1 /*
2 +----------------------------------------------------------------------+
3 | Zend Engine, SSA validation |
4 +----------------------------------------------------------------------+
5 | Copyright (c) The PHP Group |
6 +----------------------------------------------------------------------+
7 | This source file is subject to version 3.01 of the PHP license, |
8 | that is bundled with this package in the file LICENSE, and is |
9 | available through the world-wide-web at the following url: |
10 | https://www.php.net/license/3_01.txt |
11 | If you did not receive a copy of the PHP license and are unable to |
12 | obtain it through the world-wide-web, please send a note to |
13 | license@php.net so we can mail you a copy immediately. |
14 +----------------------------------------------------------------------+
15 | Authors: Nikita Popov <nikic@php.net> |
16 +----------------------------------------------------------------------+
17 */
18
19 #include "Optimizer/zend_optimizer_internal.h"
20
21 /* The ssa_verify_integrity() function ensures that that certain invariants of the SSA form and
22 * CFG are upheld and prints messages to stderr if this is not the case. */
23
is_in_use_chain(zend_ssa * ssa,int var,int check)24 static inline bool is_in_use_chain(zend_ssa *ssa, int var, int check) {
25 int use;
26 FOREACH_USE(&ssa->vars[var], use) {
27 if (use == check) {
28 return 1;
29 }
30 } FOREACH_USE_END();
31 return 0;
32 }
33
is_in_phi_use_chain(zend_ssa * ssa,int var,zend_ssa_phi * check)34 static inline bool is_in_phi_use_chain(zend_ssa *ssa, int var, zend_ssa_phi *check) {
35 zend_ssa_phi *phi;
36 FOREACH_PHI_USE(&ssa->vars[var], phi) {
37 if (phi == check) {
38 return 1;
39 }
40 } FOREACH_PHI_USE_END();
41 return 0;
42 }
43
is_used_by_op(zend_ssa * ssa,int op,int check)44 static inline bool is_used_by_op(zend_ssa *ssa, int op, int check) {
45 zend_ssa_op *ssa_op = &ssa->ops[op];
46 return (ssa_op->op1_use == check)
47 || (ssa_op->op2_use == check)
48 || (ssa_op->result_use == check);
49 }
50
is_defined_by_op(zend_ssa * ssa,int op,int check)51 static inline bool is_defined_by_op(zend_ssa *ssa, int op, int check) {
52 zend_ssa_op *ssa_op = &ssa->ops[op];
53 return (ssa_op->op1_def == check)
54 || (ssa_op->op2_def == check)
55 || (ssa_op->result_def == check);
56 }
57
is_in_phi_sources(zend_ssa * ssa,zend_ssa_phi * phi,int check)58 static inline bool is_in_phi_sources(zend_ssa *ssa, zend_ssa_phi *phi, int check) {
59 int source;
60 FOREACH_PHI_SOURCE(phi, source) {
61 if (source == check) {
62 return 1;
63 }
64 } FOREACH_PHI_SOURCE_END();
65 return 0;
66 }
67
is_in_predecessors(zend_cfg * cfg,zend_basic_block * block,int check)68 static inline bool is_in_predecessors(zend_cfg *cfg, zend_basic_block *block, int check) {
69 int i, *predecessors = &cfg->predecessors[block->predecessor_offset];
70 for (i = 0; i < block->predecessors_count; i++) {
71 if (predecessors[i] == check) {
72 return 1;
73 }
74 }
75 return 0;
76 }
77
is_in_successors(zend_basic_block * block,int check)78 static inline bool is_in_successors(zend_basic_block *block, int check) {
79 int s;
