Improve fiber backtraces

The start/resume/throw execute_data is now attached as the prev_execute_data to the bottom frame of the fiber stack when the fiber is running.

Zend/tests/fibers/backtrace-deep-nesting.phpt

@@ -0,0 +1,54 @@
+--TEST--
+Backtrace in deeply nested function call
+--FILE--
+<?php
+
+function suspend_fiber(int $level): void
+{
+    if ($level >= 10) {
+        $value = \Fiber::suspend($level);
+        failing_function($value);
+    }
+
+    suspend_fiber($level + 1);
+}
+
+function failing_function(string $value): never
+{
+    throw_exception();
+}
+
+function throw_exception(): never
+{
+    throw new Exception;
+}
+
+$fiber = new Fiber(function (): void {
+    suspend_fiber(0);
+});
+
+$fiber->start();
+
+$fiber->resume('test');
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Exception in %sbacktrace-deep-nesting.php:%d
+Stack trace:
+#0 %sbacktrace-deep-nesting.php(%d): throw_exception()
+#1 %sbacktrace-deep-nesting.php(%d): failing_function('test')
+#2 %sbacktrace-deep-nesting.php(%d): suspend_fiber(10)
+#3 %sbacktrace-deep-nesting.php(%d): suspend_fiber(9)
+#4 %sbacktrace-deep-nesting.php(%d): suspend_fiber(8)
+#5 %sbacktrace-deep-nesting.php(%d): suspend_fiber(7)
+#6 %sbacktrace-deep-nesting.php(%d): suspend_fiber(6)
+#7 %sbacktrace-deep-nesting.php(%d): suspend_fiber(5)
+#8 %sbacktrace-deep-nesting.php(%d): suspend_fiber(4)
+#9 %sbacktrace-deep-nesting.php(%d): suspend_fiber(3)
+#10 %sbacktrace-deep-nesting.php(%d): suspend_fiber(2)
+#11 %sbacktrace-deep-nesting.php(%d): suspend_fiber(1)
+#12 %sbacktrace-deep-nesting.php(%d): suspend_fiber(0)
+#13 [internal function]: {closure}()
+#14 %sbacktrace-deep-nesting.php(%d): Fiber->resume('test')
+#15 {main}
+  thrown in %sbacktrace-deep-nesting.php on line %d

Zend/tests/fibers/backtrace-nested.phpt

@@ -0,0 +1,28 @@
+--TEST--
+Backtrace in nested function call
+--FILE--
+<?php
+
+function suspend_fiber(): void
+{
+    \Fiber::suspend();
+    throw new Exception;
+}
+
+$fiber = new Fiber(function (): void {
+    suspend_fiber();
+});
+
+$fiber->start();
+
+$fiber->resume();
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Exception in %sbacktrace-nested.php:%d
+Stack trace:
+#0 %sbacktrace-nested.php(%d): suspend_fiber()
+#1 [internal function]: {closure}()
+#2 %sbacktrace-nested.php(%d): Fiber->resume()
+#3 {main}
+  thrown in %sbacktrace-nested.php on line %d

Zend/tests/fibers/backtrace-object.phpt

@@ -0,0 +1,28 @@
+--TEST--
+Backtrace in with object as fiber callback
+--FILE--
+<?php
+
+class Test
+{
+    public function __invoke(string $arg): void
+    {
+        Fiber::suspend();
+        throw new Exception($arg);
+    }
+}
+
+$fiber = new Fiber(new Test);
+
+$fiber->start('test');
+
+$fiber->resume();
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Exception: test in %sbacktrace-object.php:%d
+Stack trace:
+#0 [internal function]: Test->__invoke('test')
+#1 %sbacktrace-object.php(%d): Fiber->resume()
+#2 {main}
+  thrown in %sbacktrace-object.php on line %d

Zend/tests/fibers/debug-backtrace.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Print backtrace in fiber
+--FILE--
+<?php
+
+function inner_function(): void
+{
+    debug_print_backtrace();
+}
+
+$fiber = new Fiber(function (): void {
+    inner_function();
+});
+
+$fiber->start();
+
+?>
+--EXPECTF--
+#0  inner_function() called at [%sdebug-backtrace.php:9]
+#1  {closure}()
+#2  Fiber->start() called at [%sdebug-backtrace.php:12]

