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Always load EX(opline) into the current frame in tracing JIT when observers are enabled #13776

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Always load EX(opline) into the current frame in tracing JIT when observers are enabled #13776

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7 changes: 6 additions & 1 deletion ext/opcache/jit/zend_jit_arm64.dasc
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Original file line number Diff line number Diff line change
Expand Up @@ -9449,7 +9449,12 @@ static int zend_jit_do_fcall(dasm_State **Dst, const zend_op *opline, const zend
}

if (ZEND_OBSERVER_ENABLED) {
| SAVE_IP
if (trace && (trace->op != ZEND_JIT_TRACE_END || trace->stop != ZEND_JIT_TRACE_STOP_INTERPRETER)) {
ZEND_ASSERT(trace[1].op == ZEND_JIT_TRACE_VM || trace[1].op == ZEND_JIT_TRACE_END);
| SET_EX_OPLINE trace[1].opline, REG0
} else {
| SAVE_IP
}
| mov FCARG1x, FP
| EXT_CALL zend_observer_fcall_begin, REG0
}
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7 changes: 6 additions & 1 deletion ext/opcache/jit/zend_jit_x86.dasc
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Expand Up @@ -10187,7 +10187,12 @@ static int zend_jit_do_fcall(dasm_State **Dst, const zend_op *opline, const zend
}

if (ZEND_OBSERVER_ENABLED) {
| SAVE_IP
if (trace && (trace->op != ZEND_JIT_TRACE_END || trace->stop != ZEND_JIT_TRACE_STOP_INTERPRETER)) {
ZEND_ASSERT(trace[1].op == ZEND_JIT_TRACE_VM || trace[1].op == ZEND_JIT_TRACE_END);
| SET_EX_OPLINE trace[1].opline, r0
} else {
| SAVE_IP
}
Comment on lines +10190 to +10195
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Are you sure SAVE_IP should be called for tracing JIT?

From the first look, I would refer to check the direct condition - trace[1].op == ZEND_JIT_TRACE_VM || trace[1].op == ZEND_JIT_TRACE_END.
Why did you prefer the reverse one - trace->op != ZEND_JIT_TRACE_END || trace->stop != ZEND_JIT_TRACE_STOP_INTERPRETER?

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Because it's the reverse condition of:

				if (!trace || (trace->op == ZEND_JIT_TRACE_END
&& trace->stop == ZEND_JIT_TRACE_STOP_INTERPRETER)) {

(lines 10077) and which turns out to be the only case when trace[1] does not exist. But if that code is executed, e.g. line 10097 directly writes to IP, but not EX(opline):

| mov IP, aword [r0 + offsetof(zend_op_array, opcodes)]

so, not calling SAVE_IP would not store that.

| mov FCARG1a, FP
| EXT_CALL zend_observer_fcall_begin, r0
}
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26 changes: 26 additions & 0 deletions ext/opcache/tests/jit/gh13772.phpt
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@@ -0,0 +1,26 @@
--TEST--
EX(opline) is correctly set for nested JIT user code calls
--EXTENSIONS--
opcache
zend_test
--INI--
opcache.enable=1
opcache.enable_cli=1
zend_test.observer.enabled=1
zend_test.observer.observe_all=1
zend_test.observer.show_output=0
--FILE--
<?php

function Ack($m, $n) {
if ($m == 0) return $n+1;
if ($n == 0) return Ack($m-1, 1);
return Ack($m - 1, Ack($m, ($n - 1)));
}

var_dump(Ack(3, 3));
Comment on lines +15 to +21
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We could also cover the call_num_args > func->op_array.num_args case here with

function Ack($m, $n) {
	if ($m == 0) return $n+1;
	if ($n == 0) return Ack($m-1, 1, $n);
	return Ack($m - 1, Ack($m, ($n - 1), $n));
}

var_dump(Ack(3, 3, 3));


?>
--EXPECT--
int(61)

10 changes: 10 additions & 0 deletions ext/zend_test/observer.c
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Expand Up @@ -67,8 +67,16 @@ static void observer_show_opcode(zend_execute_data *execute_data)
php_printf("%*s<!-- opcode: '%s' -->\n", 2 * ZT_G(observer_nesting_depth), "", zend_get_opcode_name(EX(opline)->opcode));
}

static inline void assert_observer_opline(zend_execute_data *execute_data) {
ZEND_ASSERT(!ZEND_USER_CODE(EX(func)->type) ||
(EX(opline) >= EX(func)->op_array.opcodes && EX(opline) < EX(func)->op_array.opcodes + EX(func)->op_array.last) ||
(EX(opline) >= EG(exception_op) && EX(opline) < EG(exception_op) + 3));
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Interesting catch!
Should the begin/end observer handlers be called in case of exception?

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Yes.
For begin observers: generators may be resumed with an exception and continue execution (after a catch). Not calling them would hide normal execution.
For end observers - we for sure want to observe thrown exceptions.

}

static void observer_begin(zend_execute_data *execute_data)
{
assert_observer_opline(execute_data);

if (!ZT_G(observer_show_output)) {
return;
}
Expand Down Expand Up @@ -112,6 +120,8 @@ static void get_retval_info(zval *retval, smart_str *buf)

static void observer_end(zend_execute_data *execute_data, zval *retval)
{
assert_observer_opline(execute_data);

if (!ZT_G(observer_show_output)) {
return;
}
Expand Down