80 for (s = 0; s < block->successors_count; s++) {
81 if (block->successors[s] == check) {
82 return 1;
83 }
84 }
85 return 0;
86 }
87
is_var_type(uint8_t type)88 static inline bool is_var_type(uint8_t type) {
89 return (type & (IS_CV|IS_VAR|IS_TMP_VAR)) != 0;
90 }
91
is_defined(const zend_ssa * ssa,const zend_op_array * op_array,int var)92 static inline bool is_defined(const zend_ssa *ssa, const zend_op_array *op_array, int var) {
93 const zend_ssa_var *ssa_var = &ssa->vars[var];
94 return ssa_var->definition >= 0 || ssa_var->definition_phi || var < op_array->last_var;
95 }
96
97 #define FAIL(...) do { \
98 if (status == SUCCESS) { \
99 fprintf(stderr, "\nIn function %s::%s (%s):\n", \
100 op_array->scope ? ZSTR_VAL(op_array->scope->name) : "", \
101 op_array->function_name ? ZSTR_VAL(op_array->function_name) : "{main}", extra); \
102 } \
103 fprintf(stderr, __VA_ARGS__); \
104 status = FAILURE; \
105 } while (0)
106
107 #define VARFMT "%d (%s%s)"
108 #define VAR(i) \
109 (i), (ssa->vars[i].var < op_array->last_var ? "CV $" : "TMP"), \
110 (ssa->vars[i].var < op_array->last_var ? ZSTR_VAL(op_array->vars[ssa->vars[i].var]) : "")
111
112 #define INSTRFMT "%d (%s)"
113 #define INSTR(i) \
114 (i), (zend_get_opcode_name(op_array->opcodes[i].opcode))
115
ssa_verify_integrity(zend_op_array * op_array,zend_ssa * ssa,const char * extra)116 void ssa_verify_integrity(zend_op_array *op_array, zend_ssa *ssa, const char *extra) {
117 zend_cfg *cfg = &ssa->cfg;
118 zend_ssa_phi *phi;
119 int i;
120 zend_result status = SUCCESS;
121
122 /* Vars */
123 for (i = 0; i < ssa->vars_count; i++) {
124 zend_ssa_var *var = &ssa->vars[i];
125 int use;
126 uint32_t type = ssa->var_info[i].type;
127
128 if (var->definition < 0 && !var->definition_phi && i > op_array->last_var) {
129 if (var->use_chain >= 0) {
130 FAIL("var " VARFMT " without def has op uses\n", VAR(i));
131 }
132 if (var->phi_use_chain) {
133 FAIL("var " VARFMT " without def has phi uses\n", VAR(i));
134 }
135 }
136 if (var->definition >= 0 && var->definition_phi) {
137 FAIL("var " VARFMT " has both def and def_phi\n", VAR(i));
138 }
139 if (var->definition >= 0) {
140 if (!is_defined_by_op(ssa, var->definition, i)) {
141 FAIL("var " VARFMT " not defined by op " INSTRFMT "\n",
142 VAR(i), INSTR(var->definition));
143 }
144 }
145 if (var->definition_phi) {
146 if (var->definition_phi->ssa_var != i) {
147 FAIL("var " VARFMT " not defined by given phi\n", VAR(i));
148 }
149 }
150
151 /* Floyd's cycle detection algorithm, applied for use chain. */
152 use = var->use_chain;
153 int second_use = use;
154 while (use >= 0 && second_use >= 0) {
155 use = zend_ssa_next_use(ssa->ops, var - ssa->vars, use);
156 second_use = zend_ssa_next_use(ssa->ops, var - ssa->vars, second_use);
157 if (second_use < 0) {
158 break;
159 }
160 second_use = zend_ssa_next_use(ssa->ops, var - ssa->vars, second_use);
161 if (use == second_use) {
162 FAIL("cycle in uses of " VARFMT "\n", VAR(i));
163 goto finish;
164 }
165 }
166
167 FOREACH_USE(var, use) {
168 if (!is_used_by_op(ssa, use, i)) {
169 fprintf(stderr, "var " VARFMT " not in uses of op %d\n", VAR(i), use);
170 }
