From 8dedaf8512d7292c9df90bebae91362ba36e7a97 Mon Sep 17 00:00:00 2001
From: Dmitry Stogov <dmitry@zend.com>
Date: Tue, 1 Apr 2014 18:06:50 +0400
Subject: [PATCH] Use interned strings for one character strings

---
 Zend/zend_execute.c           | 12 +++++++++---
 Zend/zend_globals.h           |  1 +
 Zend/zend_string.c            |  3 +++
 ext/opcache/ZendAccelerator.c |  6 ++++++
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Zend/zend_execute.c b/Zend/zend_execute.c
index e2de52c777..bdc0e2e8db 100644
--- a/Zend/zend_execute.c
+++ b/Zend/zend_execute.c
@@ -1225,7 +1225,7 @@ static void zend_fetch_dimension_address_read(zval *result, zval *container, zva
 				zval tmp;
 				zend_string *str;
 
-				if (Z_TYPE_P(dim) != IS_LONG) {
+				if (UNEXPECTED(Z_TYPE_P(dim) != IS_LONG)) {
 					switch(Z_TYPE_P(dim)) {
 						/* case IS_LONG: */
 						case IS_STRING:
@@ -1253,13 +1253,19 @@ static void zend_fetch_dimension_address_read(zval *result, zval *container, zva
 					dim = &tmp;
 				}
 
-				if (Z_LVAL_P(dim) < 0 || Z_STRLEN_P(container) <= Z_LVAL_P(dim)) {
+				if (UNEXPECTED(Z_LVAL_P(dim) < 0) || UNEXPECTED(Z_STRLEN_P(container) <= Z_LVAL_P(dim))) {
 					if (type != BP_VAR_IS) {
 						zend_error(E_NOTICE, "Uninitialized string offset: %ld", Z_LVAL_P(dim));
 					}
 					str = STR_EMPTY_ALLOC();
 				} else {
-					str = STR_INIT(Z_STRVAL_P(container) + Z_LVAL_P(dim), 1, 0);
+					zend_uchar c = (zend_uchar)Z_STRVAL_P(container)[Z_LVAL_P(dim)];
+					
+					if (CG(one_char_string)[c]) {
+						str = CG(one_char_string)[c];
+					} else {
+						str = STR_INIT(Z_STRVAL_P(container) + Z_LVAL_P(dim), 1, 0);
+					}
 				}
 				ZVAL_STR(result, str);
 				return;
diff --git a/Zend/zend_globals.h b/Zend/zend_globals.h
index 9dae1fcfca..828acfa106 100644
--- a/Zend/zend_globals.h
+++ b/Zend/zend_globals.h
@@ -141,6 +141,7 @@ struct _zend_compiler_globals {
 	zend_stack context_stack;
 
 	zend_string *empty_string;
+	zend_string *one_char_string[256];
 
 	HashTable interned_strings;
 
diff --git a/Zend/zend_string.c b/Zend/zend_string.c
index 170cb2c200..abd784ed5f 100644
--- a/Zend/zend_string.c
+++ b/Zend/zend_string.c
@@ -57,6 +57,9 @@ void zend_interned_strings_init(TSRMLS_D)
 	str = STR_ALLOC(sizeof("")-1, 1);
 	str->val[0] = '\000';
 	CG(empty_string) = zend_new_interned_string_int(str TSRMLS_CC);
+
+	/* one char strings (the actual interned strings are going to be created by ext/opcache) */
+	memset(CG(one_char_string), 0, sizeof(CG(one_char_string)));
 #else
 	str = STR_ALLOC(sizeof("")-1, 1);
 	str->val[0] = '\000';
diff --git a/ext/opcache/ZendAccelerator.c b/ext/opcache/ZendAccelerator.c
index 1bf672e3df..cb93fbf633 100644
--- a/ext/opcache/ZendAccelerator.c
+++ b/ext/opcache/ZendAccelerator.c
@@ -382,6 +382,12 @@ static void accel_use_shm_interned_strings(TSRMLS_D)
 #if ZEND_EXTENSION_API_NO > PHP_5_5_X_API_NO
 	/* empty string */
 	CG(empty_string) = accel_new_interned_string(CG(empty_string) TSRMLS_CC);
+	for (j = 0; j < 256; j++) {
+		char s[2];
+		s[0] = j;
+		s[1] = 0;
+		CG(one_char_string)[j] = accel_new_interned_string(STR_INIT(s, 1, 0) TSRMLS_CC);
+	}
 #endif
 
 	/* function table hash keys */
-- 
2.40.0