1 /*
2 +----------------------------------------------------------------------+
3 | Zend Engine, SSA - Static Single Assignment Form |
4 +----------------------------------------------------------------------+
5 | Copyright (c) 1998-2018 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 | http://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: Dmitry Stogov <dmitry@zend.com> |
16 +----------------------------------------------------------------------+
17 */
18
19 #ifndef ZEND_SSA_H
20 #define ZEND_SSA_H
21
22 #include "zend_optimizer.h"
23 #include "zend_cfg.h"
24
25 typedef struct _zend_ssa_range {
26 zend_long min;
27 zend_long max;
28 zend_bool underflow;
29 zend_bool overflow;
30 } zend_ssa_range;
31
32 typedef enum _zend_ssa_negative_lat {
33 NEG_NONE = 0,
34 NEG_INIT = 1,
35 NEG_INVARIANT = 2,
36 NEG_USE_LT = 3,
37 NEG_USE_GT = 4,
38 NEG_UNKNOWN = 5
39 } zend_ssa_negative_lat;
40
41 /* Special kind of SSA Phi function used in eSSA */
42 typedef struct _zend_ssa_range_constraint {
43 zend_ssa_range range; /* simple range constraint */
44 int min_var;
45 int max_var;
46 int min_ssa_var; /* ((min_var>0) ? MIN(ssa_var) : 0) + range.min */
47 int max_ssa_var; /* ((max_var>0) ? MAX(ssa_var) : 0) + range.max */
48 zend_ssa_negative_lat negative;
49 } zend_ssa_range_constraint;
50
51 typedef struct _zend_ssa_type_constraint {
52 uint32_t type_mask; /* Type mask to intersect with */
53 zend_class_entry *ce; /* Class entry for instanceof constraints */
54 } zend_ssa_type_constraint;
55
56 typedef union _zend_ssa_pi_constraint {
57 zend_ssa_range_constraint range;
58 zend_ssa_type_constraint type;
59 } zend_ssa_pi_constraint;
60
61 /* SSA Phi - ssa_var = Phi(source0, source1, ...sourceN) */
62 typedef struct _zend_ssa_phi zend_ssa_phi;
63 struct _zend_ssa_phi {
64 zend_ssa_phi *next; /* next Phi in the same BB */
65 int pi; /* if >= 0 this is actually a e-SSA Pi */
66 zend_ssa_pi_constraint constraint; /* e-SSA Pi constraint */
67 int var; /* Original CV, VAR or TMP variable index */
68 int ssa_var; /* SSA variable index */
69 int block; /* current BB index */
70 int visited : 1; /* flag to avoid recursive processing */
71 int has_range_constraint : 1;
72 zend_ssa_phi **use_chains;
73 zend_ssa_phi *sym_use_chain;
74 int *sources; /* Array of SSA IDs that produce this var.
75 As many as this block has
76 predecessors. */
77 };
78
79 typedef struct _zend_ssa_block {
80 zend_ssa_phi *phis;
81 } zend_ssa_block;
82
83 typedef struct _zend_ssa_op {
84 int op1_use;
85 int op2_use;
86 int result_use;
87 int op1_def;
88 int op2_def;
89 int result_def;
90 int op1_use_chain;
91 int op2_use_chain;
92 int res_use_chain;
93 } zend_ssa_op;
94
95 typedef enum _zend_ssa_alias_kind {
96 NO_ALIAS,
97 SYMTABLE_ALIAS,
98 PHP_ERRORMSG_ALIAS,
99 HTTP_RESPONSE_HEADER_ALIAS
100 } zend_ssa_alias_kind;
101
102 typedef struct _zend_ssa_var {
103 int var; /* original var number; op.var for CVs and following numbers for VARs and TMP_VARs */
104 int scc; /* strongly connected component */
105 int definition; /* opcode that defines this value */
106 zend_ssa_phi *definition_phi; /* phi that defines this value */
107 int use_chain; /* uses of this value, linked through opN_use_chain */
108 zend_ssa_phi *phi_use_chain; /* uses of this value in Phi, linked through use_chain */
109 zend_ssa_phi *sym_use_chain; /* uses of this value in Pi constaints */
110 unsigned int no_val : 1; /* value doesn't mater (used as op1 in ZEND_ASSIGN) */
111 unsigned int scc_entry : 1;
112 unsigned int alias : 2; /* value may be changed indirectly */
113 } zend_ssa_var;
114
115 typedef struct _zend_ssa_var_info {
