Move optimizer into core

This only moves the files, adjusts the build system, exports APIs
and does minor fixups to make sure the code builds.

This does not yet try to make the optimizer usable independently
of opcache.

Closes GH-6642.

1 files changed, 123 insertions, 0 deletions

diff --git a/Zend/Optimizer/compact_vars.c b/Zend/Optimizer/compact_vars.c
new file mode 100644
index 0000000000..e70e189827
--- /dev/null
+++ b/Zend/Optimizer/compact_vars.c
@@ -0,0 +1,123 @@
+/*
+   +----------------------------------------------------------------------+
+   | Zend Engine, Removing unused variables                               |
+   +----------------------------------------------------------------------+
+   | Copyright (c) The PHP Group                                          |
+   +----------------------------------------------------------------------+
+   | This source file is subject to version 3.01 of the PHP license,      |
+   | that is bundled with this package in the file LICENSE, and is        |
+   | available through the world-wide-web at the following url:           |
+   | http://www.php.net/license/3_01.txt                                  |
+   | If you did not receive a copy of the PHP license and are unable to   |
+   | obtain it through the world-wide-web, please send a note to          |
+   | license@php.net so we can mail you a copy immediately.               |
+   +----------------------------------------------------------------------+
+   | Authors: Nikita Popov <nikic@php.net>                                |
+   +----------------------------------------------------------------------+
+*/
+
+#include "Optimizer/zend_optimizer_internal.h"
+#include "zend_bitset.h"
+
+/* This pass removes all CVs and temporaries that are completely unused. It does *not* merge any CVs or TMPs.
+ * This pass does not operate on SSA form anymore. */
+void zend_optimizer_compact_vars(zend_op_array *op_array) {
+	int i;
+
+	ALLOCA_FLAG(use_heap1);
+	ALLOCA_FLAG(use_heap2);
+	uint32_t used_vars_len = zend_bitset_len(op_array->last_var + op_array->T);
+	zend_bitset used_vars = ZEND_BITSET_ALLOCA(used_vars_len, use_heap1);
+	uint32_t *vars_map = do_alloca((op_array->last_var + op_array->T) * sizeof(uint32_t), use_heap2);
+	uint32_t num_cvs, num_tmps;
+
+	/* Determine which CVs are used */
+	zend_bitset_clear(used_vars, used_vars_len);
+	for (i = 0; i < op_array->last; i++) {
+		zend_op *opline = &op_array->opcodes[i];
+		if (opline->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			zend_bitset_incl(used_vars, VAR_NUM(opline->op1.var));
+		}
+		if (opline->op2_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			zend_bitset_incl(used_vars, VAR_NUM(opline->op2.var));
+		}
+		if (opline->result_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			zend_bitset_incl(used_vars, VAR_NUM(opline->result.var));
+			if (opline->opcode == ZEND_ROPE_INIT) {
+				uint32_t num = ((opline->extended_value * sizeof(zend_string*)) + (sizeof(zval) - 1)) / sizeof(zval);
+				while (num > 1) {
+					num--;
+					zend_bitset_incl(used_vars, VAR_NUM(opline->result.var) + num);
+				}
+			}
+		}
+	}
+
+	num_cvs = 0;
+	for (i = 0; i < op_array->last_var; i++) {
+		if (zend_bitset_in(used_vars, i)) {
+			vars_map[i] = num_cvs++;
+		} else {
+			vars_map[i] = (uint32_t) -1;
+		}
+	}
+
+	num_tmps = 0;
+	for (i = op_array->last_var; i < op_array->last_var + op_array->T; i++) {
+		if (zend_bitset_in(used_vars, i)) {
+			vars_map[i] = num_cvs + num_tmps++;
+		} else {
+			vars_map[i] = (uint32_t) -1;
+		}
+	}
+
+	free_alloca(used_vars, use_heap1);
+	if (num_cvs == op_array->last_var && num_tmps == op_array->T) {
+		free_alloca(vars_map, use_heap2);
+		return;
+	}
+
+	ZEND_ASSERT(num_cvs <= op_array->last_var);
+	ZEND_ASSERT(num_tmps <= op_array->T);
+
+	/* Update CV and TMP references in opcodes */
+	for (i = 0; i < op_array->last; i++) {
+		zend_op *opline = &op_array->opcodes[i];
+		if (opline->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			opline->op1.var = NUM_VAR(vars_map[VAR_NUM(opline->op1.var)]);
+		}
+		if (opline->op2_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			opline->op2.var = NUM_VAR(vars_map[VAR_NUM(opline->op2.var)]);
+		}
+		if (opline->result_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
+			opline->result.var = NUM_VAR(vars_map[VAR_NUM(opline->result.var)]);
+		}
+	}
+
+	/* Update CV name table */
+	if (num_cvs != op_array->last_var) {
+		if (num_cvs) {
+			zend_string **names = safe_emalloc(sizeof(zend_string *), num_cvs, 0);
+			for (i = 0; i < op_array->last_var; i++) {
+				if (vars_map[i] != (uint32_t) -1) {
+					names[vars_map[i]] = op_array->vars[i];
+				} else {
+					zend_string_release_ex(op_array->vars[i], 0);
+				}
+			}
+			efree(op_array->vars);
+			op_array->vars = names;
+		} else {
+			for (i = 0; i < op_array->last_var; i++) {
+				zend_string_release_ex(op_array->vars[i], 0);
+			}
+			efree(op_array->vars);
+			op_array->vars = NULL;
+		}
+		op_array->last_var = num_cvs;
+	}
+
+	op_array->T = num_tmps;
+
+	free_alloca(vars_map, use_heap2);
+}