
326
            check_operator_eq = true;
327
        }
328
      else if (!strcmp (argv[i].key, "no-check-operator-eq"))
329
        {
330
          if (argv[i].value)
331
            warning (0, G_("option '-fplugin-arg-%s-no-check-operator-eq=%s'"
332
                           " ignored (superfluous '=%s')"),
333
                     plugin_name, argv[i].value, argv[i].value);
334
          else
335
            check_operator_eq = false;
336
        }
337
      else if (!strcmp (argv[i].key, "enable"))
338
        {
339
          if (argv[i].value)
340
            warning (0, G_("option '-fplugin-arg-%s-enable=%s' ignored"
341
                           " (superfluous '=%s')"),
342
                     plugin_name, argv[i].value, argv[i].value);
343
          else
344
            enabled = true;
345
        }
346
      else if (!strcmp (argv[i].key, "disable"))
347
        {
348
          if (argv[i].value)
349
            warning (0, G_("option '-fplugin-arg-%s-disable=%s' ignored"
350
                           " (superfluous '=%s')"),
351
                     plugin_name, argv[i].value, argv[i].value);
352
          else
353
            enabled = false;
354
        }
355
      else
356
        warning (0, G_("plugin %qs: unrecognized argument %qs ignored"),
357
                 plugin_name, argv[i].key);
358
    }
359
 
360
  /* Register this new pass with GCC if the analysis is enabled.  */
361
  if (enabled)
362
    register_callback (plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL,
363
                       &pass_info);
364
 
365
  return 0;
366
}

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