116 uint32_t type; /* inferred type (see zend_inference.h) */
117 zend_ssa_range range;
118 zend_class_entry *ce;
119 unsigned int has_range : 1;
120 unsigned int is_instanceof : 1; /* 0 - class == "ce", 1 - may be child of "ce" */
121 unsigned int recursive : 1;
122 unsigned int use_as_double : 1;
123 } zend_ssa_var_info;
124
125 typedef struct _zend_ssa {
126 zend_cfg cfg; /* control flow graph */
127 int rt_constants; /* run-time or compile-time */
128 int vars_count; /* number of SSA variables */
129 zend_ssa_block *blocks; /* array of SSA blocks */
130 zend_ssa_op *ops; /* array of SSA instructions */
131 zend_ssa_var *vars; /* use/def chain of SSA variables */
132 int sccs; /* number of SCCs */
133 zend_ssa_var_info *var_info;
134 } zend_ssa;
135
136 BEGIN_EXTERN_C()
137
138 int zend_build_ssa(zend_arena **arena, const zend_script *script, const zend_op_array *op_array, uint32_t build_flags, zend_ssa *ssa, uint32_t *func_flags);
139 int zend_ssa_compute_use_def_chains(zend_arena **arena, const zend_op_array *op_array, zend_ssa *ssa);
140 int zend_ssa_unlink_use_chain(zend_ssa *ssa, int op, int var);
141
142 void zend_ssa_remove_predecessor(zend_ssa *ssa, int from, int to);
143 void zend_ssa_remove_instr(zend_ssa *ssa, zend_op *opline, zend_ssa_op *ssa_op);
144 void zend_ssa_remove_phi(zend_ssa *ssa, zend_ssa_phi *phi);
145 void zend_ssa_remove_uses_of_var(zend_ssa *ssa, int var_num);
146 void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int b);
147 void zend_ssa_rename_var_uses(zend_ssa *ssa, int old_var, int new_var, zend_bool update_types);
148
_zend_ssa_remove_def(zend_ssa_var * var)149 static zend_always_inline void _zend_ssa_remove_def(zend_ssa_var *var)
150 {
151 ZEND_ASSERT(var->definition >= 0);
152 ZEND_ASSERT(var->use_chain < 0);
153 ZEND_ASSERT(!var->phi_use_chain);
154 var->definition = -1;
155 }
156
zend_ssa_remove_result_def(zend_ssa * ssa,zend_ssa_op * ssa_op)157 static zend_always_inline void zend_ssa_remove_result_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
158 {
159 zend_ssa_var *var = &ssa->vars[ssa_op->result_def];
160 _zend_ssa_remove_def(var);
161 ssa_op->result_def = -1;
162 }
163
zend_ssa_remove_op1_def(zend_ssa * ssa,zend_ssa_op * ssa_op)164 static zend_always_inline void zend_ssa_remove_op1_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
165 {
166 zend_ssa_var *var = &ssa->vars[ssa_op->op1_def];
167 _zend_ssa_remove_def(var);
168 ssa_op->op1_def = -1;
169 }
170
zend_ssa_remove_op2_def(zend_ssa * ssa,zend_ssa_op * ssa_op)171 static zend_always_inline void zend_ssa_remove_op2_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
172 {
173 zend_ssa_var *var = &ssa->vars[ssa_op->op2_def];
174 _zend_ssa_remove_def(var);
175 ssa_op->op2_def = -1;
176 }
177
END_EXTERN_C()178 END_EXTERN_C()
179
180 static zend_always_inline int zend_ssa_next_use(const zend_ssa_op *ssa_op, int var, int use)
181 {
182 ssa_op += use;
183 if (ssa_op->op1_use == var) {
184 return ssa_op->op1_use_chain;
185 } else if (ssa_op->op2_use == var) {
186 return ssa_op->op2_use_chain;
187 } else {
188 return ssa_op->res_use_chain;
189 }
190 }
191
zend_ssa_next_use_phi(const zend_ssa * ssa,int var,const zend_ssa_phi * p)192 static zend_always_inline zend_ssa_phi* zend_ssa_next_use_phi(const zend_ssa *ssa, int var, const zend_ssa_phi *p)
193 {
194 if (p->pi >= 0) {
195 return p->use_chains[0];
196 } else {
197 int j;
198 for (j = 0; j < ssa->cfg.blocks[p->block].predecessors_count; j++) {
199 if (p->sources[j] == var) {
200 return p->use_chains[j];
201 }
202 }
203 }
204 return NULL;
205 }
206
