1 /*
2    +----------------------------------------------------------------------+
3    | Zend OPcache                                                         |
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    | 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: Andi Gutmans <andi@php.net>                                 |
16    |          Zeev Suraski <zeev@php.net>                                 |
17    |          Stanislav Malyshev <stas@zend.com>                          |
18    |          Dmitry Stogov <dmitry@php.net>                              |
19    +----------------------------------------------------------------------+
20 */
21 
22 #include "php.h"
23 #include "Optimizer/zend_optimizer.h"
24 #include "Optimizer/zend_optimizer_internal.h"
25 #include "zend_API.h"
26 #include "zend_constants.h"
27 #include "zend_execute.h"
28 #include "zend_vm.h"
29 #include "zend_bitset.h"
30 
31 #define GET_AVAILABLE_T()					\
32 	for (i = 0; i < T; i++) {				\
33 		if (!zend_bitset_in(taken_T, i)) {	\
34 			break;							\
35 		}									\
36 	}										\
37 	zend_bitset_incl(taken_T, i);			\
38 	if (i > max) {							\
39 		max = i;							\
40 	}
41 
zend_optimize_temporary_variables(zend_op_array * op_array,zend_optimizer_ctx * ctx)42 void zend_optimize_temporary_variables(zend_op_array *op_array, zend_optimizer_ctx *ctx)
43 {
44 	int T = op_array->T;
45 	int offset = op_array->last_var;
46 	uint32_t bitset_len;
47 	zend_bitset taken_T;	/* T index in use */
48 	zend_op **start_of_T;	/* opline where T is first used */
49 	zend_bitset valid_T;	/* Is the map_T valid */
50 	int *map_T;				/* Map's the T to its new index */
51 	zend_op *opline, *end;
52 	int currT;
53 	int i;
54 	int max = -1;
55 	void *checkpoint = zend_arena_checkpoint(ctx->arena);
56 
57 	bitset_len = zend_bitset_len(T);
58 	taken_T = (zend_bitset) zend_arena_alloc(&ctx->arena, bitset_len * ZEND_BITSET_ELM_SIZE);
59 	start_of_T = (zend_op **) zend_arena_alloc(&ctx->arena, T * sizeof(zend_op *));
60 	valid_T = (zend_bitset) zend_arena_alloc(&ctx->arena, bitset_len * ZEND_BITSET_ELM_SIZE);
61 	map_T = (int *) zend_arena_alloc(&ctx->arena, T * sizeof(int));
62 
63     end = op_array->opcodes;
64     opline = &op_array->opcodes[op_array->last - 1];
65 
66     /* Find T definition points */
67     while (opline >= end) {
68         if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
69 			start_of_T[VAR_NUM(opline->result.var) - offset] = opline;
70 		}
71 		opline--;
72 	}
73 
74 	zend_bitset_clear(valid_T, bitset_len);
75 	zend_bitset_clear(taken_T, bitset_len);
76 
77     end = op_array->opcodes;
78     opline = &op_array->opcodes[op_array->last - 1];
79 
80     while (opline >= end) {
81 		if ((opline->op1_type & (IS_VAR | IS_TMP_VAR))) {
82 			currT = VAR_NUM(opline->op1.var) - offset;
83 			if (opline->opcode == ZEND_ROPE_END) {
84 				int num = (((opline->extended_value + 1) * sizeof(zend_string*)) + (sizeof(zval) - 1)) / sizeof(zval);
85 				int var;
86 
87 				var = max;
88 				while (var >= 0 && !zend_bitset_in(taken_T, var)) {
89 					var--;
90 				}
91 				max = MAX(max, var + num);
92 				var = var + 1;
93 				map_T[currT] = var;
94 				zend_bitset_incl(valid_T, currT);
95 				zend_bitset_incl(taken_T, var);
96 				opline->op1.var = NUM_VAR(var + offset);
97 				while (num > 1) {
98 					num--;
99 					zend_bitset_incl(taken_T, var + num);
100 				}
101 			} else {
102 				if (!zend_bitset_in(valid_T, currT)) {
103 					int use_new_var = 0;
104 
105 					/* Code in "finally" blocks may modify temporary variables.
106 					 * We allocate new temporaries for values that need to
107 					 * relive FAST_CALLs.
108 					 */
109 					if ((op_array->fn_flags & ZEND_ACC_HAS_FINALLY_BLOCK) &&
110 					    (opline->opcode == ZEND_RETURN ||
111 					     opline->opcode == ZEND_GENERATOR_RETURN ||
112 					     opline->opcode == ZEND_RETURN_BY_REF ||
113 					     opline->opcode == ZEND_FREE ||
114 					     opline->opcode == ZEND_FE_FREE)) {
115 						zend_op *curr = opline;
116 
117 						while (--curr >= end) {
118 							if (curr->opcode == ZEND_FAST_CALL) {
119 								use_new_var = 1;
120 								break;
121 							} else if (curr->opcode != ZEND_FREE &&
122 							           curr->opcode != ZEND_FE_FREE &&
123 							           curr->opcode != ZEND_VERIFY_RETURN_TYPE &&
124 							           curr->opcode != ZEND_DISCARD_EXCEPTION) {
125 								break;
126 							}
127 						}
128 					}
129 					if (use_new_var) {
130 						i = ++max;
131 						zend_bitset_incl(taken_T, i);
132 					} else {
133 						GET_AVAILABLE_T();
134 					}
135 					map_T[currT] = i;
136 					zend_bitset_incl(valid_T, currT);
137 				}
138 				opline->op1.var = NUM_VAR(map_T[currT] + offset);
139 			}
140 		}
141 
142 		if ((opline->op2_type & (IS_VAR | IS_TMP_VAR))) {
143 			currT = VAR_NUM(opline->op2.var) - offset;
144 			if (!zend_bitset_in(valid_T, currT)) {
145 				GET_AVAILABLE_T();
146 				map_T[currT] = i;
147 				zend_bitset_incl(valid_T, currT);
148 			}
149 			opline->op2.var = NUM_VAR(map_T[currT] + offset);
150 		}
151 
152 		if (opline->result_type & (IS_VAR | IS_TMP_VAR)) {
153 			currT = VAR_NUM(opline->result.var) - offset;
154 			if (zend_bitset_in(valid_T, currT)) {
155 				if (start_of_T[currT] == opline) {
156 					/* ZEND_FAST_CALL can not share temporary var with others
157 					 * since the fast_var could also be set by ZEND_HANDLE_EXCEPTION
158 					 * which could be ahead of it */
159 					if (opline->opcode != ZEND_FAST_CALL) {
160 						zend_bitset_excl(taken_T, map_T[currT]);
161 					}
162 				}
163 				opline->result.var = NUM_VAR(map_T[currT] + offset);
164 				if (opline->opcode == ZEND_ROPE_INIT) {
165 					if (start_of_T[currT] == opline) {
166 						uint32_t num = ((opline->extended_value * sizeof(zend_string*)) + (sizeof(zval) - 1)) / sizeof(zval);
167 						while (num > 1) {
168 							num--;
169 							zend_bitset_excl(taken_T, map_T[currT]+num);
170 						}
171 					}
172 				}
173 			} else {
174 				/* Code which gets here is using a wrongly built opcode such as RECV() */
175 				GET_AVAILABLE_T();
176 				map_T[currT] = i;
177 				zend_bitset_incl(valid_T, currT);
178 				opline->result.var = NUM_VAR(i + offset);
179 			}
180 		}
181 
182 		opline--;
183 	}
184 
185 	zend_arena_release(&ctx->arena, checkpoint);
186 	op_array->T = max + 1;
187 }
188