171 } FOREACH_USE_END();
172
173 /* Floyd's cycle detection algorithm, applied for phi nodes. */
174 phi = var->phi_use_chain;
175 zend_ssa_phi *second_phi = phi;
176 while (phi && second_phi) {
177 phi = zend_ssa_next_use_phi(ssa, var - ssa->vars, phi);
178 second_phi = zend_ssa_next_use_phi(ssa, var - ssa->vars, second_phi);
179 if (!second_phi) {
180 break;
181 }
182 second_phi = zend_ssa_next_use_phi(ssa, var - ssa->vars, second_phi);
183 if (phi == second_phi) {
184 FAIL("cycle in phi uses of " VARFMT "\n", VAR(i));
185 goto finish;
186 }
187 }
188
189 FOREACH_PHI_USE(var, phi) {
190 if (!is_in_phi_sources(ssa, phi, i)) {
191 FAIL("var " VARFMT " not in phi sources of %d\n", VAR(i), phi->ssa_var);
192 }
193 } FOREACH_PHI_USE_END();
194
195 if ((type & (MAY_BE_ARRAY_KEY_ANY-MAY_BE_ARRAY_EMPTY)) && !(type & MAY_BE_ARRAY_OF_ANY)) {
196 FAIL("var " VARFMT " has array key type but not value type\n", VAR(i));
197 }
198 if ((type & MAY_BE_ARRAY_OF_ANY) && !(type & (MAY_BE_ARRAY_KEY_ANY-MAY_BE_ARRAY_EMPTY))) {
199 FAIL("var " VARFMT " has array value type but not key type\n", VAR(i));
200 }
201 if ((type & MAY_BE_REF) && ssa->var_info[i].ce) {
202 FAIL("var " VARFMT " may be ref but has ce\n", VAR(i));
203 }
204 }
205
206 /* Instructions */
207 FOREACH_INSTR_NUM(i) {
208 zend_ssa_op *ssa_op = &ssa->ops[i];
209 zend_op *opline = &op_array->opcodes[i];
210 if (is_var_type(opline->op1_type)) {
211 if (ssa_op->op1_use < 0 && ssa_op->op1_def < 0) {
212 FAIL("var op1 of " INSTRFMT " does not use/def an ssa var\n", INSTR(i));
213 }
214 } else {
215 if (ssa_op->op1_use >= 0 || ssa_op->op1_def >= 0) {
216 FAIL("non-var op1 of " INSTRFMT " uses or defs an ssa var\n", INSTR(i));
217 }
218 }
219 if (is_var_type(opline->op2_type)) {
220 if (ssa_op->op2_use < 0 && ssa_op->op2_def < 0) {
221 FAIL("var op2 of " INSTRFMT " does not use/def an ssa var\n", INSTR(i));
222 }
223 } else {
224 if (ssa_op->op2_use >= 0 || ssa_op->op2_def >= 0) {
225 FAIL("non-var op2 of " INSTRFMT " uses or defs an ssa var\n", INSTR(i));
226 }
227 }
228 if (is_var_type(opline->result_type)) {
229 if (ssa_op->result_use < 0 && ssa_op->result_def < 0) {
230 FAIL("var result of " INSTRFMT " does not use/def an ssa var\n", INSTR(i));
231 }
232 } else {
233 if (ssa_op->result_use >= 0 || ssa_op->result_def >= 0) {
234 FAIL("non-var result of " INSTRFMT " uses or defs an ssa var\n", INSTR(i));
235 }
236 }
237
238 if (ssa_op->op1_use >= 0) {
239 if (ssa_op->op1_use >= ssa->vars_count) {
240 FAIL("op1 use %d out of range\n", ssa_op->op1_use);
241 }
242 if (!is_defined(ssa, op_array, ssa_op->op1_use)) {
243 FAIL("op1 use of " VARFMT " in " INSTRFMT " is not defined\n",
244 VAR(ssa_op->op1_use), INSTR(i));
245 }
246 if (!is_in_use_chain(ssa, ssa_op->op1_use, i)) {
247 FAIL("op1 use of " VARFMT " in " INSTRFMT " not in use chain\n",
248 VAR(ssa_op->op1_use), INSTR(i));
249 }
250 if (VAR_NUM(opline->op1.var) != ssa->vars[ssa_op->op1_use].var) {
251 FAIL("op1 use of " VARFMT " does not match op %d of " INSTRFMT "\n",
252 VAR(ssa_op->op1_use), VAR_NUM(opline->op1.var), INSTR(i));
253 }
254 }
255 if (ssa_op->op2_use >= 0) {