Zend/tests/fibers/failing-fiber.phpt

@@ -20,5 +20,6 @@ string(4) "test"
 Fatal error: Uncaught Exception: test in %sfailing-fiber.php:%d
 Stack trace:
 #0 [internal function]: {closure}()
-#1 {main}
+#1 %sfailing-fiber.php(%d): Fiber->resume('test')
+#2 {main}
   thrown in %sfailing-fiber.php on line %d

Zend/tests/fibers/failing-nested-fiber.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Test throwing from fiber
+--FILE--
+<?php
+
+$fiber = new Fiber(function (): void {
+    $fiber = new Fiber(function (int $x, int $y): void {
+        Fiber::suspend($x + $y);
+        throw new Exception('test');
+    });
+
+    $value = $fiber->start(1, 2);
+    var_dump($value);
+    $fiber->resume($value);
+});
+
+$fiber->start();
+
+?>
+--EXPECTF--
+int(3)
+
+Fatal error: Uncaught Exception: test in %sfailing-nested-fiber.php:6
+Stack trace:
+#0 [internal function]: {closure}(1, 2)
+#1 %sfailing-nested-fiber.php(%d): Fiber->resume(3)
+#2 [internal function]: {closure}()
+#3 %sfailing-nested-fiber.php(%d): Fiber->start()
+#4 {main}
+  thrown in %sfailing-nested-fiber.php on line %d

Zend/tests/fibers/fiber-throw-in-destruct.phpt

@@ -23,5 +23,7 @@ int(1)
 Fatal error: Uncaught Exception: test in %sfiber-throw-in-destruct.php:%d
 Stack trace:
 #0 [internal function]: class@anonymous::{closure}()
-#1 {main}
+#1 %sfiber-throw-in-destruct.php(%d): Fiber->resume()
+#2 [internal function]: class@anonymous->__destruct()
+#3 {main}
   thrown in %sfiber-throw-in-destruct.php on line %d

Zend/tests/fibers/resume-running-fiber.phpt

@@ -16,5 +16,6 @@ Fatal error: Uncaught FiberError: Cannot resume a fiber that is not suspended in
 Stack trace:
 #0 %sresume-running-fiber.php(%d): Fiber->resume()
 #1 [internal function]: {closure}()
-#2 {main}
+#2 %sresume-running-fiber.php(%d): Fiber->start()
+#3 {main}
   thrown in %sresume-running-fiber.php on line %d

Zend/tests/fibers/start-arguments.phpt

@@ -24,5 +24,6 @@ int(1)
 Fatal error: Uncaught TypeError: {closure}(): Argument #1 ($x) must be of type int, string given in %sstart-arguments.php:%d
 Stack trace:
 #0 [internal function]: {closure}('test')
-#1 {main}
+#1 %sstart-arguments.php(%d): Fiber->start('test')
+#2 {main}
   thrown in %sstart-arguments.php on line %d

Zend/zend_fibers.c

@@ -44,6 +44,8 @@ static zend_class_entry *zend_ce_fiber_error;
 
 static zend_object_handlers zend_fiber_handlers;
 
+static zend_function zend_fiber_function = { ZEND_INTERNAL_FUNCTION };
+
 typedef void *fcontext_t;
 
 typedef struct _transfer_t {
@@ -331,9 +333,13 @@ static void ZEND_STACK_ALIGNED zend_fiber_execute(zend_fiber_context *context)
 	EG(vm_stack_page_size) = ZEND_FIBER_VM_STACK_SIZE;
 
 	fiber->execute_data = (zend_execute_data *) stack->top;
+	fiber->stack_bottom = fiber->execute_data;
 
 	memset(fiber->execute_data, 0, sizeof(zend_execute_data));
 
+	fiber->execute_data->func = &zend_fiber_function;
+	fiber->stack_bottom->prev_execute_data = EG(current_execute_data);
+
 	EG(current_execute_data) = fiber->execute_data;
 	EG(jit_trace_num) = 0;
 	EG(error_reporting) = error_reporting;
@@ -360,6 +366,7 @@ static void ZEND_STACK_ALIGNED zend_fiber_execute(zend_fiber_context *context)
 
 	zend_vm_stack_destroy();
 	fiber->execute_data = NULL;
+	fiber->stack_bottom = NULL;
 }
 
 static zend_object *zend_fiber_object_create(zend_class_entry *ce)
@@ -494,6 +501,7 @@ ZEND_METHOD(Fiber, suspend)
 
 	fiber->execute_data = execute_data;
 	fiber->status = ZEND_FIBER_STATUS_SUSPENDED;
+	fiber->stack_bottom->prev_execute_data = NULL;
 
 	zend_fiber_suspend(fiber);
 
