Stop JIT hot spot counting

When max_root_trace is reached, JIT in tracing mode will not
compile any new code for root trace and side trace, but
counting hot code is still going on. This patch stops counting
as soon as possible by replacing counter handler with
original handler, which increases 1.5% performance.

Signed-off-by: Wang, Xue <xue1.wang@intel.com>

Author: wxue1

ext/opcache/jit/zend_jit_trace.c

@@ -7125,6 +7125,74 @@ static zend_jit_trace_stop zend_jit_compile_root_trace(zend_jit_trace_rec *trace
 	return ret;
 }
 
+/* Set counting handler back to original VM handler. */
+static void zend_jit_stop_hot_trace_counters(zend_op_array *op_array)
+{
+	zend_jit_op_array_trace_extension *jit_extension;
+	uint32_t i;
+
+	jit_extension = (zend_jit_op_array_trace_extension*)ZEND_FUNC_INFO(op_array);
+	zend_shared_alloc_lock();
+	SHM_UNPROTECT();
+	for (i = 0; i < op_array->last; i++) {
+		/* Opline with Jit-ed code handler is skipped. */
+        if (jit_extension->trace_info[i].trace_flags &
+            (ZEND_JIT_TRACE_JITED|ZEND_JIT_TRACE_BLACKLISTED)) {
+            continue;
+        }
+        if (jit_extension->trace_info[i].trace_flags &
+            (ZEND_JIT_TRACE_START_LOOP | ZEND_JIT_TRACE_START_ENTER | ZEND_JIT_TRACE_START_RETURN)) {
+			op_array->opcodes[i].handler = jit_extension->trace_info[i].orig_handler;
+        }
+    }
+	SHM_PROTECT();
+	zend_shared_alloc_unlock();
+}
+
+/* Get the tracing op_array. */
+static void zend_jit_stop_persistent_op_array(zend_op_array *op_array) {
+    zend_func_info *func_info = ZEND_FUNC_INFO(op_array);
+    if (!func_info) {
+		return;
+	}
+    if (func_info->flags & ZEND_FUNC_JIT_ON_HOT_TRACE) {
+        zend_jit_stop_hot_trace_counters(op_array);
+    }
+}
+
+/* Get all op_arrays with counter handler. */
+static void zend_jit_stop_persistent_script(zend_persistent_script *script) {
+	zend_class_entry *ce;
+	zend_op_array *op_array;
+
+	zend_jit_stop_persistent_op_array(&script->script.main_op_array);
+
+	ZEND_HASH_FOREACH_PTR(&script->script.function_table, op_array) {
+		zend_jit_stop_persistent_op_array(op_array);
+	} ZEND_HASH_FOREACH_END();
+
+	ZEND_HASH_FOREACH_PTR(&script->script.class_table, ce) {
+		ZEND_HASH_FOREACH_PTR(&ce->function_table, op_array) {
+			if (op_array->type == ZEND_USER_FUNCTION) {
+				zend_jit_stop_persistent_op_array(op_array);
+			}
+		} ZEND_HASH_FOREACH_END();
+	} ZEND_HASH_FOREACH_END();
+}
+
+/* Get all scripts which are accelerated by JIT */
+static void zend_jit_stop_counter_handlers() {
+	for (uint32_t i = 0; i < ZCSG(hash).max_num_entries; i++) {
+		zend_accel_hash_entry *cache_entry;
+		for (cache_entry = ZCSG(hash).hash_table[i]; cache_entry; cache_entry = cache_entry->next) {
+			zend_persistent_script *script;
+			if (cache_entry->indirect) continue;
+			script = (zend_persistent_script *)cache_entry->data;
+			zend_jit_stop_persistent_script(script);
+		}
+	}
+}
+
 static void zend_jit_blacklist_root_trace(const zend_op *opline, size_t offset)
 {
 	zend_shared_alloc_lock();
@@ -7505,6 +7573,7 @@ int ZEND_FASTCALL zend_jit_trace_hot_root(zend_execute_data *execute_data, const
 
 	if (ZEND_JIT_TRACE_NUM >= JIT_G(max_root_traces)) {
 		stop = ZEND_JIT_TRACE_STOP_TOO_MANY_TRACES;
+		zend_jit_stop_counter_handlers();
 		goto abort;
 	}