zend_ssa_is_no_val_use(const zend_op * opline,const zend_ssa_op * ssa_op,int var)207 static zend_always_inline zend_bool zend_ssa_is_no_val_use(const zend_op *opline, const zend_ssa_op *ssa_op, int var)
208 {
209 if (opline->opcode == ZEND_ASSIGN || opline->opcode == ZEND_UNSET_CV) {
210 return ssa_op->op1_use == var && ssa_op->op2_use != var;
211 }
212 if (opline->opcode == ZEND_FE_FETCH_R) {
213 return ssa_op->op2_use == var && ssa_op->op1_use != var;
214 }
215 if (ssa_op->result_use == var && opline->opcode != ZEND_ADD_ARRAY_ELEMENT) {
216 return ssa_op->op1_use != var && ssa_op->op2_use != var;
217 }
218 return 0;
219 }
220
zend_ssa_rename_defs_of_instr(zend_ssa * ssa,zend_ssa_op * ssa_op)221 static zend_always_inline void zend_ssa_rename_defs_of_instr(zend_ssa *ssa, zend_ssa_op *ssa_op) {
222 /* Rename def to use if possible. Mark variable as not defined otherwise. */
223 if (ssa_op->op1_def >= 0) {
224 if (ssa_op->op1_use >= 0) {
225 zend_ssa_rename_var_uses(ssa, ssa_op->op1_def, ssa_op->op1_use, 1);
226 }
227 ssa->vars[ssa_op->op1_def].definition = -1;
228 ssa_op->op1_def = -1;
229 }
230 if (ssa_op->op2_def >= 0) {
231 if (ssa_op->op2_use >= 0) {
232 zend_ssa_rename_var_uses(ssa, ssa_op->op2_def, ssa_op->op2_use, 1);
233 }
234 ssa->vars[ssa_op->op2_def].definition = -1;
235 ssa_op->op2_def = -1;
236 }
237 if (ssa_op->result_def >= 0) {
238 if (ssa_op->result_use >= 0) {
239 zend_ssa_rename_var_uses(ssa, ssa_op->result_def, ssa_op->result_use, 1);
240 }
241 ssa->vars[ssa_op->result_def].definition = -1;
242 ssa_op->result_def = -1;
243 }
244 }
245
246 #define NUM_PHI_SOURCES(phi) \
247 ((phi)->pi >= 0 ? 1 : (ssa->cfg.blocks[(phi)->block].predecessors_count))
248
249 /* FOREACH_USE and FOREACH_PHI_USE explicitly support "continue"
250 * and changing the use chain of the current element */
251 #define FOREACH_USE(var, use) do { \
252 int _var_num = (var) - ssa->vars, next; \
253 for (use = (var)->use_chain; use >= 0; use = next) { \
254 next = zend_ssa_next_use(ssa->ops, _var_num, use);
255 #define FOREACH_USE_END() \
256 } \
257 } while (0)
258
259 #define FOREACH_PHI_USE(var, phi) do { \
260 int _var_num = (var) - ssa->vars; \
261 zend_ssa_phi *next_phi; \
262 for (phi = (var)->phi_use_chain; phi; phi = next_phi) { \
263 next_phi = zend_ssa_next_use_phi(ssa, _var_num, phi);
264 #define FOREACH_PHI_USE_END() \
265 } \
266 } while (0)
267
268 #define FOREACH_PHI_SOURCE(phi, source) do { \
269 zend_ssa_phi *_phi = (phi); \
270 int _i, _end = NUM_PHI_SOURCES(phi); \
271 for (_i = 0; _i < _end; _i++) { \
272 ZEND_ASSERT(_phi->sources[_i] >= 0); \
273 source = _phi->sources[_i];
274 #define FOREACH_PHI_SOURCE_END() \
275 } \
276 } while (0)
277
278 #define FOREACH_PHI(phi) do { \
279 int _i; \
280 for (_i = 0; _i < ssa->cfg.blocks_count; _i++) { \
281 phi = ssa->blocks[_i].phis; \
282 for (; phi; phi = phi->next) {
283 #define FOREACH_PHI_END() \
284 } \
285 } \
286 } while (0)
287
288 #define FOREACH_BLOCK(block) do { \
289 int _i; \
290 for (_i = 0; _i < ssa->cfg.blocks_count; _i++) { \
291 (block) = &ssa->cfg.blocks[_i]; \
292 if (!((block)->flags & ZEND_BB_REACHABLE)) { \
293 continue; \
294 }
295 #define FOREACH_BLOCK_END() \
296 } \
297 } while (0)
298
299 /* Does not support "break" */
300 #define FOREACH_INSTR_NUM(i) do { \
301 zend_basic_block *_block; \
302 FOREACH_BLOCK(_block) { \
303 uint32_t _end = _block->start + _block->len; \
304 for ((i) = _block->start; (i) < _end; (i)++) {
305 #define FOREACH_INSTR_NUM_END() \
306 } \
307 } FOREACH_BLOCK_END(); \
308 } while (0)
309
310 #endif /* ZEND_SSA_H */
311
312 /*
313 * Local variables:
314 * tab-width: 4
315 * c-basic-offset: 4
316 * indent-tabs-mode: t
317 * End:
318 */
319