@@ -547,6 +555,7 @@ ZEND_METHOD(Fiber, resume)
 	}
 
 	fiber->status = ZEND_FIBER_STATUS_RUNNING;
+	fiber->stack_bottom->prev_execute_data = execute_data;
 
 	zend_fiber_switch_to(fiber);
 
@@ -578,6 +587,7 @@ ZEND_METHOD(Fiber, throw)
 	fiber->exception = exception;
 
 	fiber->status = ZEND_FIBER_STATUS_RUNNING;
+	fiber->stack_bottom->prev_execute_data = execute_data;
 
 	zend_fiber_switch_to(fiber);
 

Zend/zend_fibers.h

@@ -67,6 +67,9 @@ typedef struct _zend_fiber {
 	/* Current Zend VM execute data being run by the fiber. */
 	zend_execute_data *execute_data;
 
+	/* Frame on the bottom of the fiber vm stack. */
+	zend_execute_data *stack_bottom;
+
 	/* Exception to be thrown from Fiber::suspend(). */
 	zval *exception;
 

ext/reflection/php_reflection.c

@@ -6790,6 +6790,7 @@ ZEND_METHOD(ReflectionFiber, getTrace)
 {
 	zend_fiber *fiber = (zend_fiber *) Z_OBJ(Z_REFLECTION_P(ZEND_THIS)->obj);
 	zend_long options = DEBUG_BACKTRACE_PROVIDE_OBJECT;
+	zend_execute_data *prev_execute_data;
 
 	ZEND_PARSE_PARAMETERS_START(0, 1)
 		Z_PARAM_OPTIONAL
@@ -6798,6 +6799,9 @@ ZEND_METHOD(ReflectionFiber, getTrace)
 
 	REFLECTION_CHECK_VALID_FIBER(fiber);
 
+	prev_execute_data = fiber->stack_bottom->prev_execute_data;
+	fiber->stack_bottom->prev_execute_data = NULL;
+
 	if (EG(current_fiber) != fiber) {
 		// No need to replace current execute data if within the current fiber.
 		EG(current_execute_data) = fiber->execute_data;
@@ -6806,6 +6810,7 @@ ZEND_METHOD(ReflectionFiber, getTrace)
 	zend_fetch_debug_backtrace(return_value, 0, options, 0);
 
 	EG(current_execute_data) = execute_data; // Restore original execute data.
+	fiber->stack_bottom->prev_execute_data = prev_execute_data; // Restore prev execute data on fiber stack.
 }
 
 ZEND_METHOD(ReflectionFiber, getExecutingLine)

ext/reflection/tests/ReflectionFiber_backtrace.phpt

@@ -0,0 +1,74 @@
+--TEST--
+ReflectionFiber backtrace test
+--FILE--
+<?php
+
+function suspend_fiber(): void {
+    Fiber::suspend();
+}
+
+class Test
+{
+    public function __invoke(string $arg): void
+    {
+        suspend_fiber();
+    }
+}
+
+$fiber = new Fiber(new Test);
+
+$fiber->start('test');
+
+$reflection = new ReflectionFiber($fiber);
+
+var_dump($reflection->getTrace(DEBUG_BACKTRACE_PROVIDE_OBJECT));
+
+?>
+--EXPECTF--
+array(3) {
+  [0]=>
+  array(6) {
+    ["file"]=>
+    string(%d) "%sReflectionFiber_backtrace.php"
+    ["line"]=>
+    int(4)
+    ["function"]=>
+    string(7) "suspend"
+    ["class"]=>
+    string(5) "Fiber"
+    ["type"]=>
+    string(2) "::"
+    ["args"]=>
+    array(0) {
+    }
+  }
+  [1]=>
+  array(4) {
+    ["file"]=>
+    string(%d) "%sReflectionFiber_backtrace.php"
+    ["line"]=>
+    int(11)
+    ["function"]=>
+    string(13) "suspend_fiber"
+    ["args"]=>
+    array(0) {
+    }
+  }
+  [2]=>
+  array(5) {
+    ["function"]=>
+    string(8) "__invoke"
+    ["class"]=>
+    string(4) "Test"
+    ["object"]=>
+    object(Test)#2 (0) {
+    }
+    ["type"]=>
+    string(2) "->"
+    ["args"]=>
+    array(1) {
+      [0]=>
+      string(4) "test"
+    }
+  }
+}