[c++] Support fibers in static initialization guard

Author: salkinium

ext/gcc/cxxabi.cpp.in

@@ -27,6 +27,9 @@ void __cxa_deleted_virtual()
 
 %% if with_threadsafe_statics
 #include <atomic>
+%% if with_fibers
+#include <modm/processing/fiber.hpp>
+%% endif
 %% if is_avr
 %#
 // Even thought the actual guard size is uint64_t on AVR, we only need to access
@@ -71,6 +74,10 @@ __cxa_guard_acquire(guard_type *guard)
 			// We got called from inside an interrupt, but we cannot yield back
 			modm_assert(not is_in_irq, "stat.rec",
 					"Recursive initialization of a function static!", guard);
+%% if with_fibers
+			// we're not in an interrupt, try to yield back to the initializing fiber
+			modm::this_fiber::yield();
+%% endif
 		}
 		value = UNINITIALIZED;
 	}

ext/gcc/module_c++.lb

@@ -92,6 +92,7 @@ def build(env):
         "with_threadsafe_statics": with_threadsafe_statics,
         "with_memory_traits": env.has_module(":architecture:memory"),
         "with_heap": env.has_module(":platform:heap"),
+        "with_fibers": env.has_module(":processing:fiber"),
         "is_avr": is_avr,
         "is_cortex_m": is_cortex_m,
     }

test/modm/ext/cxa_guard_test.cpp

@@ -16,10 +16,10 @@
 extern "C"
 {
 
-#ifdef MODM_CPU_ARM
-using guard_t = uint32_t;
+#ifdef MODM_CPU_CORTEX_M
+using guard_t = int32_t;
 #else
-using guard_t = uint64_t;
+using guard_t = int64_t;
 #endif
 
 int __cxa_guard_acquire(guard_t*);

test/modm/processing/fiber/fiber_guard_test.cpp

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2023, Niklas Hauser
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#include "fiber_guard_test.hpp"
+#include "shared.hpp"
+#include <modm/architecture/detect.hpp>
+
+extern "C"
+{
+
+#ifdef MODM_CPU_CORTEX_M
+using guard_t = int32_t;
+#else
+using guard_t = int64_t;
+#endif
+
+int __cxa_guard_acquire(guard_t*);
+void __cxa_guard_release(guard_t*);
+void __cxa_guard_abort(guard_t*);
+
+static guard_t guard{0};
+
+}
+
+void
+FiberGuardTest::setUp()
+{
+	state = 0;
+}
+
+// ================================== GUARD ===================================
+static void
+f1()
+{
+	TEST_ASSERT_EQUALS(state++, 0u);
+	TEST_ASSERT_EQUALS(guard, guard_t(0));
+
+	TEST_ASSERT_EQUALS(__cxa_guard_acquire(&guard), 1);
+	TEST_ASSERT_EQUALS(guard, guard_t(0x10));
+	// now while initializing yield to another fiber
+	modm::this_fiber::yield(); // goto 1
+
+	TEST_ASSERT_EQUALS(state++, 2u);
+	__cxa_guard_release(&guard);
+	TEST_ASSERT_EQUALS(guard, guard_t(1));
+}
+
+static void
+f2()
+{
+	TEST_ASSERT_EQUALS(state++, 1u);
+	TEST_ASSERT_EQUALS(guard, guard_t(0x10));
+	TEST_ASSERT_EQUALS(__cxa_guard_acquire(&guard), 0); // goto 2
+
+	TEST_ASSERT_EQUALS(state++, 3u);
+	TEST_ASSERT_EQUALS(guard, guard_t(1));
+}
+
+
+void
+FiberGuardTest::testGuard()
+{
+#ifndef MODM_OS_HOSTED
+	modm::fiber::Task fiber1(stack1, f1), fiber2(stack2, f2);
+	modm::fiber::Scheduler::run();
+#endif
+}
+
+// =============================== CONSTRUCTOR ================================
+static uint8_t constructor_calls{0};
+struct StaticClass
+{
+	uint8_t counter{0};
+	StaticClass()
+	{
+		constructor_calls++;
+	}
+
+	void increment()
+	{
+		counter++;
+	}
+};
+
+static StaticClass& instance()
+{
+	static StaticClass obj;
+	return obj;
+}
+
+void
+FiberGuardTest::testConstructor()
+{
+	TEST_ASSERT_EQUALS(constructor_calls, 0);
+
+	instance().increment();
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+	TEST_ASSERT_EQUALS(instance().counter, 1);
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+
+	instance().increment();
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+	TEST_ASSERT_EQUALS(instance().counter, 2);
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+
+	instance().increment();
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+	TEST_ASSERT_EQUALS(instance().counter, 3);
+	TEST_ASSERT_EQUALS(constructor_calls, 1);
+}

test/modm/processing/fiber/fiber_guard_test.hpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2020, Erik Henriksson
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#pragma once
+
+#include <unittest/testsuite.hpp>
+
+/// @ingroup modm_test_test_architecture
+class FiberGuardTest : public unittest::TestSuite
+{
+public:
+	void
+	setUp();
+
+	void
+	testGuard();
+
+	void
+	testConstructor();
+};