CPP: fix static objects init for MWDT toolchain

The constructors of static objects are stored in ".ctors"
section. In case of MWDT toolchain we have incompatible
".ctors" section format with GNU toolchain. So let's use
initialization code provided by MWDT instead of Zephyr one
in case of MWDT toolchain usage.

As it is done for GNU toolchain We call constructors of
static objects but we don't call destructors for them.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>

cmake/linker/arcmwdt/target.cmake

@@ -112,7 +112,6 @@ macro(toolchain_ld_baremetal)
   zephyr_ld_options(
     -Hlld
     -Hnosdata
-    -Hnocrt
     -Xtimer0 # to suppress the warning message
     -Hnoxcheck_obj
     -Hnocplus
@@ -120,6 +119,11 @@ macro(toolchain_ld_baremetal)
     -Hnoivt
   )
 
+  # We only use CPP initialization code from crt
+  if(NOT CONFIG_CPLUSPLUS)
+    zephyr_ld_options(-Hnocrt)
+  endif()
+
   # Funny thing is if this is set to =error, some architectures will
   # skip this flag even though the compiler flag check passes
   # (e.g. ARC and Xtensa). So warning should be the default for now.

include/arch/arc/v2/linker.ld

@@ -94,6 +94,13 @@ SECTIONS {
 #include <linker/kobject-text.ld>
 	} GROUP_LINK_IN(ROMABLE_REGION)
 
+#if defined(CONFIG_CPLUSPLUS) && !defined(CONFIG_CPP_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
+	/* .init section with code iterating over static objects constructors */
+	SECTION_PROLOGUE(.init,,ALIGN(4)) {
+		KEEP(*(.init*))
+	} GROUP_LINK_IN(ROMABLE_REGION)
+#endif /* CONFIG_CPLUSPLUS && !CONFIG_CPP_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
+
 	_image_text_end = .;
 	_image_rodata_start = .;
 
@@ -111,6 +118,13 @@ SECTIONS {
 #include <snippets-rodata.ld>
 
 #include <linker/kobject-rom.ld>
+
+#if defined(CONFIG_CPLUSPLUS) && !defined(CONFIG_CPP_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
+		. = ALIGN(4);
+		_fctors = .;
+		KEEP(*(.ctors*))
+		_ectors = .;
+#endif /* CONFIG_CPLUSPLUS && !CONFIG_CPP_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
 	} GROUP_LINK_IN(ROMABLE_REGION)
 
 #ifdef __MWDT_LINKER_CMD__
@@ -225,6 +239,11 @@ SECTIONS {
 	}
 
 	/DISCARD/ : {
+#if defined(CONFIG_CPLUSPLUS) && !defined(CONFIG_CPP_STATIC_INIT_GNU) && defined(__MWDT_LINKER_CMD__)
+		*(.dtors*)
+		*(.fini*)
+		*(.eh_frame*)
+#endif /* CONFIG_CPLUSPLUS && !CONFIG_CPP_STATIC_INIT_GNU && __MWDT_LINKER_CMD__ */
 		*(.note.GNU-stack)
 		*(.got.plt)
 		*(.igot.plt)

include/linker/common-rom.ld

@@ -52,7 +52,7 @@
 	}
 	ASSERT(SIZEOF(initlevel_error) == 0, "Undefined initialization levels used.")
 
-#ifdef CONFIG_CPLUSPLUS
+#ifdef CONFIG_CPP_STATIC_INIT_GNU
 	SECTION_PROLOGUE(_CTOR_SECTION_NAME,,)
 	{
 		/*

kernel/init.c

@@ -198,11 +198,8 @@ static void bg_thread_main(void *unused1, void *unused2, void *unused3)
 	boot_banner();
 
 #if defined(CONFIG_CPLUSPLUS) && !defined(CONFIG_ARCH_POSIX)
-	/* Process the .ctors and .init_array sections */
-	extern void __do_global_ctors_aux(void);
-	extern void __do_init_array_aux(void);
-	__do_global_ctors_aux();
-	__do_init_array_aux();
+	void z_cpp_init_static(void);
+	z_cpp_init_static();
 #endif
 
 	/* Final init level before app starts */

subsys/cpp/CMakeLists.txt

@@ -1,6 +1,8 @@
 # SPDX-License-Identifier: Apache-2.0
 
-zephyr_sources(
+zephyr_sources(cpp_init.c)
+
+zephyr_sources_ifdef(CONFIG_CPP_STATIC_INIT_GNU
   cpp_init_array.c
   cpp_ctors.c
   cpp_dtors.c

subsys/cpp/Kconfig

@@ -75,4 +75,12 @@ config RTTI
 
 endif # LIB_CPLUSPLUS
 
+config CPP_STATIC_INIT_GNU
+	# As of today only ARC MWDT toolchain doesn't support GNU-compatible
+	# initialization of CPP static objects, new toolchains can be added
+	# here if required.
+	def_bool "$(ZEPHYR_TOOLCHAIN_VARIANT)" != "arcmwdt"
+	help
+	  GNU-compatible initialization of CPP static objects
+
 endif # CPLUSPLUS

subsys/cpp/cpp_init.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2021 Synopsys, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Author: Evgeniy Paltsev
+ */
+
+#ifdef CONFIG_CPP_STATIC_INIT_GNU
+
+void __do_global_ctors_aux(void);
+void __do_init_array_aux(void);
+
+void z_cpp_init_static(void)
+{
+	__do_global_ctors_aux();
+	__do_init_array_aux();
+}
+
+#else
+
+#ifdef __CCAC__
+void _init(void);
+
+void z_cpp_init_static(void)
+{
+	_init();
+}
+#endif /* __CCAC__ */
+
+#endif /* CONFIG_CPP_STATIC_INIT_GNU */