256 if (ssa_op->op2_use >= ssa->vars_count) {
257 FAIL("op2 use %d out of range\n", ssa_op->op2_use);
258 }
259 if (!is_defined(ssa, op_array, ssa_op->op2_use)) {
260 FAIL("op2 use of " VARFMT " in " INSTRFMT " is not defined\n",
261 VAR(ssa_op->op2_use), INSTR(i));
262 }
263 if (!is_in_use_chain(ssa, ssa_op->op2_use, i)) {
264 FAIL("op2 use of " VARFMT " in " INSTRFMT " not in use chain\n",
265 VAR(ssa_op->op2_use), INSTR(i));
266 }
267 if (VAR_NUM(opline->op2.var) != ssa->vars[ssa_op->op2_use].var) {
268 FAIL("op2 use of " VARFMT " does not match op %d of " INSTRFMT "\n",
269 VAR(ssa_op->op2_use), VAR_NUM(opline->op2.var), INSTR(i));
270 }
271 }
272 if (ssa_op->result_use >= 0) {
273 if (ssa_op->result_use >= ssa->vars_count) {
274 FAIL("result use %d out of range\n", ssa_op->result_use);
275 }
276 if (!is_defined(ssa, op_array, ssa_op->result_use)) {
277 FAIL("result use of " VARFMT " in " INSTRFMT " is not defined\n",
278 VAR(ssa_op->result_use), INSTR(i));
279 }
280 if (!is_in_use_chain(ssa, ssa_op->result_use, i)) {
281 FAIL("result use of " VARFMT " in " INSTRFMT " not in use chain\n",
282 VAR(ssa_op->result_use), INSTR(i));
283 }
284 if (VAR_NUM(opline->result.var) != ssa->vars[ssa_op->result_use].var) {
285 FAIL("result use of " VARFMT " does not match op %d of " INSTRFMT "\n",
286 VAR(ssa_op->result_use), VAR_NUM(opline->result.var), INSTR(i));
287 }
288 }
289 if (ssa_op->op1_def >= 0) {
290 if (ssa_op->op1_def >= ssa->vars_count) {
291 FAIL("op1 def %d out of range\n", ssa_op->op1_def);
292 }
293 if (ssa->vars[ssa_op->op1_def].definition != i) {
294 FAIL("op1 def of " VARFMT " in " INSTRFMT " invalid\n",
295 VAR(ssa_op->op1_def), INSTR(i));
296 }
297 if (VAR_NUM(opline->op1.var) != ssa->vars[ssa_op->op1_def].var) {
298 FAIL("op1 def of " VARFMT " does not match op %d of " INSTRFMT "\n",
299 VAR(ssa_op->op1_def), VAR_NUM(opline->op1.var), INSTR(i));
300 }
301 }
302 if (ssa_op->op2_def >= 0) {
303 if (ssa_op->op2_def >= ssa->vars_count) {
304 FAIL("op2 def %d out of range\n", ssa_op->op2_def);
305 }
306 if (ssa->vars[ssa_op->op2_def].definition != i) {
307 FAIL("op2 def of " VARFMT " in " INSTRFMT " invalid\n",
308 VAR(ssa_op->op2_def), INSTR(i));
309 }
310 if (VAR_NUM(opline->op2.var) != ssa->vars[ssa_op->op2_def].var) {
311 FAIL("op2 def of " VARFMT " does not match op %d of " INSTRFMT "\n",
312 VAR(ssa_op->op2_def), VAR_NUM(opline->op2.var), INSTR(i));
313 }
314 }
315 if (ssa_op->result_def >= 0) {
316 if (ssa_op->result_def >= ssa->vars_count) {
317 FAIL("result def %d out of range\n", ssa_op->result_def);
318 }
319 if (ssa->vars[ssa_op->result_def].definition != i) {
320 FAIL("result def of " VARFMT " in " INSTRFMT " invalid\n",
321 VAR(ssa_op->result_def), INSTR(i));
322 }
323 if (VAR_NUM(opline->result.var) != ssa->vars[ssa_op->result_def].var) {
324 FAIL("result def of " VARFMT " does not match op %d of " INSTRFMT "\n",
325 VAR(ssa_op->result_def), VAR_NUM(opline->result.var), INSTR(i));
326 }
327 }
328 } FOREACH_INSTR_NUM_END();
329
330 /* Phis */
331 FOREACH_PHI(phi) {
332 unsigned num_sources = NUM_PHI_SOURCES(phi);
333 for (i = 0; i < num_sources; i++) {
