Add configuration opcache.jit_max_trace_length

Max length of a single trace. A long trace generates long JITTed
code, which influences the performance slightly.
opcache.jit_max_trace_length range is [4,1024], the default value
is 512.

Signed-off-by: Wang, Xue <[email protected]>
Reviewed-by:   Su, Tao   <[email protected]>

Author: wxue1

ext/opcache/jit/zend_jit.h

@@ -115,6 +115,7 @@ typedef struct _zend_jit_globals {
 	zend_long   max_recursive_calls;   /* max number of recursive inlined call unrolls */
 	zend_long   max_recursive_returns; /* max number of recursive inlined return unrolls */
 	zend_long   max_polymorphic_calls; /* max number of inlined polymorphic calls */
+	zend_long   max_trace_length; 	   /* max length of a single trace */
 
 	zend_sym_node *symbols;            /* symbols for disassembler */
 

ext/opcache/jit/zend_jit_trace.c

@@ -7591,7 +7591,7 @@ int ZEND_FASTCALL zend_jit_trace_hot_root(zend_execute_data *execute_data, const
 	zend_jit_op_array_trace_extension *jit_extension;
 	size_t offset;
 	uint32_t trace_num;
-	zend_jit_trace_rec trace_buffer[ZEND_JIT_TRACE_MAX_LENGTH];
+    zend_jit_trace_rec *trace_buffer = (zend_jit_trace_rec *)malloc(JIT_G(max_trace_length) * sizeof(zend_jit_trace_rec));
 
 	ZEND_ASSERT(EX(func)->type == ZEND_USER_FUNCTION);
 	ZEND_ASSERT(opline >= EX(func)->op_array.opcodes &&
@@ -7926,7 +7926,7 @@ int ZEND_FASTCALL zend_jit_trace_hot_side(zend_execute_data *execute_data, uint3
 	zend_jit_trace_stop stop;
 	int ret = 0;
 	uint32_t trace_num;
-	zend_jit_trace_rec trace_buffer[ZEND_JIT_TRACE_MAX_LENGTH];
+    zend_jit_trace_rec *trace_buffer = (zend_jit_trace_rec *)malloc(JIT_G(max_trace_length) * sizeof(zend_jit_trace_rec));
 	uint32_t is_megamorphic = 0;
 	uint32_t polymorphism = 0;
 

ext/opcache/jit/zend_jit_vm_helpers.c

@@ -360,7 +360,7 @@ ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL zend_jit_loop_trace_helper(ZEND_OPCODE_HAN
 	trace_buffer[idx].info = _op | (_info); \
 	trace_buffer[idx].ptr = _ptr; \
 	idx++; \
-	if (idx >= ZEND_JIT_TRACE_MAX_LENGTH - 2) { \
+	if (idx >= JIT_G(max_trace_length) - 2) { \
 		stop = ZEND_JIT_TRACE_STOP_TOO_LONG; \
 		break; \
 	}
@@ -372,7 +372,7 @@ ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL zend_jit_loop_trace_helper(ZEND_OPCODE_HAN
 	trace_buffer[idx].op3_type = _op3_type; \
 	trace_buffer[idx].ptr = _ptr; \
 	idx++; \
-	if (idx >= ZEND_JIT_TRACE_MAX_LENGTH - 2) { \
+	if (idx >= JIT_G(max_trace_length) - 2) { \
 		stop = ZEND_JIT_TRACE_STOP_TOO_LONG; \
 		break; \
 	}

ext/opcache/zend_accelerator_module.c

@@ -258,6 +258,19 @@ static ZEND_INI_MH(OnUpdateUnrollL)
 		ZEND_JIT_TRACE_MAX_LOOPS_UNROLL);
 	return FAILURE;
 }
+
+static ZEND_INI_MH(OnUpdateUnrollT)
+{
+	zend_long val = zend_atol(ZSTR_VAL(new_value), ZSTR_LEN(new_value));
+	if (val > 3 && val <= ZEND_JIT_TRACE_MAX_LENGTH) {
+		zend_long *p = (zend_long *) ZEND_INI_GET_ADDR();
+		*p = val;
+		return SUCCESS;
+	}
+	zend_error(E_WARNING, "Invalid \"%s\" setting. Should be between 4 and %d", ZSTR_VAL(entry->name),
+		ZEND_JIT_TRACE_MAX_LENGTH);
+	return FAILURE;
+}
 #endif
 
 ZEND_INI_BEGIN()
@@ -336,6 +349,7 @@ ZEND_INI_BEGIN()
 	STD_PHP_INI_ENTRY("opcache.jit_max_recursive_calls"       , "2",                          PHP_INI_ALL,    OnUpdateUnrollC,  max_recursive_calls,   zend_jit_globals, jit_globals)
 	STD_PHP_INI_ENTRY("opcache.jit_max_recursive_returns"     , "2",                          PHP_INI_ALL,    OnUpdateUnrollR,  max_recursive_returns, zend_jit_globals, jit_globals)
 	STD_PHP_INI_ENTRY("opcache.jit_max_polymorphic_calls"     , "2",                          PHP_INI_ALL,    OnUpdateLong,     max_polymorphic_calls, zend_jit_globals, jit_globals)
+    STD_PHP_INI_ENTRY("opcache.jit_max_trace_length"          , "512",                        PHP_INI_ALL,    OnUpdateUnrollT,  max_trace_length,      zend_jit_globals, jit_globals)
 #endif
 ZEND_INI_END()
 
@@ -849,6 +863,7 @@ ZEND_FUNCTION(opcache_get_configuration)
 	add_assoc_long(&directives,   "opcache.jit_max_root_traces", JIT_G(max_root_traces));
 	add_assoc_long(&directives,   "opcache.jit_max_side_traces", JIT_G(max_side_traces));
 	add_assoc_long(&directives,   "opcache.jit_prof_threshold", JIT_G(prof_threshold));
+	add_assoc_long(&directives,   "opcache.jit_max_trace_length", JIT_G(max_trace_length));
 #endif
 
 	add_assoc_zval(return_value, "directives", &directives);