|
| 1 | +/* |
| 2 | + +----------------------------------------------------------------------+ |
| 3 | + | Zend Engine, Removing unused variables | |
| 4 | + +----------------------------------------------------------------------+ |
| 5 | + | Copyright (c) 1998-2017 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: Nikita Popov <nikic@php.net> | |
| 16 | + +----------------------------------------------------------------------+ |
| 17 | +*/ |
| 18 | + |
| 19 | +#include "ZendAccelerator.h" |
| 20 | +#include "Optimizer/zend_optimizer_internal.h" |
| 21 | +#include "zend_bitset.h" |
| 22 | + |
| 23 | +/* This pass removes all CVs that are completely unused. It does *not* merge any CVs. |
| 24 | + * This pass does not operate on SSA form anymore. */ |
| 25 | +void zend_optimizer_compact_vars(zend_op_array *op_array) { |
| 26 | + int i; |
| 27 | + |
| 28 | + ALLOCA_FLAG(use_heap1); |
| 29 | + ALLOCA_FLAG(use_heap2); |
| 30 | + uint32_t used_cvs_len = zend_bitset_len(op_array->last_var); |
| 31 | + zend_bitset used_cvs = ZEND_BITSET_ALLOCA(used_cvs_len, use_heap1); |
| 32 | + uint32_t *cv_map = do_alloca(op_array->last_var * sizeof(uint32_t), use_heap2); |
| 33 | + uint32_t num_cvs, tmp_offset; |
| 34 | + |
| 35 | + /* Determine which CVs are used */ |
| 36 | + zend_bitset_clear(used_cvs, used_cvs_len); |
| 37 | + for (i = 0; i < op_array->last; i++) { |
| 38 | + zend_op *opline = &op_array->opcodes[i]; |
| 39 | + if (opline->op1_type == IS_CV) { |
| 40 | + zend_bitset_incl(used_cvs, VAR_NUM(opline->op1.var)); |
| 41 | + } |
| 42 | + if (opline->op2_type == IS_CV) { |
| 43 | + zend_bitset_incl(used_cvs, VAR_NUM(opline->op2.var)); |
| 44 | + } |
| 45 | + if (opline->result_type == IS_CV) { |
| 46 | + zend_bitset_incl(used_cvs, VAR_NUM(opline->result.var)); |
| 47 | + } |
| 48 | + } |
| 49 | + |
| 50 | + num_cvs = 0; |
| 51 | + for (i = 0; i < op_array->last_var; i++) { |
| 52 | + if (zend_bitset_in(used_cvs, i)) { |
| 53 | + cv_map[i] = num_cvs++; |
| 54 | + } else { |
| 55 | + cv_map[i] = (uint32_t) -1; |
| 56 | + } |
| 57 | + } |
| 58 | + |
| 59 | + free_alloca(used_cvs, use_heap1); |
| 60 | + if (num_cvs == op_array->last_var) { |
| 61 | + free_alloca(cv_map, use_heap2); |
| 62 | + return; |
| 63 | + } |
| 64 | + |
| 65 | + ZEND_ASSERT(num_cvs < op_array->last_var); |
| 66 | + tmp_offset = op_array->last_var - num_cvs; |
| 67 | + |
| 68 | + /* Update CV and TMP references in opcodes */ |
| 69 | + for (i = 0; i < op_array->last; i++) { |
| 70 | + zend_op *opline = &op_array->opcodes[i]; |
| 71 | + if (opline->op1_type == IS_CV) { |
| 72 | + opline->op1.var = NUM_VAR(cv_map[VAR_NUM(opline->op1.var)]); |
| 73 | + } else if (opline->op1_type & (IS_VAR|IS_TMP_VAR)) { |
| 74 | + opline->op1.var -= sizeof(zval) * tmp_offset; |
| 75 | + } |
| 76 | + if (opline->op2_type == IS_CV) { |
| 77 | + opline->op2.var = NUM_VAR(cv_map[VAR_NUM(opline->op2.var)]); |
| 78 | + } else if (opline->op2_type & (IS_VAR|IS_TMP_VAR)) { |
| 79 | + opline->op2.var -= sizeof(zval) * tmp_offset; |
| 80 | + } |
| 81 | + if (opline->result_type == IS_CV) { |
| 82 | + opline->result.var = NUM_VAR(cv_map[VAR_NUM(opline->result.var)]); |
| 83 | + } else if (opline->result_type & (IS_VAR|IS_TMP_VAR)) { |
| 84 | + opline->result.var -= sizeof(zval) * tmp_offset; |
| 85 | + } |
| 86 | + } |
| 87 | + |
| 88 | + /* Update TMP references in live ranges */ |
| 89 | + if (op_array->live_range) { |
| 90 | + for (i = 0; i < op_array->last_live_range; i++) { |
| 91 | + op_array->live_range[i].var -= sizeof(zval) * tmp_offset; |
| 92 | + } |
| 93 | + } |
| 94 | + |
| 95 | + /* Update CV name table */ |
| 96 | + { |
| 97 | + zend_string **names = safe_emalloc(sizeof(zend_string *), num_cvs, 0); |
| 98 | + for (i = 0; i < op_array->last_var; i++) { |
| 99 | + if (cv_map[i] != (uint32_t) -1) { |
| 100 | + names[cv_map[i]] = op_array->vars[i]; |
| 101 | + } else { |
| 102 | + zend_string_release(op_array->vars[i]); |
| 103 | + } |
| 104 | + } |
| 105 | + efree(op_array->vars); |
| 106 | + op_array->vars = names; |
| 107 | + } |
| 108 | + |
| 109 | + op_array->last_var = num_cvs; |
| 110 | + |
| 111 | + free_alloca(cv_map, use_heap2); |
| 112 | +} |
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