334 int source = phi->sources[i];
335 if (source < 0) {
336 FAIL(VARFMT " negative source\n", VAR(phi->ssa_var));
337 }
338 if (!is_in_phi_use_chain(ssa, source, phi)) {
339 FAIL(VARFMT " not in phi use chain of %d\n", VAR(phi->ssa_var), source);
340 }
341 if (ssa->vars[source].var != ssa->vars[phi->ssa_var].var) {
342 FAIL(VARFMT " source of phi for " VARFMT "\n", VAR(source), VAR(phi->ssa_var));
343 }
344 if (phi->use_chains[i]) {
345 int j;
346 for (j = i + 1; j < num_sources; j++) {
347 if (phi->sources[j] == source && phi->use_chains[j]) {
348 FAIL("use chain for source " VARFMT " of phi " VARFMT
349 " at %d despite earlier use\n", VAR(source), VAR(phi->ssa_var), j);
350 }
351 }
352 }
353 }
354 if (ssa->vars[phi->ssa_var].definition_phi != phi) {
355 FAIL(VARFMT " does not define this phi\n", VAR(phi->ssa_var));
356 }
357 } FOREACH_PHI_END();
358
359 /* Blocks */
360 for (i = 0; i < cfg->blocks_count; i++) {
361 zend_basic_block *block = &cfg->blocks[i];
362 int *predecessors = &cfg->predecessors[block->predecessor_offset];
363 int s, j;
364
365 if (i != 0 && block->start < (block-1)->start + (block-1)->len) {
366 FAIL("Block %d start %d smaller previous end %d\n",
367 i, block->start, (block-1)->start + (block-1)->len);
368 }
369 if (i != cfg->blocks_count-1 && block->start + block->len > (block+1)->start) {
370 FAIL("Block %d end %d greater next start %d\n",
371 i, block->start + block->len, (block+1)->start);
372 }
373
374 for (j = block->start; j < block->start + block->len; j++) {
375 if (cfg->map[j] != i) {
376 FAIL("Instr " INSTRFMT " not associated with block %d\n", INSTR(j), i);
377 }
378 }
379
380 if (!(block->flags & ZEND_BB_REACHABLE)) {
381 if (ssa->blocks[i].phis) {
382 FAIL("Unreachable block %d has phis\n", i);
383 }
384 continue;
385 }
386
387 for (s = 0; s < block->successors_count; s++) {
388 zend_basic_block *next_block;
389 if (block->successors[s] < 0) {
390 FAIL("Successor number %d of %d negative", s, i);
391 }
392 next_block = &cfg->blocks[block->successors[s]];
393 if (!(next_block->flags & ZEND_BB_REACHABLE)) {
394 FAIL("Successor %d of %d not reachable\n", block->successors[s], i);
395 }
396 if (!is_in_predecessors(cfg, next_block, i)) {
397 FAIL("Block %d predecessors missing %d\n", block->successors[s], i);
398 }
399 }
400
401 for (j = 0; j < block->predecessors_count; j++) {
402 if (predecessors[j] >= 0) {
403 int k;
404 zend_basic_block *prev_block = &cfg->blocks[predecessors[j]];
405 if (!(prev_block->flags & ZEND_BB_REACHABLE)) {
406 FAIL("Predecessor %d of %d not reachable\n", predecessors[j], i);
407 }
408 if (!is_in_successors(prev_block, i)) {
409 FAIL("Block %d successors missing %d\n", predecessors[j], i);
410 }
411 for (k = 0; k < block->predecessors_count; k++) {
412 if (k != j && predecessors[k] == predecessors[j]) {
413 FAIL("Block %d has duplicate predecessor %d\n", i, predecessors[j]);
414 }
415 }
416 }
417 }
418 }
419
420 finish:
421 if (status == FAILURE) {
422 zend_dump_op_array(op_array, ZEND_DUMP_SSA, "at SSA integrity verification", ssa);
423 ZEND_ASSERT(0 && "SSA integrity verification failed");
424 }
425 }
426
